 Hello, I am Dr. Satish Kumar Kashi, Professor in Civil Engineering, Walchand Institute of Technology, Solapur, introducing to you a topic Introduction to Deep Foundations. Learning outcomes of this session, at the end of this session the students will be able to list the types of deep foundations, they will also be able to suggest appropriate type of deep foundation for a particular site situation. Deep foundation is a type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation. Some of the common reasons for adopting deep foundations is, when very large design loads are there or a poor soil is there at shallow depths and site constraints like the property lines. For deep foundations, the depth is greater than breadth, such that d by b ratio is usually more than 4 or 5. The deep foundations transport the load of super structure vertically to the rock strata lying much deep, hence deep foundations are used when shallow foundations cannot support the load of the structure. Now, let us classify the deep foundations. The deep foundations can be broadly classified into pile foundations, pier foundations, well or chasen foundations. Deep foundations that way can be made up of timber, steel, reinforced concrete or prestige concrete also. First, we will discuss pile foundations. Piles are relatively long slender members that transmit the foundation loads through soil strata of low bearing capacity to deeper soil or rock strata having very high bearing capacity. These foundations are used for economic construction purposes or soil considerations and when it is desirable to transmit a load to strata beyond practical reach of shallow foundations. Piles are also used for angering the structures. Piles are also acid structures in reducing lateral and overturning forces. Now we can see this particular building, this is the building, this is the ground level. Here there is a basement and below that the piles are reaching up to the hard strata through this particular soft soils. Here this is a load coming from a structure. Here a group of piles is there which transmit the load to the high density soil or high bearing capacity soil through number of piles. So here the piles are provided with the pile cap so as the load can be equally distributed to these particular piles. This particular picture shows you a building constructed over a soft soil but transmitting its load through soft soil, through pavement up to the wet rock available to great depth may be say 15 meter, 20 meter, 22 meter and so on. What metals are used for piles? The metals can be steel in form of edge sections, steel pipe sections, concrete piles can be there, site cast or precast piles can be wood, pile can be timber piles piles also can be made up of composite material. Now here this typical picture shows a spiral red threads for an auger for piling. It means here we are going to have a pile foundation. So before that by using auger we are excavating the ground and making a vertical shaft for inserting a pile. Piles can be precast piles, driven piles or piles can be cast into piles, a driven pile. A driven pile is relatively long slender column provided to offer support or to resist the forces. A driven pile is made up of pre-formed material, it will have a predetermined shape and size, it can be physically inspected prior to and during the installation of a pile. Here the pile that is a driven pile is installed by impact hammering, vibrating or pushing into the earth. Now here this picture shows us the concrete piles driven into the ground for a deep foundation of a large building site. So these are the concrete piles and these are driven into the ground. Driven precast concrete piles. So we can define driven precast concrete piles as the precast concrete pile is a fabricated high strength pre-stress concrete column which is impact driven into the soil by means of an adjustable hydraulic or a diesel hammer. Now here we can see the driven precast concrete piles. So these are the piles laid here and the piles which are driven into the ground one can see here. Here we can see the driven piles which are in form of steel H piles. So whenever we are going for piles we will always find for steel piles H sections are used preferably because the H section has almost I X section I Y Y equal and the buckling can be registered. Now let us discuss about the board cast in situ piles. Board cast in situ pile is constructed by digging a hole into the ground by suitable means such as a percussive or rotary method with the use of temporary or permanent casing or a drilling mud. So here a pile drilling operation is going on by using auger removing the soil and thereafter a reinforcement cage is inserted here and then a pile is concreted here to have. Sometimes this casing also can be kept at its place if required. So this was something about it board cast in situ pile. Now a pile group. So we need to group a pile so as to transmit a load when loads are very heavy. So a pile group with a set of piles that have a pile cap that means they act together to carry the load. So the pile cap would normally be in contact with the ground and the piles would be designed to share the pile load at the ultimate state. So here we can see this is a bridge these are the bridge piers are transferring the load to pile cap and through pile cap load is transferred to the piles and ultimately load is transferred to the hard startup below. Let us have some questions pile foundations are used when the soil at shallow depth is weak or highly compressible for large heavily loaded structures while good founding startup at great depth uneven loading different parts of structure with weak soils in upper layers ground improvement at shallow depths is not feasible and uneconomical and out of these answers you will find all the above answers are correct. Second question the advantage of steel piles over concrete piles in solution is easy high driving energy can be applied during the solution load capacity is high they are economical. So A, B, C are the correct answers but D is not they are not economical. Now let us discuss about well foundations well foundation is a type of deep foundation which is generally provided below the water level for bridges. Cason or well have been used for foundations of bridges and other structures since Roman and Mughal periods. Here we observe a bridge resting on well foundations. So these are the well foundations which are provided for a bridge. This is a bridge superstructure as we observe well foundation. So this typical well issue here. So this is a well foundation a well extending up to hard startup a well curve here transferring load to the hard startup. Here a well foundation under construction you can observe. So this is a shuttering which is being constructed for the RCC well and here you can find one completed RCC well. So this is the RCC structure and this is the reinforcement in the circumference of the RCC well foundation. You can observe this is open at top it is also open at bottom and after finishing the work we close the bottom by bottom plug and the upper surface is again closed for supporting the load. So question in a well foundation top end is open but bottom end is closed during construction. Bottom end is open but top end is closed during construction. Both ends are kept closed during construction. Both ends are kept open during construction but closed after the construction. So the answer D is correct. Now let us discuss pneumatic caisson foundation. The term caisson is derived from the French word casse which means a box or chest. It consists of on ground construction of reinforced concrete caisson having working chamber inside the lower part and pressurized air supply to working chamber to prevent underground water from coming in the excavation work and finally sinking the caisson. We can observe this here. So here this is the pressurized air supply arrangement provided here. The work space is here observe this is the water level here this is the river bed and we are sinking this particular pneumatic caisson. So people will work here in this work space they will dig at the curve and the caisson will be lowered and these are the partial access shafts or tubes are provided here. People will not work continuously here because they need to work at pressurized air. There is one more type of foundation drill pier. A drill pier is a deep foundation system. It uses large diameter concrete cylinder constructed by placing fresh concrete and reinforcing steel into a drill shaft. It is also called as a caisson drill shaft cast in drill hole piles or cast in situ piles. So this is a drill pier foundation and it is reinforced and at the bottom you will find you will find a base resistance is provided here. This diameter can vary as we want and so on. So these are the references which are used for this presentation. Thanks a lot.