基于离散元的边坡矢量和稳定分析方法研究

基于离散元方法对获取的块体单元、节理的应力场处理后得到坡体整体应力场，结合矢量和法安全系数的定义提出了一种边坡稳定性分析方法即VSM-UDEC法。首先通过滑块试验验证了多种情况下UDEC接触应力计算和单元应力的精确性，结果表明，UDEC接触应力和块体单元应力的精确程度很高（接触应力相对误差基本低于0.2%），能够满足矢量和安全系数计算要求。采用VSM-UDEC法分别对直线型滑面和圆弧型滑面算例进行了分析，并与相应的理论解和严格极限平衡法（Morgenstern-Price法）进行了对比。结果表明，对于直线型滑面VSM-UDEC法安全系数与理论解几乎相同，而对于圆弧型滑面该方法与极限平衡法结果基本一致。最后将VSM-UDEC法运用到锦屏I级水电站左岸边坡工程实例中，结果表明，假设块体为刚体时VSM-UDEC法安全系数与极限平衡法（Sarma法、Morgenstern-Price法）结果吻合较好，此外，VSM-UDEC法能够考虑坡体内结构面对稳定性的影响，较极限平衡法更能反映边坡的变形分布情况。鉴于UDEC在模拟边坡破坏方面优点较多且矢量和法安全系数物理意义明确，VSM-UDEC法有望在边坡稳定性分析中有较好的应用前景。

Vector sum method for slope stability analysis based on discrete elements

Based on the whole slope stress field obtained from block element and the joint stress field calculated by distinct element method, combining with the definition of vector sum method (VSM), a new slope stability analysis method is proposed, namely VSM-universal distinct element code (VSM-UDEC) method. Firstly, the accuracy of contact stress and element stress calculated by UDEC under various conditions is verified by the slider test. It is shown that the contact stress and element stress fields have high precision (i.e., the relative error of contact stress is less than 0.2%), which satisfies the condition of safety factor calculation. Numerical simulations of a linear sliding surface and a circular sliding surface are analyzed by the VSM-UDEC method. Numerical results are compared with the solutions by the corresponding theory and the rigorous limit equilibrium method (Morgenstern-Price method). It is indicated that the safety factor obtained by the VSM-UDEC method is almost identical with that by the theoretical solution in the case of linear sliding surface, and is consistent with that by the limit equilibrium method in the case of circular sliding surface. Finally, the VSM-UDEC method is applied to analyze the stability of the left bank slope of the Jinping-I Hydropower Station. The results demonstrate that the safety factor by the VSM-UDEC method is good agreement with that by the limit equilibrium methods (Sarma method, Morgenstern-Price method) when blocks are regarded as rigid. Moreover, the VSM-UDEC method can be considered as the effect of the structural surface in the slope body on the slope stability, and thus it has more advantages than the limit equilibrium method to reflect the actual stability and deformation distribution situation of the slope. UDEC software has good applications of simulating slope failure process and VSM has the clear physical significance of safety factor, and therefore, the VSM-UDEC method may have good prospects of applications in the slope stability analysis.