考虑土体非均质性的三维土坡稳定性上限分析

基于极限分析上限法,构建了三维土质边坡牛角状对数螺旋锥体破坏机制.通过与经典文献解答的对比分析,验证了方法的可靠性.探讨了忽略土体体积压缩耗能对三维土坡稳定性系数的影响,并分析了不同坡角、不同内摩擦角和不同宽高比三维土坡稳定性随土体非均质性变化的规律.计算分析结果表明,在内摩擦角较大而坡角和宽高比均较小的情况下,土体体积压缩耗能需要考虑;而在内摩擦角和坡角均较大或仅内摩擦角较小的情况下,土体体积压缩耗能可以被忽略.三维土坡稳定性随非均质性的增强而下降,当坡角越小或内摩擦角越大时,边坡稳定性受土体非均质性的影响越大;边坡宽高比反映边坡的三维效应,三维效应强的边坡的稳定性受土体非均质性的影响越大,其稳定性系数在土体非均质性很强时小于三维效应较弱的边坡.

Upper Bound Limit Analysis on Stability of Three Dimensional Slopes Considering Soil Nonhomogeneity

The log spiral cone failure mechanism of three dimensional slopes was built based on the upper bound limit analysis method. The present method was verified by comparing the results with the published data of the classical literature. The energy dissipation due to soil volume compression was neglected and the corresponding influence on the stability of three dimensional slopes was investigated. Then, the effects of soil nonhomogeneity on the stability of three dimensional slopes with different inclination angles, internal friction angles and ratios of width to height were explored. The results show that the influence of the energy dissipation due to soil volume compression should be considered when the internal frication angle is large but the inclination angle and the ratio of width to height is small. However, when both the internal friction angle and the inclination angle are large or just the internal friction angle is small, the energy dissipation due to soil volume compression could be neglected. The stability of three dimensional slopes decreases with the increase of nonhomogeneity and the decrease magnitude becomes larger when the slopes have smaller inclination angles or larger internal friction angles. In addition, the three dimensional effects of slopes are reflected by ratios of width to height. Slopes with stronger three dimensional effects are greatly affected by nonhomogeneity. When the nonhomogeneity is very strong, the stability factors of slopes with stronger three dimensional effects are smaller than those of slopes with weaker three dimensional effects.