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中文核心期刊

边坡稳定分析的虚功率法

A VIRTUAL POWER SLOPE STABILITY ANALYSIS METHOD

  • 摘要: 基于有限元计算所得应力场的改进极限平衡法, 对渗流与有效应力耦合作用强烈的边坡或地基的稳定性分析具有优势. 本文提出了边坡稳定分析的虚功率法, 即基于极限分析的上限定理, 利用机动许可的组合刚体滑动机构和有限元应力场, 用滑动机构的速度间断面上的抗滑力功率与滑动力功率的比值计算安全系数. 通过分步优化方法, 获得边坡给定滑动机制的稳定安全系数. 对2个典型折线滑动机构的边坡案例进行了分析, 比较了采用静力平衡应力场和静力许可应力场对安全系数的影响. 指出基于土体线弹性本构模型所得的有效应力场计算的稳定安全系数, 也是边坡稳定安全性的一个不错的度量. 算例中本文计算所得的边坡稳定安全系数, 与文献中推荐的答案很接近, 其滑动机制与有限元强度折减法分析所得的滑动机制基本一致, 安全系数也接近, 表明本文提出的方法是合理的边坡稳定分析新方法, 为边坡和地基的稳定性分析提供了新的选择.

     

    Abstract: The improved limit equilibrium method, which bases on the finite element stress field to analyze the stability of a slope, has an advantage in the analysis of the stability of a slope or a foundation with complex geological composition and strong coupling effect of seepage and effective stresses. In this paper, a virtual power method for slope stability analysis is proposed. The safety factor is calculated by using the ratio of anti-slip power to sliding power on the velocity discontinuities of the sliding mechanism by using the permissible velocity field for maneuvering of the combined rigid body sliding mechanism and the finite element stress field. The stability safety factor of a given sliding mechanism of the slope is obtained by the method of a step by step optimization strategy. Two typical sliding slope cases with weak interlayers are analyzed, including the comparison of the influence to the safety factor results of the stress fields whether static equilibrium only or also hydrostatic allowable. The safety factor in virtual power safety factor method based on linear elastic effective stress field is still a good measure to the stability of a slope even if it is not the best while the stress field is not static permissible. Slope safety factors calculated here are very close to the reference answers in the literature, the sliding mechanisms are consistent with and the safety coefficients are close to that of by the strength reduction finite element method. These show that the proposed method is reasonable. The proposed method is an alternative for the stability analysis of slopes and foundations.

     

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