基于新主滑趋势方向的矢量和边坡稳定分析方法

Vector sum analysis method for slope stability based on new main sliding trend direction

矢量和法安全系数求解的关键在于确定边坡的真实应力状态和主滑趋势方向,其求得的安全系数与边坡的真实应力状态和最终确定的滑动趋势方向紧密相关。现有矢量和法多基于单一抗滑力或滑动力确定滑坡体主滑趋势方向,但边坡的滑动实际上是抗滑力和下滑力共同作用的结果,在主滑趋势方向的定义中也需要考虑两者的共同作用。因此,将整个滑坡体作为隔离体,基于隔离体上作用的外荷载,滑动体底部法向力和极限抗滑力的整体矢量合力方向确定主滑趋势方向,进而通过矢量和法安全系数的定义确定滑坡体的安全系数。经理论推导及标准考题验证,基于新主滑趋势方向得到的最危险滑动面位置、安全系数和主滑趋势方向均与常规边坡稳定分析结果具备可比性,且基于新主滑趋势方向的边坡安全评价结果更偏于安全和便于工程师采取更具针对性的边坡支护措施。

The key to solving the safety factor of the vector sum method lies in determining the real stress state and the main sliding trend direction of the slope. The safety factor obtained by the vector sum method is closely related to the real stress state of the slope and the final sliding trend direction. The existing vector sum method is mostly based on a single anti-slide force or sliding force to determine the main sliding trend direction of the landslide. However, since slope sliding is actually the result of the combined action of the anti-slide force and the sliding force, the combined action of the two needs to be considered in the definition of the main sliding trend direction. In this study, we take the whole landslide body as an analysis object and the main sliding trend direction is first determined based on the overall vector resultant direction of the external load of the isolation body, the normal force, and the ultimate anti-sliding force at the bottom of the sliding body. After that, the safety factor of the landslide body is determined by the definition of the safety factor of the vector sum method. Finally, with the theoretical derivation and verification of standard test questions, the most dangerous sliding surface position, safety factor, and main sliding trend direction derived based on the new main sliding trend direction are comparable with those of the conventional slope stability method. What’s more, the slope safety evaluation based on the new main sliding trend direction are more safe, and more convenient for engineers to take more targeted slope support strategies.