A Discrete Numerical Study of the Effect of the Thickness and the Porosity of the Sand Cushion on the Impact Response Due to the Rockfall

Song Yuan,Jun Liu,Peng Zhao,Bo Zhang,Xibao Wang,Liangpu Li

doi:10.32604/cmes.2022.018507

Abstract

The prevention and the reduction of the rockfall are the common measures of the prevention and the reduction of disasters. When the rock-shed resists the impact of the rockfall, the force that acts on the structure consists of the cushion dead load and the impact-induced load, of which the dynamic process of the propagation of the impact-induced load is complex. Therefore, we conducted a numerical study to investigate the impact of the rockfall. Considering the highly discrete characteristic of the sand, we developed a numerical model on the basis of the discrete element method (DEM). The numerical model, which simulation results were validated by the results of real-scale experiments, was used to investigate the dynamic response of the impact force of the rockfall and the transmission of the impact force under the different magnitude of the falling height and the different thickness of the sand cushion. The results of our study indicated that the cushion thickness had little effect on the impact of the rockfall, and the dense sand cushion generated higher impact force than did the loose sand cushion. Although the high thickness enhanced the buffer performance of the sand cushion, the additional force induced by the dead load of sand cushion was significant. Therefore, to determine the appropriate thickness of the sand cushion, we suggested designers consider the buffer performance and the dead load of the sand cushion. The analysis presented in this paper provided a practical estimation of the impact-induced force of the thick sand cushion.

Highlights

IntroductionThe topographical and the geological characteristics of western China are extremely complex
We discussed the buffer performance of the sand cushion, the impact force of the rockfall, and the force that acted on the slab
The numerical analysis presented in this paper focused on the dynamic response of the sand cushion to the impact of the rockfall, of which the main conclusions of the numerical analysis were: (1) When the thickness of the sand cushion was increased above 1 m, the additional thickness had little effect on the buffer performance of the sand cushion

Summary

Introduction

The topographical and the geological characteristics of western China are extremely complex. The earthquake, the extreme weather, and secondary disasters occur frequently. The rockfall is a common geological hazard, which occurs unexpectedly [1]. Rock-sheds have been widely applied as protective structures [2]. According to the survey that was conducted by the Sichuan Communication Surveying & Design Institute on the rock-sheds and the open-cut tunnels that were built after the Wenchuan Earthquake, nearly 80% of the structural damage to the rock-sheds or the tunnels was induced by the rockfall [3,4]. The ability of rock-shed to resist the impact of the rockfall needs to be deeply explored

Results

Discussion

Conclusion