不同顶推力下盾构施工对地层变形的影响分析

Analysis of Influence of Shield Construction on Ground Deformation under Different Driving Force of Jack

盾构施工参数不当会引起过大的地表沉降与地层变形,造成安全事故与经济损失。本文以广州市轨道交通十八号线万顷沙站~横沥站区间隧道工程为背景,采用MIDAS/GTS NX有限元软件,改变刀盘顶推力参数,研究盾构掘进引起的地表沉降变化以及地层变形规律,并结合实际施工过程分析了土体变形的原因。结果表明:表层土体在盾构施工作用下发生沉降,其形态符合peck提出的沉降曲线;在较小刀盘顶推力下,完成一半掘进环数管片施作时的施工工况地表沉降最小;地表沉降峰值随着刀盘顶推力的增大而减小,但减小的幅度趋于稳定;顶推力的增大能降低掌子面土体的塌陷程度;12000kN刀盘顶推力下地表沉降趋势与现场实测数据基本吻合,说明本次数值模拟结果较为准确,对隧道施工有一定的指导意义。

Improper shield construction parameters will cause excessive ground settlement and ground deformation,resulting in safety accidents and economic losses.In this paper,the tunnel project between Wanqingsha Station and Hengli Station of Guangzhou Rail Transit Line 18 was taken as the engineering background,and MIDAS/GTS NX finite element software was used to change the thrust parameters of cutterhead top.The surface subsidence change and stratum deformation law caused by shield tunneling were studied,and the causes of soil deformation were analyzed combined with the actual construction process.The results show that the surface soil settlement occurs under the action of shield construction,and its shape conforms to the settlement curve proposed by peck.Under the small cutter head top thrust,the surface settlement of the construction condition is the smallest when the half tunneling ring number segment is completed.The peak value of surface subsidence decreases with the increase of the thrust of the cutterhead,but the decrease tends to be stable.The increase of the top thrust can reduce the collapse degree of the soil on the palm surface.The ground settlement trend under the thrust of 12000kN cutter head is basically consistent with the measured data,indicating that the numerical simulation results are more accurate and have certain guiding significance for tunnel construction.