Testing and Analysis of Two Offshore Drilled Shafts Subjected to Lateral Loads

A lateral-load test was conducted at an offshore site on two 1.22-m-diameter drilled shafts penetrating through 13.1 m of dense sand overlying clay. The lateral-load test was conducted by pulling the two shafts toward each other under a specified lateral load and then relaxing the load to zero. This procedure was repeated for 40 cycles at each load level. With each load increase the application sequence was repeated to a maximum lateral load of 500 kN. Throughout the test, measurements were made of deflection and slope at the top of the shaft, and measurements of slope along the length of the shaft were obtained using a slope inclinometer.

A computer model was used to predict the behavior of a drilled shaft under the test conditions, and computed results were compared with measured results. At a lateral load of 500 kN, values of deflection were computed to be 20 to 30% less than measured.