Pile foundation can be categorized in two types, shallow foundation and deep foundation. Both of the foundation plays the same role which is to transfer the loading from the structure above to the ground. Shallow foundation a part of the whole structure. Its plays an important role in transferring the load from the structure to the ground. There are several material used for the pile such as timber, steel and concrete. The piles are drive, drilled or jacked into the soil. Pile group is a type of arrangement which is commonly constructed under a massive structure which will transfer the applied load to the deeper and stronger soil strata. Many buildings and structure required the use of deep foundation to develop the bearing capacity of stronger soil layers. Hence, pile group are one of the deep foundations which commonly used for massive structures. Additionally, the piles will have to sustain the vertical load applied on top and significant lateral loads may be occur and must be accounted for in design. These lateral loads can be come from wind forces, collisions, wave, slope failure and etc. The carrying capacity or the settlement for pile group is totally different with an isolated single pile under the same applied loading. This is due to the group effect of a pile group which wills causes larger soil disturbance compare to single pile installation. Besides, the zone stresses for pile group is also extended to larger width and deeper depth than the zone under a single pile. The behavior of the pile group is depends on the loading transferred to the soil and the soil characteristics. Its ultimate bearing capacity and the total settlement for a pile group is not the same as a single pile. However, pile group is affected by several factors that will cause the changes of its behavior such as:
Soil modulus- The water table under the depth of soil with the seepage pressure will affect the modulus cohesionless