Shaking table test study on seismic optimization comparisons of multi-anchor piles for strengthening soil slopes under earthquake

To study the distribution characteristics and spatial variations of the acceleration and dynamic soil pressure responses of slopes strengthened by multi-anchor piles under earthquake action, the optimal seismic performances of multi-anchor piles were discussed. In this paper, the regional spatial distribution characteristics along the pile elevation were obtained through the preliminary analysis of time-domain characteristics of the stability, the acceleration and the dynamic earth pressure of a multi-anchor pile slope model by large shaking table test. Then, the correlation of the damage level of the slope strengthened by multi-anchor piles was obtained by using Fourier change and statistical probability scatter matrix operation. Finally, regional differences of seismic deformation Sd were calculated by SPECTR with or without optimization of multi-anchored pile slope model. The results show that, under the action of different earthquake intensities, the slope model shows a continuous spatial deformation effect of regional damage and failure, and the spatial distributions of the acceleration and the dynamic earth pressure show an outstanding response to the unoptimized lateral amplitude of the pile structure. The acceleration lag difference along the elevation is mainly caused by the propagation stage after the main earthquake, the correlation between the seismic earth pressure and the acceleration response of each group before the pile in the same earthquake area is very weak, and the ground motion characteristic of the foreshock is not simply repeated superposition of the ground motion sequence of all levels. The shock absorbing layer with polystyrene foam(EPS plate) and multi-anchor piles with energy dissipation spring as self-coordination device of the anchor head play a buffering and energy dissipation role on the deformation of slope body under earthquake action, and the optimization effect is related to the position of the shock absorbing layer. Under the actions of low and medium strength earthquakes, the telescopic deformation of the energy-dissipating spring device of the anchor head improves the deformation coordination of the multi-anchor pile along the elevation and the seismic wave propagation characteristics of the pile. Under the action of a high-strength earthquake, the sliding surface of the pile is highly sensitive to the earthquake and EPS has plastic deformation, which increases the relative displacement value on the optimized side and is easy to cause"bulging"failure or shear failure on the sliding surface of the multi-anchor pile easily forming the seismic weak link of the multi-anchor pile. These results are helpful to provide theoretical basis for the optimal seismic design of multi-anchor piles. © 2021, Science Press. All right reserved.