基于数值应力场的极限平衡法及其工程应用

 数值分析可较准确地计算岩土体应力分布，但求解安全系数存在诸多困难；极限平衡法计算安全系数概念明确、过程简单，但假设过多，精度又受到限制。利用数值分析得到的应力场，计算潜在滑动面上正应力分布，再按滑面正应力修正的方法求解出满足所有平衡条件的安全系数。这种基于数值应力场的极限平衡方法充分利用数值方法与极限平衡法的优点，得到理论上更合理的安全系数。将这种新的极限平衡方法应用于武都水库坝基的深层抗滑稳定性分析，并与传统的极限平衡法及有限元强度折减法进行比较，计算结果满意，并被坝基加固设计所采纳。

LIMIT EQUILIBRIUM METHOD BASED ON NUMERICAL STRESS FIELD AND ITS APPLICATION TO ENGINEERING

By using numerical method，the stress distribution can be reasonably obtained，but it is not easy to obtain the factor of safety. With limit equilibrium method，the factor of safety can be readily derived，but its precision is limited due to over-assumptions. From the stress field by numerical analysis，the normal stress distribution over the potential slip surface is calculated，with which the factor of safety is satisfied with the whole equilibrium conditions by using the method of normal stress modification. Such a limit equilibrium method based on numerical stress takes full advantages of the numerical analysis and the limit equilibrium with theoretically yielding more reasonable solution for the factor of safety. This method has been applied to the stability analysis of the deep foundation of Wudu reservoir dam and the computational results are shown to be satisfactory by comparison with the conventional limit equilibrium method and the strength reduction FEM，which has been adopted in the design of dam foundation treatment.