盾构隧道施工过程建模影响因素分析

为研究盾构隧道施工过程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体影响因素耦合作用分析,构建盾构隧道开挖过程仿真模型,给出地表沉降和隧道垂向应力;然后,进一步模拟去除其中一种因素的隧道开挖过程,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。结果表明:一方面,建模过程中各种因素对地表沉降的影响大于对隧道垂向压力影响;另一方面,盾构机推进给开挖面土体压力、盾尾灌浆延迟管片拼装造成的暂时性土体支撑力不足、盾构机刀盘转动给开挖面土体扭力等因素对模型解算造成的影响最大。本研究对提高盾构隧道施工过程建模的准确性和实效性,指导盾构隧道施工具有重要指导作用。

Analysis on Influencing Factors of Shield Tunnel Construction Modeling

In order to analyze the influences on modeling of the shield tunnel construction process, firstly, the coupling effects of the influence factors between the shield precursor and the rock-soil mass are analyzed, and the excavation process is simulated with FLAC3D to give the ground settlement and the tunnel vertical stress; secondly, by means of removing one of the influence factors from the simulation model, the ground settlement and the tunnel vertical stress are also calculated; finally, based on Fast Fourier Transform, the ground subsidence and the tunnel vertical stress are analyzed by comparison, and the influence effects for modeling of all kinds of the factors are found out. Results show that on one hand, the influence effects to the ground settlement are more than that to the vertical pressure of the tunnel; on the other hand, the factors having max effect to the simulation results include the soil-rock stress of the excavation workface caused by the shield boost, the temporary low support strength caused by the grouting at the end of the shield delaying the shield tunnel segment assembly and the soil-rock torsion force of the excavation workface caused by the shield cutter-head running. The study will play important role in enhancing the accuracy and the effectiveness of the shield tunnel construction modeling.