Influence mechanism of pipe jacking tunnel passing through existing subway tunnel
In order to study the influence of the construction of the existing subway tunnel running through the pipe jacking tunnel on the existing tunnel and surrounding soil,based on the self-designed indoor pipe jacking test device,model test and finite element numerical simulation were used to study the influence mechanism of the existing subway tunnel running through the cable tunnel.The surface displacement,existing tunnel strain and soil pressure above the existing tunnel were mainly analyzed in test,and the model test with numerical simulation and comparative verification was supplemented.The results show that the surface displacement is inversely proportional to the buried depth of the pipe jacking tunnel.When the buried depth of the new tunnel is less than 1.5D,the buried depth has a great influence on the surface displacement.The variation trend of soil on both sides of the pipe jacking axis is basically symmetrical,and the greater the distance from the pipe jacking axis,the smaller the soil deformation.The influence of pipe jacking tunnel construction on the displacement change of the existing tunnel mainly focuses on the position where the pipe jacking tunnel is orthogonal to the existing tunnel.The existing tunnel gradually presents a state of uplift with the jacking of the pipe jacking tunnel,and the arch of the tunnel bulges earlier than the vault.The maximum longitudinal additional strain of the tunnel arch occurs in the middle of the tunnel,that is,the position of the symmetric plane,and the closer to the axis of the pipe jacking tunnel,the greater the change of the additional strain.The change of additional strain is inversely proportional to the thickness of the layer.Due to the influence of many objective factors in the experiment,although there are some differences in numerical values between the results of numerical simulation and model test,there is consistency in the variation law,which further verifies the reliability of the model test conclusions.In order to more accurately explore the influence mechanism of different crossing modes on the surface and existing tunnels,further systematic analysis should be carried out according to the field monitoring data and combined with theoretical research to provide technical reference for pipe jacking construction.6 tabs,23 figs,19 refs.
NETL
NSTL
万方数据
