Estimating Pile Axial Bearing Capacity by c-Φ Derived from Pressuremeter Test
T-L. Gouw
ABSTRACT: Due to its rather brittle nature, retrieving undisturbed samples of Jakarta cemented greyish stiff clay, often found at a depth of 30 to 120 m, is very difficult. Good and reliable effective shear strength parameters, i.e., c’ and Φ’ values, obtained from triaxial test are hardly available. By modifying cavity expansion theory, Gouw (2017) was able to derive these effective shear strength parameters through Pressuremeter in situ test stress strain curve. It was found Jakarta cemented clay exhibiting a drained behaviour when loaded. Its effective cohesion, c’, values are linearly increasing with depths, averaging from around 95 kPa at 20 m to around 475 kPa at 100 m depth, while its effective friction angle Φ’ values are within 20o – 30o, averaging to around 24o. The values found to be similar to the values derived from CIU triaxial compression test from relatively good undisturbed samples. This paper presents the methodology in deriving the shear strength parameters and then applying the derived Pressuremeter c’ and Φ’ values to estimate the pile axial bearing capacity through finite element simulation and comparing it with the commonly known SPT method applied in Jakarta.
KEYWORDS: Pressuremeter, Modified cavity expansion theory, Effective shear strength parameters, Pile axial capacity.
