Seismic behavior of geosynthetic reinforced retaining structures with cohesive backfills

Abstract

In this study, seismic performance of geosynthetic-reinforced modular block retaining walls back lled with cohesive, ne grained clay-sand soil mixture was investigated. Four model walls were constructed and shaking table tests performed for three 1=2 scaled (wall height 190 cm) and one 1=4 scaled model walls were evaluated to investigate the e ects of back ll type, the in uence of reinforcement length and the scaling e ects. Scaled versions of the recorded El Centro and Kobe earthquakes were applied to the model walls. Polyester geogrids were used in the tests with a vertical spacing of 20 cm. Reinforcement length to wall height ratio was 0.8 (for one model 0.6 was used). A 12.5o battered facing was constructed with modular hollow concrete blocks. Model walls were instrumented by 8 accelerometers, located on facing and on back ll surface. 8 laser displacement transducers were used and 15 strain gages were located on three geogrid layers at top, mid and bottom heights of wall. Maximum and permanent displacements on front wall, acceleration ampli cation ratios on front wall and inside the back ll, strain values to calculate tensile loads on reinforcements and visual observations for facing and back ll surface were the results of this test to evaluate the performance of cohesive back lled model wall. No stability problem was occurred under extreme seismic loading. Any indication of failure was not observed except minimal residual deformations on the facing during base excitations. And acceptable tension cracks were observed on the back ll surface after nal seismic motions. As a result it can be said that; the model walls with cohesive back ll performed well under seismic loading conditions when compared with granular back lls and checked with the limit design values described in previous studies.