基于矢量分析方法的边坡下滑推力计算

边坡抗滑稳定分析一直都是岩土力学与工程中的重要研究方向之一，研究成果众多。针对规范不平衡推力法在实际工程应用中的不合理现象，根据边坡抗滑稳定矢量和分析方法原理，提出了基于矢量分析的边坡矢量下滑推力计算方法，推导了二维及三维边坡强度储备型和超载储备型矢量下滑推力表达式。采用矢量分析方法计算了两个二维算例及一个三维算例的下滑推力，二维算例结果表明：矢量下滑推力方向受滑面倾角变化影响较剩余下滑推力小，矢量下滑推力在滑面不同位置处的变化比剩余下滑推力光滑，避免了剩余下滑推力精度受折线形滑面倾角变化影响过大的问题，当滑面为单折线时矢量下滑推力与剩余下滑推力相同。三维算例结果与对边坡稳定的已有认识保持一致。最后，采用这两种方法对西部某工程滑坡的下滑推力进行了分析，计算中主要考虑3种工况，分别为自重、暴雨和地震工况。结果表明，矢量下滑推力较剩余下滑推力有很好的改善。探讨了矢量下滑推力较剩余下滑推力的进步之处。

Calculation of downslide thrust of slope based on vector analysis method

The stability analysis of slope has been a classic research field in geomechanics and geotechnical engineering. Numerous research results and analytical methods have been proposed in this regard. To overcome the defects of imbalance thrust force method adopted in the practical specification, both two-dimensional and three-dimensional formulations of strength margin and overload margin downslide thrust are developed, based on the principle of the vector sum analytical method of slope stability. Two 2D numerical examples and a 3D numerical example are investigated. The results of 2D numerical examples indicate that the variation of obliquity of sliding surface has less significant influence on the direction of vector downslide thrust than on the direction of residual downslide thrust. The vector downslide thrust curve is smoother than the residual downslide thrust curve, which helps avoid the problem that the precision of the residual downslide thrust is significantly influenced by the variation of obliquity of the polyline-shaped sliding surface. The results of vector downslide thrust and residual downslide thrust are the same when the sliding surface is a single polyline, and the result of 3D numerical example by the proposed method is consistent with the common understanding of the slope stability. The proposed procedures are used to calculate the downslide thrusts of a landslide in the western China under three working conditions, including the gravity condition, rainfall condition and seismic load condition. The results show that the vector downslide thrust result has been better improved compared to the residual downslide thrust. Finally, the potential improvements in the vector downslide thrust method are discussed.