Research On The Influence Of Ground Load On The Force And Deformation Of Shield Tunnel

With the continuous acceleration of social urbanization,the urban population continues to increase,leading to frequent congestion in urban ground transportation.In order to alleviate the pressure on surface transportation caused by the increase in urban population,more and more cities have begun to vigorously develop underground transportation systems.Urban subways are an important part of the underground transportation system.The increasing number of urban shield tunnels will increase the probability of ground stacking near the shield tunnels.Large-area ground stacking will cause stress redistribution in the tunnel,leading to changes in the stress and deformation of the tunnel lining structure;when the stacking load is too large,it will even cause damage to the tunnel lining segments and gaps at the interfaces between the segments Phenomena such as enlargement and failure of bolts can threaten people’s lives and property in serious cases.Based on the above problems,the main research work of this paper is as follows:1.This article mainly focuses on the experimental research on the impact of ground load on the force and deformation of the adjacent shield tunnel.The model test is carried out by changing the ground load position,the buried depth of the tunnel and the height of the groundwater line below the shield tunnel,and the model is analyzed.The changing law of the confining pressure and deformation of the tunnel in the test.The theoretical calculation and midas gts finite element software are used to calculate the force and deformation of the tunnel in the actual working conditions corresponding to the model test,and then the results obtained are compared and analyzed to mutually verify the correctness of the model test,theoretical calculation,and finite element model.After verifying the reliability of the finite element model,the verified finite element model was used to simulate the grouting reinforcement around the tunnel and the reinforcement of the steel ring in the tunnel,and the settlement of the tunnel and the deformation of the segments under the condition of ground pile loading were analyzed.2.The research results show that when the equivalent value of the heap load is accumulated step by step,the change of the tunnel confining pressure basically shows an equivalent increase;the change of the tunnel confining pressure shows an overall decrease with the increase of the eccentric distance within a certain range In the experiment,the confining pressure of the tunnel on the eccentric side is significantly smaller than that on the non-eccentric side when the stacking position is 0.5 D0(D0 is the outer diameter of the segment)and 1 D0,when the stacking position is 1.5 D0,the confining pressure on both sides of the tunnel The amount of change is basically the same;as the buried depth of the tunnel increases,as the thickness of the soil at the top of the tunnel increases,the impact of the ground load on the confining pressure of the tunnel is relatively reduced.The greater the ground load,the greater the settlement of the shield tunnel and the greater the vertical convergent deformation of the tunnel;the farther away from the surcharge,the smaller the settlement of the tunnel,the smaller the vertical convergent deformation of the tunnel,and the smaller the lateral convergent deformation;when the size of the heap remains unchanged When the buried depth of the tunnel is greater,the vertical convergent deformation and settlement of the tunnel will be smaller;the maximum settlement of the deep layer of the soil is always kept closest to the heap load;compared with the use of dry sand,the vertical tunnel will be The convergent deformation and settlement are significantly reduced;the theoretical calculation results are in good agreement with the trends of the indoor model test results,and the numerical simulation results are more consistent with the indoor model test results.3.The grouting method is used to reinforce the surrounding soil of the tunnel,which can make the vertical deformation of the tunnel under heap load much smaller than the vertical deformation without reinforcement,and it has a certain inhibitory effect on the settlement of the tunnel;the use of inner steel ring and UHPC reinforces the inner wall of the tunnel,which can significantly reduce the vertical deformation of the tunnel under the action of the heap load,but has a small effect on the settlement of the tunnel.Figure 88 table 8 reference 68...