新建隧道下穿对既有隧道稳定性影响研究

Influence of underpass of new tunnel on stability of existing tunnel

为研究相同地质条件下,不同开挖方式对既有隧道稳定性的影响。以深圳地铁9号线下穿工程为背景,利用FLAC3D有限元软件,建立了隧道开挖的三维数值模型,分析不同开挖方式对新建隧道和既有隧道的应变影响,并与现场监测值进行了对比分析。研究结果表明:数值模拟所得不同开挖方式的应变与实际测量结果的趋势相似,但对隧道稳定性的影响从大到小依次为:全断面法,台阶法,CD法,双侧壁导洞法。考虑到施工成本和时间成本,该工程的最佳开挖方案为台阶法。

To study effects of excavation methods on the stability of existing tunnel,a 3D numerical model of tunnel excavation is established based on the finite element software FLAC 3D taking Shenzhen Metro Line 9 as an example.The effects of excavation methods on the strain of the new and existing tunnels.The simulated results are compared with the field monitoring data.The results show that the strain of tunnel by different excavation methods obtained from simulation and field monitoring holds a similar pattern.The impacting extent of excavation method on the tunnel stability(from large to small)is full section method,step method,CD method and bilateral wall tunnel method.Comprehensively considering the cost of construction and time,the optimal excavation method for the project should be step method.