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应用极限分析上限法研究软土隧道开挖面的稳定性,提出了纯粘土地基中不排水条件下隧道开挖面稳定性问题的改进破坏模式,并推导了隧道开挖面稳定计算的理论公式;编制相应的计算程序,优化得到了维持开挖面稳定的支护压力最优上限解。通过与已有极限分析上限法和极限分析有限元上限解的对比,验证了本文改进破坏模式的有效性,为工程设计提供了可靠的理论依据。同时,将支护压力表示为土体粘聚力、地表超载和土体重度三相叠加的形式,给出了各自影响系数的表达式,并对之进行了分析讨论。
The upper bound method of limit analysis is used to study the stability of the excavation surface in soft soil tunnel. The improved failure mode of the stability of the excavation surface of the tunnel under undrained condition in pure clay foundation is proposed, and the theoretical formula of stable calculation of tunnel excavation surface is deduced ; Compile the corresponding calculation program and optimize the upper limit solution of retaining pressure to maintain the stability of excavation surface. The validity of the improved failure mode in this paper is verified by comparison with the existing upper bound limit analysis and upper bound finite element upper bound solutions, which provides a reliable theoretical basis for engineering design. At the same time, the support pressure is expressed as the form of three-phase superposition of soil cohesion, surface overloading and soil mass. The expression of the influence coefficient is given and analyzed and discussed.