Contribution of using geogrid under a shallow foundation on sand subjected to static and repeated loads: Laboratory testing and numerical simulations

Abstract

This paper focuses on the use of a certain punched and drawn geogrid to increase the bearing capacity of a circular shallow foundation subjected to a combination of static and repeated loads. In the experiments, the foundation is first subjected to a prespecified static load, afterwards, a repeated load derived in different proportions of the applied static load is superimposed to that static load. The variables investigated in the tests are the number of geogrid layers, the amplitude of repeated load, and the number of load cycles. The effect of these variables is also investigated by a finite element numerical modeling approach verified with one-dimensional site response analysis, and as a consequence of this effort that refers to the innovation of the study, the consistency between the results obtained from both methods is observed. The test results show that the displacements of the shallow foundation increase rapidly in the first 100 load cycles in all cases. After that, the rate of increase is reduced until about 2000 load cycles and the displacements become negligible. From the experiments, 2 geogrid layers were found to be quite effective in reducing displacements due to both static and dynamic loading cases. In other respects, finite element simulations of the physical experiment have produced numerical results in good agreement with the test results. Plus, the main contribution of the numerical simulation is to indicate the deformed mesh outputs of the model including the geogrids for the foregoing variables.