纵向倾斜地表盾构隧道掌子面三维挤出破坏分析

Analysis on Three-dimensional Extrusion Failure of Shield Tunnel Face with Longitudinal Declined Ground

为完善隧道掌子面稳定性评价体系,基于极限分析上限法,考虑倾斜地表及掘进深度的影响,推导浅埋隧道掌子面三维被动支护力的上限表达式,并进一步采用规划程序优化计算获得了极限支护力最优上限解.研究表明:掌子面支护力与土体黏聚力比随无量纲参数γD/c(γ为土体容重,D为隧道断面直径,c为土体黏聚力)、掘进深度与隧道埋深比、地面超载与黏聚力比大致呈线性变化趋势,而与隧道埋深与断面直径比、地表倾斜角度、内摩擦角呈非线性变化趋势.内摩擦角、地表倾斜角度、隧道埋深与断面直径比和掘进深度与隧道埋深比对被动破坏模式影响显著,而无量纲参数γD/c和地面超载与黏聚力比对被动破坏模式影响较小.

In order to improve the stability evaluation system of tunnel face, considering the effects of declined ground and tunneling footage, the upper bound expression of supporting force for threedimensional shallow tunnel face was derived and the optimal upper bound solution of supporting force was obtained by further using the planning procedure. The results show that the ratio of supporting force of tunnel face to soil cohesion is linearly affected by the dimensionless parameter γD/c （γ is soil bulk density, D is tunnel section diameter,c is soil cohesion）, ratio of tunnel footage to tunnel depth, and ratio of ground overload to soil cohesion, whereas it is nonlinearly affected by the ratio of tunnel depth to tunnel section diameter,inclined ground surface angle, and internal friction angle. The internal friction angle, inclined ground surface angle, ratio of tunnel depth to tunnel section diameter, and ratio of tunneling footage to tunnel depth have a significant effect on the passive failure mode,while the dimensionless parameter γD/c and ratio of ground overload to soil cohesion have less effect on it.