双线隧道近距离下穿对既有供水隧洞的影响

Influence of Short-Distance Underpass of the Double-Line Tunnel on the Existing Water Supply Tunnel

以黑白面将军山隧道工程为依托,运用数值模拟的方法,对采用CD法施工双线公路隧道近距离下穿既有供水隧洞引起的沉降及受力情况进行分析,以验证所用开挖工法是否适用。研究表明:下穿隧道开挖越靠近供水隧道正下方,供水隧道沉降增长速率越快;受隧道开挖影响较大的区域为距交叉投影中心0.75B(B为隧道跨度)范围以内。下穿施工过程中,供水隧洞衬砌最小主应力极值为-19.9 MPa,小于C30混凝土的轴心抗压强度标准值20.1 MPa;最大主应力极值为1.42 MPa,小于C30混凝土的轴心抗拉强度标准值2.01 MPa,表明所用开挖工法可以保证隧道下穿施工不会对既有供水隧洞造成损害。

Based on the Black and White Jiangjunshan Tunnel project,this paper uses the method of Numerical Simulation to analyze the settlement and stress of the existing water supply tunnel caused by the CD method for the construction of the double-line highway tunnel under the existing water supply tunnel at a short distance,so as to verify whether the excavation method used can guarantee the existing water supply tunnel.Normal use of water supply tunnel.The results show that the settlement of the water supply tunnel is faster when the excavation of the underpass tunnel is closer to the position directly below it.The water supply tunnel that is greatly affected by tunnel excavation is within the range of 0.75B from the cross-projection center(B is the tunnel span).During the underpass construction,the minimum principal stress of the water supply tunnel lining is-19.9 MPa,which is less than the standard value of the axial compressive strength of C30 concrete of 20.1 MPa;the maximum value of the maximum principal stress is 1.42 MPa,which is less than the standard value of the axial tensile strength of C30 concrete.The maximum principal stress value of the water supply tunnel section just above the excavation tunnel will increase rapidly,changing from compressive stress to tensile stress.It shows that the excavation method used can ensure that the tunnel underpass construction will not cause damage to the existing water supply tunnel,and can ensure the normal use of the water supply tunnel.