中文摘要：

通过引入圆锥椭圆截交线计算公式,改进浅埋隧道掌子面三维被动破坏多椭圆锥体几何参数的计算方法。基于非线性破坏准则和极限分析上限法,推导浅埋隧道掌子面三维被动支护力的上限表达式,并进一步采用非线性规划程序优化计算获得了极限支护力最优上限解。通过对比分析,验证本文方法的可靠性;同时分析非线性抗剪强度参数对被动破坏极限支护力和破坏模式的影响,并绘制相应的破坏模式图。研究表明：被动破坏极限支护力与地面超载σs及地层容重γ大致呈线性变化,而与非线性参数m、量纲一化的参数c0/σt及超负荷比C/D呈非线性变化;非线性参数m、量纲一化的参数c0/σt和超负荷比C/D对破坏模式影响显著,而地面超载σs对破坏模式影响则较小。研究成果为隧道掌子面稳定性分析提供一种新思路,进一步完善了隧道掌子面稳定性评价体系。

英文摘要：

The method of calculating the geometric parameters of the three-dimensional passive failure elliptical cone of shallow tunnel face was improved through introducing the expression for the elliptical locus of the intersection between the cone and plane. The upper bound expression of the passive failure pressure on three-dimensional shallow tunnel face and the optimal upper bound solution of passive failure pressure were obtained based on the upper bound limit analysis and nonlinear failure criterion. Reliability of this method was verified by comparing with other results. The effect of non-linear shear strength parameters on pressure and failure modes was investigated. Besides,the figures of failure modes were drawn. The passive failure pressure changes basically linearly with the ground overload σs and soil density γ,but changes nonlinearly with the nonlinear parameters m,dimensionless parameter c0/σt and critical pressure ratio C/D. The failure modes were found to depend significantly on the nonlinear parameters m,dimensionless parameter c0/σt and critical pressure ratio C/D,but the ground overload σs had smaller effect on failure modes.