Abstract:This paper examines six case histories of load tests on reverse circulation method installed drilled shafts, with or without tip
grouting, under axial load. Shaft displacement readings based on both telltale/extensometer and rebar gage are compared first.
Subsequently, effect of loading cycle on shaft elastic modulus estimation is evaluated. The load versus displacement relationships
at shaft head, the t-z curves of clay layer and of gravel layer are other important concerns and are compared in the paper. In addition,
the adhesion factor α and the parameter β based on the pile load test results are suggested in the paper.