Shaking table test on dynamic response of a deposit slope with a weak interlayer reinforced by the pile-anchor structure

Abstract

Owing to its low shear strength, the presence of a weak interlayer frequently plays an adverse role on slope stability. Through a shaking table test, this study investigated the dynamic response of the deposit slope with weak interlayer at the exit of the Zheduo Mountain Tunnel reinforced by pile-anchor structures. The acceleration field of the slope, peak value of the dynamic earth pressure of the pile, deformation of the pile, anchor cable tension and load-sharing ratio were considered. The findings demonstrate that as an earthquake intensifies, the slope soil behind a pile gradually becomes compressed; subsequently, tension cracks emerge at the back edge of the slope and expand significantly, eventually forming a penetrating sliding surface. Under various earthquake intensity levels, the acceleration amplification coefficient of the slope increases with the elevation. A weak interlayer can amplify the amplitude of the Fourier spectra, which results in a difference in the vibration between the deposit and bedrock and damage to the slope. When the acceleration exceeds 0.3g, the soil behind pile begins to squeeze it, and the peak value of the dynamic earth pressure first increases and then decreases along the elevation of the pile, reaching its maximum near the sliding surface. The load-sharing ratio of the pile-anchor structure steadily decreases as the peak acceleration of the seismic wave, tension of the anchor cable, and limiting effect of the anchor cable on the pile displacement increase. We suggest that the amplification effect of seismic acceleration should be considered in the seismic design of pile-anchor structures, with local reinforcement near the sliding surface of the pile, and the load-sharing ratio of the structure should be flexible.