针对深埋软土盾构隧道施工中的围岩压力问题,依托龙泉倒虹吸盾构隧洞,采用FLAC3D数值模拟软件,研究盾构掘进过程中围岩压力的演变规律及影响因素。通过建立三维模型,模拟开挖面支护、盾壳作用、同步注浆及管片拼装等关键施工环节,分析地层损失率、拱效应演化及围岩压力分布特性。结果表明:盾构掘进过程中,围岩压力变化可分为刀盘影响、盾壳通过及盾尾注浆三个阶段,其中盾尾注浆阶段地层损失率显著增加;深埋软土围岩压力主要由“压力拱”和“摩擦拱”共同作用决定,拱效应区分布于拱肩范围,松动区位于拱顶;同步注浆压力对地层损失率和围岩压力影响显著,而开挖面支护力影响较小。研究结论可为类似工程的设计与施工优化提供理论依据。

This study investigates the evolution characteristics and influencing factors of surrounding rock pressure during shield tunneling in deep soil layers, based on a new shield tunnel project. Using FLAC3D numerical simulation, a three-dimensional model was established to simulate key construction processes including excavation face support, shield shell effect, synchronous grouting, and segment assembly. The analysis focuses on ground loss rate, arching effect evolution, and distribution characteristics of surrounding rock pressure. The results indicate that: The variation of surrounding rock pressure during shield advancement can be divided into three stages: cutterhead influence, shield shell passage, and tail void grouting, with the grouting stage exhibiting a significant increase in ground loss rate; In deep soil layers, the surrounding rock pressure is predominantly governed by the combined effect of “pressure arch” and “friction arch”, where the arching zone is distributed around the tunnel shoulders while the loosening zone is located at the crown; Synchronous grouting pressure has a notable impact on both ground loss rate and surrounding rock pressure, whereas the influence of excavation face support pressure is relatively minor. The findings provide a theoretical basis for optimizing the design and construction of similar projects.