 Today's discussion is now having discussed all these things you must have realized that soils are no more a innate material they are not a dead material lot of things are happening inside the moment bacteria comes it becomes a dynamic system for human beings we say no your carrier is a function of time and the place where you would be you will be in a different continent after 2022 you will be flourishing or you will be doing something clear. Soils are also like that I emphasized most of the time that the properties of the soils are a function of x, y, z and t and the best example I gave you. So truly speaking soils are living entities they are not dead entities we have treated them always like the dead materials so you bring soil from the lab from the field pulverize it put it in the oven 100 degrees centigrade you bake it you have removed lot of things which were present and which contribute to the properties of the soils. So you filter them out for the sake of your convenience so whatever practice of engineering you are doing is only partial it is not full so soil is a living entity and hence it is quite susceptible and sensitive to the environment in which it stays we call up we talk about sensitive soils is it not we have given you I have talked about several examples where how the environment is influencing the characteristics of the soils you change the pressure temperature conditions depressurization occurs something starts leaking out of it human body clear emotions something changes somebody says something and look at this your poor pressure starts dissipating through your eyes so all similar. So environmental influence is very very important we will talk about this just like human and living beings you know and then of course I like saying this that lot of heritage parentage linkage genetics memory emotions and response to external stimulus which we have to take into account if you want to do contemporary geomechanics it is so unfortunate that most of the time we do not bother about all these things for us soil is a inert material it is not so clear so now ultimately this answer comes from the rock cycle the way you are formed the way the soil was formed so heritage heritage parentage is nothing but the way you were formed in which family you took birth all the background goes in your name clear by virtue of taking birth in that family linkage the linkage is between your parents offsprings rocks soils mineralogy is same only the composition of minerals is different because of the formation or recreation of the soils genetics we talk about genetics also we will talk about memory effect in geotechnical engineering hysteresis loading unloading you know you do unloading load versus sediment chadar and reload it what happened that point of over consolidation remains unique point correct so you do number of cycles of consolidation plate load test what happens material remembers that it has behaved like NC OC again it becomes NC so beyond this pressure it has to behave like normally consolidated clear so this is the memory effect it remains in the memory of the material how it has to behave exposure to certain stresses and the material recognize is immediately I should behave like normally consolidated not like OC material this is correct emotions I just give an example what emotions are I will say something to you arch you start crying dissipation of emotions clear we have several examples consolidation is a good example of this we will talk about this at the same time I say something very good you feel elated joyous face glows emotions getting reflected on your face is it not swelling and shrinking behavior would be one of this you can look at it like this responses to external stimulus that is what actually we are trying to study so we are trying to create a matrix of all these traits which are similar to human body so for us and environmental geomechanics one of the important things is that we should treat this material as a living material clear we should not say that this is a dead material there is no life in it it is not so leave marine clays for certain time what do happen they decay this question I asked in the very first lecture and you were trying to answer that despite the best possible sampling despite the best possible testing despite the best possible softwares which we can think of why our systems are failing this is the answer now you are getting today hope you remember the question which we discussed sometime back so everything is best possible the best possible sampling very undisturbed sample you have taken you got the best possible parameters clear best possible computer codes you are using to get the answers to the questions but still when the systems are in place they fail why because the properties were time dependent which you did not take into the account they decay they may become better also they get upgraded also microbial activity so this is the issue which we have completely ignored but in real life you will observe that these activities are playing a very very important role unless you include them things are not going to happen properly and that is what calls the new era geomechanics you know the environment the soil is not going to interact with the pure water which you use in the laboratory you are interested in solving the problems where the landfill leachers are getting intruded into the foundations and they are trying to eat up the foundations clear so these are the situations which we have to study is this part clear so when we talk about all this you know this thing I enjoy talking to my PG students you must have heard about the punch tantras the 5 elements of life which we which create the life in your language you must be using different languages different terms to define this so punch that was another elements and G1 is life so you know shitage it is horizon Gagan is sky Pawak is fire gel is water and Samir is air interplay of all these 5 elements creates the entire geomechanics that is very interesting is it not when we are kids we were taught all these things when we have become professional we have forgotten all these things that is the only thing we are unable to handle the situation properly so what these first 2 elements do any guess infinity the first assumption in all your models is semi-infinite soil mass whether it is ranking whether it is bosonisk so you have cut across the 2 the entire hemisphere you say the bottom the bottom portion I am only interested in not the top portion which is the atmosphere environmental scientist will take care of so you say semi-infinite beneath the ground only you are considered that is the domain in which you work horizon and sky sky is nothing but the environmental conditions weathering conditions you remember where they get deposited horizon so soils after disintegration after weathering they get deposited somewhere alright now what happens with sky and fire this is a formation of the soil environmental conditions at elevated temperatures disintegration of the rocks formation of soil clear and this formation of the soil is taking place in the semi-infinite domain now if I consider water and air these are the transportation agencies deposition and transportation agencies so I like this philosophy now if you start looking at the material with which you are dealing that is the soils and if you know the genesis of the material now your angle changes perception changes looking at the things the way you do is changing correct so you think of a totality now so if this is a situation you know what happens we have defined soils in different physical terms physical only you know these are all physical terms particle size nothing more than that so most of the geomechanics which we study is blind of anything which is beyond physics of the matter we do not give much value to the chemistry mineralogy biology biotic activity and so on the whole classification system is based on particle size so boulders cobbles gravel sand clays silt is that organic matter based on particle size one interesting thing and the philosophical thing is the way the size decreases what happens to the activity of the material it enhances correct so this is how the experiences the more and more experience you are the more and more refined you becomes clear you become and then what happens the activity increases person becomes more productive it is so unfortunate that we do not talk anything about organic matter much in geomechanics why all your tests are related and are valid until 2 microns Stokes law less than that is the what form of the material colloids and colloids are the one which control the properties of fine grained materials maximum I think you are having this discussion sometime back so you will realize that the role of the organic matter and colloids is so much it governs almost 99% of the properties of the fine grained material but we unfortunately ignore it why because we do not have tools to characterize it it is so sad are you realizing the limitations are there and the logic given to the limitations is do not consider them this is not correct so modern day geomechanics concentrates mostly on less than 2 micron fraction why because this material is the most notorious most active and most creative material that creates what you want to you are getting this point so this is a very interesting flaw I think you will realize that because of the limitations of detection of a certain phase we have ignored it completely are you getting this point so look at few symptoms I am just trying to draw a relationship between you know the human body and the soils with which you are working rocks we are not working remember because I said that they are the parents the chances of they are getting contaminated adulterated delineated clear affected are less as compared to the offsprings which are innocent young might get affected more clear so we are trying to draw a relationship between or understanding between you know soils and the human body because once you understand human body then soils can be mastered better most of the tools are same by the way so soil is a particular material all of you know and still it is much more complex than steel steel is made by human beings correct so between us and soil is what steel because we created steel rocks are naturally occurring standard material created by nature the standard material created by human beings steel then human beings and soils it is a four phase system now you try to see what happens so most of the time you must have realized the properties of soils depend upon soil type you always say what is the soil type size of the grains shape of the grains what are the minerals which are present in it agreed then we talk about what is the second thing which we talk about water content air content degree of saturation the way you divide these studies is conventional geomechanics two phase system unconventional unsaturated soil mechanics three phase system and today I introduce in the lecture multi phase system electrochemical effects we will be talking about them climatic effects I think I have given you enough indication about how humidity temperature pressure permafrost conditions influence the properties of the soils stress history this is what we were discussing sometime back memory effect so soil understands what is the OCR what is the QCR what is the NC material and what is the pre-consortion pressure so look at the response less than pre-consortion pressure it is OC material more than the pre-consortion pressure it is NC material you keep on repeating the loading unloading what happens the NC behavior becomes almost uniform clear it is a continuous curve whatever perturbations have happened in between they become a loop hysteresis I was talking about and that goes into the memory of the system that has been exposed to this much pressure in the past still in my opinion predicting soil response is easier than predicting human beings response why human beings are much more complicated but what do we do we try to understand the response of soils in accelerated environment decelerated environment extreme environmental conditions and so on why because these type of conditions exist somewhere so the main emphasis of environmental geomechanics is to simulate all these things and the logic is soils are more workable you know than the living beings and living beings have come out of the soils so this is the complete logic look at the symptoms which are common between human beings and soil just to make you sure that what we are discussing had lot of similarity you know obesity people like us meet particularly what is this aneroxia then we talk about high blood pressure most of us suffering with that then we have greediness agreed then we have epilepsy then we have fractures then we have petting and the last but not the least is urinary problems a geotechnical engineer deals with all of these issues in particular the last one much more see page problems everywhere so obesity is expansive behavior of the soil you eat too much you absorb too much water soil aneroxia shrinkage clear instability high blood pressure over pressure then we have greediness instability of the system epilepsy liquefaction loss of sense so particles start boiling fractures failures is it not failures of different types collapse of the foundation retaining walls the structure which we are making on the system what is fatigue cyclic loading so you keep on doing cyclic loading 550,000, 10,000, 1 lakh this is how you design your pavements you want to see what is the resilient modulus of the system when it collapses clear and urinary problem which I have already talked about drainage conditions for us very very important otherwise everything will be in a mess look at the bodies of the dams we design filters drainage conditions and so on so what are the challenges and the concerns which we are facing as a professional any idea the bottom line of the whole discussion today is that I cited few examples where I was trying to show you that the systems with which we are dealing soils is live number one and when we understand the human body better in today's world you know medicine and surgery has advanced quite a lot but not our subject our subject is not advanced so much still we are talking about the old concepts so there are challenges there are concerns how to first of all change the subject itself how to lay the foundations of new concepts and some of the new concepts I have discussed in today's lecture so what geotechnical engineering professionals should be involved with what they should be doing 3 things diagnostics so look at your soil mechanics course the way it is taught first 5 lectures are only testing you know classification how soils got formed how they were depositing residual soils are like this transported soils are like this fine-grained soils are like this coarse-grained soils are like this hundreds of tests are done to characterize them even the shear strength here is also diagnostics under the action of a normal stress confining stress and shearing how the material is going to behave so when we say NCOC behavior we forget about the material whether it is sand or clay we do not bother we simply talk in terms of state of stress it is immaterial whether we are dealing with the sands or we are dealing with the clays so diagnostics is very important like medicinal medicine medical sciences most of the efforts are being made by geotechnical engineers particularly environmental geomechanics guys to understand the material symptoms and abnormalities so our profession is mostly go to the site try to understand what is happening and unfortunately you will not find any of these things written the books because subject is young the type of pollution which you are producing from your industry might not be similar to the one which is being produced anywhere in the world so the interaction with this system is going to have with the soils and the rocks is going to be absolutely different as compared to the one which has ever been studied so this becomes more of a case study type of subject evidence based are you getting a feel of this so take each case as the way a medical practitioner takes a human body each patient is different the medicine which might work on me will not work on you we are different in constitution so here most of the effort is on understanding the symptoms and abnormalities and once you have understood this and this is diagnostics for which there are several tests we will spend lot of time studying the geomaterial characterization I will spend lot of time in making you understand how physical characterization is done how chemical characterization is done how mineralogical characterization is done how biological characterization is done how thermal characterization is done how electrical characterization is done, how magnetic characterization is done of the soils. So, this is going to be very intricate and then once I have done the diagnostics characterization I have understood the problem a bit I will start treating the material clear. After diagnostics what medical practitioners do they prescribe you something they write down prescription. So, take this, this, this is medicine and see me after 2 weeks, 3 weeks, 1 month clear and slowly and slowly it tapers down medicine also. So, first is adequate correction and then comes prolonged monitoring, follow up, patient is very serious put in him or her in ICU. So, we want to monitor, we want to see how effective the prescription is so most of the techniques which are used now a days in geotechnical engineering are monitoring. And monitoring is done with the help of either satellites or with the help of sensors or with the help of electronic gadgets it could be x-ray based, it could be SEM based whatever. So, we will discuss all these things quite in details alright.