临近既有河道的隧道掘进引起的地表沉降

Surface settlement induced by tunneling near existing river channel

传统的隧道施工诱发地面沉降问题的研究通常假定地面为水平,目前针对大直径盾构或顶管隧道工程在既有河道附近的复杂边界条件下掘进所引起的地面沉降的研究不足.以杭州某泥水平衡掘进顶管法隧道工程实例为背景,基于影像源法,考虑土体非均匀收敛,采用叠加原理给出临近既有河道条件下隧道施工引起地表沉降的解析解,并与工程实测数据进行对比.参数分析表明,隧道与河道间的水平距离越小,地表沉降槽的非对称性越显著,由隧道掘进引起的地表沉降越大;与无河道情况相比,沉降槽峰值的增幅最大可超过30%,从环境保护和施工安全的角度出发,在实际工程中隧道施工时应尽量远离河道;随着隧道埋深的增大,由隧道掘进引起的地表沉降越小,而当隧道拱腰深度大于邻近既有河道深度时,靠近河道附近的地表沉降明显大于无河道情况下的,此时更应重视既有河道的影响.

The research on ground settlement induced by tunnel construction usually assumes that the ground is horizontal.Currently,there is insufficient research on ground settlement for large-diameter shield or pipe jacking tunnel engineering under complex boundary conditions near existing river channels.An analytical solution of the surface settlement caused by tunneling near the existing river channel was proposed,based on the background of a slurry balanced pipe jacking tunnel project in Hangzhou and considering the non-uniform convergence of the soil with the virtual mirror technology and the superposition method.The comparison with the measured data verified the rationality of the solution.Further parameter analysis showed that the smaller the horizontal distance between the tunnel and the river channel,the more significant the asymmetry of surface settlement trough,and the greater the surface settlement induced by the tunneling.Compared to the absence of a river channel,the peak increase in settlement trough may be greater than 30%.Tunneling construction was advised to be as far away from the river channel as possible in the actual project from the perspective of environmental protection and construction safety.The surface settlement caused by the tunneling decreased as the burial depth of the tunnel increased.The surface settlement near the river channel was significantly greater than that with the absence of the river channel,when the depth of the arch waist of the tunnel was greater than the depth of the adjacent river channel.In this sense,more attention should be paid to the influence of the existing river channel.