深埋盾构隧道开挖面三维对数螺旋破坏模式的上限分析

相对于盾构隧道施工的大量需求与快速发展的状况，国内在盾构工法特别是大型深埋盾构隧道施工技术和理论研究方面还存在不足，特别是水压条件下深埋盾构隧道开挖面稳定问题。基于极限分析上限法和水土压力统一参数，对考虑水压影响的均质土深埋隧道开挖面稳定性计算方法进行研究，建立了考虑水压影响的深埋盾构隧道开挖面三维对数螺旋破坏模式模型，并推导了其极限支护压力计算公式。然后利用土层厚度加权平均法，可将上述方法应用于多层土深埋盾构隧道开挖面稳定性的评价中。最后，以上海长江盾构隧道实际工程为例，采用本文推导的极限分析上限三维对数螺旋破坏模式方法计算并分析其极限支护压力，并将计算结果与前人研究和规范方法计算的结果进行对比分析。通过该研究可改进与完善水压条件下深埋盾构隧道极限支护压力确定方法，从而为考虑水压条件下盾构隧道施工支护压力的合理确定提供理论依据。

Upper bound limit analysis of three-dimensional log-spiral failure mode of deep shield tunnel face

In contrast to the high demands and fast development of shield tunnels, significant deficiencies exist in the shield tunneling techniques and theoretical researches for large-scale deep tunnels, and especially under hydraulic conditions, the issues related to the stability of the deep shield tunnel face become even more prominent. Based on the upper bound limit analysis and the unified parameters of water and earth pressures, the face stability of tunnel in the homogeneous soil is studied with considering the effect of water pressure. A three-dimensional log-spiral failure model of the deep shield tunnel face is designed; and then an equation for calculating the limit support pressure is developed. Based on the soil thickness-weighted average method, the developed theoretical procedure is applied to evaluate the face stability of tunnel in multilayered soils. The limit support pressure of the face in the Shanghai Yangtze River tunnel is determined with the proposed upper bound limit method of three-dimensional log-spiral failure mode. The calculated results are compared with the previous studies and the simulated results. Through this research, the calculation methods of the limit support pressure of deep shield tunnel face under hydraulic condition can be improved, providing a theoretical basis for the determination of the reasonable support pressure during the construction of shield tunnel.