孔隙水压力效应下非均匀地层盾构隧道稳定性分析

Stability analysis of shield tunnel under heterogeneous pore water pressure effect

为了确定盾构隧道穿越不均匀地层时由上下地层间力学性质差异所引起的开挖面支护力,以组合对数螺旋线模型为基础,建立非均匀地层中盾构开挖面失稳模型,使用极限分析上限法推导了不均匀地层盾构隧道开挖面极限支护力上限解,借助非线性优化技术手段,求出极限支护力最优解,与已有成果进行对比。并研究了孔隙水压力等其他不同参数对支护力上限及开挖面前方潜在破坏区域的影响。结果表明:上下部地层支护力随地层内摩擦角和黏聚力的增大而降低,上下部的极限支护力随着土体重度以及孔隙水压力系数的增大而增大;破坏范围随着内摩擦角和孔隙水压力系数的增大而减小,黏聚力和土体重度对破坏范围影响较小。

In order to determine the support force of the excavation face caused by the difference of mechanical properties between upper and lower strata when the shield tunnel passes through the uneven stratum,the instability model of the shield face in the uneven stratum was established based on the combined logarithmic spiral model,and the upper limit solution of the ultimate support force on the excavation face of the shield tunnel in the uneven stratum was derived using the limit analysis and upper limit method.By means of nonlinear optimization technology,the optimal solution of limiting support force was obtained and compared with the existing results.The influence of other parameters such as pore water pressure on the upper limit of support force and potential failure area in front of excavation was also studied.The results show that the upper and lower supporting forces decrease with the increase of internal friction angle and cohesion,and the upper and lower limiting supporting forces increase with the increase of soil weight and pore water pressure coefficient.The failure range decreases with the increase of internal friction angle and pore water pressure coefficient,and the cohesion and soil weight have little influence on the failure range.