A Comparative Seismic Study of Wrap-Faced Retaining Wall Embankment Using Sands of Bangladesh

Abstract

Wrap-faced Sand Reinforced Retaining Wall (WSRW) Model is a worthwhile method that has been used worldwide for studying the seismic performance and successful implementation to fix the erosion problems in low-lying areas for earthquake resiliency purposes. In this research, a holistic WSRW model was built to compute its response under three different earthquake loading conditions namely˗ Kobe, Loma and Koaecli. The model was implemented using a shake table at the laboratory of Bangladesh University of Engineering and Technology (BUET). Several parameters were utilized. Such as, base acceleration (0.1 g, 0.15 g, 0.2 g), relative density (For Sylhet sand relative density of 48%, 64% and 80%, and for local sand relative density of 26%, 45% and 57%), surcharge (0.7 kPa, 1.12 kPa and 1.72 kPa). It was observed that, strain, face displacement and acceleration amplifications were decreased at higher relative density and surcharge pressure but were increased with high base accelerations. For instance, for a Sylhet sand sample with 48% relative density under the Kobe earthquake testing, acceleration amplifications for base accelerations of 0.1 g and 0.15 g are, respectively, 6.5% and 2.7% less than base accelerations of 0.2 g at normalized elevation 0.5 using a surcharge pressure of 0.7 kPa. However, at normalized elevation 0.5 for the Local sand sample with 26% relative density under Kobe earthquake testing employing the same surcharge pressure, acceleration amplification of 0.1 g and base acceleration of 0.15 g are respectively 10.6% and 7.7% less than base acceleration test for 0.2 g. Another result from the experiment of the Loma earthquake with a surcharge load of 0.7 kPa and 0.1 g base acceleration of Sylhet sand reveals that sample with 80% face displacements as well as relative density of 64% are respectively 12.9% and 8.2% less than the sample with relative density of 48% at normalized elevation 0.625. For similar base acceleration and similar surcharge load Local sand model experiments, samples with face displacements of 57% and relative density of 45% are respectively 14.2% and 8.5% less than the samples with relative density of 26% which is observed at normalized elevation 0.625. In the case of the local sand model, at normalized elevation 0.5, samples having the similar base acceleration and surcharge load, strains of a relative density of 57% and 45% are respectively 10% and 5.1% less than the sample having a relative density of 26%. Seismic characteristics observed from this research are beneficial for not only the design but also construction of WSRW.