大断面矩形顶管施工对近接斜交既有隧道影响研究

Research on the Influence of Construction of Large-section Rectangular Pipe Jacking on Adjacent Obliquely Intersected Existing Tunnel

为研究大断面矩形顶管施工对地表及近接斜交下方既有隧道的影响规律,依托南京某地下通道顶管法施工工程,采用FLAC 3D数值模拟方法,针对土舱压力、注浆压力和水平净距等参数进行敏感性分析。结果表明:土舱压力和注浆压力比的变化会对地表沉降产生显著影响,注浆压力比取1.0,土舱压力取0.1 MPa时对地表的影响最小;顶管施工会引起下方既有隧道隆起,既有隧道的竖向位移变化率随着施工的进行而逐渐增大;始发井始终存在的注浆压力造成既有隧道测试段虽然距离施工隧道最远却产生竖向位移最大的现象。

In order to study the influence of construction of large-section rectangular pipe jacking on the ground surface and existing obliquely intersected tunnels,based on the pipe jacking construction of an underground passage project in Nanjing,sensitivity analysis was performed on chamber earth pressure,grouting pressure ratio and horizontal clearance by using FLAC3 D numerical simulation method.The results show that the change of chamber earth pressure and grouting pressure ratio have a significant impact on the surface settlement.When the grouting pressure ratio is set to 1.0 and the chamber earth pressure is set to 0.1 MPa,the impact on the ground surface is the least.The influence on existing tunnel is uplift,the vertical displacement change rate of the existing tunnel gradually increases with constructing;The grouting pressure always exists in the launching shaft,which causes the maximum vertical displacement in the test section of the existing tunnel although it is the furthest from the new-constructed tunnel.