Effect of geosynthetic reinforced fill on the frequency content of earthquake zones

Abstract

Destructive seismic loadings pose a great threat to the structural integrity of the soft soils underlying foundations in terms of service quality and serviceability. One of the e ective means of improving soil is to make use of geosynthetic materials. Geosynthetics are commonly used as a reinforcement element in reinforced soil underlying foundations, to diminish the e ects of earthquakes on structures. It is a proven fact that geosynthetics increases the bearing capacity of the soil and decreases the overall or partial settlement of soil under static loadings. The aim of the presented thesis is to understand the e ect of the geosynthetic reinforcement, particularly geogrid, on the seismic behavior of the soft clayey soil underlying gravel ll, and examine the seismic performance of the geogrid reinforced soil under di erent ground motions. The identical prototypes of unreinforced and geogrid reinforced ll were numerically modelled using the nite element software. The focus of the study is to determine the impacts of di erent peak ground accelerations under di erent frequency of motions on the seismic performance of unreinforced and reinforced cases on the same model made up of soft clayey soil overlain by gravel. The comparison of unreinforced and reinforced cases were evaluated following numerical analyses of the average values of acceleration for the selected points and average energy values were computed with Arias Intensity. The hypothesis was that geogrid would absorb the energy and thus the energy at the selected points would be lessened in the reinforced case. Results show that most of the reinforced cases decreased the transmitted energy through the soil and the proposition is true for 70% of the results. However, the energy di erence between the reinforced and the unreinforced cases is so minimal that gravel overlying soft clayey soil may have a greater in uence than geogrid on the seismic behavior of soil.