Cyclic response of footing on geogrid-reinforced sand with void

Abstract

This paper describes laboratory tests on footing constructed on unreinforced and geogrid-reinforced sand with circular a void subjected to a combination of static and repeated loads. The settlement of the footing was measured for up to 5000 cycles of loading and unloading. The variables examined in the testing program include the number of geogrid layers, the location of the void within the soil, the amplitude of cyclic load, and the number of load cycles. The results show that the footing performance due to cyclic loading is better for thicker geogrid reinforced sand with a void than for unreinforced sand with no void. In addition, a critical region was found to exist under the footing, under which a void results in increased footing settlement. Overall, the results indicate that the reinforced soil-footing systems with sufficient geogrid-reinforcement and sufficient void embedment depth behave much more stiffly and are thus capable of handling greater loads with lower settlement than those in unreinforced soil without a void. The undesirable effect of the void on the footing behavior can be eliminated. In addition, the results show that the values of footing settlement increase rapidly during the initial loading cycles; thereafter the rate of settlement is reduced significantly as the number of loading cycles increases.