中文摘要：

论述边坡失稳是滑动土体受张拉和剪切的复合破坏行为,而不是单一剪切破坏的结果,并探讨适用于岩土材料的张拉Mohr-Coulomb剪切复合破坏准则。在采用现行只含单一剪切破坏材料模型的大型有限元程序进行土坡稳定分析时,可通过二次程序开发加入此张拉–剪切复合破坏材料模型,或在数值计算中以剪切破坏区与张拉破坏区刚好连通作为边坡失稳破坏判据2种方法来考虑土体的张拉破坏。采用有限元法和快速拉格朗日有限差分法对7种形式的土坡进行了数值模拟分析与比较。计算结果表明,在考虑土体张拉–剪切复合破坏条件下,2种数值计算方法的分析结果相当。由于土体的抗拉强度小于抗剪强度,因而在不考虑土体的张拉破坏条件下,计算所得边坡稳定安全系数均可能较理论结果偏高1%～10%,故在边坡稳定分析中考虑土体的张拉破坏是必要的。同时,获得了这7种形式的土坡失稳时,对应张拉–剪切复合滑动面形状的规律性认识,可用来检验其他边坡稳定分析法所搜索到的最危险滑动面的合理性。

英文摘要：

The authors consider that unstable slopes are caused by composite failure of tension and Mohr-Coulomb shear of sliding soil mass,but not caused by single shear failure.The composite failure criterion,which is applicable to rock and soil,is discussed.When the prevailing large-scale finite element programs that only the single shear model is included in their material models are used to analyze soil slope stability,there are two ways to consider shear failure of soil mass.The one is to redevelop subroutine of user-defined mechanical model,which can express the composite failure criterion of soils.The other is that the just connection between the shear failure zone and tension failure zone should be regarded as the criterion of sliding failure of soil slopes.Numerical modeling analysis is performed with seven kinds of soil slopes by using the finite element method and the fast Lagrangian finite difference method.The comparisons show that the results from the two methods considering the composite failure of tension and shear of soil mass coincide very well.Since the tension strengths of soils are lower than those of shear strengthsi,f the tension failure of soil mass is not taken into accountt,he factors of safety of slope stability are possibly 1% to10% higher than those of theoretical ones.Thereforei,t is necessary to consider the tension failure of soil mass in soil slope stability analysis.Meanwhile,some laws about the shapes of composite sliding surface of the seven sorts of soil slopes are obtained;and they can be used to judge whether critical sliding surface searched by other analytical methods of slope stability is reasonable or not.