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土体由于沉积而具有天然的非均质性,但关于非均质地基中隧道开挖面稳定性的研究却很稀少,在实际盾构隧道工程中均按均质地基对待。但这一简化并没有考虑非均质性对保持开挖面稳定所需最小支护压力的有利作用,以及对破坏模式的影响。故文中采用基于tresca准则的弹塑性有限元法来研究黏聚力随深度线性变化的纯黏土地基中平面应变隧道的开挖面稳定性,模拟了土体失稳渐进破坏的全过程。最终验证了无量纲化的有效性,得到了各种工况时保持土体稳定的最小支护压力值,并发现了黏聚力线性变化斜率对深埋隧道破坏模式的影响,可为理论分析和工程实践提供依据。
The soil has natural heterogeneity due to sedimentation. However, the research on the stability of tunnel excavation surface in the heterogeneous foundation is very rare, which is treated as homogeneous ground in the actual shield tunneling project. However, this simplification does not consider the beneficial effect of inhomogeneity on the minimum support pressure needed to maintain the stability of the excavation face and the impact on the failure mode. In this paper, the elasto-plastic finite element method based on tresca criterion is used to study the excavation surface stability of the plane strain tunnel in a pure clay foundation whose cohesion varies linearly with depth, and the whole process of progressive failure of the soil is simulated. Finally, the validity of non-dimensionalization is verified, and the minimum support pressure value for maintaining soil stability under various working conditions is obtained. The influence of the linear slope of cohesion on the failure mode of deep tunnels is also found, which can be used for theoretical analysis And engineering practice to provide the basis.