广深港客运专线隧道下穿地铁施工安全分析

针对广深港客运专线某隧道下穿地铁3号线工程,采用数值模拟与现场监测的方法,研究客运专线隧道下穿既有地铁线路施工的安全性。利用三维强度折减法,对三维数值模拟模型进行计算得到整体安全系数。研究结果表明:当采用三台阶法施工时,既有地铁隧道结构竖向位移为5.4 mm,与监测结果较吻合,满足运营要求;整体模型安全系数为3.78,夹岩保持稳定。根据计算与监测结果可知:近接工程安全。最后,提出相应设计对策,应采取管棚作为预支护措施、旋喷桩改良地层、复合式衬砌结构,采用控制爆破开挖减少对地层破坏,支护早封闭勤量测。

Safety Analysis of Guangzhou-Shenzhen-Hongkong Dedicated Passenger Railway Tunnel Passing under Metro

With reference to the construction of line 3 of Guangzhou-Shenzhen-Hong Kong Dedicated Passenger Railway under metro,numerical simulation and site monitoring are employed to study the safety of the construction.By adopting 3D shear strength reduction method,the global safety factor is obtained with 3D numerical model calculation.The results show that when three-step construction is employed,the vertical displacement of existing metro tunnel structure is 5.4mm,which is more identical to the monitoring result and satisfies the operation requirement;the global safe factor is 3.78 and the rock mass remains stable.The analysis and monitoring results show that the closed-spaced engineering is safe.Finally,such corresponding design measures are provided as pipe shed for pre-support,horizontal rotate pile to improve stratum,complex lining structure,and controlled blasting to reduce the disturbance of surrounding rock and early lining closing with frequent measurement.