Hi everyone and welcome to this Science Exchange series from the University of Western Australia. My name is Sam Elingworth, I'm a Senior Lecturer in Science Communication here at UWA and the Science Exchange series has been put together as a way to bring the amazing research that's done in the Faculty of Science out to other people and to other communities so that people can understand and realise the important work and the impact that we're having on society as well. So today I'd like to introduce our speaker who is Dr Michelle Olath, who is a post-doctoral research fellow in the School of Psychological Science at UWA. Michelle researches health at the intersection of sleep and psychology, investigating how poor sleep impacts brain and mood health and function and creating interventions to help people attain better sleep for better health. She recently returned from Wisconsin where she was invited to work on the oldest and most influential sleep database and currently works with the Health Promotion Unit at UWA, co-creating a brief sleep intervention for university students. So please Michelle take it away. Hi everyone, thanks for joining us today and thanks Sam for that introduction, that was lovely. So we're just going to get on into it.   And so the thoughts go and go. And while many of us can relate to this kind of a feeling or these kinds of thoughts from time to time, it's up to about 40% of the population that have these problems chronically and may actually end up with a diagnosis of a sleep disorder. So before I continue this, I'd just like to acknowledge that I'm presenting from Wajak Nungar land and I'd like to acknowledge the strength and resilience of the Nungar elders. Today we're going to talk a little bit about what sleep is, why you do it, what healthy sleep is, why sleep is important and then I'm going to talk to you a little bit about the research that I'm doing with the health promotion team and the school of psychological science in university students. And then we're going to end with some tips that you can take home to improve your sleep. Sleep is actually a behaviour and it's a reversible state of reduced awareness and selective responsiveness to your environment and in people this kind of looks like laying down, closing your eyes and moving very little but in different species this actually looks, it can look quite different. So for most people we have one consolidated period of sleep but depending on your culture you may actually have two or more periods of sleep and for people with little babies this might look like lots of little blocks of sleep for those babies. So sleep is a behaviour, it's impacted by culture, it's impacted by environment and it's impacted by the kinds of things you have going on in your day. In this picture here what you're looking at is a sort of a hypnogram we call it and what this shows is that sleep is at one solid state, sleep is actually many different states where you sort of you will go down into light sleep and then your sleep will get deeper and you'll get less responsive as you go down into deep sleep and during the night it's completely normal for you to wake up lots of little times during the night. In fact often these periods of wake are things that you won't even notice but some might you might notice and if you wake up and you notice about three to four periods of time awake during the night this is completely normal and expected. Those sleep, sort of sleep types of sleep, deep sleep, light sleep and dreaming sleep are thought to actually contribute to different components of your health. Light sleep is thought to be really important for good mood and for memory and learning and deep sleep is very important for you for recovery from physical exercise. There was some really cool research going on down at the Centre for Sleep Science a couple of years ago where look I wouldn't be putting my hand up for it but they were dipping athletes into ice baths after they were doing intense exercise and they were showing that these guys were dipping down into deep sleep quicker and getting a longer period of deep sleep and that was translating to better sports recovery. Now I just want to put up a poll if that's okay Sam just wait for your responses. Okay so what you can see here the point of this poll is to show you that sleep isn't just impacted by your environment and sleep isn't just this sort of this universal state that everyone experiences. Sleep is quite individual and when we're trying to give sleep advice some of the things that we might say to people are cut down on caffeine use because caffeine can impact your sleep but for some people that's just not true and you need to actually look at how individual factors impact your sleep. So we try to give these sorts of recommendations but what really need to be doing is using a sleep diary to track what individual factors affect your sleep. Okay all right thanks very much for that. Okay so let's move into I think we've kind of got a bit of an idea of sleep what is it. All right now sleep why do you do it? So sleep serves a vital function it's actually something that you can't live without you can survive for about 21 days without food but you can only survive for about 14 days without sleep. Sleep serves a very important biological function so after about four days without sleep you'll actually start to hallucinate. You'll start to not be able to tell what's real and what isn't real. There's some amazing studies done back in the 60s I think they were where they had a volunteer deprive himself of sleep for three to four days and after three to four days he was still able to his motor functions was still really good he could still play ping pong and get amazing scores but he actually thought he was a famous footballer which he wasn't okay. So and then after about 10 days you start to organ start to break down it's not a pretty process. So sleep serves a very important biological process and as such your body is going to force you to sleep and what you can see on screen here is that on the vertical axis as you go up along vertical axis that's an increase in your want to sleep so your sleep drive and as you go along the horizontal axis that's time over about two days. Now we think of your sleep drive or your your sort of your biological pressure to sleep as having two separate drives so we think of it as having a sort of a C drive which is your biological pressure to sleep. We call it a sleep drive because that stands for circadian or clocks. Now every single cell inside your body has a clock inside it and it tells you when to sleep.  So every day I think most people will be able to recognize this around two or three o'clock in the afternoon most people start to feel a little bit sleepy and then also around two three o'clock early in the morning as well that's when you'll probably get some of your deepest sleep because that's when our sort of our circadian drive is at its strongest. There is also a H drive and this is the drive sort of the homeostatic drive that's why it's called the H drive and this is the physiological pressure that builds up over the course of the day and that's why you can see two arrows here because it's over the course of two days of the sort of these metabolites that you build up throughout the day and one of those is adenosine and adenosine is actually blocked by caffeine and that's why caffeine or it competes for binding with caffeine and that's why caffeine is one of those chemicals you can have that gives you this oh sort of feeling of more awakeness because it's stopping your adenosine from binding but all sorts of tablates build up throughout the day and that also adds to your sleep pressure so that you want your body wants you to sleep healthy sleep now healthy sleep for most young adults or adults is around seven to nine hours but allowing for individual variability anything from about six to ten hours is considered a healthy amount of sleep healthy sleep is is not just quantity though it's also quality so and the quality is a little bit hard to gauge unless you have EEG on because when we're looking for quality of sleep we're looking for nice big fat waveforms as they go and to show that your brain's getting into a nice deep sleep we're looking for a big consolidated period of sleep where there's not too many awakenings but for you guys at home quality of sleep basically is if you can wake up the next day and after about a half hour or so period of sleep inertia you can feel awake and you can feel like you can get the things done that you need to get done then we'd say you probably have good quality sleep another way that you can gauge your quality of sleep so quantity is a component to healthy sleep as quality as is quality and another way that you can gauge your healthy sleep is to calculate your sleep efficiency and basically this is a kind of a way of saying are you getting and the amount of time you're spending bent is enough of it or a good chunk of it spent asleep and basically what you do is you take the total time that you think you slept you put that in the first box you take you divide that by the total time that you actually spent in bed so that's lights out to lights on times it by 100 and you get your percentage sleep efficiency if it's over about 80 85 percent it's 85 percent or above then we would say you have good sleep efficiency so saying that your sleep drive got high enough you didn't spend too much time in bed and it's a pretty good gauge of how good of quality you're getting why is sleep important and now we're getting to the title of my talk sleep one of the fundamental reasons that sleep is important is because it cleans your brain now the there is a system in your brain called the glimphatic system and it's a bit synonymous to the limb fatigue system and that's why it's ended up with the name glimphatic system so we all know that our limb fatigue system is an important part to washing bacteria or pathogens that might get in because it's an important part of our immune system your brain doesn't have an immune system in it so it doesn't have a way of washing these metabolites that it builds up because it's been working very hard throughout the day in the system that they found only a few years ago is actually the glimphatic system and it only really operates maximally when you're asleep so when you're asleep there are all these perivascular systems inside your brain that open up about 60 percent more and all of the cells in your brain actually reduce in size and when that opens up to that 60 percent more that's when it can wash out all of those metabolites like adenosine and it can replenish all of those those sort of those energies that you need to be able to feel brain to be able to work properly there's a lovely quote that says that you can think of it like having a house party you can either entertain the guests might have fun and do lots of thinking or you can clean up the house but you can't really do both at the same time so when you sleep you clean house this sleep or this cleaning your house seems to be imperative to physical health performance and also mood health if you aren't getting enough sleep your mood will be more labile people with sleep disorders often have more relationship problems they can't perform to their best and their immune system actually doesn't work as well as it could as well so I'm going to share with you a little bit about the sleep research that we're doing with university students so I've been working on a project which is a collaboration between the school of psych and the health promotion team and this has been funded by the local drug action group and in university students they appear to be quite vulnerable to sleep disorders especially a disorder called insomnia and also to circadian rhythm disorders insomnia is where you have trouble trying to get to sleep staying asleep or you don't have good quality sleep and this happens despite having the right environment for good sleep as well and circadian rhythm disorders are a desynchronization between your internal sleep weight rhythms and the light darkness cycle so anyone with teenagers or if you are a teenager you'll kind of recognize this as being wanting to be awake later into the evening then would be good for your university schedule which might start around nine o'clock in the morning or eight o'clock if you've decided to sign up for some of those early tuition sessions over on the east coast this is part of the reason that some schools have decided to start putting high school hours later on in the day start times around 10 or 11 in the morning so the sleep problems in university students impact on their grades their mental health and also increase the use of stimulants and alcohol and there are a few programs out there that use CBTI which is a cognitive behavioral therapy for insomnia and they also use mindfulness and they're showing a really good impact on student health and demonstrating more effectiveness than medications however these don't seem to they seem to target disorders rather than poor sub or sort of poor sleep or suboptimal sleep and these interventions have been taken from adults and then manipulated to sort of suit young adults there's also they're also quite long so on average they they have at least four sessions of about 45 minute interventions and there tends to be quite a high dropout rate and also these interventions are peer led too so they seem to be a little bit problematic because university students don't tend to actively seek help so the intervention that we are using we're calling good night poor sleep and this is GPS or navigating your sleep and what we want to use this is to try and address the gaps in the literature that are there for university students when we go and do a bit of a literature review we find that the things that are on the screen at the moment are the things that are problematic for sleep for university students so using digital devices late at night the type of day so they tend to sleep more on weekends than on workdays poor sleep hygiene or poor sleep knowledge these kinds of things when we talk to the university students these are the things that they said that they endorsed were the most problematic for them so we were running focus groups earlier on in the year to try and find out what kinds of things they were endorsing and saying were problematic so what we want to do what we're doing now is we collect a lot of this data and we're going to start going out to colleges and running some interventions now to be able to address these factors and stay tuned later on in the year hopefully we'll have more information about that okay so I said to you as well that I would give you some information on what you could do to improve your sleep when you're at home so first and foremost make sure that you don't have an underlying sleep problem so if you are concerned about your sleep always reach out to your GP and have a chat to them however if you want to make some simple changes at home the thing that you kind of want to look up is sleep hygiene and basically sleep hygiene is in tune with the talk it's about cleaning up your sleep and your sleep habits to make sure that you have a really strong behavioral association between your bed and sleep so during the day one of the things that you can do is you can have a wind down routine so so when I'm talking about this with people I like to say one of the things that you think of is what would you do to put a small child to bed you would make sure they have a really solid routine they'd go bed at the same time and they'd wake up at the same time and the research tells us that those having a really good consistent routine around your sleep particularly the same work wake up time is really important because that allows your brain and your body to understand what time to release the melatonin to make you go to sleep and the cortisol to make you wake up in the morning and that's one of the most important things you can do to make sure that you have a good quality sleep period if you like your naps and it doesn't really work in with your work schedule kudos to you if you can fit a nap in with your work schedule you want to limit your naps to about 20 to 30 minutes and the reason you want to do that is because that will mean that it won't impact your nighttime sleep because 20 to 30 minutes doesn't allow you get down to that deep sleep and it won't really stop you having a high sleep drive later on in the evening another thing you can do is make sure that you have an outlet for stress early on in the evening so talk to a friend organize your or early on in the day sorry not in the evening or talk to a friend organize your to-do list to write in a journal and get some exercise stop if you one of those what was it 27% so they could drink coffee if you're one of the other people then make sure you stop drinking coffee about eight hours before your bedtime because that's about how long it takes for the caffeine to get out of your system try not to eat a heavy meal with foods that might irritate your digestive system too close to bedtime and this might include the different things for different people people talk to me about cheese and onions and but chili things that irritate your digestive system are definitely things that are problematic keep your fluid intake down and this includes alcohol or water so less than four glasses of water over the afternoon and that's so that you don't wake up during the night needing to go to the bathroom if you're thirsty you probably want to be able to increase your your fluid intake earlier on during the day so make sure you reserve your bed for sleep and for sex and this is important because if you're watching screens in bed it makes bed a really exciting place to be and you don't want to do that screens are really bad for many reasons and if there are any parents with teenagers watching this talk they'll be giving me a good hurrah yay this one because screens a screen time one a lot of the things that we do on our screens answering emails or going on social media is interesting or it's stressful so that can be a bad thing because it's raising that kind of emotional and cognitive arousal just before bed but the light itself that comes out of a lot of our digital devices is blue light and that blue light goes into your suprachiasmatic nucleus that one we were talking about earlier and it actually makes your body think that it's daytime so it can push your your nighttime sleep further away into the evening and that's not necessarily great you can get some pink filters that you can put on your computer if you want to use your devices but i'd say go back to good old-fashioned books have a really nice sleep space make it cozy make it comfortable have it to around 19 to 20 degrees celsius and in when you're in bed it's okay to have about 10 to 20 minutes to need to fall asleep if you're falling asleep in less than five minutes it would suggest that you're actually sleep deprived get some sunlight on you in the morning because that helps you reset your body clock and during the day make sure you do things like that will battle fatigue so get up from your desk move around do some exercise get out the sun drink plenty of water have good nutrition because sometimes feeling sleepy during the day isn't anything to do with the nighttime sleep that's to do with your daytime fatigue as well okay so we've talked a little bit about sleep hygiene so those are some nice tips that you can take home and i think i think that's the end from me sam so i can go to questions if we want to that's great thank you michelle that was absolutely fascinating and i've picked up loads of tips myself i'm actually one of those people who can have a coffee like up to five minutes before they go to sleep which is quite nice and i've got loads of questions myself but i'm gonna go to the participants first so just reminding people to drop questions into the q&a box so a question here hi michelle it's a really nice talk and thanks for sharing in the afternoon around two to three p.m i normally feel tired and want to sleep please could you give me advice to reduce tiredness at this time okay so first of all that's a really normal time for you to feel a bit sleepy because your um sleep pressure your sleep drives are starting to build up during that time so there's nothing abnormal going on look there's lots of different things that you could do i would say book up to do some exercise go for a walk go outside get some fresh air uh you could have a 20 to 30 minute nap if you really wanted to get up even just stretching simple stretching or planning to have a talk with a friend at that point in time those kinds of things you can battle your sleep drive with things that you find exciting or stimulating that's great thank you a question here from um brenton lesk who asks what are your thoughts on blue light blocking glasses are they just a sales gimmick oh no they're actually yeah they really work so um blue light blocking glasses do work i've got there's a fair bit of research on them they do do things you can also get the opposite side of things where you can get um the glasses and allow more blue light here that's so strange there's some really cool applications that you can get that will help you manage jet lag and i was in wisconsin for a conference with romela one of the two uh the the uh one of my coat one of my researchers that i work with a lot um old head of school for school psychology um and she had this lovely app and what this app did is it divided her day up into when she should wear blue light blocking glasses when she should have a coffee when she should have a nap and those processors were helping her adjust her jet lag so that when she got back into australia her sleep was and adjusted a little bit and was easier for her to get back in so rubbing your feet on the carpet and whatever other tricks they used to have don't work blue light glasses oh that's great so this is a question from kylie and i'll just add my own bit to the end so it says how long do you need to put your device away before wanting to go to sleep and i want to add to that does it depend on the person because i know that for example i can look at my phone up to a minute before i go to sleep whereas my partner my wife is the complete opposite it needs like an hour or so away from the screen is it depends on the person or is the general advice there so that is a you've asked me a lovely complicated question and it depends on the type of light it depends on the intensity of light because the screens all give different intensities so i would say and it depends on the individual as you've said sam your yourself and your wife are completely different so i would say the best way that you can have you could have a look at is to download one of the free to use sleep diaries and to just run some experiments with yourself try putting away your device half an hour before bed and doing something else that's relaxing and see if that helps or maybe you need to expand that time where you can shrink that time so the sleep health foundation have a sleep diary that you can download it used for free and you can track and i guess tune your fine tune how early away you need to put your device so then it works for your sleep right thank you um michelle so jane come uh karmic nanny has asked hi thank you for this i work with young children and get a lot of questions from parents on sleep or lack thereof what are your thoughts on sleep training and at what age do you think it is appropriate okay so there's there's a lot of sleep training courses out there lots of different ones um and some of them have some good research behind them and they have paired sleep training up with attachment to make sure that the child is still getting their emotional needs met and some of these courses can be really helpful there's some excellent ones coming out of canada and some of the courses unfortunately don't have a lot of research behind them so i would say there's a mixed bag out there you need to do your research behind which one you're going to use before you engage with one um and you need to probably pick one that has some some solid research behind it as well and more than anything you need to make sure you're working with the parent and the child to make sure the parent is understanding that they still need to be meeting the child's emotional needs but that they're getting their stress levels down as well because sleep is really important for the parents too to make sure they can function well during the day now absolutely absolutely um a question here from Alex Wheeler who says if you don't feel sleepy at 2 to 3 p.m. and that's actually Alex's most alert time much later in the day and struggle to wake up in the morning at all is there any hope for changing sleep patterns to become less of a night owl and maybe more from a morning person instead oh okay so you guys are all asking amazing difficult questions so that's going to depend on your chronotype so Alex it sounds like you might be an evening or a night owl chronotype and your chronotype does it does change when you feel most able to go to sleep so that will make things a little bit more difficult for you that will change as you get older often people not all the time there are some night owls often people as they get older will switch to be a more morning chronotypes or what do they call the morning larks um but you can use light therapy to make sure that you shift your sleep period so what you want to be doing is you want to be using early morning lights you want to be getting outside early in the morning to be able to bring your sleep period forward a bit more um and that that can that can tend to help you out a little bit uh so light therapy and give yourself some compassion because maybe you're one of those evening chronotypes that's great so um a question here from Geraldine who asks how does the current research account for the few folks who don't sleep a lot for example three hours and yet seem able to function normally is that true can these people function normally or is it or are they actually is that actually a misnomer um so that's a complicated question again okay so there are there's a lot of people out there so I think I think there's a lot of very famous politicians that often claim that they can sleep for about three to four hours but then I would say they're also they often make a lot of mistakes too so very public mistakes so perhaps they're not actually getting the amount of sleep that they do need if you decide that you're going to squish your sleep period down to three to four hours over time you will actually start to get less sensitive to your sleep cues so there may be a false perception that you need less sleep um however they're accounting for individual variability if you've taught your body over a certain period of time to sleep for less that sleep period does become I guess more consolidated your body does learn to compensate for it however I would say it's a bit of a still a bit of a misnomer and I'd say these people are probably just less sensitive to their sleep cues because there was a lovely big piece of research out there where they showed that people who were sleeping five hours or less their alertness was the equivalent to them having a blood alcohol level of 0.05 so they were driving dangerously but they weren't aware that they were driving dangerously wow I mean I wonder if part of that you know it's related to like the Dunning-Kroger effect as well you know this idea that people just don't understand the extent to which they are like you say massively sleep deprived so another question here um thank you for your talk for my question what is the reason as to why people have a difficult time waking up this person says that they would normally sleep for nine hours but then would always struggle waking up even after that long sleep is there any way to remedy that particular predicament right there could be lots of different reasons for that so you could be sleeping out of tune with your chronotype you could be oversleeping so sometimes if you are actually needing less sleep than that and you're oversleeping that actually increases your sensation of sleep inertia so it makes you feel sleepier for longer in the morning as well it also could mean that your quality of sleep isn't great it's a it could be lots of it could be an underlying sleep issue it could be over use of alcohol in the evening to sort of get to sleep which then disrupts sleep throughout the night because it increases your cortisol levels throughout the night or could be having a poor routine around sleep so lots of reasons I guess could lead to that one of the best things you could probably do is download that sleep diary and then have a look at a few of those things and see if changing just one decreases that sleep inertia in the morning and makes you be able to get up easier and then sort of fiddle with another one instead but also experiencing sleep inertia in the morning for about half an hour sometimes to an hour is completely normal because it's your body switching from one state of awareness to another right so there's a couple of questions just more generally asking about like how they can improve their sleep patterns and I think that's you know get this sleep diary look at look at monitoring yourself so that's really useful some slightly different questions here Georgina asks I have heard about sleep and its role in reducing dementia is this related to the cleaning function of sleep and the shrinking of the cell oh come on over and do a phd with us Georgina that is where we're at at the moment so there is correlational research to show that poor sleep early on in life is associated with the increased risk of later life dementia and for mild cognitive impairment but it's association so we don't know if it's causative but we do know they're associated okay great and then a question here from Claire who asks how good are wearable sleep trackers are they accurate at tracking your sleeping patterns and then also for me to add on to that is there a danger sometimes when we look at those sleep tracking patterns that we can then get into this you know cycle where we're like oh no I'm not getting the exact amount of sleep and they can actually negatively reinforce maybe some of those bad habits that we've got okay so the sleep trackers that we have that are out there the commercially available ones they're just as good as they've done some studies that show that they're just as good as the ones that you can buy if you're running a sleep clinic or if you're in a medical setting so equivalent however because they record and guess your sleep off an algorithm they're not as accurate as what you could get if you're measuring sleep we're using EEG so the only way we can actually know whether you are or aren't asleep and whether you're the only way we can know definitively oh gosh and that's even low that's even it's got another tangent onto it in my brain right now as well and the only way we can definitively know if you're asleep is if we have before using EEG so this is kind of measuring your brave brain wave forms the sleep trackers don't tend to do that I think they're are starting to become some commercially available ones so you need to allow about a 10 error on either side so if it said your sleep efficiency is 75% could actually mean that it's 65 all the way through up to 85 and 85 is good sleep efficiency so you need to give it there's a fair amount of error I guess you could say you can't put too much confidence in them but as they're getting a decent gauge on your sleep you could get a sort of a guesstimate on how much sleep you're getting and whether it's decent quality and then yes to answer your question Sam we can get definitely into a bit of a worry spiral or a spiral or a stress spiral over getting enough sleep and that's one of the worst things that we can do you've got to you really need to accept that you're going to have imperfect sleep and if you have enough energy during the day then that's that's really what you should be aiming for that's great thank you and question here from Samantha who says that they suffer from chronic pain and random dislocations which makes their sleep awful have you got any specific advice that they could maybe think about for addressing that so chronic pain is one of those horrible ones because as we know poor sleep then impacts pain and pain impacts sleep I would say that if you haven't gone to see your pain team then go and see them and have a talk to them about sleep and a lot of the activities that a pain management team will talk to you about like mindfulness will also help you with your sleep as well thank you Michelle so Alex has got a question here and which reverts back to this idea of what we should be using our bedrooms for what do you think about having a study desk in your bedroom should your designated work area be somewhere else ideally yes because essentially what you want to do is build a really strong association between your bed and sleep however again comes down to individual variability if you're not having any trouble sleeping and your office desk is in your room there's nothing wrong with that but I and so I know for myself one of the big naughties is that we say don't read or watch tv in bed but I could listen to podcasts and read just before I go to sleep and I have no problems with it so I would say track your sleep individually if that is if your sleep is problematic for you that would be one of the first things that I would move to take your study desk out of your room great and then just on this subject of tracking your sleep someone's asked when they look at their tracker they constantly have above average awake time and light sleep time and below average REM time is there any way that they can actively try to improve the amount of time they spend in the REM phase again allowing for the fact that there's probably some area of error in how those can trap your REM or not sure so yeah exactly there's going to be a fair amount of error for that and I'm not really aware of any sort of scientific ways that we have of increasing your REM sleep cold showers seem to increase your deep sleep probably relaxing activities beforehand are going to increase the quality of sleep beforehand so mindfulness meditation things that you might find relaxing but I'm not really sure of anything to particularly target increased REM sleep okay great and then last question now I mean just because we're running out of time we've got so many questions um thank you very much for this presentation just one question even after several days of roughly eight to nine hours of sleep I sometimes wake up exhausted and need sometimes more than one hour to get out of bed or my partner can just jump out of bed as soon as they hear the alarm they usually do not wake up at night and seem to be having quite a deep sleep does that mean that their sleep quality is low do you think um so it could mean many things again I would say use a sleep diary and track the kinds of habits that you have around your sleep and see whether there are some things that you could do some sleep hygiene things that you could do to clean up your sleep one of the things that you could do most importantly assuming that you're not already doing it is have a sleep period where you wake up at the same time every day and go to sleep at the same time every day if everyone comes away from this talk and makes one change to their sleep that's the one I would say to pick um there's some amazing research done by a man called Till Ronenberg and he looks at people who because we exist in a society where work operates from nine to five um where that's not necessarily the right sort of pattern for everyone and so we're sleeping out of our natural phase and his research takes people and it allows them to sleep according to their chronotype and they're allowed to sleep to the time of day they want to and then just go to work and everyone has a different sort of pattern and a different time they like to sleep and his research shows that if you allow people to sleep according to all of their different patterns and timings they actually have better mood better productivity um but there's a lot of variability out there so make some changes but unfortunately you might also just be sleeping out of what your body naturally wants you to do that's great thank you so much Michelle and I learned loads we had an incredible number of questions so I know our participants must have as well so thank you very much everyone for joining us today thank you for Sarah for running the back end of these talks and thank you very much Michelle for such a fascinating and enlightening topic stay safe everyone and we look forward to seeing you at the next science exchange webinar thank you and goodbye


Hello and welcome to the Rugged Rockhound. Today, I have something a little different. One of my subscribers, Keith Cunningham, thank you Keith, has done a, well we're doing a rock swap and he sent his first. So this arrived about two days ago and it's just been sitting there and I've been anxious to open it but I wanted to do an unboxing so I needed to have time to do this. So I'm looking forward to this. I have no idea what's in here. I'm so excited to see what Keith sent me and after I open this and make a video I'm going to be sending him the return box. I've got some cool stuff lined up for him so stay tuned Keith. Anyway, so let's get into it. Let's see what's in here. So we've got a list here of the different things that Keith has sent me. That's awesome. That'll help because some of these I'm not familiar with. Okay. Actually, what I should probably do is put the macro lens on. That'll probably work better. Yeah, let me quickly put the macro lens on. All right, and poof, I have a new shirt on. Long sleeve. Actually, it was too overcast and you couldn't really see the stuff so I waited for the sun to come out. Yeah, now everything should be more visible for you guys. Let's take a look here. Okay, first one. Oh, that looks like a beautiful agate and good to have a spray bottle so we can see what the stuff looks like. Oh, look at that. That is a nice looking agate, but you can see light coming through that thing. Very nice. I do like good agates and that's a nice looking one. Definitely have to do something with that. Next is another agate. Very nice. Very solid color. You can barely see the little bands going through it. Yeah, it's pretty cool though.  Oh, I like this one. Okay, look at this one. This one's got some nice red jasper going along the bottom of it and it's got a really nice pattern to it. Then you got some other jaspers and agates in there. You can even see some agate banding in there. That's beautiful stuff. Looks like maybe a vein of calcite at the top too. I don't know, a lot of cool stuff going on there. All right, this looks like a thunder egg from Oregon because that's commonly what they look like. So yeah, that looks like a thunder egg from Oregon. That's a nice looking agate. So if you look inside this beautiful one, it looks like it's got some carnelian in there. Oh, that's beautiful. Maybe we can see some light coming through it. Maybe, maybe not. But yeah, look at that color right in there. So I kind of want to cut that one open. We'll see. I might have to do that. Okay, we got a nice little geode right here. Some nice crystals in there. And yeah, it doesn't look like it formed in a volcanic unit. Maybe it did. I don't know, because I don't know where these are from. So I don't know. But yeah, it's definitely a geode. Got some nice crystals in there. Ooh, that looks like a nice agate right there. Well, that's really nice. Beautiful patterns in there. It's almost, I think it's almost what you call a plume agate. It's really pretty stuff though. Okay, this looks like kind of a strange geode. Well, that is strange. This is a very strange one. Look, it's very kind of a tan brown, but it does have the botryoidal habit on the surface. And it's got this little layer here that's almost a bluish color. Oh, that's a very interesting looking geode. Oh, now this one's beautiful. This looks a lot like that crazy lace agate that we get here in Utah. It's beautiful. It's got a lot of color and pattern in it. Look at those circles there. That is nice stuff. Yeah, I like this stuff. There's definitely some things I could make with that. Here is a nice little agate. Probably from Montana. I've seen a lot of stuff from Montana and this looks like it's probably from there. All right, what do we got next? Okay, it's some more of that brown geode we had. So we had this one. This looks like some more of it. Definitely, you can see that botryoidal habit. Really cool. It's like a calcidney geode. Just a piece of one. So it would have been bigger originally. That is really cool. I've never seen anything in Utah that has that color with the botryoidal habit and it's very solid. It doesn't let any light through. Here is another agate. Probably another Montana agate. Cool. Let's light through. I don't know if you can see it, though. Another Montana agate. I do really want to get up to the Yellowstone River and go look for some of these because I've never actually gone and looked for agates and wood and stuff at the Yellowstone River. One of these days I will because that would be a lot of fun. Okay, we got another geode here. Nice crystals in there. Another one of these geodes. Very much like that one we saw earlier. I don't know how well you can see in there and see the crystals. It's kind of dark but it is pretty nice. Yeah, I don't know where these come from. Keith's going to have to tell me where these come from. Let's check my... It might be from Indiana. So we got geodes from Indiana. So I'm not sure if it's the crystal ones or if it's those brown botryoidal ones. I'm going to guess though it's probably these crystal ones. Oh, this is definitely one of those geodes from Indiana or like those other ones. I'm going to say that the Indiana ones. But that one hasn't been cut open yet. I'm going to have to cut that one. Oh, wow.  Okay, let's take a look at this thing. So look at that beautiful big seam of agate. And it looks like it's forming in a volcanic. You can definitely see something that looks very volcanic. Air pockets bubbly. So yeah, definitely looks like it formed in volcanic rock. That's really cool though. That's a thick seam of agate. And it's definitely letting light through. Don't know how well you can see that in there but yeah, that's really cool. Here's a broken geode. Got some nice crystals all over that. Nice. This is definitely looks like a thunder egg from Oregon. I've got the nice classic volcanic look on the outside. Nice and full. Yeah, definitely has got to be an organ. Thunder egg. Oh, this one's really cool. This is very green. Sorry, I kind of just quickly sprayed it. Very green. It looks like it has wood texture. So, oh yeah, I'm going to say this is probably petrified wood. I've never found petrified wood that's green though. That's really cool. Actually, limb cast from Oregon. So this might be some green wood from Oregon. I don't know. Really cool though. Some more agate. Nice. I like the little...  They look like craters on a moon or something. This is a very interesting looking stone. So yeah, this is very interesting looking. So it looks like it's fractured. So it was brecciated. So the rock broke up and it looks like it filled in with calcite maybe. Kind of a white yellow calcite. It might be quartz. I'll have to test it and see if it's calcite or quartz. And the rock that broke up looks like it might be volcanic. I'm seeing what looks like little pink feldspar crystals through it. So this might be a brecciated volcanic rock. Nice little piece of kind of a brown colored jasper. There you go. Some nice jasper. Ooh, here we've got some nice red jasper. So that's pretty looking. I like the little splotches and patterns in it. Yeah, that's a nice jasper. Another nice agate. This one has some better banding than a lot of the other ones. Ooh, this one might be a nice one to cut. We'll have to see. Interesting, okay. So this is kind of probably another one of those strange looking agates where we've got this like red banding of jasper. Some nice other colors and patterns right in it. Yeah, maybe it's another one of those sea maggots. Really cool. Oh, hello fossils. So this rock's got some nice fossils on it. So you can see some nice crinoid stems in there. Some broken shells kind of all over it. Looks like we've got some corals going through here as well. That looks like a coral. That looks like a broken shell right there. So you got some clam and oyster shells, corals and crinoid stems. This would probably look very nice cut and polished. So this looks like layers of algae growth. So this could be a stromatolite. In fact, I think he said in this thing, yeah, he's got some stromatolites from Michigan. So that's probably a stromatolite. Looks like it. It's got the nice pattern to it. Ooh, this is nice. So this right here definitely looks like some fossil. So these are fossil corals. And I remember right, I think these are what they call Petoskey stones. Petoskey. I'm actually not very familiar with them. I need to go get myself familiar with some of this Michigan stuff. But yeah, it's a nice stone though. Probably what would look really nice cut and polished. This looks like one of those geodes that has kind of that tan colored calcydine that's kind of botryoidal. This looks like a big one. So I'm looking forward to cutting that. Okay, this looks like from this side, like a thunder egg. And from this side though, you've got a nice hollow pocket. So I guess we'd call it a geode. But it's got a nice agate in it. Very nice. Interesting. Okay, this is definitely very different from anything I've seen around here. So it's got this green, I don't know if that's like a serpentine. Kind of looks like a serpentine. Or maybe it's a green jasper. I don't know. And then the main rock, the host rock definitely looks kind of like a granite or some kind of volcanic with pink feldspar and other stuff in it. I don't know, this is very different from things I'm familiar with around here. I'm going to have to probably do some research on this one. Another nice agate. Nice blue color. Now, something I kind of want to do with this is you see how it's got this surface that's got all kind of the red and stuff. And then you've got the nice colorless right through here. If you can cut it just right to where there's just a thin layer of this on top of this stuff, you can make it look like an ocean, like the bottom of the ocean or some cool landscape or seascape. So this looks like a good candidate to try and cut both sides to see if you can make that happen. Because if you can, they look so cool. Yeah, I'm going to probably try that with this. Okay, looks like we've got some more red jasper. Nice. And it's got some little bands in it too. So this is pretty stuff. You've got some little agate and stuff. Here's another agate probably from Michigan. Well, that's a very interesting rock. Looks like we've got some agates going on here. Got a little bit through here. This is where it seems to get really nice right here through that. Cool. So it'll probably look really nice once you cut into it. Oh, another one to get cut up. And then, okay, this looks like some classic thunder egg to me where it's got the nice layers showing where the water was as it filled in with the the quartz basically is what it is. Microcrystalline and got some nice agate banding. Yeah, that's a good looking thunder egg right there. Looks like another geode with the kind of that tan colored calcydine. Here's some more of that nicer red jasper that's got, you know, those different colors of red that make a nice pattern. Another nice piece of agate. Once again, probably from Montana. Let's see if there's light going through this one. Yeah, you should be able to see a little bit going through it. Oh, that looks like a geode probably from Oregon. So it's probably a thunder egg. Oh, looks like another one of those that we need to cut open. Now this, this looks like a big chunk of pink feldspar. So this probably formed in or around granite, probably in a pegmatite. So for those who aren't familiar, a pegmatite is where you get kind of a zone of the last little bit of magma as it's cooling underground, where you also have the gases, which can form pockets. And that's where you can get cool pockets of crystals like smoky quartz. But yeah, this looks like pink feldspar and looks like we've got some mica crystals in there as well, kind of muscovite and biotite. We've got another nice little geode here. Looks like we've got some nice dark agate banding along the edge here too. I wonder if maybe cutting along one of the edges would be really cool. Here's another one of those tan geodes I need to cut open. There's another nice piece of agate, probably from Montana. And once again, it's got some of that darker kind of red orange. That might be really nice. Ooh, this has got some nice layering in it. Nice banding. This could be a piece of petrified wood. Yeah, it's probably a piece of petrified wood. Those are probably the tree rings. So tumbled piece of petrified wood maybe from Montana. Here we've got some of that material polished. So yeah, there's got to be something about this material. It's got to have a name to it. I'm going to go look it up, but it's beautiful with that green and the red, which I think is feldspar. I'm not sure about the green. It's taken a nice polish, so maybe it is kind of a green jasper. Another polished stone looks like kind of an agate. A few different things going on in it. And now we're getting into the bags. So this bag says white skin agate from Mexico. So maybe pull just a couple of these out and get a feel for what it is. Okay, so they have this little white skin on the outside of it. That's probably why they're called white skin. And you get some little banding in there. Seem to be mostly white though or clear. Do these have any color? Oh, this is a little better like that. So maybe those are kind of the pieces you're looking for. Agua Nueva Seamagat. Okay. Oh, I like that stuff. Okay, I like this. So the Agua Nueva Seamagat, look at that color in there. It's almost a purple. Oh, that's beautiful. I like that stuff and got nice big quartz crystals there too. Here's another piece of it. That is nice stuff. I really like that stuff. Well, look at that. That's some neat looking stuff. So mossy agate. So that stuff I've been fined over by a little Moab, I guess technically you could probably call it a moss agate. A lot of the pieces I have have similar patterns in it. Neat. Cool stuff.   So yeah, probably a metamorphic rock. Some polished agate or calcidine, because there's some banding right there. So yeah, agate. Here's some more polished agate it looks like. All right, some more of that material polished. Once again, it looks like a granite to me. Yeah, that looks like a granite. And the last few. Oh, some red in there. It's probably a red agate. It's got some little dendrites or moss that's red. Well, that's cool. It's probably a mix of things, quartz, agate, jasper. Neat stone though. And the last one is some more of that material that it's got the green in it with what looks like volcanic with pink feldspar, maybe a granite. And that's it. So thank you so much, Keith. That was pretty cool. That was a lot of fun. A lot of neat stuff. I can't wait to cut some of this open. There's some neat looking stuff there. So we'll look forward to that. And yeah, once again, thank you, Keith. I'll get you a box packaged up and sent to you as soon as I can. All right. Well, until next time, remember, there's treasure everywhere.


Welcome to advanced geotechnical engineering course which is being offered under the program of NPTEL phase 2 being developed at IIT Bombay. So as you all know the soil mechanics are part of geotechnical engineering plays an important role in the behavior of civil engineering structures. So this course is being offered for graduate students as well as for practicing engineers who are actually going to use or work in the area of geotechnical engineering. Myself Professor BVS Vishwanatham, I am professor at department of civil engineering with geotechnical engineering as specialization. My research areas include centrifuge modeling of geotechnical structures, research in geotechnical engineering, soil reinforcement, geosynthetics and details of my work can be seen at website www civil.iatp.ac.in backslash tilde Vishwanatham. My email ID is given here Vishwanatham at the rate civil.iatp.ac.in. So this course we would like to cover in the following heads. First we will introduce ourselves to origin and nature of the soils as engineering materials. As you all know soil and rocks are the major engineering materials which are used in civil engineering construction. And then we will try to classify the soils and try to look into the clay mineralogical aspects. Thereafter soil compaction, soil water interaction, permeability and seepage and effective stress will be covered. After this consolidation behavior of the soil and methods for accelerating consolidation of the soil will be introduced. Having done this the stress strain strength response of soils will be discussed in depth and as an application to this earth retaining structures and stability analysis of slopes will be covered. This is followed by buried structures and their behavior and this course will be given a closure with geotechnical physical modeling. This course is covered in 8 modules. In module 1 soil composition and soil structure will be covered. After the soil composition and soil structure we will be looking into soil formation, types of soils and their characteristics, particle sizes and shapes, their impact on engineering properties, soil structure, clay mineralogy, soil water interaction, consistency, soil compaction and concept of effective stress will be introduced here in this module. At each module we will be actually having problems and also self-evaluation and tutorial problems so that this will bring close to the subject what you learnt in the previous lectures which are actually there in this module. As a second module we will be covering permeability and seepage, permeability and seepage force and effective stress during seepage. Laplace equations of flow particularly fluid flow in soil in one dimensional, two dimensional and three dimensional seepage, flow nets, aniostropic and nanomersenous medium confined and unconfined seepage and along with practical examples will be discussed in this module. In module 3 the compressibility and consolidation and under this the stresses in soil from surface loads, Terzaghi's one dimensional consolidation theory, application in different boundary conditions, ramp loading that is the loading which is actually carried out happens in the field, determination of coefficient of consolidation, CV for normally and over consolidated soils along with some practical examples, compression curves, secondary consolidation, radial consolidation and the settlement of compressible soil layers and methods for accelerating consolidation settlements will be discussed in this module 3. In module 4 stress strain relationship and the shear strength of soils will be discussed. In this module we will be discussing stress state, Mohr's circle analysis and pole principle stress in the space and stress paths in PQ space, Mohr Coulomb failure criteria and its limitations, correlation with the PQ space and stress strain behavior, isotropic compression and pressure dependency, confined compression, large stress compression, definition of failure, interlocking concept and its interpretations, drainage conditions and traction behavior of stress state and analysis of unconfined, unconsolidated, undrained, consolidated, undrained, consolidated drain and other special tests, stress paths in traction and octahedral plane elastic modulus from the traction test will be introduced. So in this at the end of this module what we will do is that we will try to see number of problems and we will also try to have some tutorial problems. So this will actually allow you to understand in a better manner in this module. As module 5 and 6 as an application of shear strength what we learnt in module 4 what we do is that we will try to learn earth retaining structures in this earth pressures, stress changes in soil near retaining walls, earth pressures and pressure, estimation of earth pressure under drained and undrained loading and stability of slopes particularly stability analysis of a slope and final critical slip surface, sudden drawdown conditions and effective stress and total stress analysis, seismic displacements and marginally stable slopes and we will be introducing briefly to reliability based design of slopes and methods for enhancing stability of unstable slopes. There are many methods so that we can actually discuss some important methods so that how a stability of an unstable slope can be improved. In module 7 we will try to understand about the buried structures. These are very prominent or important nowadays with urban constructions. The load on pipes, Marston's load theory for rigid and flexible pipes, trench and projection conditions and minimum cover pipe flotation and liquefaction. So these are some of the critical conditions like liquefaction and then behavior of the pipes subjected to flotation and all will be discussed. Finally under 8th module we will be discussing geotechnical physical modeling, the physical modeling methods, applications of centrifuge modeling and its relevance to geotechnical engineering, centrifuge modeling of geotechnical structures with practical examples will be discussed. So if you look into this, the geotechnical engineering is the branch of civil engineering concerned with the engineering behavior of ad materials. Geotechnical engineering uses principles of soil mechanics and rock mechanics. So here is the soil mechanics and rock mechanics to investigate subsurface conditions and materials which is very very important. So if you look the soil mechanics is the branch of science that deals with the study of physical properties of soil and the behavior of soil mass subjected to various types of forces. Whereas the rock mechanics is the theoretical and applied science of the mechanical behavior of rock and rock masses. So soil mechanics is the branch of science that deals with the study of the properties of the physical properties of soil and the behavior of soil mass subjected to various types of forces. The forces can be gravity forces or seepage forces or external loading etc. The rock mechanics is the theoretical and applied science of the mechanical behavior of rock and rock masses. So in this slide a series of geotechnical engineering construction activities which are actually formed with soil is shown. A natural slope or natural slope which is a geotechnical structure which is actually formed either because of the erosion or because of the gravity loading. So this natural slope which is actually shown and then in order to allow the urban construction sometimes along the hilly terrains the cut and fill method is adopted the slopes will be cut and then allowed for the slopes to the roads to construct. So this infrastructure development makes some of the existing natural slopes unstable. So hence there is a need for understanding about the behavior of these slopes under the natural conditions are subjected to some adverse effects. Here whenever if there is a requirement of storage of water then this particular structure is called embankment dam and which is required to prevent the leakage of the water through the dam. So this particular structure which is actually called as an embankment dam. So if you see here this particular structure is a building foundation for a 1 or 2 stories building. So here the foundation transmits the loads to the subsoil and it should be such that the settlement should be minimum. In this slide when the slope is steeper and if it is required then there is a need for the supporting. So if this is called a supported excavation or if you are using a braces for this it is called braces excavation or supported excavation. And in this case the next structure which is actually shown is a tunnel and which is required nowadays because of the urban constructions. So for the metros and other applications you need to have the underground constructions. So this particular cross section shows tunnel which is embedded in soil or it can be in the rock. So this is lining of the tunnel material and here in this particular figure part of the figure of this slide it shows buried pipe and which we will be discussing in the subsequent lectures. So this is a buried pipe at a certain depth below the ground level. And here in this particular figure it shows a road embankment above the existing ground level. So this is a typical structure which is very common as far as civil engineering construction for highway and railway applications is concerned. In particularly if you have got a soft soil and if there is a requirement of the large loads to be transferred to the deeper stratas then it is required to construct foundations such that the loads are actually transferred to the harder stratas which are actually there below. So here this is a cross section which actually shows the building on the pile foundation. So these yellow members which are actually shown are the piles and here this particular surrounding soil which may be can offer a frictional resistance or sometimes if it is in the form of a clay it derives the strength only from the bearing. So in this particular cross section what you see is geosynthetic reinforced soil walls which are actually very popular in urban construction nowadays because of the requirement of the construction of the steep walls in urban areas and where you can actually have different slip roads and highway intersections in the congested areas. So this is possible to construct with economical construction so that this can lead to you know large economics in the civil engineering construction. In this particular slide the left cross section of the figure which actually shows an ash pond dam so this is actually a started dike where the ash is actually deposited once the ash this portion is filled then the second dike is constructed above the started dike and to have economics the compacted ash is actually used as a filler and then it is surrounded by a soil so that this can actually have less prone for erosion. And here so like this you know it can actually go up to 3 to 5 levels so the total height of the structure can go up to 20-25 meters so this requires you know the understanding about the stability of this type of ash dams and also in retaining these ash safely. And because of the development and generation of the municipal solid waste there is a requirement for municipal solid waste landfills that means that the waste which is actually incinerated or generated has to be finally dumped safely in the ground or above the ground and this construction or this type of a geotechnical structure is called landfill. If the leachate which is actually generated is recirculated and from periodically so that this can actually avoid periodic treatment of the this can avoid intermittent treatment of the leachate so this is actually if that is the case then it is called bioreactile landfill. The recirculation of leachate allows the landfill to undergo decomposition rapidly and this can actually lead to the you know this particular areas can release for the future constructions. So in this slide a typical structure of construction on soft soil is shown so this is a typical oil storage tank which is actually constructed on soft soil and wherever it is close to the coastal belt there is a requirement there is a possibility that you have got soft soil. So in order to allow the construction that soft soil has to be consolidated so that the settlements are minimum. So here in this it involves construction on the soft soil particularly different techniques for accelerating the construction of the soft soil then this type of constructions can be made possible to have a better performance. So here this particular construction it shows a sea wall which actually protects the land from the waves which are actually arise because of the because of the waves which are arise because of the water which is actually there. So this is actually sea bed which also requires to understand about the stability that is from the stability point of view and these are windmill foundations which are actually these windmill foundations are nowadays used for production of the wind energy from the wind. So these are sometimes when they are located in the sea they are called they are located in offshore and sometimes they are also located on the onshore. So you have if you have got a windmill foundation which is there in the sea the typical foundation with the racker piles would look like this and this is a typical oil rig for a offshore foundation which is actually shown here on racker pile. So we have seen the different types of geotechnical structures and all these structures are subjected to typical failures for example if you have got a road which is on the soil which actually have inadequate drainage that can lead to if it is on the expansive soil the sub grade can undergo failure like this and if you have got a railway track on the soft soil formation there is a possibility of mud pumping like this and if you have got some instability because which is because of the sea page or because of some landslides then this or earthquake this type of instabilities can cause and if you have got a landfill and if the stability is not ensured either because of some mining work or some other problem then this type of landfill failure can cause and this is a close view of municipal solid waste which is in particular generated in Mumbai and which shown and this is the typical lead shade which is actually shown here. So the degree of contamination levels are very high and so if you wanted to see the impact on the engineering properties of the soil and all is required to be understood very clearly. So here the typical slope which is actually shown along the railway track and these type of failures are very common because of the sea page which actually takes place during the monsoon and here a typical railway track which is actually subjected to a track subsidence is shown. So geotechnical engineering if you look into the definition it is simply the branch of engineering that deals with structures built of or in natural soils and rocks. This subject requires knowledge of strength and stiffness of soils and rocks and methods of analysis of structures and hydraulics of groundwater flow. So you are required to understand the structures which are actually built of or in natural soils and rocks. So this subject requires knowledge of the strength and stiffness of soils and rocks, methods of analysis of structures and hydraulics of groundwater flow. So in this course we will be concentrating mostly on the soil behavior and soil stiffness and the methods of analysis of structures resting on the soil predominantly. As a course context I would like to introduce here an understanding of the engineering behavior of the ground and interaction between the ground and any structures built or in the ground is essential for civil engineers. So that means that this particular understanding about this subject which involves the engineering behavior of the ground and the interaction between the ground and any structure like retaining wall, interacting with the soil built on or on the ground is essential for civil engineers. Before introducing and giving references of this particular course I will be giving the quote which is actually given by Carl Tazaghi 1883 to 1963 who is known as the father of soil mechanics. Here it says like this, unfortunately soils are made by nature not by man. Many times in soil mechanics what will happen is that engineer requires to use the soils which are actually available in the nature. And the products of nature are always complex as soon as we pass from the steel and concrete to earth the omnipotence of the theory ceases to exist. Natural soil is never uniform we are going to see that there are different types of soils and its properties change from point to point while our knowledge of its properties are limited to those few spots at which the samples have been collected and tested. In soil mechanics the accuracy of computed results never exceeds that of a crude estimate and the principle function of theory consists in teaching us what and how to observe in the field. So here some selected references are listed in these are these references are listed in the alphabetical manner. Atkinson 2007 which will be following for majority of the portions of this course the mechanics of soils and foundations and which is published by Taylor and Francis in 2007 and this is the second edition which I included here. Eisen A 2005 soil mechanics the basic concepts and engineering applications Taylor and Francis London and which is published I think in the first edition and Craig 2004 this is the title of this book is Craig's soil mechanics spawn fresh Taylor and Francis London and New York 7th edition thus BM 2008 advanced soil mechanics Taylor and Francis London and New York 3rd edition. Fang and Daniels 2006 introductory geotechnical engineering and environmental perspective Taylor and Francis London and New York 1st edition. Fredlund and Rahatzo soil mechanics and for unsaturated soils John Willey and Sons New York 1st edition. Hols and Kovacs which we will be discussing basically for stress parts 1981 and introduction to geotechnical engineering Prentice Hall New Jersey. Kaniraj SR 2008 the mechanics of soils and foundations Tata McGrahill publishing company New Delhi 10th print, McCarthy 2007 essentials of soil mechanics and foundations basic geotechnics Prentice Hall New Jersey 7th edition, Parry RHG 2004 more circles stress parts and geotechnics. So here we will be discussing mostly about the stress parts and then the failure criteria which are actually involved with the stress stiffness response of soils and the spawn press Taylor and Francis and London and New York 2nd edition. Wood DM geotechnical modelling basically here we will be covering the geotechnical physical modelling involved which is in the module 8 of this course. So as a source of the soil first let us look into the origin of the rock and origin of the soils. So the rock the source of the soils most of the non-organic materials that are identified as soil originated from the rock as the parent material. As you all know that the rocks that form the earth surface are classified as to origin as igneous sedimentary and metamorphic rocks. Igneous rocks sedimentary rocks are metamorphic rocks. These igneous rocks are formed directly from the molten state of magma. The molten magma that cools rapidly at or near earth surface are called extrusive or volcanic type rocks. Examples for this are basalt, rheoloids and andesites. If the molten rock cools very slowly the different materials segregate into large crystals forming a coarse grained or granular structure that trapped in deep at deeper depths. Intrusive or plutonic type examples for this type of rock which is actually formed when the molten rock cools very slowly that is granite which consists of quartz and pels part, cyrites and gabros. Because of the isilka content these rocks are called as acidic rocks. They decompose to predominantly sandy or gravelly with little clay. So you see here when these rocks with isilka content when they decompose they form a predominantly sandy or gravelly with little clay. This is actually used as good construction material. Rocks whose minerals contain iron, magnesium, calcium or sodium but little silica such as the gabros, diabetes, basalt are called as basic rocks. The rocks whose minerals contain iron, magnesium or calcium or sodium but little amount of silica these rocks are called as basic rocks. Examples are gabros, basalt. And the solution of the magma is cooled very very rapidly. The minerals do not separate into crystals but solidify as amorphous vitreous rocks such as examples volcanic scoria, pumice and obsidian. The rock types that are intermediate between acidic and basic include trachites, diorites and andesites. They are easily break down into the fine textured soils due to their mineral components. So the rocks that are intermediate between acidic and basic rocks the examples include trachites, diorites and andesites they easily break down into the fine textured soils due to their mineral components. The clay portion of the fine textured soil is the result of the primary rock minerals decomposed to form secondary minerals not small fragments of the parent rock minerals. The properties and behavior of the clay soils are different from those of gravel, sand and silty soils. So the clay portion of the fine textured soil is the result of the primary rock minerals decomposing to form secondary minerals. So the properties and behavior of clay soils are different from those of gravel and sand and silty soils. This is one of the reason for different behavior of the properties of the clay. When it comes to sedimentary rocks these are actually formed from the accumulated deposits of soil particles or remains of certain organisms that become hardened by pressure or cemented by minerals. Cementing materials such as silica, calcium carbonate, iron oxides are abundant in this type of rocks. Example limestones, dolomites the present proposal new name is dolostone and sandstone are shale or conglomerate and briscia these are the examples of the sedimentary rocks. The shales are predominantly formed from the deposited clay and silt particles. The degree of the hardness of this shale depends upon the type of minerals the bonding that developed and in the presence of foreign materials. The hardness is mainly due to the external pressures and particle bonds not due to the cementing materials that is this is mainly due to the external pressure which has been subjected and the particle bonds not due to the cementing material which is actually due to any cementing materials. When exposed to an environment water or ale shales tend to expand and de-daminate this is one of the problem in some parts where the shale soils are available and then they have planar types of failures and the slopes with very small inclinations or mild inclinations can be subjected to planar failures and breakdown of the shale the fragments of various sizes and varying sizes and clay particle sizes. So if the shale actually breaks and it gets fragmented into clay particle sizes. Limestone is predominantly crystalline calcium carbonate that is calcite formed under water. So limestone dolomite is referenced as a karst or karstic terrain and here in this particular photograph a typical formation of a sink hole which is actually shown and here this is due to the canty which is formed because of the soluble nature of the ingredients present in the ground water. So these types of formations cause problem to the infrastructure particularly pipes which are actually pipes which are located on this type of structures or any structures which are actually resting on this type of formation can be subjected to distress. So weathering of limestones predominantly fine size particles will be reduced. So what we are seeing is that we have seen igneous rocks and we have seen sedimentary rocks. Let us look into the third type of the rock which is called metamorphic rock. The source of this metamorphic rocks either igneous or sedimentary rocks. The results when any type of existing rock is subjected to metamorphism the change brought about the combinations of heat pressure and plastic flow so that the original rock structure and mineral compositions are changed. So here the plastic flow means a slow viscous movement and rearrangement within the rock mass due to external forces. So limestone after subject into metamorphism converts into marble. Shell to slate and slate or phylite, granite to gnaze and sandstone to quartzite. So if metamorphism of limestone yields to marble, metamorphism of shell yields to slate or phylite, metamorphism of granite yields to gnaze and metamorphism of sandstone yields to quartzite. The gnaze is a foliated rock with distinctive bending that results from the metamorphism of granite. Distinction between gnazes and shears is not always clear upon weathering gnaze and shears decompose to form silt sand mixers with mica content. Soils from phylites are more clay and decomposition of quartzite reduces sands and gravels. So decomposition of quartzite produces sands and gravels. Decomposition of phylites produce clay material. So this is a typical example of metamorphism which is actually shown in the site. So if you look into this slide the rocks are subdivided into igneous, sedimentary and metamorphic and when they are subjected to weathering either due to physical or chemical means and they get divided into transported or sometimes when the weathering takes place when the soils deposit at their location then that is also called a residual. So when the transported soils and the soil is now broadly classified as boulders, gravel, sand, silt and clay. So this particular gravel, sand, silt and clay if you see the size of the particle keeps on decreasing as we traverse from gravel, sand, silt and clay. So rock whose chief mineral is quartz minerals with high silica content decomposes to predominantly sandy and gravelly soil with little clay. So these are acid rocks and they are light colored in nature. Six rocks decompose to the fine textured silt and clay soils. The clays are not small fragments of the original materials that exist in the parent rock. This we have discussed earlier. This results the primary rock minerals decomposing to form secondary minerals. So if you look into this the major soil types based on the practical size if you classify just now we discussed that in the type of formation we said that the gravel, sand, silt and clay they originate from the different types of rocks. The gravel and sands are considered to be coarse grained soils with large particle sizes and silt with very tiny particles of disintegrated rocks and clay particles are considered as fine grained soils because of their small particle sizes. Clay soil is plastic over certain range of water content and still silt soil possess little or no plasticity. So clay soil is plastic in nature if it can be remolded without cracking and breaking we can say that the clay soil is plastic and over range of water content. So the practicals larger than gravel are called cobbles or boulders. So soils can be grouped into two broad categories as we see based on the deposition based on the sizes we have actually divided into different types like gravel, sand, silt and clay based on the method of deposition residual which is actually called or formed when weathering of the rock and the remaining at the and weathering of the rocks takes place and their soils remain at the location of their origin itself. This is because a material which possess little mineralogical resemblance to the parent rock. Soil which actually resembles which remains there at the origin itself and it resembles the parent rock characteristics predominantly. And there is another type which is called transported. These transported soils are called those materials that have been moved from their place of origin like by agencies like gravity, water, glaciers or man either singularity or in combination. So characteristics of the residual soils depend upon the climate conditions, humidity, temperature, rainfall. Some islands actually have the residual soils where the soil gets originated and then deposited at its place of origin. So the characteristics of these residual soils are predominantly depending upon the humidity, temperature and rainfall and the natural drainage part pattern and form an extent of the vegetation cover. So these are the prime factors on which the characteristics of the residual soils are depend on the depend. Now the transported soils we said that there is an agency which actually transports if it is transported by running water then it is called alluvial deposits and if they are deposited in quite lakes they are called lochestrine deposits. If they are deposited in seawater and they are called as marine deposits, if they have been transported by wind or air then it is called aeolian deposits and if there is a glaciation which actually takes place because of the large movements of the sheets of ice then they are called glacial deposits. These are actually predominant in hilly areas. And colluvial that is deposited through action of the landslide and slope wash where this particular types of deposits are possible. So according to the transporting agency and method of deposition we subdivide this transported soils into alluvial, lochestrine, marine, aeolian, glacial where the glaciation is predominant and colluvial deposits. Because of the transported soils are layers this is basically a windblown deposit with very uniform fine silt particle and possess a slight cementation. So this is the reason why if suppose if there are some unsupported vertical cuts they stand vertical because of the cementation which is present in the particular soil which is transported by wind. So this formed in arid and semi arid regions and with yellowish light brown color. Which is a fine grained slightly cemented volcanic ash and which is deposited by wind or water. So tuft is an example of transported soil. Glacial till is a heterogeneous mixture of boulders, gravel, sand, silt and clay which is predominantly in hilly region and where the glaciation is predominant. And warwood clay which is an example of transported soil which is nothing but which is formed by alternating layers of silt and clay deposited in fresh water with glacial lakes. One band of silt and clay deposited each year. So each layer is approximately 10 mm thick or so. So this particular transported soil is called a warwood clay. Marl very fine grained soil of marine origin imperimble and which is highly compressible and greenish in color. Heat which is highly organic soil consisting almost entirely of vegetable matter in varying stages of decompositions. So it is basically a fibrous type of material and it is fibrous in nature and brown to black in color and highly compressible deposits. So these pt soil deposits are also called as marshy lands where the construction needs to be done with care. The major soil deposits based on the ambience, geography and topography they are called as expansive. These expansive soils also have high shrink and swell characteristics attributed to the mineral which is actually present in these expansive soils. The basic color is black. This is due to the presence of iron, magnesium and titanium. Marine deposit very soft and may contain organic matter and laterate soil red in color due to Fe2O3 and the loss of silica which is due to the intense chemical weathering and this particular loss of silica due to the intense chemical weathering is called laterization and this causes lot of problems in laterate soil deposits. Alluvial is alternate layers of sand, silt and clay and desert is nothing but a wind blown deposit and which is uniformly graded in nature. This is a boulder clay which consists of all ranges of particle sizes. Here the distribution of the predominant soil deposits in India are shown here in this particular slide where in this portion where the desert soils which are actually transported by wind are shown here. Basically here the Aeolin deposits are there and along the coastal belt the Indian coastal peninsula is about 6500 kilometers and majority of the Indian coastal peninsula has marine soil deposits and in this portion which is actually here shows the expansive soil deposits. So the construction in these areas which is difficult and in this particular portion here it is shown here the laterate soils. So if you look into north to south and west to east there are the different ranges of soils which makes engineering difficult and where there is a relevance of the subject as far as Indian context is concerned. So if you look the consistency of the soil mass the formation of soils from the weathering of the parent rock and wide range of the soil solids are possible. The behavior of the soil mass under stress is a function of the material properties such as size and shape of the grains. So if you wanted to see understand about the material properties and its behavior the size and shape of the grains gradation like what type of particles and how the combination is there whether it has actually has got fine grain portion or coarse grain portion and mineralogical composition type of mineral which is actually present in the particular soil arrangement of the grains and inter particle forces. So the behavior of the soil mass under stress is a function of the material properties such as size and shape of grains, gradation, mineralogical composition, arrangement of the grain inter particle forces. So material properties are now if you look into this is a function of the constituents of the soil mass. The soil is a particulate material which means that the soil mass consists of accumulation of individual particles that are bonded together by mechanical or attractive means though not strongly as by rock. In the rock there are the materials which are actually with permanent bonding the spaces between solid particles are referred here as voids or pore spaces. The spaces between solid particles are referred here as voids or pore spaces and if these voids are filled with water then it is called pore water and they exert pressure on the voids it is called as the pore water pressure. In soil in most rock the voids exist between particles and voids may be filled with a liquid usually water, gas or usually air. So in soil if the majority of the rocks also they do have voids. So voids existing between particles and voids may be filled with air then in that case it actually is divided into if it is only predominantly air then it is called as a two phase system which will be introduced in the next slide and if it is filled with water only it is again also called as a two phase system but here it is called water saturated all the voids are actually filled with water and there is also possibility that partially saturated soil where you have got air, water and solids. So actual soil bulk consists of soil particles water and air. Air is actually occupied here in the space which is actually shown here and here is actually portion which is actually shown as with water. So this type of soil deposits which are actually above the ground water table and this particular zone from here to here is called as Vados zone and here this zone is called unsaturated soil and the soil mass which is actually there below the solids which are actually filled with water is called saturated soil here and here it is called partially saturated soil. If there is no water here then there is only air and solids and if the here below water table the soil mass is actually completely filled with soil voids are completely filled with water. The water surrounding particles at points of contact with water particles and filling in the small void spaces. So the consistence of the soil mass what we are saying is that there is a solid phase liquid phase and gaseous phase and if you have solid and gaseous or predominantly air which is called as dry state when the solid and liquid which is there predominantly then there is this phase is called as saturated state. So here a typical three phase system is shown where soil solids and you have got air and then water which is filled with the remaining portions. So idealization if you idealize this three phase system then it is called gas or air, liquid and solids. The solid phase consists of primary rock forming minerals such as greater than 2 micro meters and poor reactivity prone to disintegration. So this is basically a solid phase and clay minerals the basic material that form the soil mass size less than 2 micro meters and high reactivity and the cementing material this is basically carbonates and organic matter high water absorption compressible and unstable in nature. So solid phase which is actually there in the part of a phase system which is introduced in the previous slide this can be primary rock forming minerals and clay minerals cementing material and organic matter. Second phase basically it consists of water or dissolved salts where we have pure water or polluted water and this is polluted water because of the levels of contamination which is actually introduced in the previous slides. And the dissolved salts sometimes you have got water soluble and water insoluble and water soluble salts which are predominantly chloride sulphates and bicarbonates not capable of binding solid grains. And gaseous phase predominantly consists of air and gases and if only you have got air and solids which is called as two phase system dry soil and if you have got two phase system again with water and solids it is called as a saturated soil. So we have a dry soil saturated soil and partially saturated that is referred as three phase soil system. In the three phase soil system in order to reduce relationship between volumetric ratios and weight ratios the soil which is actually here is idealized as the three phase system is idealized as air water and solids. On the left hand side the volume is given here and the right hand side weight is actually shown here. So here W suffix S is called the weight of solids and here W is the weight of water and weight of air as 0 but it actually has got volume which is called as volume of the air volume of water. Volume of water plus volume of air is called volume of voids. That means that in the three phase soil we have got volume of voids which is actually both air and water will be there. If you have got a dry soil then you have got volume of air only. If it is a saturated soil you have got volume of water only. So here this solid portion volume is referred here as volume of solids. So if you look into this W is nothing but weight of solids plus weight of water. If suppose the weight of water is 0 in case of a dry soil then you have got weight of solids only and total volume of the soil mass is nothing but the volume of the solids and volume of the water and volume of the air. So total volume is nothing but volume of solids plus volume of voids. So this is the case for the partially saturated soil. So as a part of self-evaluation in this, so in this lecture what we have tried to understand is that we have introduced ourselves to the different modules which are actually going to be there in this particular advanced geotechnical engineering course and we also have discussed about the different ranges of geotechnical structures which are actually possible. Like we have said that natural slopes or slopes, embankment dams or foundations particularly building foundations and shallow foundations or deep foundations or road embankments or some windmill foundations and offshore foundations like we have ranges of geotechnical structures. All structures which are actually they are predominantly the resting in or on the soil and the soil is actually is a major predominant material and if you see a typical foundation and the foundation should transmit the loads and the settlement should be minimum so that the safety can be ensured. So all these geotechnical structures which are actually there should be understood such a way that they should not fail and ensure performance during their lifetime of the design. So in this particular lecture what we have done is that we have actually discussed about the origin of the soil. The origin of soil is predominantly basically from the rocks, predominantly that rocks are igneous sedimentary metamorphic rocks and these rocks are basically when you are actually have different states of either metamorphism can takes place because of the either source from igneous or sedimentary rocks and we also discussed that some types of sedimentary rocks which are actually have some ingredients which are soluble with in the which are present in the ground water can actually dissolve the rock and form sink holes and which these are very popular in the United Kingdom called as crastic stones or crastic formations. So as a self evolution in this I would like you to list the soil types included in coarse grain category and fine grain category. So if you come across any soil type kindly look into the type of soil and list to the soil type whether it is a coarse grain type or fine grain type and why there is a difference in behavior of natural place and other soil types such as sands and sills. At this primitive stage if you can able to understand why there is a difference in behavior of the natural place and other soil types whether any can be if you can relate to what we discussed in this lecture and this answer you will be able to answer. And what does the term plastic means in relation to clay soils and what are laterates or laterate soils and why are such soils are considered in the category of required special consideration on construction projects. And for any soil investigation project any geotechnical engineering project or any project is engineering project you require to understand about the extent of the soil horizontally as well as vertically in such situation we do at number of selected locations boreholes. So any particular from any borehole data tested in your location or if you have come across any borehole data list the soil types and rock types. So this will allow you to converse with the subject which we are going to cover in advanced geotechnical engineering course.