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非均质是软黏土地基中比较普遍的现象,而目前隧道开挖面稳定研究中比较成熟的理论主要是针对均质土体。因此,从塑性极限分析上限法的基本原理出发,采用平面应变隧道刚体平动破坏模式(多块体上限法),考虑软黏土地基的非均质性,推导了平面应变隧道极限支护压力关于隧道埋深、土体重度及土体强度的上限公式。通过与其他方法的比较分析,证明了极限分析方法在隧道开挖面稳定性方面的可行性;利用该方法的计算结果详细探讨了隧道开挖面稳定的影响因素;而且由计算结果可知,地基土的非均质性在影响隧道开挖面极限支护压力的同时,也影响着隧道开挖破坏面的位置和形状,为工程实践提供重要的理论依据。
Heterogeneity is a common phenomenon in soft clay foundations. At present, the more mature theories in the study of tunnel face excavation are mainly for homogeneous soils. Therefore, based on the basic principle of the upper limit method of plastic limit analysis, the planar rigid tunneling failure mode (multi-block upper limit method) is adopted, the pressure of limit support of the plane strain tunnel is deduced based on the heterogeneity of soft clay foundation Tunnel depth, soil mass and soil strength of the upper limit formula. Through the comparison and analysis with other methods, the feasibility of the limit analysis method in the stability of tunnel excavation surface is proved. By using the calculation results of this method, the influencing factors of the stability of tunnel excavation surface are discussed in detail. And from the calculation results, The heterogeneity of soil affects the pressure of extreme supporting of tunnel excavation surface and affects the location and shape of the damaged surface of tunnel excavation, which provides an important theoretical basis for engineering practice.