Bearing Capacity of Deep Foundation Socketed into Granitic Rock

Abstract

With advancements in drilling techniques and improved coring tools, deep foundations socketed into granitic rock have been widely used to support the heavy loads imposed by the high-rise buildings and bridges. To optimize the pile design, designers are often required to estimate the pile’s bearing capacity and subsequently validate the design parameters with pile load tests. Most of the time, the pile’s bearing capacity is calculated based on empirical models suggested by various researchers around the world. However, these equations may not be suitable, as the data used to derive them were based on the pile load tests carried out at various location, likely with different construction methodologies. This paper aims to develop an empirical model to estimate the pile shaft resistance in granitic rock based on uniaxial compressive strength (UCS) by using data from twelve pile load test results performed in Southeast Asia and three pile load test results carried out in East Asia. Thirteen of the piles tested by using bi-directional static load test (BDSLT) method and remaining tested by conventional top-down static load test method (SLT). Comparison between the actual test data and estimated capacity by using existing empirical models is also presented. This paper also further demonstrates the maximum displacement of pile shaft segment in rock upon reaching failure. For pile shaft resistance not reaching its ultimate value, a suitable method is applied to predict the ultimate shaft resistance values. End bearing capacity obtained from the pile tests is also presented herein as reference.