区间隧道长距离密贴下穿既有车站变形特征分析

Analysis of Deformation Characteristics of Long-distance Interval Tunnel Closely Underneath Crossing the Existing Station

既有结构在隧道长距离密贴下穿过程中极易受到扰动而产生较大沉降,为分析既有结构的安全性,依托北京地铁19号线区间隧道零距离下穿既有4号线新宫站工程,将数值模拟与现场监测相结合,研究既有结构在施工全过程中的沉降变形特征。结论表明:(1)对地层进行全断面深孔注浆加固可有效控制既有结构沉降;(2)下穿段区间隧道二衬施作引起既有结构沉降最大,施工全过程中既有车站沉降小于3 mm的限值;(3)两侧疏散口沉降集中发生在既有站两侧隧道施工过程中,施工全过程中既有疏散口沉降小于3 mm的限值。

The existing structure is susceptible to disturbance and tends to produce large settlement in the process of longdistance tunnel closely underneath crossing.In order to analyze the security of existing structure,the numerical simulation and on-site monitoring were combined to study the settlement and deformation characteristics of existing structure in the whole process of interval tunnel of Beijing Metro Line 19 closely underneath crossing the existing Xin Gong station of line 4.The results are as follows:(1)the settlement of existing structure can be effectively controlled with the technology of full section deep hole grouting.(2)The settlement of existing structure caused by the construction of secondary lining in the underneath crossing section is the largest,and the settlement of existing station is less than the limit value of 3 mm in the whole construction process.(3)The settlement of evacuation exits on both sides mainly occurs in the construction process of tunnels on both sides of existing station,and the settlement is less than the limit value of 3 mm in the whole construction process.