盾构隧道掘进面失稳螺旋破坏机制分析

Two-dimensional spiral failure model of the heading face of shield tunneling

针对盾构隧道掘进面稳定问题,提出二维对数螺线机动破坏模型。通过对机动模型进行离散,实现破坏区域内部系统耗散功率精确计算,并利用上限分析法推导出有效支护压力上限解。采用最优化对失稳破坏模式及对应极限支护压力进行计算。研究表明,随着土体强度提高,失稳区域缩小,破坏高度降低,支护压力相应减小;对比分析显示,二维对数机动模型对掘进面失稳模式及支护压力预测结果与数值分析及已有理论模型较为吻合。选取模型试验作为算例进行验证表明,二维对数机动模型与试验结果较接近,可为工程设计提供理论依据。

This research develops a two-dimensional logarithmic spiral dynamic failure model to solve the problem of heading face instability of shield tunneling.By discretizing the dynamic failure model,the dissipation power of the system in the failure zone can be calculated accurately,and the upper bound solution of support pressure can be derived by using the upper bound method.Based on the current solution,the failure mode of instability and the corresponding limit support pressure at collapse were obtained by optimization.Through parameter analysis,the influence of soil strength on the failure mode and limit support pressure was analyzed.The results showed that with the increase of soil strength,the failure zone becomes smaller and the failure height and support pressure decrease correspondingly.The analytical solutions,including the failure mode and limit support pressure,obtained by the two-dimensional logarithmic spiral model were compared with those obtained by the numerical simulation and the existing analytical solutions.The comparative analysis showed that the analytical solutions by the proposed model are in good agreement with those from numerical simulation and other existing theoretical models.Finally,the model test was selected as an example to verify the model and the results showed that the solutions from the proposed model are close to the previous test results.The analytical solutions from the two-dimensional logarithmic dynamic failure model can provide a theoretical basis for engineering design in predicting the failure mode and limit support pressure.