Strip footing behavior on reinforced sand with void subjected to repeated loading

This paper describes a series of laboratory model tests on strip footings supported on unreinforced and geogrid-reinforced sand with an inside void. The footing is subjected to a combination of static and cyclic loading. The influence of various parameters including the embedment depth of the void, the number of reinforcement layers, and the amplitude of cyclic load were studied. The results show that the footing settlement due to repeated loading increased when the void existed in the failure zone of the footing and decreased with increasing the void vertical distance from the footing bottom and with increasing the reinforcement layers beneath the footing. For a specified amplitude of repeated load, the footing settlement is comparable for reinforced sand, thicker soil layer over the void and much improved the settlement of unreinforced sand without void. In general, the results indicate that, the reinforced soil-footing system with sufficient geogride-reinforcement and void embedment depth behaves much stiffer and thus carries greater loading with lower settlement compared with unreinforced soil in the absent of void and can eliminate the adverse effect of the void on the footing behavior. The final footing settlement under repeated cyclic loading becomes about 4 times with respect to the footing settlement under static loading at the same magnitude of load applied.