Stability analysis of loose accumulation slopes under rainfall: case study of a high-speed railway in Southwest China

Abstract The high and steep slopes along a high-speed railway in the mountainous area of Southwest China are mostly composed of loose accumulations of debris with large internal pores and poor stability, which can easily induce adverse geological disasters under rainfall conditions. To ensure the smooth construction of the high-speed railway and the subsequent safe operation, it is necessary to master the stability evolution process of the loose accumulation slope under rainfall. This article simulates rainfall using the finite element analysis software’s hydromechanical coupling module. The slope stability under various rainfall situations is calculated and analysed based on the strength reduction method. To validate the simulation results, a field monitoring system is established to study the deformation characteristics of the slope under rainfall. The results show that rainfall duration is the key factor affecting slope stability. Given a constant amount of rainfall, the stability of the slope decreases with increasing duration of rainfall. Moreover, when the amount and duration of rainfall are constant, continuous rainfall has a greater impact on slope stability than intermittent rainfall. The setting of the field retaining structures has a significant role in improving slope stability. The field monitoring data show that the slope is in the initial deformation stage and has good stability, which verifies the rationality of the numerical simulation method. The research results can provide some references for understanding the influence of rainfall on the stability of loose accumulation slopes along high-speed railways and establishing a monitoring system.