Load Capacity of Drilled Shafts Socketed in Andesite Rock

In this paper, the behavior and performance of four instrumented drilled shafts and two barrette piles socketed in andesite rock in Taipei are evaluated based on the results of pile load tests. The tests include two compressive and two tensile tests conducted on the drilled shafts and two tensile tests conducted on the barrette piles. The load versus displacement curve at the pile head and t-z curves along the shaft, especially for the part socketed in andesite rock, are main concerns and are presented and discussed in the paper. The value of the load corresponding to the intersection of the load deformation curve and three times the initial tangent slope is used to determine the ultimate capacity of each pile. Comparison of the andesite rock unit frictional resistance of each pile shows the average of the measured values is approximately half of the value suggested by the method of O'Neill and Reese (1999) and is much smaller than the value suggested by the method of Chen (1999).