Analysis Of Surrounding Soil Deformation Caused By Shield Construction Based On Field Test

In the construction of urban rail transit,the application of large-diameter mud-water shield tunneling construction is more and more extensive,but the impact of large-diameter shield tunnel construction on the surrounding environment is more complicated.The more complex the conditions of the shield excavation are,the more difficult the construction of the shield and the impact on the surrounding environment are.And even the improper construction may cause serious environmental impact.Therefore,the research and analysis of the impact of large-diameter shield construction on the surrounding environment under composite formation conditions can provide some guiding suggestions for the application of similar shield and formation conditions.In this essay,the disturbance data of the surrounding soil deformation were obtained that caused by shield tunneling construction through field tests based on the large-diameter mud-water shield tunnel excavation project in the south extension of Guangzhou Metro Line 4.And the disturbance deformation law of surrounding soil was analyzed among the construction of the large-diameter shield tunnel.The main work and conclusions of this thesis are shown as follows:(1)The field test was carried out to obtain the mechanism analysis of the vertical displacement of the ground surface and the vertical displacement of the deep soil during the construction of the shield tunneling.By proposing the concept of the vertical displacement rate of soil,the vertical displacement rate of the soil surface at each measuring point was analyzed.After that,the regulation of forward and backward impacted areas of the shield tail grouting were determined.At the same time,the rationality of the impacted areas determination is verified by combining the field test data.(2)The new two-dimensional longitudinal ground surface vertical displacement prediction model and three-dimensional surface vertical displacement model were proposed in the shield tunneling process.At the same time,combined with the field test data and other researchers'field test data,the models of soil vertical displacement proposed in this paper were verified and analyzed.It was concluded that the model method can be applied to the actual shield tunnel construction.(3)For the field test,the horizontal horizontal displacement data of the soil during the shield construction process(including the depth position corresponding to the maximum horizontal displacement of the soil,the main disturbance area of the horizontal displacement of the soil,etc.)are analyzed.It was found that the maximum distribution of the horizontal displacement of the soil forms a strip-shaped area with the angle between the center of the tunnel less than or equal to(45°-??2)(?is the equivalent friction angle from the tunnel bottom to the surface).It is also found that the upper and lower boundaries of the main disturbance area of the horizontal displacement of the soil lines are parallel and are tangent to the tunnel,and the angle between the upper and lower boundary lines and the horizontal line of the horizontal displacement is about the calculated slip angle of the soil(45°-??2).In addition,combined with the field test data analysis of this essay and other researchers'field test data to verify the rationality and reliability of the proposed law,so as to provide a certain reference for the actual shield tunneling construction and tunnel line selection.