合肥地区复合地层盾构掘进参数控制研究

为保证合肥地铁盾构隧道的施工安全,基于合肥地层情况,通过PLAXIS 3D 岩土有限元软件模拟穿越软土、硬岩及复合地层3 种不同地层条件的盾构掘进过程,研究开挖面支护力N、盾构钢壳锥度引起的收缩率C 和壁后注浆压力p 对地表沉降和围岩变形响应的影响规律。研究结果表明: 1)支护力N 和注浆压力p 对地表沉降的影响受地层和埋深的限制较大,收缩率C 则相对较小;2)从地表沉降上看,盾构掘进参数(N、C、p)对软土层的影响最大,复合地层次之; 3)p 对管片上浮和管片内力的影响显著,不宜设置过高,软土层对p 最为敏感,硬岩和软硬复合地层次之。最后,将这些影响规律应用于合肥地铁4 号线某区间的盾构掘进参数控制中,结合现场数据分析,结果表明盾构掘进姿态正确,地表沉降稳定,掘进参数合理可靠。

Study on Parameters Control of Shield Tunnelingin Composite Strata in Hefei Area

In this paper, the shield tunneling process of Hefei Metro under 3 different strata conditions, i. e. soft soil,hard rock and composite strata, is simulated by geotechnical finite element software PLAXIS 3D. And then theinfluences of support force N of tunneling surface, shrinkage rate C caused by the taper of shield steel shell and groutingpressure p behind lining on surface settlement and deformation of surrounding rock are studied. The study results showthat: (1) For the surface settlement, the stratum condition and burial depth have a greater limitation on N and p thanthat on C. (2) The impact of shield tunneling parameters (N, C and p) on surface settlement of soft soil layer is largerthan that on surface settlement of composite strata. (3) The p has a significant influence on segment floating and internalforce, which should not be overlarge; the soft soil layer is most sensitive to p, followed by hard rock and soft-hardcomposite formation. The study results are applied to the control of shield tunneling parameters in a section of HefeiMetro Line 4, and according to the fiel data analytical results, the shield tunneling attitude is correct, the surfacesettlement is stable, and the tunneling parameters are rational and feasible.