 In the last class, last to last class, we have discussed, we are discussing about the dams. So, one part is remaining about the type of dams that is embankment dams. Embankment dams are massive dams made of earth or rock. They rely particularly on their weight, own weight to resist the flow of water just like concrete gravity dam. If you look at this embankment dam, this is your foundation and this is your heel and toe and crest of this and this part is your total from here to here is considered as a width. Then there is a reservoir, then there is a reservoir, then upstream face, then this is your total height and plan view upstream face and downstream face as well as span has been shown here. So, embankment dams may be classified as three parts. One is your simple embankment that means homogeneous throughout upstream less permeable material. Then second is your impervious foundation and third is your impervious core or zoned embankment. If you look at this embankment dams, generally have some sorts of water proving inside called the core. So, this part is, this is your core, it is a water proving and this part is called core material which is covered, this core is covered with earth or rock fill. It has been covered with earth or may be it is your rock fill. Water will seep in through this earth or rock fill, but should not seep into the core that means water will pass through this earth or rock fill and it should not seep through this core. The water will seep into the core material and should stop at the seepage line. If I make it into, if you look at this embankment dam, it has been generally considered with this earth or rock fill and inside this earth and rock fill, there is a, there is, this is called core or it is a core material. Generally, in this core material is called water proving that means it is not completely water proving that means the seepage through the core is less as compared to the seepage through this rock or pervious materials. So, forces on this embankment dams, you can say that main force is because of your water. Then another one is your uplift force that means water passes through this, then there will be a uplift force. Embankment dam, this figure, it is one of the example Wolf Creek Dam in New United States. This is built on by embankment dam. Then coffered dam, another part is called coffered dam, these are all temporary structures, temporary structures made up with silt, pile or watertight that allow construction operation. That means temporarily it block, temporarily it block this water flow so that in one side you can do this construction. So, if you look at this, this is your temporary or coffered dam where you can do this construction work. That means it allow or it diverse flow from construction area. That means inside construction area it will not allow water to flow, it will divert this water from this construction area till this work or construction has been completed. This is called coffered dam. In Hoover Dam one of the example, this is 726.4 feet high and 1,244 feet across at the top and 660 feet thick at the base and 45 feet thick at the top. This is your Hoover Dam example has been total storage capacity is about 33,500 acre feet total storage capacity and can store up to 2 years average flow from Colorado river. One of the example this is Hoover Dam from Colorado river it can store up to 2 years of average flow or 2 years water can be stored. Hoover Dam in the top view it has been shown if you look at this Hoover Dam it is a massive structure in United States over the Colorado river. Then this is your top view of this Hoover Dam. If I this is all about your classification and what are the different types of dams then we will start this next part is your reservoir and dams. In these dams now you need to have this let me start with this different types of dams once again. Once again if I summarize different types of dam it can be classified into three parts as I said earlier one is your gravity dam second is your earth dam third is your earth dam. In gravity dam the cross section may be it is a rigid monolithic structure rigid monolithic structure this is your gravity dam this is a rigid monolithic structure this is this part is your cross section and this is towards your length direction and minimal differential movement tolerated and dispersed moderate stress on the valley floor or wall. Earth dam is a kind of high strength concrete wall and it is a convex face of stream if you look at this this earth dam is a in earth shape with convex this is a convex face of stream and thin wall structures as we have discussed earlier it is a very thin wall structures and relatively flexible it is relatively flexible huge stresses imposed on valley wall and floor huge stresses imposed on this wall and as well as this floor. Then third part is your earth dam it is a earth or rock with impermeable core right now we have discussed this that means a impermeable core is in between and surrounded by earth or rock field and core of clay generally if you look at here core of clay or concrete extended below the ground then sand or gravel drains build to got fluid pressure sand or gravel drains has been put it so that it will reduce or allow the permeability allow the seepage so that it will reduce this fluid pressure then low stress apply to the valley floor and walls low stress apply to the valley floor and walls. If you look at this earth dam this is earth dam this core if I take this is a cross section this is a cross section this core it this is your core this core is made up of by clay or concrete it extended beyond the ground surface if this is my ground surface it extend beyond the ground surface and the side by these are the sides the side by it is a side by means of sand rock or gravel so that it reduce this pressure fluid pressure on this core and low stress applied to valley floor on the wall that means low stress apply to the valley floor or the walls. Once again this example earth dam if you look at this clear picture here earth dam this is in earth safe with a very thin thickness thickness is very thin then this is your gravity dam by means of own gravity it resist this whatever the forces coming on to this then this is your embankment or ardent dam ardent dam this is typical example of ardent dam then buttress dam all this dams previously we have discussed now some of the examples in clear bigger pictures some of the examples suzeland one of the earth dam in the suzeland whether it is if you look at this is the earth safe earth dam in the suzeland then by and dam today this is this I can then what are the forces applied in dams as we have discussed vertical static forces lateral force applied by water body one is the vertical static force other is your lateral force by means of water body then different dynamic forces taken into consideration in the form of water wave action overflow of water then earthquake and tremors by means of if there is earthquake earthquake force has to taken into consideration ice are freezing generally in western country particularly european country what will happen in the water reservoir the moment in during winter this water become ice by means of freezing once it become ice by means of freezing it will impact ice will become a solid it will impact a force so these are all your dynamic forces to be taken into consideration in case of dam so typical cases of dam failure by means of earthquake now how this once the dam has been constructed one another aspect is your how this ground improvement technique has been then has been done for dams that means poor geological conditions can be improved in two ways that means improving load bearing properties one is your by doing ground improvement you can improve the load bearing properties other is your you can control the seepage by means of ground improvement control this seepage so ground strengthening if I put it if I make this all into particularly four parts one is your gravel sand silt and clay gravel is more than ten sand is two silt is about between two two zero point zero zero two and clay is less than about zero point zero zero one mm grain size generally for sand and silt rolling bolting and pre loading has been done to strengthening this bearing properties and gravity drainage and well point with drainage well point different well point with drainage has been applied if there are gravels generally you can go for vibro flotations and explosives as well as you can go for grouts you can go for grouts for ground improvement or that means improving load bearing properties between silt and clay if there is a mixture of silt as well as clay you can go for chemical treatment or thermal treatment chemical as well as thermal treatment if it is purely clay then electro osmosis has been applied for particularly clay soils. So these are all this ground improvement techniques or ground improvement method to improve your load bearing properties now if I say come back to in details rock bolts rolling and pre loading rolling and pre loading particularly compress ground in for structures it completely compress the ground compress the ground improve these post dam compaction improve your post dam compaction gravity drainage and well points what is the meaning of this gravity drainage and well points that means sand and gravel channels and shallow wells shallow wells generally we put it nearby the dam. So electro osmosis that means insert conduction rods into fine grained clay rich bedrock have an electric field so de water ground via this flow of electric current by means of flow of electric current you can de water the water then your vibro flotation that means it is a mechanical method mechanically vibrating plates with load compresses low density gravel sand if there is a gravel sand of low density by means of vibro flotations that means it is a mechanical vibration by means of vibrating plates you can improve this bearing capacity explosives sometimes we use this explosives particularly explosives that means it is useful in water structures gravel if there is a water structure if there is a water saturated gravel water saturated gravel in that case once you use this explosives what will happen water will come out from this saturated gravel that means it is bulk density will increase and hence this strength will increase then grout material particularly in case of grout materials you inject inside the ground surface so by means of material injecting it will mix with your soil so it will increase its bearing capacity so that means material injected inside the ground or inside this dam then chemical treatment what are the chemical treatment chemical treatment meaning means it reacts solutions injected into the ground that means there are some solutions it has been injected inside the ground so that it will react with material to alter the properties that for example sodium chloride solution injected into smetic rich mud if there is a mud smetic rich mud if I inject sodium chloride what will happen it will react with this mud then it will improve that means it will stabilize this your ground so chemical treatment means these are all over view what is the meaning of this rolling and preloading grab gravity drainage and well points vibro flotation explosives grouts chemical treatments then come back to your thermal treatment thermal treatment means freezing or heating thermally that means freezing with injected liquid nitrous oxide to consolidate loose ground during excavation to consolidate loose ground during excavation that means if I freeze by means of nitrous oxide that means what will happen it become hard that means if there is an excavation it becomes hard so it will allow it will allow the loose ground to consolidate then heating by burning petroleum under pressure how the heating has been done heating generally done by burning petroleum under pressure in the surface by means petroleum material has been taken under pressure the burning has been applied in the surface so cause it causes thermal metamorphism it causes thermal metamorphism that means what will happen by means of burning it hardens your ground and cuts the porosity cuts the porosity means it hardens the ground cuts the porosity means it won't allow the flow that means it completely hard so these are the different techniques these are the different techniques has been used to improve this bearing capacity of ground this is called by means of ground improvement techniques so this different techniques once again I am repeating once is your rock bolt rolling and preloading gravity drainage well points then your vibro flotation explosives grouts chemical treatments and thermal treatments these are the treatment has been generally applied so that bearing capacity has to be improved if you look at a very simple example there is a dam hard face of the dam this is your hard face of your dam hard face of your dam that means sometimes what happen reprap to kill the wave energy what will happen you put some stones along the hard face or reprap you can apply some stones or bricks so that this wave energy again and again the wave what will travel this reservoir this wave again and again it will impact a cyclic load it will impact a cyclic cyclic load that means this wave energy has to be reduced if the hard face of the dam has been repraved or by means of filling hard safe has been done by means of rock or stones then core and rear of the dam if this is the core this is the core rear of the dam then another face of the there if there is a reservoir once there is a wave form at the what will happen at the bottom by means of water it will come and it will stored here so injected grout cotton injected grout cotton by means of grouting if you come back here material injected inside the ground so that it become hard so what will happen the seepage here or may be erosion because of your wave because of your wave wave what will happen there is a chance of at the bottom at the bottom hard face of the dam erosion may be possible to make or to reduce this erosion what will happen injected grout grout has been injected inside and it become harder if you look at here these are the grout materials injected inside means up to a long distance so that what will happen it will make harder so that it will reduce this erosion or erosion may be completely reduced now if you come back to this exhibition to this rock if you come back here now if you look at here there are cases there are cases what will happen water flows from here to here or may be it passes through this dam what will happen there may be possible that it may uplift force may act that means pressure at the bottom of the dam will be more so what will happen once there will uplift force it will take out completely your dam to prevent this what will happen anchors pre stress anchors if you look at this point two point two pre stress anchor at this at this exit point has been provided what will happen by means of pre stress anchor by means of pre stress anchor along with this grouting along with this grouting so that it will become hard and this is your pre stress anchor what will happen this anchor will resist this anchor will resist against your uplift so if you look at here this this black shape this black shape which I have marked in the red color this is a pre stress anchor the moment there is uplift force the moment there is uplift force it is trying to take out or may be uplift by means of water pressure this anchor will prevent this anchor will prevent to go to do this anchoring again pre stress anchor at the same time also at the same time this soil because water is passing through this this soil has to be become most strata means hard strata so what will happen again your grouting has been done these are all your grouting has been done so that this strata become harder so you can prevent it then drains you can at the same time you can at the same time up run drains these are the drains has been provided so that what will happen once there is a seepage once there is a seepage below the dam below the dam what will happen water passes and passing through this or may be water passes through the body and coming if it is earth and dam what will happen there are some point there are some point drainage should be given so that water will be accumulated so water will be accumulated at this point so you can take out or may be pumping out may be procedure may be taken out so this flow by this means of by this ground improvement technique what will happen we completely change the flow pattern inside your dam so that means flow pattern has been completely changed it has been resisted means particularly uplift force has been resisted by means of your pre stress anchor at the same time in the downstream in the downstream phase we have to provide also drainage so that water can be accumulated these are all your typical cases typical cases example how this ground improvement technique has been done from the beginning from the upstream phase to downstream phase so that this dam will be stubble or may be this bearing capacity of this dam or the load carrying capacity can be increased now next part of this dam we are going to start with this different constructions and monitoring of earth dam how it has been constructed how this monitoring process how day to day basis it has been monitored that we are going to discuss the reasons for construction and monitoring that means what are the different reasons for construction monitoring this that means during construction you need to have monitor this construction process ensure proper material are used because this is a huge structure you will have to ensure proper material has been used then ensure proper construction and design is followed that means whatever the design has been made according to the design proper construction has been made that you should ensure then quickly modify design and construction practice based on encounter site condition this is most important what will happen these are all your based on designs you can go for construction suppose if the moment you go to the site there are some obstacles you find it out or encounter during condition or may be site condition immediately what will happen you should modify the design as well as your construction practices based on your site conditions so it is imperative to have full time site inspection while this particularly dam construction is going on full time site inspection is mandatory inspection requirement must not hinder or slow down contractor second is your must work with contractor must consider contractor construction practices means you should consider also construction practices whatever the construction practices has been made now construction monitoring materials let us start with this materials materials grain size distribution analysis of material grain size grain size distribution analysis of material if you look at here what are the different material if this there is an art dam first one is your core core is your impermeable then filters then drains then second is your makes your material installed meets specifications whatever the material you install it makes standard specifications it should not be arbitrary then makes your that the borrow material do not change the borrow material means this construction material whatever you are taking suppose this is the art then dam to be constructed in the site particularly the site then what happen from where the art the material you are going to take it you will take it near by somewhere else this is called pit area this is called pit area that means during construction every time you cannot change the pit area suppose you are taking material from this area one phase of this construction at least once it started you have taken material from here next time you cannot change the pit area from different sites then what will happen this once this material will change the property will change also the grain size distribution will change accordingly the strength also will change that means makes your the borrow material that means from one borrow the material should be change taken for the construction point of view then material test once for this material construction has been decided that means this is the borrow site from where this material will be taken for your construction you do triaxial extension means extensive triaxial test and shear test including filter as well as core core material and filter you will have to do in the laboratory as well as for core material because core material what it says if this is my core that means core material is less permeable core material is less permeable that means it is impermeable for the you need to have your consolidation test so that you can find it out coefficient of consolidation CV coefficient of consolidation you need to have that means consolidation for core material you need to have these are all means once this material you are taking for construction what are the routine test required these are I am discussing then hydraulic conductivity hydraulic conductivity means how much this particularly k value permeability what is your permeability value for laboratory test that means for filters for filters either you go for constant or falling hard method either you go for constant or falling hard method for core you need to have your triaxial test then field clay that means for field clay if there is there then double ring double ring in filter in filter meter then centrifuge permeate permeate meter this test is required for field then procto test basic compaction test you need to have the source material in boropit the source material from where you are going to take the material for that you need to have your procto test and material hold to the side then what are the field compaction that means on compacted layer thickness on compacted layer thickness field compaction test you need to have that is your 300 mm maximum then compaction equipment is suitable then compaction equipment is suitable different compaction equipment is required then moisture content and maximum dry density moisture content and maximum dry density that means nuclear density sand cone and rubber ballon for moisture content and maximum dry density makes your nuclear density is calibrated that means once you are going to find it out for moisture content a particular moisture content and maximum dry density of your material then make sure that whatever the instrument you are using it should be calibrated a slight error in your laboratory test, it will make lot of difference during this construction. Goal of compaction, why you are doing this compaction? Place loose soil in the field and compact it to make soil strong as possible. That means, strong as possible means, in soil if I say strong as possible that means, it will be have maximum shear strength, very little settlement, settlement will be less, maximum shear strength as well as low hydraulic conductivity, low hydraulic conductivity means less permeable. Then find soil in lowest e minimum, e minimum is your void ratio, e minimum lowest e minimum is your density will be more highest dry unit weight. That means, you need to have find soil of lowest e minimum e minimum lowest void ratio that means, lowest void ratio means, voids are very less that means, what will happen its density will be more. We will discuss all other parts may be in the next class. So, I will stop it here.