辉绿岩侵入花岗岩地层条件下大跨度地铁车站暗挖施工方法比选

Comparative Selection of Large-span Metro Station Underground-excavated Construction Method under Diabase Intrusion into Granite Formation Condition

目的:青岛地铁6号线华山一路站处于辉绿岩侵入花岗岩地层而形成的复杂异质地层中,不同施工方法下车站开挖力学响应、围岩变形与地面沉降差异较大,需要从中优选出最优的施工方法。方法:依托青岛地铁6号线华山一路站(该站为辉绿岩侵入花岗岩地层复杂异质地层)工程,对CD(中隔壁)法、CRD(交叉中隔壁)法、双侧壁导坑法和初支拱盖法4种施工方法进行了三维数值模拟分析,对比了各施工方法下地面沉降、隧道洞周围岩变形和车站塑性区的分布规律,进而优选出合理的施工方法。结果及结论:车站开挖后围岩产生非对称变形,辉绿岩一侧的地面沉降及围岩变形均大于花岗岩一侧,辉绿岩一侧的塑性区也大于花岗岩一侧;双侧壁导坑法和初支拱盖法在地面沉降及围岩变形上的控制效果较好;在变形程度和破坏区域发展方面,双侧壁导坑法和初支拱盖法优于CRD法,CRD法优于CD法,所以双侧壁导坑法和初支拱盖法控制变形的效果较好,数值分析后认为这2种施工方法均可行。初支拱盖法是最优施工方法。监测结果表明,初支拱盖法在控制围岩变形和地面沉降上效果良好。

Objective:Qingdao Metro Line 6 Huashan 1st Road Station is in complex and heterogeneous stratum formed by diabase intrusion into granite formation,different construction methods adopted for the station excavation will cause distinct mechanical responses,surrounding rock deformation and land subsidence,thus the optimal construction method needs to be selected.Method:Based on the engineering project of the above station(located in the complex and heterogeneous stratum of diabase intrusion into granite formation),a 3D numerical simulation analysis is carried out on four construction methods,including CD(center diaphragm)method,CRD(cross diaphragm)method,double-side heading method and primary support arch-cover method.The land subsidence,tunnel hole surrounding rock deformation and station plastic zone distribution due to different construction methods are compared and the optimal construction method is selected.Results&Conclusion:After station excavation,the surrounding rock exhibits asymmetric deformation,with greater land subsidence and surrounding rock deformation on the diabase side compared to the granite side;the double-side heading method and primary support arch-cover method demonstrate better control over land subsidence and surrounding rock deformation;in the aspect of deformation and destruction area development,the double-side heading method and primary support arch-cover method outperform the CRD method,and the CRD method outperforms the CD method.Therefore,the double-side heading method and primary support arch-cover method are effective in controlling deformation,and both methods are deemed feasible based on numerical analysis.The primary support arch-cover method is considered the optimal construction method.Monitoring results indicate that the primary support arch-cover method effectively controls surrounding rock deformation and land subsidence.