Video 1: Response of the Soil to the Environment
Now, comes the issue that you know, how, what is meant by the response of soil to the environments;different type of environments, I think I had discussed about you know soil and structures,we interact with each other, we call them as soil structure interaction and soils areused to create a structures and sometimes, structures are created in the soil mass orsometimes where structures are created on the soil mass, clear.So, laying the foundation is on the soil mass, making embankments, different type of returningstructures with the soil mass and when you are creating conduits, cavities, tunnels,this is inside the soil mass.So, soil structure interaction is a very interesting question, which people are trying to address.Yes, each of these statements which I have talked about on in a web has environmentalattributes associated with it, clear.So, when you are talking about the aerobic, anaerobic conditions as deeper you go in thesoils, you will be having switch over from organic to inorganic situation, alright, theseare good example.So, different type of environmental conditions might be associated with the systems whichyou are talking about.Now, pore fluid is the one which is present in the pores in the form of either gases orliquids or the combination.And present day you know, way of looking at this is when you derive a parallel or equivalentbetween a human body and the soils is; if I can diagnose you by taking some sample ofyour blood, alright similarly, I can diagnose the soils or geomaterials by taking a sampleof pore fluid.So, pore fluid is the one which is present in the pores either in the form of the liquidsor in gases, we will discuss this in detail, how to extract pore fluid.Because there your syringes may not work what doctors do, is it not, very difficult to takeout pore fluid from the soils.So, what type of techniques are used to sample pore solutions from the soils and the geomaterials,it could be concrete, it could be rocks, it could be soils, this has to be studied ina very, very different manner.In other words, the pore fluids also depict the state of the environment which is presentinside the soil mass, clear.The temperature, the pressure, the humidity, the type of bacterial growth under aerobic,anaerobic condition, the type of gases which are getting form are an indication of whattype of processes and the mechanisms are happening in the soil system.So, pore fluid characteristics are becoming very, very important to discuss.Interaction of soil with heat, I think I gave you ample examples.You know, when soils come in contact with elevated temperature, this could be a forgingunit, this could be something like you know, you might be having a furnace, foundationfor a furnace or you might be having a rolling forging units somewhere in an industry, wherethe drop; hammer drop produces a lot of heat, rocket launching pads you know, differenttypes of cables which are buries inside the soils for industrialisation.And most of the time, when you do ground improvement, you inject chemicals in the soils and thesesoils might react with the chemicals.Nuclear waste disposal is a good example of how soil heat interaction occurs; nuclearwaste is at elevated temperature.Similarly, leachates which are coming out of the landfills might also be at elevatedtemperature and this might react with the soils, alright.So, I am sure you must be realising that these issues, these types of interactions have notbeen discussed until now in the conventional subjects because the conventional subjectsare devoid of the environmental conditions in which the soils are living or located,alright.So, soil chemical interaction I am sure now it is clear to you, contaminants getting dischargedeither inside the soil or on the soil mass would create a soil chemical interaction.And you want to see what happens after the interaction occurs, soil bacteria interaction,I gave you ample examples, you know, pathogenic discharges, these sludges are not treatedproperly and if you take out the sediments and pile them up somewhere, this is goingto become part of the geoenvironment.Soil root interaction; I think we discuss about this so, those of you, who might geta chance to work in stabilisation of soil based on vegetation is picking up.And this is being done at several places in my consulting also I have used this conceptof soil root interaction at different tailing ponds in the country and where I have recommendedvetiver grass, if you aware of vetiver grass; vetiver is the name of the grass, it growsvery fast and the roots penetrate through the soils, vetiver, vetiver, so this is thevariety of the grass which is you know, quite commonly available or you can transport itand you can grow it on the slopes of or embankments.So, the beauty is the root acts as a reinforcement and it hold the soils, you check the photographs,I will also show you it is a good example of how soil root interaction occurs.If you look at the physics behind this, roots produce suction, alright and when suctiongets created, truly speaking this becomes a soil suction interaction, clear, a 3 phasesystem that means the pores are now filled up with air, water.And this dynamics of the air and water guides the properties of the soil, similarly soilbacteria interaction also does the same thing, bacteria might be producing gases becauseof decomposition of the organic matter and once these gases produce and they remain inthe soil, the whole system becomes very susceptible to temperature and pressure, alright.So, these type of dynamics people are studying.Then, of course soil electrical; electric or charge you may say interaction, so soilheat and soil electric phenomena could be coupled also, passage of current through aconductor produces heat, alright, so this is a very interesting mechanism where peoplewould like to study what happens.Water present in the soil is a dipole, clear; it is a polar material, polar liquid.So, now if the polar liquid gets exposed to the electric magnetic field, how the propertiesof the fluid themselves will change?Alright, so these type of things become very important when you are talking about differenttypes of sensing tools which you are using them whether electrical signals are used todetect something in the soil mass, I will talk about this separately in the form ofelectrical characterisation of soils, thermal characterisation of soils, chemical characterisationof soils, biological characterisation of soils and so on.The last in these series would be this soil and liquid, water interaction so, I am sureyou must have come across that the soil which contains water and this water is of differenttypes, you call this as an environmental water also, we call this as a you know gravitationalwater, free water, water, bound water, adsorb water, so these concepts are becoming very,very pertinent in discussion nowadays.
Video 2: Case Studies
So, just to show you some of the examples of you know how this is being done, I thinkthis is what I had been talking about, I will show you few cases where the type of problemwhich I am dealing with you know, this is the beautiful example of the problem withwhich most of my students are related right now.Hindalco industries is the largest industry in the world which produces alumina and productionof alumina is because of digestion of bauxite.So, whatever residues are left over, this is known as red mud, now the question is;where you are going to throw the red mud, so this is becoming a big problem for thesociety and hope you can realise that lot of dust is there and you know, the disposalplaces have to be defined very clearly and if you see you know, these are the red mudponds and I do not know how many of you have visited such type of red mud ponds.A huge area are about 100 acres land where the height of the landfills or the heightof the disposal ponds would be 40 metres, it is a huge challenge, you know, the moreand more bauxite which you are digesting to produce alumina, the volumes of the red mudwhich is an industrial by-product is increasing and if you research on this subject, you willrealise that red mud contains lot of caustic in it, so its pH is about 12 to 13.So, you are stacking a material on the surface of the earth, which is highly basic in nature,clear so this is a hazard associated with this.Now, the question is how would you handle this, how would you; you know, dispose it,whatever, these are the challenges which we are supposed to handle.Now, look at the second situation which I have included over here, they have severalunits in India which are operating and this is from Utkal no, this should be I think fromBelgaum, I do not know whether you have seen this or not, this is the refinery; aluminarefinery and when you drive from Bombay towards Kerala or Karnataka, then on the way, youwill realise that there is a big stack of you know red mud and this is the Nationalhighway, Mumbai highway you can see.So, handling disposal maintenance of this type of huge disposal facility which havebeen created as a you know as a consequence of modern-day civilisation is a big challenge,brainstorm your session; to brainstorm and give the answers to the industry.This is the eastern part of the country, from Utkal which I have taken, I do not know howmany of you know this place, it is in Orissa, so this is a unit where the processes beingdone and the disposal is being done at several kilometres away, so piping, pumping of thered mud or the industrial by products which are coming out is a big issue.So, designing of these retention ponds is a big question, big challenge unfortunately,not many people are aware of you know, the practice of dealing with the waste which ischemically activated, had it been soils 200 years, 500 years, 1000’s of years, peoplehave the experience of handling with these soils and making retention system but whenit comes to the chemically active systems, how would you handle them, how would you usethem, how would you create something out of this is a big question.Another example I thought I will show you is of again Hindalco, this is from the Renukoot,in the Mirzapur district of UP, so look at this, I mean these are the; so this is theRenu river and you know this is the belt, where most of the thermal power plants orlot of mining is going on and this is the huge plant where the alumina refinery is Renukootand look at this the way the red mud is being disposed and now the question is how to tackleit in a scientific manner.And you should read about this accident which occurred sometime back, Ajka aluminium plant,you know which happened in Hungary, so these are the you know slope stability issues whichyou should be dealing with as an environmental geotechnology; geotechnologist.These are all soil, water environment interaction examples.So, WCL coal mines, where a lot of acid mine drains and drainage is taking place you know,if you see, zoom this system, you will realise that lot of mining is going on, you know theseare the extra deep mines or which WCL is trying to do and this is where I work on the miningissues, geoenvironmental issues let it to mining operations, these are the extra-largemines, the diameter would be about 7 to 10 kilometres.And they are trying to go up to several 100’s of metre deep in the ground to excavate thecoal, so these types of problems you can realise now to see you know, you can imagine thata large portion of this soil has been cut, so these slopes remain unstable most of thetime, you have to stabilise them, I am doing a project right now at WCL Bhanegaon project,this is what is known as Bhanegaon and I hope you can realise that if I tell you the intricacyof the things you know, this is the river.So, most of the mines are you know in the vicinity of the rivers, alright, look at this,this is the confluence of the mine for the rivers, this is one river and this anotherriver and this is where the mines are located, so lot of discharge takes place when you excavateand you know that becomes a very critical issue that how would do mining against excessivedischarge.Remember, these are simple slopes stability problems.But when they are having an issue which is associated with an environment, it could beseepage, it could be chemicals, it could be temperatures, it could be bacterial pathogenicand so on, so we are talking about different type of situations, while these are the challengeswhich we have to face as a geotechnical engineering in today’s world.This is our landfill, extremely close to IIT campus, this is the Deonar dumping landfill,when you go towards VT from the eastern express highway, you will realise there is a hugeland and when you are landing inside the Bombay city, you know when the pilot announces crudestations, landing ex-stations, so point if you start looking at down, then you will realiseyou can see some part of the landfill quite clearly.So, this is another issue where landfill fire took place in the recent past, the whole Bombaycity had tough time, you must have seen the photographs which was released by NASA about2-3 years back you know, show the magnanimous nature of you know how much the landfillsare responsible for polluting the water bodies, if the designs are not done properly, so whatyou are seeing over here is this is the Deonar dumping and look of the population; the populationis just right up to the brim of the landfill you know, they are in fact living over there.Because they do not find the land, so this is the modern day civilisation which we haveso much proud of, I hope you can realise, look at the densely populated areas in thevicinity of the landfill and then there are water bodies, streams of water which are gettingpolluted because of landfills, leachates, or the gases which are coming out of it, alright.So, this gives you about an example of what type of interaction we are talking about.So, I have talked about different sectors, industrial processes and even the you know,at municipal level also the type of pollution which is becoming a big threat to the modern-daycivilisation, mining, dredging; we will talk about all these sectors slowly and slowly.“Professor – student conversation starts” Actually, you are saying that you are workingwith WCL sectors in case of mines, so what is the actual problems they are facing, canyou please mention.All problems and problems and problems, nothing which is not a problem there starting fromsite selection to dumping of the over burden to creation of the material for reclamationof the mines to stability of the mines, to seepage in the mines to toxic water whichis coming out of the mines, where to discharge it, how to treat it, how to put it back inthe rivers to social issues, political issues, agricultural lands lost so, many things howto minimise the area where this stacking can be more and more higher that is what everybodywants.Then, how to utilise this material for other purpose, “Professor – student conversationends” yeah so I think I can show you the lagoons also in fact in Bombay, this is theGhatkopar lagoon you know, have you ever seen a lagoon, so these are the aerators, whichare aerating yes, mixing and aerating, so that these water gets cleaned up, so theseare the aerators which are installed over here and yeah, “Professor – student conversationstarts”.Sir, is it possible to quantify the strength that is provided by the vegetation, roots,is it possible to quantify the strength; quantify, yeah, of course, yes, lot of papers are there,it is a new subject all together, so they do; you will be surprised to know that thegeotechnical engineers take out the roots and they find out the tensile strength ofthe roots also and they implement it in the models which they have done; 3D models, sothis is where the subject is.All sorts of interactions are being modelled now in your software’s, how the propertieschange over period of time, I remember I had written a proposal where I wanted to see howroots migrate in the soil, I wanted to capture everything electronically by using a set ofsensors and then I want to relate it to the growth of the canopy of the tree, somehowthis project was not funded, all this happens, so I wanted to study.Because see as I said a farmers will never study the mechanics of the problem beneath200 to 300 centimetres, alright, maximum, so that is the zone in which they are interested,beyond that is our realm, so we have to understand how roots migrated, for me it is say tensilestrength of soils when the roots migrate into it, reinforcement of the soil because of secondary,tertiary roots and so on.So, my perception of looking at the problem is different, yeah, yes, quantification hasbeen done, please read recent paper.Sir, one more question is that you said about the acid draining while mining, is it possiblethrough non-mining activities like some construction of tunnels or something, yeah, so whereveryou have pyrite or iron sulphide and when it gets exposed to the atmosphere, oxygenated,oxidised, then sulphuric acid is going to get form.And how long will the effect lasts, how long means, no once the acid comes out and startsflowing in the water body, you read about what is happening in the Assam, most of therivers are polluted, people cannot drink water, so these are the issues, so these are thecontemporary issues you should be aware of, you know, what is happening, how would theydo cultivation because the acids are present in the water, this water cannot be used forvegetation.Yes, please, sir, if we compare the strength of the roots of the plants, will that be likecomparable to a geo materials, sir, geotextiles, Reshmi, the biggest issue is without plant,without roots, what is the strength of the material and if I grow them what is goingto happen, so an engineer always talks about pros and cons, clear, so sometimes back Isaid that roots can be used, grass can be used to stabilise the slopes.Now, if I want to quantify the whole thing, I would like to see from initial condition,how much the material has got upgraded or it has deteriorated, you never know, the rootsmight deteriorate the rocks also, you must have seen, sometimes the vegetation on theyou know, concrete creates cracks also, so this is where judiciously, you have to understandthe mechanism, so may be very opened answer to your question is that you have to observewhat is happening.And then you have to understand the whole mechanism, so that’s why I say where mostof these mechanisms, the process require lot of time of your life.Sir, can we use all type of plants means for water; no, there are different types of varieties,I mean you should read in, I mean I am not a plant pathologist; some are good for soiland some or not, yeah, groundwater depletion, I agree with you, yes, yes, yes, so that isa big subject.What type of vegetation and weight of the vegetation itself is going to be a big problemso, suppose you are stabilising the slopes and if you plant a mango tree over there,it is going to be suicidal.Recently, I read in Punjab there was a problem related with groundwater depletion due topaddy cultivation, correct, not paddy, there are few trees which uptake lot of water particularly,eucalyptus is one, there are different type of tress.So, this is where you sit down and you have to talk to the you know, plant pathologist,the guys who are experts in subjects; particular subject, so this is what we do so, like mylaboratory we talk about nutrition of the soils and with this nutrition on the soil,what can be grown, sometimes the nutrition can also be changed, I can create a nutritiondepending up on the requirement that is where the science of or the technology of the soilscomes in the picture catering to the requirement of a project, you create something, alright.So, you have to do all these, if the subject intrigues you when read more and more on differenttypes of varieties of plants, yeah, so another example of the question could be some timeback when I was dealing with a contaminated soil and we wanted to rectify it, so I hadrecommended some varieties of the plants for phytoremediation, so phytoremediation is avery big subject in geotechnical engineering on which lot of people are working already.So, what species of chemicals can be logged, alight, logged in the sense that once yougrow these type of plants, they have a up take capacity and they will sorb all thesetype of heavy metals, concentrations of chemicals and this chemical concentration cannot movefrom one place to another place, passivation, so these are big, big subjects, people likeyou should come forward and study them.Sir, we have seen that soil interaction with heat, chemical etc., what about magnetic field,yeah, so this is less studied but my student one, Dr. Susha Lekshmi, so her thesis if yousee in the paper which she has published is the magnetic characterisation of soils, thiswas published about 2 years back in ASTM, go through that paper and I think our labwas the first to talk about the magnetic characterisation of the soils.And generalise the magnetisation behaviour of the soils, so we are trying to classifythe soils based on their magnetic characteristics and why we are doing this, because we wantto understand the soil moisture content, so you might not have thought by this time thathow critical the soil moisture content is and soil moisture content depend upon themagnetic characteristics of the soils.“Professor – student conversation ends”.
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