What is pile group effect?
The term group effect refers to the fact that a group will generally exhibit less lateral capacity than the sum of the lateral capacities of the individual piles. This happens because each pile in a pile group affects the soil resistance around other piles. The piles in the other rows have lower resistances.
What is group capacity of piles?
Capacity of pile group is the sum of the individual capacities of piles, but it is influenced by the spacing between the piles. Piles are driven generally in groups in regular pattern to support the structural loads. The structural load is applied to the pile cap that distributes the load to individual piles.
Why are piles constructed in groups?
Pile groups or clusters are often used to carry significant loads transferred from superstructures, as shown in Fig. 21.1. For offshore jacket structures, the transfer of loads from upper structures to pile groups is often ensured by the installation of pile sleeves, as shown in Fig.
What is pile group efficiency?
The efficiency of a pile group r\g is defined as the ratio of the actual capacity of the group to the summation of the capacities of the individual piles in the group when tested as single piles.
How do I know how many piles I need?
Both the dynamic and static formulas indicate that an allowable load of 15 tons per pile is reason- able. The number of piles required to support the load is 180/15 = 12 piles.
Why pile head is removed?
Pile Chipping is the extra pile that is above the cutoff level, which provided for good and sound concrete. The main purpose of chipping is to remove the surplus slushy concrete (a mixture of concrete, slurry, and mud) over the cutoff level. When concreting is going on, the black slush comes out from the borehole.
Why pile foundation is used for weaker soil?
Pile foundations are used in the following situations: When there is a layer of weak soil at the surface. This layer cannot support the weight of the building, so the loads of the building have to bypass this layer and be transferred to the layer of stronger soil or rock that is below the weak layer.
What is block failure in a group of piles?
Block failure occurs generally when the spacing of piles is less than about three times the pile diameter. In this case, the soil, bound by a perimeter of the pile group over the embedded length, acts as a single unit or block. Individual pile failure occurs when the piles are spaced at about eight times the diameter.
What is the maximum allowable settlement for a pile?
Pile settlement analysis showed that total expected maximum settlement value was 15.6 mm. It includes 2.1 mm settlement of pile deformation from vertical compressive loads. For such structure, foundation settlement should not be more than 2% of pile diameter.
What is pile load test?
Static pile load testing is one of the most common methods for testing the actual in-situ capacity of a pile. The test program involves the direct measurement of pile head displacement in response to a physically applied load. Piles can be tested for compression, tension or lateral loads. …