Evaluation of Lateral Response of Drilled Shafts in Rock

Abstract

Drilled shafts socketed into rock have been widely used as a foundation for bridges to resist both vertical and lateral loads. Although numerous research efforts on rock socket drilled shafts under vertical loads have been carried out, similar research efforts on rock socketed shafts under lateral loads have been lacking. Few existing published analysis methods are still in their early stage of development due to meager lateral load tests data for verification. Additionally, most existing lateral load tests were performed on drilled shafts socketed in rock with a relatively thick layer of overlying soils, which may limit the extent of interaction between the rock and the shaft. The main objective of this paper is to present a lateral load test result on two fully instrumented drilled shafts 2.44 m in diameter socketed in shale. The effect of the overlying soil was isolated by using a larger diameter casing during the load test. An existing analysis method is evaluated using the presented load test and additional two load tests compiled from literature. It is found that the existing method tends to under predict the deflections by 53% to 97% for the three actual load tests studied.