DETERMINING THE CAPACITY OF A PILE WITH THE CONDITION OF ENCOUNTERING SOIL WITH MANY LENSES

Abstract

In a structural construction, one of the important parts that need to be made to support the structure is the foundation.
The foundation plays a crucial role, so if there is a settlement in the foundation of a structure, an investigation is
needed to address it. In a project in Serpong, South Tangerang, there is a case where there is a layer of soil with
lenses, which is a condition where there is a hard soil layer with an N-SPT value greater than 50 and a thickness of
about 1-4 m, this hard soil layer is located between two layers of soil with an N-SPT values less than 50. The presence
of these soil lenses, located at depths of 8 m, 14 m, 24 m, and 42 m with varying thicknesses, cannot be identified
through the Cone Penetration Test (CPT) and is feared to cause a settlement in the pile foundation. This is because
the maximum capacity of the cone penetration test is only up to 2.5 tonf and cannot penetrate these soil lenses. This
research uses soil data in the form of two boring log data, which will then be analyzed and compared for the axial
bearing capacity and the settlement that occurs if the foundation piles occupy each soil condition that has a soil lens
layer. The Meyerhoff and Hanna method is used to calculate the ultimate bearing capacity, while the Alpha
Thomlinson method is used to calculate the settlement.