孔隙水压力作用下盾构隧道开挖面支护力上限研究

基于极限分析上限定理和空间离散技术，构建了适用于在饱和土体中掘进的盾构隧道开挖面上限破坏机制。在此基础上，将孔隙水压力做的功率作为一个外力功率引入上限定理的虚功率方程，通过优化计算，得到了孔隙水压力作用下盾构隧道开挖面支护力的上限解。为了证明上限解的有效性，基于数值模拟技术计算了孔隙水压力作用下隧道开挖面极限支护力的数值解，并将得到的数值解和上限解进行了对比分析，结果表明，上限解和数值解非常接近。最后，分析了参数变化对开挖面支护力和破坏面的影响，分析结果表明:孔隙水压力对支护力上限解影响明显而对开挖面破坏范围的影响不大。

STUDY ON THE UPPER BOUND SOLUTION OF SUPPORTING PRESSURE FOR SHIELD TUNNEL FACE SUBJECTED TO PORE WATER PRESSURE

Based on the upper bound theorem and spatial discretization technique, an upper bound failure mechanism for a shield tunnel face that can be applied to saturated stratum was established. By regarding the work rate of pore water pressure as an external loading work rate, the effect of pore water pressure is introduced into the virtual work rate equation of the upper bound theorem, and the upper bound solution of supporting pressure for tunnel face subjected to pore water pressure was obtained by optimizing calculation. To evaluate the validity of the upper bound solutions, the ultimate supporting pressures for tunnel face subjected to pore water pressure were computed by numerical simulation. The numerical solutions were compared with the upper bound solutions. The comparing results show that the upper bound solutions are very close to the numerical solutions. Finally, the influence of parameters variation on the upper bound solution and the failure surface of the tunnel face was studied. The parametric analysis demonstrates that pore water pressure has significant influence on the upper bound solution of supporting pressure while it has slight influence on the range of failure surface of tunnel face.