 The most important out of all this is energy. I think last year in Goa conference professor Santa Marina spoke about this topic. If you want to go through these slides, I of course I cannot present those slides here because that is a violation of copyright act, but I have a copy of this his lecture and if you are interested you can go through. Well, this is a very thought provoking concept in recent trends where you talk about energy and geomechanics. I think this is a subject which will keep you occupied for another 50 years at least. We understand that there is a increase in demand of energy in the next decades and unfortunately what we have done is we have already exploited the fossil fuel enough. So, dependency on fossil fuels and environmental consequences are very well known to everybody. You take what is coal ash, fly ash. You burn coal to produce electricity industries and whatever you are dumping out is nothing but the waste. You do not know what to do with this waste. The magnitude of the waste is so much that you are helpless. So, fossil fuels are depleting, environmental consequences are increasing. So, what we should do next? Now, this is where actually geotechnical engineering can come into the picture. So, the role of geotechnology extends to all energy resources including fossil fuels, nuclear energy and renewable sources. Any idea? Have you heard of few words which are in being used quite often these days? Kunal? No, that is alright, but it will not give you energy. So, that is actually we were talking about the materials. So, as a material you can utilize as a new material. So, fly ash can be a new material, silica fumes can be a new material. The industrial glass fibers can be a new material which you can what he was talking about carbon fibers can also be a new material which can be used for civil engineering practices. Here what we are talking about is something different. Here we are talking about the materials which are going to give you energy. Now, this is there actually we should remember that the soils are very complex in nature and their intricate behavior gain critical relevance in the context of energy geoengineering. And classical concepts are revisited to gain new understanding. How? This is one of the links we are talking about the frozen ground and methane hydrates. So, gas hydrate is a very big and very new subject in geotechnology nowadays. This is where you require the help from physicist, chemist, material scientist, you know cryogenics and geotechnical engineers. I will talk about methane hydrate bearing sediments which are also known as gas hydrates in the next slide. Now, these are the future source of energy. Once you have exploited entire hydrocarbon in the form of petrol, the next layer in the ground would be methane hydrates. What are hydrates? When you take water put it in the fridge what happens? It gets hydrated crystals are formed these are the crystals of ice. The same thing is happening in nature where the ice crystals are getting formed and methane gets trapped into them clear. So, if I am not very wrong the government of India's budget on gas hydrate project in the year 2007 was 25000 crores on which ONGC is working and reliance is working. And I think in India your KG basin is the place where Krishna Godavari and some parts of northeast where you have lot of gas hydrates potential. So, this is a very good topic for research. The type of laboratories which you require for this are mind boggling. You have been doing triaxial testing. Now, what this requires is triaxial testing along with the methane gas present into the sediments. So, this becomes a multiphase system where you are talking about methane gas, water and sediments and then you are trying to find out the shear strength of the sediments. Carbon sequestration, Kunal I wanted you to answer this point. Yes. So, carbon sequestration is a very big subject in the present day engineering society. Everybody is talking about carbon sequestration. Whatever carbon dioxide is present in the environment well you need not to go so complicated. The best thing is you trap the carbon dioxide and force it into the aquifers. So, the aquifers which are carrying water you think of aquifers which are full of carbon dioxide clear. So, what is going to happen? You are recharging the aquifers with carbon dioxide and this becomes your fossil fuel for tomorrow. So, this is where most of the research is going on right now. This is known as carbon carbon dioxide sequestration or carbon sequestration and so on. Sequestration is nothing, but forced penetration of something into an aquifer or in the ground. So, I have given you lot of ideas where geotechnical engineering profession can head to all right. You want to say something more about carbon dioxide sequestration? Yes. Basically a promising area. Let me go further to explain to you what is a gas hydrate and lot of research. Why geotechnical engineer should adopt this type of ideas and research activities? We should be proud of taking geotechnical engineering by now I am sure. So, basically a gas hydrate consists of a water lattice in which light hydrocarbon molecules are embedded resembling a dirty ice. So, this is how you know the hydrocarbon molecule gets trapped in a cage like structure and it is nothing, but the hydration of the entire thing. So, this becomes a crystal. Now, what happens is that these crystals are lying below the sea surface and normally the temperature at which they grow would be minus 27 to minus 40 degree centigrade. The complexity and the beauty of the engineering should be that you take out from a depth of 8 kilometers, 10 kilometers, 15 kilometers and so on or even less in such a way that their melting does not take place. If you can trap them at a depth of approximately 12 kilometers, 8 kilometers, 10 kilometers, you can get energy from these type of structures. So, what are the challenges? Can you speculate what will be the challenges if you try to tap the energy or if you try to tap gas hydrates? Good. So, temperature is a very big issue. Now, if you do excessive mining, what happens to the ground? Sorry, if you take out excessive water, petroleum, gas, what happens to the ground? Subsidence. You must have heard of subsidence, is it not? This is nothing but land subsidence. Now, if you take out too much of hydrates from the ocean bed, what is going to happen? This will be the subsidence of sea bed. So, you wanted to tap all gas hydrates, but if you are not cautious and your technology is not very good, what you will do? You will destroy the entire energy source in the form of gas hydrates. So, this is a very, very interesting area of research. The challenges are, in fact, this was the proposal which I had submitted to IEO, TONGC for my own research. The challenges are estimation and determination of thermal properties of geomaterials, soils, sediments, rock mass lying in between the sea floor and BSR. The BSR is nothing but bottom simulating reflector surface. This goes up to a depth of almost 2 to 3 kilometers below the ocean bed, where the temperatures would be, you know, is interesting. The water column as you go deep down, the temperature becomes almost 0. So, somewhere very close to the bottom, to the sea floor, the temperatures would be of the order of 0 degree, 2 degree. But if you go further deep down in the sediments, the temperature starts decreasing and becomes minus 25, minus 47, minus 50 degree centigrade. So, this is the zone where these type of crystals or hydrates will form. The geotechnical aspect of this is estimation of hydraulic conductivity. We talk about hydraulic conductivity only till now, is it not? Water moving out of sediments in soils or rocks. But now the days have come where we have to talk about gas conductivity. You are not any more interested in water alone. So, you should talk about the gas conductivity in sediments. What is the meaning of this? The hydraulic conductivity word should get replaced by gas conductivity. Or truly speaking, you will have soon coefficient of fluid conductivity, not coefficient of hydraulic conductivity. So, that is an obsolete word. So, we normally do not use in our research coefficient of permeability. We never use this word. You agree or no, Sushit? What is that we use nowadays? We always use the word hydraulic conductivity because we are forcing water only to seep through the porous system. You replace it by petroleum, gas, crude oil, whatever it becomes, the fluid gets changed. And that is where the difference is in hydraulic conductivity, a small k and incipient conductivity capital K of a system. If you remember the small k equal to capital K multiplied by what? Rho by mu, density divided by viscosity. So, this is how actually the good application would be when you talk about estimation of hydraulic and gas conductivities of these geomaterials or their representative samples. And ultimately what is the idea? The ultimate idea is that we should be able to assess sea bed stability. So, this is where actually because I have been working in thermal properties of soils and rocks. I think they approached us to solve these problems where what should be the flux induced into the sediments which is just sufficient enough to deep freeze the hydrates so that they can be collected in a fluid form. Unfortunately this project did not get materialized because of some other reasons. You talk about landslides, you talk about slope stability. Now here the emphasis is the stability of sea bed. Why sea bed stability is required? One of the reasons I told you, if you are doing something which is very aggressive you may lose the entire reservoir of methane which is nothing but a cooking gas or source of energy. The second thing is ultimately where the vessels are going to stand or where your jackups are going to stand, they are going to stand only on the sea bed. So, you induce any sort of instability in the sea bed. What happens? Further production process or engineering process gets affected. So, this is how actually this is becoming a very important issue which is going to govern the economy of nations. So, most of the people you will find a working I would say good researchers have adopted this type of activities in their profession and they are working on not three phase models, they are working on multi phase models. So, where you have soil, water, ice and air clear. So, this becomes a four phase model. Now let me make it a seven phase model. How? Your air is contaminated with some chemical fumes and solids are also contaminated with some solid form of the contaminants. So, I have added two more phases to this. Now ice may be of different properties depending upon its freezing point and so on. So, it becomes a multi phase system. So, basically the need of the hour is to develop the mechanics of the material which is a multi phase model. So, be ready for that as a professional. Any suggestions? It looks like a star war serial say something. Is this coherent or becoming very incoherent? Sneha, here please. Let us take a few minutes pause. Yeah, let us sum it up what we have discussed in today's lecture till now quickly. Any suggestion, any idea? Yes please. Ravi or shall I proceed further? This was just to wake you up. Now let us come to the subject orient organization. We are students of geotechnical engineering and where we talk about geomechanics and geomechanics has two components rock mechanics and soil mechanics. Most of us do not talk about rock mechanics much. I do not know why, but the fact is this rock mechanics has not got much due as compared to soil mechanics. Any reason for this? The subject is very tough or what? Why? That is right. The soil is degraded from rock. So, what is going to happen? So, most of the time we are searching for some plain areas where we can easily rest upon our infrastructure. We do not explore it like that. We do not expect the building to be on mountainous area. You are saying something Kunal. Yeah, zone of interest as a civil engineer is close to the surface rather than going much deep inside. That is one of the reasons. Wait for some more reasons in the due lectures and let us see what is the main difference why we do not talk about rock mechanics much. Well in soil mechanics we deal with foundations, retaining structures, seepage, slopes, dams and so on. Now this is where I have kept geo environment. Of course, geo environment constitute of both the rocks and soil and the groundwater. Now what happens is this fellow geo environment it constantly threatening or challenging geomechanics. Why? Soil is the young material. He was talking about weathering and soil formation from rocks. A mature person is not going to get affected much by what nature or what society or what circumstances you know. But however, a young material like soil gets definitely affected a lot. Any easiest possible simple example comes to your mind which shows vulnerability of soil to nature that is much much complicated. Sorry, much much complicated. Take some dry soil in your palm, add two drops of water. What happens? All the properties are changed. The color changes, the order starts coming out of it. You feel some burning sensation in your palm if it has more calcium. You agree? So, the idea is you need not to go to all those complexities. I am not talking about that. What I am simply saying is that soil is a very young nascent material and very very vulnerable to environmental changes. Add some water, dry it again. Clear? It gets solidified. Apply a bit of pressure. It breaks, cumbles. It has no strength. Go to the beaches. Dry sand, you cannot walk. A wave comes. All the sand gets wet. You can walk, you can run, you can build a building over it. But again when it dries up, everything is lost. Clear? Look at the look at the activity of the material. You agree or no? It is no more a passive material. It is basically we have not given it much due. We think that what soil is going to do ultimately. Truly speaking, it is a very intelligent material. It knows how to behave in a given circumstances. What are the circumstances? You have added water. It knows it should express its anger, heat, friction, you know. That smell comes out and so on. So, this is what I say. The effects on soils are much more pronounced and the reason is it is a new material. In terms of when you talk about geological cycle, how soils are formed. Rocks are million years ago. Soils are quite young. So, they are more you know vulnerable to changes and that is why we talk about changes affecting the behavior of the soil when environmental conditions are quite aggressive. Clear? So, what it indicates? This indicates that this type of material should be treated in a very different manner. So, this is what my practice is or my idea is when I discuss with these concepts to all of you with all of you and the like-minded people who are doing research in this area all over the world, they treat soil as a very active material be it sands, be it clay or whatever. Any other idea which comes to your mind? It should be included here. Let us proceed further. So, now the question is can you define soil mechanics? So, if you want to understand what is soil mechanics, you have to define what is meant by soil or what is soil? Try some of you. How would you define soil? Binil. Sorry, soil does not understand what is consolidation? Sir, it is the uppermost crust of the earth which is formed of weathered rocks. Binil, okay. Agedic ulcerase. Let us see the definition. It is basically a loose agglomeration of mineral and organic material which is extending from the ground surface down to the solid rock. Anything which is lying above the rock is weathered, but what are its constituents? Its constituents are basically minerals and organic inorganic material. So, when you say that the marshy lands or the marshy soil or the organic soils, they are having a big amount of organic material in themselves and every soil will having some minerals. So, basically the process is very important. See, it is an algorithm where the process are inbuilt in the material. So, when you say a soil is of Aeolian type, everything is you know tagged to this that Aeolian soils will behave like this. Did you follow this point? The soils which are blown up by air, they have very fine particles which can travel hundreds of kilometers and they get deposited. So, many things are imbibed into the properties of the material. Material understands that what it is from where it has come and what how it has to behave and Aeolian soil will always remain suspended in the atmosphere. It will create mist you know in the different type of seasons. If it is very hot, the mist remains in air and if it is very cold, it becomes fog. It knows how it has to behave. You cannot change that property at all. The activity remains you know tagged to it. The second thing is the location. The location is from the surface of the ground to above the rock crust or earth crust and so on. Unfortunately, there is no proper definition for this material. So, it keeps on changing with respect to the profession and the person who is using it. Any example to substantiate this? That is right. Yes. So, what is the difference between a rock and a soil? How would you differentiate between rocks and soils? Have you heard of Moh scale? Moh scale. Moh scale that is one of the ways to differentiate between rocks and soils. For diamond, what is the Moh scale number? 10. 10. What about your nails? What is the Moh number? I think 3. I am also not very sure it is 3 I think. So, between 3 to 10 normally things will fall in. But this is a chalk, talk. Talk is one ok. So, the question is this is a very very abstract way of defining the things. So, is there any definition which is more befitting when you define soils? You talk to a farmer. He does not bother about clay and silt and gravel and stones and all these things. He only bothers about a fertile land, non fertile land. You talk to a potter who does pottery. For him this soil can be used for making pottery, this soil cannot be used for making pottery. Clear? You talk to a person who is a aquaculturist or the people who are doing paddy plantation. So, they love a certain type of soil. For them other things are all useless. Clear? How about the horticulturist? Those who are into the plantation of ornamental plants, roses and so on. So, the idea is depending upon the profession everybody has own liking disliking and a definition for the soil. Clear? So, truly speaking there is no definition as such where you can say that what is soil what is rock. But then the question is very confusing to civil engineers what is soil and what is rock. So, one is moe number another one is sorry yes I think you are very close to what it should be, but what is the difference? See the difference is if you see it in day or in light or if you see it in night the difference should be very pertinent. One of the ways to differentiate is hardness whatever requires cutting, explosion is rock. And whatever does not fall in this category is soil you agree. So, this is a simple definition, but quite practical as far as civil engineering profession is concerned. I think time is also over. So, I will continue in the next lecture.