考虑软化影响深度的土坡浅表层稳定性分析方法研究

Study on Analysis Method for Shallow Surface Stability of Soil Slope Considering Softening Influence Depth

为分析土坡浅表层稳定性,基于极限分析上限法理论,将滑面设为对数螺旋面,考虑坡体浅表层土体软化影响深度,建立了浅表层滑动破坏机构,推导了浅表层稳定系数的隐式计算公式,反映了稳定系数与坡面长度、软化影响深度、土体强度参数之间的关系。算例分析表明:边坡浅层旋转破坏机构得到的稳定系数与既有的三段式极限平衡法及数值模拟的结果均较为接近,且比数值模拟结果略微偏大。同时,随着坡面长度的增加,稳定系数逐渐减小到一稳定值;在某一软化影响深度时,稳定系数存在最小值;土体内摩擦角比黏聚力对浅表层稳定系数的影响更为显著。

In order to analyze the shallow surface stability of the soil slope, based on the upper bound limit analysis, set the sliding surface as the logarithmic helicoidal surface, establish the sliding failure mechanism for the shallow surface considering the softening influence depth of the soil in the shallow surface of the slope and derive the implicit calculation formula of the stability coefficient in the shallow surface, which reflects the relationship between the stability coefficient and the length of the slope, softening influence depth and strength parameters of the soil. The analysis results show that the stability coefficient obtained by the shallow layer rotating failure mechanism of the slope are close to those obtained using the existing three-stage limit equilibrium method and numerical simulation method, and the result computed using the proposed method is slightly higher than that obtained by the numerical simulation method. Also, the stability coefficient gradually decreases to a stable value with the increase of slope length, and there is always minimum stability coefficient under a certain softening influence depth. The internal friction angle of soil has more significant influence on the stability coefficient of shallow surface than the cohesion.