暴雨作用下岩质边坡生态护坡体稳定性的数值分析
Numerical Analysis of the Stability of Ecological Slope Protection Systems of Rock Slopes Under Heavy Rainfall

为了研究暴雨作用下岩质边坡生态护坡体的稳定性，基于Duncan-Chang模型和剪切损伤模型，开发了护坡根土复合体及其与基岩接触面相互作用的力学模型，并通过ABAQUS中的UMAT和FRIC子程序接口对模型进行了开发实现。利用开发的模型分析了开挖坡度、植物类型和基岩风化程度三个因素对护坡土体稳定性的影响，发现边坡开挖坡率和植物类型对护坡土体稳定性的影响显著。与开挖坡率为1:0.75工况相比，开挖坡率为1:1.00时护坡土体的最大位移减小14.79%，开挖坡率为1:1.25时护坡土体的最大位移减小25.35%。与无植物工况相比，种植狗牙根草或香根草后护坡土体的最大位移值可减小60%~80%。另外，种植狗牙根草或香根草时，护坡土体的最大位移随基岩风化程度的增大而减小。从护坡土体的力学特性与水力特性的耦合作用出发，分析了降雨作用下岩质边坡护坡土体变形破坏机理与破坏方式，并研究了降雨作用下植物对护坡土体变形的影响，发现狗牙根草能降低护坡土体渗透系数，减少降雨入渗，有利于护坡土体的稳定性。香根草根系生长过程易在土体内部形成优势渗透通道，增大土体的渗透系数，护坡土体的变形量更大。
In order to study the stability of ecological protection slope bodies of rocky slopes under the influence of heavy rain, a mechanical model of the root-soil composite body and its interaction with the rock contact surface was developed based on the Duncan-Chang model and shear damage model. The models were developed and implemented through ABAQUS using the UMAT and FRIC subroutine interfaces. Based on the developed model, the influences of slope excavation slope, plant type, and rock weathering degree on the stability of slope protection soil were analyzed. It was found that the slope excavation slope and plant type significantly affect the stability of the protection soil. Compared with the slope excavation ratio of 1:0.75, the maximum displacement of the protection soil decreased by 14.79% when the slope excavation ratio was 1:1.00, and by 25.35% when the slope excavation ratio was 1:1.25. Planting Bermuda grass or vetiver grass reduced the maximum displacement of the protection soil by 60% to 80% compared to the non-vegetated scenario. Additionally, when planting Bermuda grass or vetiver grass, the maximum displacement of the protection soil decreased with the increase in rock weathering degree. Starting from the coupling effect of the mechanical and hydraulic characteristics of the protection soil, the deformation and failure mechanism of the rocky slope protection soil under rainfall conditions was analyzed, along with the influence of plants on the deformation of the protection soil. It was found that Bermuda grass can reduce the permeability coefficient of the protection soil, reduce rainfall infiltration, and contribute to the stability of the protection soil. The root growth process of vetiver grass easily forms dominant permeation channels inside the soil, increasing the soil’s permeability coefficient and causing greater deformation of the protection soil.