基于位移等值面的边坡点安全系数分析

Analysis of Slope Point Safety Factor Based on Displacement Isosurface

为了计算坡体局部稳定性并定量分析边坡滑动机理,本文提出一种新的点安全系数计算方法。假定边坡体内任一点的潜在滑动面与通过该点的合位移等值面具有位置一致性,选用Bezier双三次曲面对通过节点的位移等值面进行拟合,曲面上点的位移梯度即为曲面在该点的法向量,节点位移矢量在位移等值面上的投影为该点的滑动方向,据此计算破坏面上的正应力和滑动方向的剪应力。定义边坡点安全系数为该点抗剪强度与滑动方向上剪应力的比值。与基于应力状态的点安全系数不同,本文方法在位移等值面上定义点安全系数,考虑了边坡体的实际滑动方向,更符合边坡的破坏特征。通过ACADS边坡考题验证本文方法的正确性,本文方法能够为边坡工程三维稳定性分析和滑动机理研究提供思路。

In this paper,a new slope point safety factor calculation method was proposed in order to calculate the local stability of slope body and quantify the slope sliding mechanism.Assuming that the potential sliding surface at any point in the slope has a positional consistency with the combined displacement isosurface passing through this point,a Bezier bicubic curved surface was used to fit the displacement isosurface passing the point.The gradient of the surface point was the normal vector of the surface at that point and the projection of the point displacement vector on the displacement isosurface was the sliding direction of this point,whereby the normal stress on the failure surface and the shear stress in the sliding direction were calculated,to define the slope point safety factor as the ratio between the shear strength at the point and the shear stress in the sliding direction.Different from the traditional definition based on the stress state,the new definition in this paper,which is based on the displacement isosurface and considers the actual sliding direction of the slope body,is more consistent with the slope failure characteristics.The correctness of the proposed method has been verified by using the ACADS examination questions.In addition,the proposed method provides a guidance for the three dimensional stability analysis and sliding mechanism study of slope engineering.