SEISMIC RESPONSE OF DUAL STRUCTURE SLOPE BASED ON SHAKING TABLE MODEL TEST

Geological disasters such as slope failure, caused by earthquake, are very common in meizoseismal area. The dual structure slope is composed of underlying rock mass and overlying soil mass. The seismic responses of dual structure slope with anchor-frame reinforcement remain unclear. Based on the prototype slope with dual structure at the ZK132+300 of Fuyong Expressway, a 1/20 downscale model slope is designed and built. Shaking table tests with 20 loading cases are then conducted in the key laboratory of disaster prevention of Fujian Province. The influences of slope elevation, seismic wave amplitude and seismic wave spectrum on the PGA amplification coefficients are focused in this article. Some conclusions can be drawn as follows. The PGA amplification coefficients inside and upon the slope increase with the slope elevation and magnify dramatically at the top of slope. The anchor-frame support restrains the PGA amplification coefficients upon the slope, comparing with their counterparts inside the slope. Due to the plasticity of soil, the PGA amplification coefficients decease linearly or exponentially with the seismic wave amplitude. Excited by the seismic waves with same amplitude and different spectrums, there exists some difference among the PGA amplification coefficients upon the slope. However, the distinction due to seismic wave spectrum fades away with the slope elevation and vanishes at the top of slope. The failure characteristic of model slope during shaking table tests is carefully inspected and described. The cracks only occur near the free face of slope top and slope shoulder, and no interconnected crack and overall instability occur during tests. It is concluded that the anchor-frame reinforcement can improve the seismic performance of soil slope significantly.