Deformation and Stability Characteristics of Layered Rock Slope Affected by Rainfall Based on Anisotropy of Strength and Hydraulic Conductivity

Chengzhi Xia,Liang Zhang,Jie Dong,Ziqiang Zhu,Guangyin Lu,Lianrong Wu,Shuai Luo

doi:10.3390/w12113056

Chengzhi Xia, Liang Zhang + Show 5 more

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https://doi.org/10.3390/w12113056

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Abstract

The strength and hydraulic conductivity anisotropy of rock slopes have a great impact on the slope stability. This study took a layered rock slope in Pulang, Southwestern China as a case study. The strength conversion equations of the seriously weathered rock mass were proposed. Then, considering the anisotropy ratio and anisotropy angle (dip angle of bedding plane) of strength and hydraulic conductivity, the deformation and stability characteristics of rock slope were calculated and compared with field monitoring data. The results showed that the sensitivity analysis of strength and hydraulic conductivity anisotropy could successfully predict the occurrence time, horizontal displacement (HD), and the scope of the rock landslide. When the anisotropy ratio was 0.01 and the dip angle was 30°, the calculated HD and scope of the landslide were consistent with the field monitoring data, which verified the feasibility of the strength conversion equations. The maximum horizontal displacement (MHD) reached the maximum value at the dip angle of 30°, and the MHD reached the minimum value at the dip angle of 60°. When the dip angle was 30°, the overall factor of safety (FS) and the minimum factor of safety (MFS) of the rock slope were the smallest. By assuming that the layered rock slope was homogeneous, the HD and MHD would be underestimated and FS and MFS would be overestimated. The obtained results are likely to provide a theoretical basis for the prediction and monitoring of layered rock landslides.

Highlights

Rainfall is one of the main factors that trigger landslides [1]
) + Q = mw γw where H is the total head, the unit is m; x and y are the coordinates in the direction of x and y; kx is the hydraulic conductivity in the x-direction, the unit is m/s; ky is the hydraulic conductivity in the y-direction, the unit is m/s; Q is the applied boundary flux, mw is the slope of the storage curve, t is the time, the unit is s; γw is the unit weight of water, the unit is N/m3
Based on the fluid–solid coupling theory, the layered rock slope produced the corresponding displacement under the action of the fluid

Summary

Introduction

Rainfall is one of the main factors that trigger landslides [1]. In the past two decades, research on rainfall-induced soil landslides has been gaining popularity [2,3,4,5,6], but research on rock landslides is less reported [1,7,8,9,10,11,12]. According to available statistical data, more than 90% of rock slope failures are related to fluid hydraulic conduction [13]. Water 2020, 12, 3056 and by strength characteristics; both factors should be considered to assess the stability of slopes. The physical and mechanical behaviors of anisotropic rocks, such as sandstone [16,17] shale [18,19,20], slate [21,22], and phyllite [23,24], have become a hot topic over the last decades [25]. As a kind of layered rock, has an obvious bedding structure [26]. The layered structure of slate rock induces strength anisotropy. The rock strength in the direction parallel to the layers is considerably smaller than in other directions [27]

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