The Analysis Of Shield Undergoing Driving Effects On The Buildings

In order to solve the problem of traffic congestion caused by economic development,the urban rail transit were built in more and more cities.And most of the construction of subway tunnels need to use shield construction undergoing the building-intensive distribution of the city,which would leads to ground subsidence cracking,building deformation and damage.So the study of the deformation on the surface and building caused by shield construction undergoing the building is an urgent problem to be solved.The left shield driven tunnel crossing a three-tier frame structure of Hefei Metro Line 1 Ge Da Dian Station to Wang Hu City Station was taken as the background,with MIDAS/GTS software for numerical simulation and analysis of construction site monitoring data to study the construction site by means of surface EPB shield sedimentation due to construction were studied.The research work and conclusions are as follows:1.This paper summarized the current research situation and the principle of surface subsidence caused by shielded crossing buildings in China and abroad,the research status of surface and the building deformation caused by shield construction and the principle of soil disturbance and surface subsidence caused by shield construction undergoing the building..2.The three-dimensional model was established with the background of actual engineering,and the settlement are simulated as follows:(1)On the direction of vertical shield driving,the maximum cumulative settlement value of the cross section was on the symmetry axis of the two tunnels.The influence range of settlement trough was 2.3 times the depth of the tunnel,and the cross section had the tendency to shift to the direction of the building load.(2)The longitudinal subsidence curve was basically the same as that without the upper structure load,but the spring back of the curve was affected by the load of the building.(3)The foundation subsidence process of the building consisted of three smooth sections and two drastic changes,and there were secondary subsidence deformation obviously.The left line's earlier excavation had a greater impact on the settlement of the upper building(4)The load of the upper structure had a small effect on the position of the settling tank and the position of the anti-bending point.Compared with the condition without the load of the upper structure,the final settlement value at the time of stabilization was 39%;(5)The maximum settlement of the surface decreased with the increase of the eccentricity ratio(the eccentricity ratio = midline of building to left line tunnel axis horizontal length/building half-length),and the maximum settlement had a tendency to move towards the direction of the building.When the eccentricity ratio was 1.5,the maximum settlement of the tunnel was basically the same as that without the upper building,the width of the settling tank increased.(6)The surface subsidence decreased with the increase of the elastic modulus and grouting pressure of the soil.When the internal friction angle was in the range of 14°~24°,the increase of the value could effectively reduce the surface settlement.The two-lane tunnel was in the construction state,the secondary subsidence caused by the later construction of the tunnel with the upper structure load was larger than the tunnel without the upper structure load.3.Analysis of site monitoring data,could be obtained that the surface and building deformation curve caused by the shield crossing the building was basically the same with numerical simulation.