超近接上跨既有隧道施工影响分区及加固措施效果

Impact Zoning and Effect of Reinforcement Measures for Ultra-closeConstruction Overcrossing Existing Tunnel

为探明新建隧道施工的扰动影响范围以提出施工对策,从而保障既有隧道的安全运营,依托北京地铁新机场线上跨既有地铁10号线工程,采用FLAC^(3D)有限差分软件对不同埋深、净距下的既有隧道进行了施工仿真计算分析。基于既有隧道拱顶位移控制标准,即控制值2 mm和预警值1.4 mm,将扰动影响分域划分为强影响区、弱影响区和无影响区。根据施工影响分区及工程特点,提出了超前管幕和超前管幕+夹土注浆2种加固措施,并进行数值模拟分析。结果表明:超前管幕加固措施位移减小64.05%;超前管幕+夹土注浆加固措施位移减小70.23%。结合现场控制标准,近接施工采取超前管幕+夹土注浆加固措施能够保障新建隧道的施工安全性及既有隧道的运营安全。

The purpose of this study is to guarantee the safe operation of tunnels by identifying the disturbance of new tunnel construction to existing tunnels.The construction of Beijing Metro New Airport Line overcrossing the existing Metro Line 10 tunnel was taken as a case study.The disturbance was simulated using FLAC 3D with varying burial depth and clearance of the existing tunnel.According to the control value(2 mm)and warning value(1.4 mm)of vault displacement control standard for the existing tunnel,the disturbance impact zone was divided into strong impact zone,weak impact zone and non-impact zone.Furthermore,according to the construction impact zoning and engineering characteristics,two reinforcement measures were proposed and numerically simulated.The two measures are:advance pipe curtain,and advance pipe curtain plus soil grouting.Results demonstrate that the control effect(vault displacement reduction rate)of advance pipe curtain is 64.05%,while the advance pipe curtain plus soil grouting 70.23%.Considering on-site control standards,we recommend that the advance pipe curtain plus soil grouting could ensure the construction safety of the new tunnel and the operation safety of the existing tunnel as well.