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基于多块体极限分析上限法,推导了不排水条件下饱和黏性土地基中隧道环向开挖面稳定支护压力的计算公式。编制相应的计算程序,优化得到了隧道环向开挖稳定的最优上限解答。通过与已有极限分析上限解答的对比,验证了多块体极限分析上限法在隧道开挖稳定性分析的适用性。对照隧道开挖稳定的最优上限解的变化规律及相应破坏面的形状,详细分析了隧道埋深比、土体重度及强度非均质性对开挖面极限支护压力和因隧道开挖产生的滑动面范围和位置的影响。在此基础上,进一步基于隧道失稳的简化破坏模式推导了黏性土地基隧道开挖稳定的极限支护压力的简化上限解。通过与已有离心模型试验的对比验证,指出本文上限解可直接用于工程中初步确定开挖面支护压力,为隧道工程设计提供可靠的理论依据。
Based on the upper limit method of multi-block limit analysis, the formula for calculating the steady supporting pressure of the tunnel face in saturated clayey soil under undrained condition is deduced. Compile the corresponding calculation program and optimize the upper limit solution to the stability of the tunnel circumferential excavation. Through the comparison with the existing upper bound limit analysis, the applicability of multi-block upper bound limit analysis in tunnel excavation stability analysis is verified. According to the variation law of optimal upper limit solution of tunnel excavation stability and the shape of the corresponding failure surface, the effects of tunnel depth ratio, soil bulk density and strength heterogeneity on the ultimate support pressure of excavation face and tunnel excavation The resulting sliding surface area and location of the impact. On this basis, the simplified upper limit solution of the ultimate support pressure for the tunneling of cohesive soil foundation is derived based on the simplified failure mode of tunnel instability. Through the comparison with the existing centrifugal model test, it is pointed out that the upper limit solution of this paper can be directly used in engineering to initially determine the supporting pressure of the excavation face and provide a reliable theoretical basis for the tunnel engineering design.