基于FLAC3D的盾构隧道施工过程建模影响因素分析

Analysis on influence factors of modeling for construction process of shield tunnel based on FLAC3D

基于FLAC3D对盾构隧道施工过程模拟,研究建模影响因素及其影响程度。首先,综合隧道开挖过程中盾构机前体与岩土层间相互作用的影响因素来模拟隧道开挖过程,确定地表沉降和隧道垂直(Z)方向应力;然后,分别模拟去除其中一种因素后的隧道开挖过程,并求出相应的地表沉降和隧道垂向应力;最后,基于傅里叶变换对各种情况下的地表沉降量和应力应变状况进行比较分析,找出各因素对建模的影响程度,从而为利用FLAC3D进行盾构隧道施工模拟时的影响因子的选择提供参考。研究结果表明:一方面,建模过程中的各种因素对地表沉降的影响大于对隧道Z向压力影响;另一方面,盾构机推进给作业面土体压力、盾尾灌浆延迟于管片拼装造成的暂时对土体支护力不足、盾构机刀盘转动给作业面土体的扭力等因素对模型解算造成的影响最大。

The influence factors and impact of modeling for construction process simulation of shield tunnel based on FLAC3D were studied. Firstly, by integrating the influence factors of interaction between the shield machine precur- sor and rock and soil, the process of tunnel excavation was simulated to determine the surface subsidence and tunnel vertical （Z） stress; Secondly, the process of tunnel excavation after removal of one factor was simulated respectively, and the corresponding surface subsidence and tunnel vertical stress were derived ; Finally, the quantity of surface sub- sidence and the stress and strain status under various conditions were compared and analyzed based on Fourier trans- form. The impact of each factor on modeling was found out, so as to provide reference for the selection of influence factors when simulating the construction process of shield tunnel by FLAC3D. The results showed that on the one hand, the influence of various factors on surface subsidence were larger than that on tunnel vertical（Z） stress in mod- eling process; on the other hand, the following factors made the greatest impact on the model solution： the pressure on work surface soil by shield machine advancing, the temporary insufficient supporting capacity to soil by delaying of shield tail grouting to segment erection, and the torque to work surface soil by cutter rotation of shield machine.