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与水平地面地基土体的对称破坏模式不同,临坡地基土体随不同工况呈现较明显的多种破坏模式。基于上限分析有限元技术,通过对临坡地基土建模,得到非线性上限规划模型,采用可行弧内点算法对其进行求解。将计算结果转换成相应的速度场和能量耗散图,并与文献结果进行对比分析。分析结果表明,上限有限元法能够较清楚地模拟出临坡地基破坏的几种模式,并得到合理解。通过把临坡地基承载力转为Terzaghi建议的分项系数叠加形式,对分项系数N_c、N_γ、N_q的变化规律进行讨论,发现N_c和N_q变化趋势基本符合现有的单调变化规律,但对于N_γ而言,由于破坏模式改变造成了破坏体体积变化,得到N_γ发生非单调改变的变化规律。以临坡基础完全不受斜坡影响的距离α_0/B作为绝对安全距离,并给出部分计算图表,为斜坡地基设计提供参考。
Different from the symmetrical failure mode of soil on horizontal ground, the soil on slope foundation shows obvious multiple failure modes under different working conditions. Based on the finite element analysis of upper bound analysis, a non-linear upper-bound programming model is obtained by modeling the subgrade soil, and the feasible arc-interior point algorithm is used to solve the problem. The calculation results are converted into the corresponding velocity field and energy dissipation map, and compared with the literature results. The analysis results show that the upper bound finite element method can simulate several modes of failure of slope foundation more clearly and get a reasonable solution. By changing the bearing capacity of foundation on the slope to Terzaghi’s suggested sub-coefficient superposition form, the variation rules of the sub-coefficients N_c, N_γ and N_q are discussed. It is found that the trend of N_c and N_q basically conforms to the existing monotonous variation law. However, In the case of N_γ, the change of non-monotonous change of N_γ is obtained due to the change of failure mode volume. Taking the distance α_0 / B which the slope foundation is not affected by the slope as the absolute safety distance, some calculation charts are given, which can provide a reference for the design of slope foundation.