 So, now I would like to show you some videos so that you may realize how a geotechnical engineer speculates that what type of infrastructure can be created by utilizing sheet piles. Once that is clear, then we will go into the analysis part of it. I wish to show you some of the YouTube videos which would clear your idea and concepts about how infrastructure is being done with the help of sheet piles. I will email these links to you as well and this is where he has tried to show the type of sheet pile construction which are being done. I think you can look at this. This is the basic unit of a sheet pile for a better connection, better connectivity. You can have a concrete sheet pile or reinforced concrete sheet pile also, advantages, disadvantages are given. This is how the you know their attachments are done or interlocking is done. So, this is the interlocking system. These two units are the mirror units, each unit is embedded into the ground and then they are interlocked. This is how the sheet pile wall is being created. This is the first installation followed by the next hammering of the sheet piles and they got embedded into the soil mass. So, this is the ground level. You take the sheet pile, the sheet pile would be something like this. So, it will be something like this. You can hold it from top and push it down or tamp it from the top. I think this video will give you a very clear idea about how sheet piles are installed. So, this is how the sheet piles are lifted and then look at the way the installation takes place. So, this area what you are observing here is going to be excavated. You want to create an underground facility. So, this is how the cordoning off of the entire area can be done. So, this is how the connections are being done interlocking and once the unit gets fixed with the previous unit, you can tamp it from the top. So, this is basically mechanization of construction in geotechnical engineering. Nowadays, we have the best possible machines and tools which can be utilized to construct the facilities within no time with lot of precision. Otherwise, I am sure you will realize it is very difficult to tamp the sheet pile into the ground and that was one of the deterrents earlier days. You see now how this has been pushed into the soil mass. So, soil mass should be soft. So, depending upon the resistance which is being offered by the soil, you can adopt a technique of installation. So, this is what I was explaining over here that if you want to create underground space, you can just tamp the sheets of piles into the ground and then you can create the desired space. There is another good video of the installation of the PVC sheet piles. PVC sheet piles are mostly used for retaining the leachates which are coming out of the landfills. The concept here is that the edge of the sheet which is being pressed into the soil happens to be very sharp, all right. So, in this system where I showed a very sharp edge, what will be the free body diagram of the sheet pile. So, suppose if I take a sheet pile over here, a good question would be draw the free body diagram. So, thickness is absolutely less, all right, few centimeters or mm. So, once you are tamping it inside, the first thing is friction will get mobilized, all right. So, the moment friction gets mobilized, it becomes a non-ranking wall. This is a deviation from the Rankine theory because later on you will see that most of the analysis which we will be doing for analyzing the sheet piles would be based on Rankine theory only. But then we tend to ignore this shear stress. Why? Because it is a very thin element which is being inserted into ground and this is a cutting edge. So, there cannot be much resistance offered by the soil here. So, this is a cutting edge, all right. So, this system which is a flexible system goes into the ground or remains outside and gives you the advantage. The paradox is though the element is flexible, we assume the system which gets created because of the sheet pile is a rigid system, rigid body. So, we apply the concept of rigid body to analyze it, approximations, fine. Another thing which you must have realized is that when you are designing these sheet piles, the whole idea is to convert the pressures into what form, deflection. But excessive deflection is going to cause the failure. So, deflection should be within control. So, having done these concepts, now I will introduce the concept of how to create different types of sheet pile structures by using sheet pile units. That will follow after few videos. So, again to continue with this video, now you can realize that the way sheet piles have been inserted and you have created a cofferdam. So, this is the industry which might be polluting, which might be spilling out lot of chemicals into the ground and I want to control that, okay. So, this is the industry which is, which might be producing different types of chemicals which are leaking, alright and then there is a water table, there is an aquifer and we do not want any leakage or any chemicals to migrate into the fresh water and contaminate the whole thing. So, this is where the sheet pile has been installed. So, this confines the whole area and makes it leak proof. Let us move on to some other examples of sheet pile. I think this is a concrete pile which is being driven into the sea wall and I hope this shows how the sea wall is being created. So, the whole sheet pile has been held as a between the calipers and these calipers are pushing the pile deep inside the ground and you can see there is a top head of the pile which is being either damped by percussion, the pile will break. So, it has to be pressed, alright and then you can see the movement of the pile inside the ground. So, this is what you are talking about the concrete sheet piles. The basic idea is to create a space which I can utilize by excavation or by loading it on the top. These are expensive infrastructures where you have to spend a lot of money to create the workable land. It is the same driving in and you can see how the joints are created over here. If you concentrate on this part of the video, you can see how the joints are being created and then ultimately all small, small segments put together they form a monolith structure. This is another good way of looking at this how interlocking of two elements of sheet piles has been done. So, next time when you are passing by and you see any excavation going on, please have a close look at how the excavations are being done and there have been many disasters also in the recent past when the design was not done properly. So, once you have created inside space, you can excavate it. The sheet pile is in between the tongs and the tongs are pressing them down. Hope this gives you a fair idea about how sheet piling is done. This is same thing again to show you how the installation is done in a clear manner. So, what as a geotechnical engineer we would like to do it, we like to analyze these systems by using the concepts whatever we have studied so far, mostly the earth pressure theory and the material properties in terms of shear strength characteristics. This is a good example of waterfront structures and how they are being made by using sheet piles. This is a very specialized construction, first the form work has been done and then followed by insertion of the sheet pile for maintaining the alignment. I think this is good enough to give you an idea about how the sheet piles are done. This shows that how anchoring can be done. So, I will be talking about the anchoring phenomena also, how anchors are being used for creating the sheet piles and for their better stability. This could be simple anchors, this could be pre-drilled anchors or even self-drilling anchors many times depending upon your budget. So, basically the whole wall is being pushed back side, ok. So, if I want to attain much higher heights what I should be doing, I have to pull them back. So, this becomes an anchorage system, I will be discussing about this. See most of the time this nearsurface disposal facilities for nuclear activists are also tend to more than 10 meter deep, alright. Second thing is rather than creating such type of space it is always better to create a small shaft and then install your canisters over there, but yes technically this can be used. But imagine the volume of soil mass of the rocks which we are going to remove. So, if you have to create a rock system there is no point in doing the sheet piles because rocks are self-stable. This is meant only for retaining the soils or compacted soils. Second thing is you have to take a decision based on the cost and the advantage which you are going to get, fine, yes, but one of the good examples would be if I want to create a shallow disposal facility within which is within 10 to 7 meters of depth this could be a good answer or solution. So, you have to design a barrier system truly speaking the sheet pile acts as a barrier over there, yes, implement that. Applications are so many it depends upon how you are using these concepts.