Influence of Geogrid Reinforcement of Sand in Transfer of Dynamic Loading to Underground Structure

Abstract

The knowledge of the stress distribution and displacements that occurred in and around the openings is required for the safe design and construction of underground structures. The effect of geogrid reinforcement on the transfer of dynamic load to the underground structure is the subject of this research. Within the soil, a PVC pipe was used to replicate the underground structure. To look at soil, footing, and underground tunnel to dynamic loading, a physical model was created to test the resistance of the soil, footing, and underground tunnel to dynamic loading. There were 58 different models tested in total. With two relative densities, two models are tested under static load. The total number of tests carried out is 58 models using two relative densities (40% and 80%). Two models were tested under static load All the other 56 model tests were tested under dynamic load with two amplitudes corresponding to (0.5 ton and 1 ton) using two frequencies 1 and 2 Hz for each load amplitude. For each amplitude and frequency of the load, the sand models were tested without geogrid and with geogrid of two widths (1B and 2B), where B is the width of the footing, for each amplitude and frequency of the load. In addition, three geogrid depths from the model surface were verified: 0.5B, 1B, and 1.5B. The pressure above the tunnel’s crown was found to be reduced by 13-65% when geogrid reinforcement was used.