 the course contents, the reference books as well as the examination which is nothing unique as per the institute norms. So let us start our discussion on you know because the geotechnical engineering is basically the mechanics of soils alright. So it so happens that this is the material and the mechanics you are aware of all of you have studied fluid mechanics you have done any course or not yet you still you are doing this semester already finished very good. So you have done fluid mechanics, you have done solid mechanics, you have done engineering mechanics. So mechanics nothing but the tools which we are using to understand the response of the material and in this case it so happens because we are talking about the geotechnical engineering our material is going to be either soils or rocks alright. Now there is a very interesting interplay between the soils and the rocks. So it is a good idea to understand what is the origin of the material all of us have some heritage alright we belong to some place linkage and so on. So the origin is the first question how soils are formed. So in today's discussion I will be focusing on how soils as a material which is going to be used by civil engineers particularly geotechnical engineers alright for various applications. So the materials part is either soils and rocks and then I would like to see what forms what rocks might form soils which is the normal process but it might so happen that soils might also form rocks I hope you are aware of this is it not. So it is a reversible process parents definitely they give you know they create offsprings sometimes it might happen that the offsprings might also create something which is look alike parents. So we will talk about the origin how the origin of the soils has occurred. In the process we will also try to define what this material is we will try to define the material soils alright the most important characteristic of this material is it gets formed by some process and then it gets either transported or it remains at that place only what is known as residual now this is what is normally known as formation okay. So the first thing is origin before that comes how to define this material how the formation of the soil occurs and this is where we will talk about several issues like conditions of formation. Now formation is a very deceptive alright say incomplete term it might so happen that the formation could be you know strata itself is also known as formation so suppose if I say that this is the ground level normally we define the soil surface like this is what is known as geo-microbiosphere so anything which is existing below the ground level is our domain alright so this is the domain in which lot of geo is earth and in this system there could be microbial activity there could be different type of activity which might be taking physics might be occurring physical chemical and the logical thermal and what not. So if I say that the whole strata is stratified strata is plural and stratum is singular so each of this layer if I say layer alright number 1, number 2, number 3 and so on unless you hit the mantle or the core these are all the layers layer 1, layer 2, layer 3 alright so the strata is the entire thing strata is layer now as I was saying the formation could be connoting to please remember these few words in the beginning of the course then our language becomes same and I hope you will not have any difficulty later on. So if I want to define the layer number 1 this is the formation clear now you must have realized you know somewhere here we have hills you know Himalayas and somewhere down the geographical line this is you know this would be let us say Oogle and I hope you understand why I am drawing this this is the journey which the entire system is going to traverse means travel what is going to happen here because of various activities like the system is going to get fragmented those of you who might have gone for trekking in Himalayas or the hilly terrains you must be realizing lot of boulders big piece of the you know rocks they keep coming out so that is one process which is what is known as weathering we will discuss about this later on. So it so happens that the big chunks of the rocks they get detached from the parent body by some process it could be physical take a hammer start hammering it the system gets you know converted into small small pieces there could be a chemical weathering taking place alright because of the chemical actions and this could be the fundamental property of the soils or rocks there could be a combination of the two there could be a thermal activity which might be occurring over here temperatures go very high and the system develops thermal stresses cracks develop when the rains come all these cracks get filled up with water and these boulders start rolling down alright. So this is what actually we are going to talk about so formation includes how ultimately traveling from point number A to somewhere in the plains you know water plains, gangetic plains so those of you are from the central portion of India Delhi UP Uttarakhand not Uttarakhand Uttarakhand still goes into the hilly terrain so these are the plain areas where the slopes of the you know ground are not much and then ultimately what happens this thing over comes over and gets into a ocean is this okay. So this whole journey A to B to C we are trying to capture 2, 3 things which are very important how the fragments get formed in other words how the soils get formed what is causing them to come from A to B this is what is known as a transportation agency. So formation is going to depend upon the cause you know and this cause is going to be mostly weathering and this weathering could be either physical chemical it could be even microbial alright sometimes people also call this as a biological and this could be the combination of X, Y and Z as well so this is as far as the formation is concerned. The second term which will be going to introduce which we are going to introduce would be what causes soils and how they get transported in your opinion what are the transporting agencies which you might be aware of which would move the fragmented portions of the rocks from A to B and B to C very nice so transporting agencies would be either water yes in most of the cases this is water sorry rains, winds, air nice good next sorry very good it could be gravity yes why not what else so it so happens something detaches over here because of the weathering action so weathering is nothing but disintegration this causes this integration alright is this part clear are you realizing the material with which you are going to work is this okay so it depends upon all these things it is a big matrix water, air, gravity anything apart from this which might be transporting agency living organisms will not transport the soil their role is different so living organisms what you are trying to connote to is microbial activity that is responsible for creating the weathering process or disintegration of the rocks fine I mean I cannot justify your answer so anybody else you think that living organisms yeah human beings if you are saying then yes that is possible we are the biggest culprit is this okay so mostly you know have you have water you have air you have gravity you have human activities another interesting thing over here is see some very intelligent material soils we will talk about this later on why it is so intelligent because simple answer is it gives rises to it gives rise to the entire what you call it life this is correct or not life originates from soils so we talk about the cause we talk about the transportation agencies there are few materials which get disintegrated but unfortunately they cannot get transported so we talk about deposition characteristics and normally we term them as residual which one is going to be more experienced more knowledgeable more workable all adjectives which you can think of you should attribute to this a person who stays all the time in his or her home or the one who comes out travels meets people takes his or own decisions there is a lot of similarity between what we are studying and what I just said look at the process they were form somewhere because of some external agencies fragmentation took place the second thing came in the picture transportation it carried the material up to a certain distance and this distance could be geological distance of few thousands of kilometers agreed in the process what is going on all these agencies are giving lot of rubbing effects abrasive effects you must have seen when you go to the Himalayas you know big big boulders are lying over there but as you come down towards let us say Kanpur Varanasi Gaya and all these areas what happens all these big boulders have got converted into a small particles sands clear so this in this process of grinding the type of grinding which you are going through at IIT Bombay what is happening you are becoming more knowledgeable or no whatever it is so you are getting exposed to different type of environmental conditions this is correct so a system which gets transported because of the transporting agencies keeps everything in its memory so it is not a inert material it is not a dead material it is a very intelligent and live material all right this is another attribute of the science so this is memory based and no wonder why silica is used as a basic ingredient for designing chips because the basic constraints of the entire thing is silica so we will talk about this memory effects in the material alright I will be using this term quite a lot what is memory of the material there is no other intelligent material like soils in the history of civilization steel do you really talk about the memory effect do you talk about how it was formed do you talk about how it was deposited you know how it is going to behave how it is going to react no we do not use these terms at all so that is the difference and that is why it becomes very important to study the mechanics of the soils this is part clear so we will talk about all these things coming to the second thing which was talking about the depositional characteristics how the deposition is taking place whether the soils are residual or they are transported so I was giving a logic the guy who never came out of the house he was born in the same house alright attend youth in the same house and became a big person in the same house and is also going to die in the same house there is something of this sort residual means the disintegration took place over here unfortunately there was no transporting agency transporting agency is nothing like teachers like us who might be carrying you along with us to some destination is this okay and then depending upon your fate you may get deposited somewhere you may settle down in a profession clear so this is what the depositional characteristics are there are few guys who remain in the profession for 20 years like me 25 years 30 years they might be getting rotten and they are another breed of the people who keep on changing their jobs every now and then another similarity are you getting this point so these guys are going to have a very different type of characteristics and memory in their brains so this is a very interesting thing which we can use for designing our structures when we are dealing with the systems which are either transported or which are is this part okay because what is my job my job is to put all of you in order I told you 2 o'clock means 2 o'clock everybody is there so I am going to dictate tomorrow with this material as another this material look this is how you have to behave because I am a technologist I am an engineer I want you to behave like this are you getting this point and that is what the engineering is all about that is what the technology is all about so I have a material clear I would like to dictate with it how I have to use the principles of mechanics which is nothing but the physics and mathematics put together tools understand and in the process all this happens ask any question I think I have given you the preface of today's discussion rest is all bookish if it is not clear please discuss so this is the preface of today's discussion anything which you like to add so suppose somebody asked you a question introduce yourself you are asking something last week you remember down the stairs yes suppose somebody says introduce yourself how would you introduce yourself this is the introduction of the material clear now make it a habit wherever you go in life today onwards Google where you are what type of soil deposits are available there you will learn a lot of things and if possible make it a habit to collect some samples also system retains what has happened in the past all right so the memory is what when you came here you are carrying some imprints of what happened in your childhood all right so when we talk about the engineering issues associated with the material we will talk about what the material carries in its mind clear and based on that it has a tendency to behave to exhibit its response so my name is Ankit Ankit yeah so how microbial weathering takes place okay that is interesting thing I think you should search it out on Google read some papers if you are really interested what microbes produce any idea microbes in soils produce gases and these gases could be hydro carbons agreed so imagine the system it is like a control volume where there is a lot of organic matter I do not know I should not have introduced this word right now but I am introducing you can capture all these things so this is organic matter all right so wherever the organic matter is the bacterial activity is going to harp so this is the bacteria inside and what this bacteria is going to do organic matter provides nutrition carbon nitrogen sulfur all right hydrogen oxygen and so on now what is going to happen you have provided enough food to the bacteria what is going to do it is going to be active what it does it eats up the material disintegration started it is a microbial or biological disintegration of the material deterioration of the material clear lot of R and D is being done in this context and those of you are interested in going for higher studies should note these words carefully geotechnical engineering has a lot of potential for R and D both in the industry as well as academics so my emphasis is to give you more ideas about what is happening in the world today rather than bookish knowledge all right so is this part clear so what microbes do they try to eat up the system at the same time they might create the system also so they act both ways so they may deteriorate or they may upgrade any system a good example of this is please go and check in on the net MICP these are all research ideas so this is a very interesting area in which lot of research is being done in the area of geotechnical engineering soil mechanics microbial activity and just check it on the net is this okay so what bacteria does is one of these processes if this is happening I should not bother but if this is happening the system follows the chain this onwards correct so this is the microbial disintegration fine I just wanted to provoke your thoughts what humans are doing I want to create a time in Bombay Antilia from where I brought all the materials geomaterials from somewhere in the minds of Rajasthan clear or let us say from Orissa or some south you know there are a lot of stones which are available in Kadapa region so humans also transport the material a beautiful example of this would be reclamation so most of the islands which are being created all over the world how many islands have been created in last 2-3 years look at the geography of the world of the world it is not stationary you know when we were kids we used to use the same book for 30 years the Atlas now what was happening Atlas keeps on changing every month yesterday something has happened it is a good example now so what has happened the geography is going to change so South China see what is happening China is expanding next time when you go to Singapore when you are landing just sit on the seat number a or last one edge and tip down what you will see a lot of activity going on in the ocean what do they do they bring soils from different places they dump them over there and they are creating islands you got the answer to your question so humans are also becoming extremely notorious in transporting the soils but this is how the civilization is how many islands India has constructed in last five years all strategic check it on net you understand so the geographical boundaries are changing why because it is my wish I would like to bring material from somewhere and dump it somewhere the same process I am following look at this the material was created by human activity by mine it I brought it in the barges over the pipelines or whatever I transported it and I deposited it so what nature was doing in millions of years I have done it in 5 years 10 years palm islands pearl islands world islands these are beautiful example of creation of land ok so human activity is associated let us say with the land reclamation search it out more yourself about this thing this itself is the formation of rock shall I add man made this is okay microbially induced calcite precipitation now because of this what is coming out of the bacterial secretion the system gets upgraded formation of rock takes place I can use it for my different applications very good question yes sir how a chemical can be used how can suppose if I go somewhere on the hill it rains and I carry a say 100 liters of sulfuric acid concentrated 5 molar sulfuric acid and I will pour it on the system what is going to happen chemical interaction clear so you are adding something chemically to create disintegration or weathering of the material clear so this could be by hammering as I said physical it could be chemical you add some chemical compounds in it have you ever seen any blasting which was done in any of the projects you know in the rocks so what do they do they drill holes they put chemicals and then they wait for 24 hours and what happens room clear the rock becomes this this fragmented is a chemically induced weathering of rocks for making highway projects is there any natural chemical phenomena phenomena of weathering good question have you heard about arsenic oozing out of soils in the western eastern part of the country this is one of the chemical processes which might be bacteria driven if you see any acid acid in pH it will be less than 4 point but go to the genesis industrialization and too much of industrialization means that most of your industries are emitting socks nox box so all these things will be in the environment and then what happens so when clouds forms these gases will also get trapped inside the clouds okay so when it starts precipitating rains precipitation means rains when it start precipitating that sulfur sulfur dioxide nox nitric oxide anything will get mixed with water and it will turn it into acid because yes because yes because so it will get precipitated on the rocks like if first of all such kind of rain happens in the region of Himalayas so the kind of chemicals that were precipitated over there might try to might trigger the disintegration of the rocks correct any other example which comes to your mind is this okay you have understood acid rains are a good example of how human activities are going to create more and more chemical weathering of the system including the buildings which you have constructed so let us start now with the conventional discussion let us say how to define soils you will be surprised to know that this is the material which has several definitions you know why so everything is a material so when I say define soils you say this boy is not very good very casual remark oh he is excellent he is a ten-pointer whatever you say like this you define a person by using some attributes in this case what happens is most of the attributes are a function of so it so happens that these functions these are the functions of the profession you understand is such an interesting material what is the meaning of this what is your name say your name at least Ashish sorry why you cannot follow my words or what so the definition of the material depends upon the attributes which are profession dependent how would you complete this statement depending on properties the function of the soil not the function of the soil I said the definition of the material depends upon the attributes and one of the attributes is the profession in which you are what is your hobby what you do apart from that poetry apart from that so suppose if you are a pottery maker many people who do sculptures is it not how would you define soil by the way most of my research on cracking characteristics of soils you know my guru was the guy who came for mood and ego who was doing your pottery making I called him in the lab and then after that I might have guided I do not know two three PhDs and several papers which I have written on cracking characteristics of soils and my question to him was that why your pots do not crack because this is the answer which BCC I was looking for and I was a consultant to BCC I hope you are aware of before 2011 World Cup I made their pitches I gave them a recipe so my big question in the mind was that let me create pictures which will never crack of course the spinners will not be very happy with me so why I am telling you this is this story is because if I am in this profession what would I like I would not like any system to crack but just now what I had said if I am creating pitches a spinner would like pitch to crack in the third hour of the match why then we have so many in our team we will go and finish the game in two days you are getting the point so what I what twist I have given the material is defined by the attributes which are mostly dependent upon the profession so you might be a border sculpture or you might be a player in what type of games you use soils in what type of sports you use change soils or what number 2 yes okay see my connotation is more on the terms very nice good in London is how many types of tennis you have varieties why how many types of courts you have yes now you could link the subject with the practice are you getting the point so why do they have these four grand slams why they want to test whether this guy is going to be a winner on all type of terms or not remember so you have clay courts clear you have grass courts also which one is grass courts we invalid excellent you are right so that means depending upon what sports you are playing and what are the requirements you can play with this material you can define the material is this okay football is not a very direct answer it should be either mostly tennis where the ball impinges and then you must have studied your mechanics course reverse English forward English all those things have you heard or not earlier ethnic 10 plus 2 physics no swing why the ball swings late cutter in cutter all these things are derived by the material properties if I can control over here everything the response is going to be different understand so it is nothing but the engineering properties which I have to modulate and the pitches are ready so tennis course is a good idea your cricket pitches are very good idea anything else apart from that basket ball not going to be of much because he but it is about you do not imping the ball intentionally on the ground when you are playing of course for bounce and all fine so anyway so this is their agriculture is a big profession is it not farmers of the country how do they check soil they do not have a laboratory what do they do they will just touch the soil they will rub it add some water again rub it smell it and they will tell you whether this type of soil is good for this particular produce or not why why they are so experienced I mean they must be checking some attributes for them the requirement of the soil is different fine suppose I am a florist you know what is florist the guy who is producing flowers they are very particular about you know a type of soil which should be used for creating a sudden breed of flowers it is a big business apart from this any other profession quickly tell me what are the other professions where you use soils sorry yeah construction okay so we will keep ourselves we will place ourselves engineering electronics not in the soil form so is extracted form of let us say silica which is one of the constituents of the soils so I will not put it in this matrix because of this reason alright we are talking about right now natural systems and professions okay but the answer is good at nano level we can think of yes any other profession sorry mining will come in engineering S&T let us say science and technology beauticians skin care where do they use soils you never bothered about it no Vargavi Vargavi yes please okay nice so