| With the development of economy,our country has entered the peak period of the construction of subway.While,the construction of subway has led to changes of the distributions of ground displacement and stress,and resulted in additional internal force and deformation on adjacent buildings,which would affect the reliability of the buildings.Shield tunneling has become a common subway construction method.Thus,the influence of shield construction on the ground displacement and adjacent buildings has already become the important issue encountered in the current development and utilization of underground space,as well as its control measures.The above issue will be studied by the methods of engineering analogy,theoretical derivation,theoretical analysis and field experiment analysis in this thesis.The main research contents and conclusions will be shown as follow:1?By the theoretical analysis of the ground disturbance and deformation mechanism caused by shield construction,the induced factors are divided into two categories:mechanical effect,which mainly includes face additional pressure caused by cutterhead(q),cutterhead friction(fd),skin friction along the shield(fs),and grouting pressure at shield tail(p),and ground loss,which mainly includes the part caused by the gap of the shield tail.A three-dimensional solution of ground displacement for mechanical effect was derived by integral of Mindlin solution in this thesis.What's more,combining the Loganathan solution with Verruijit solution,a three-dimensional displacement solution based on oval-shaped ground deformation pattern has been deduced.2?The comparison between the quantitative analysis of the influence of mechanical effect and that of soil loss on ground displacement shows that the displacement caused by soil loss accounts for about 95%of the total displacement.Usually,the construction method of tail void grouting and secondary grouting has been adopted to reduce the gap of the shield tail in order to control the ground displacement.However,the gap can't be completely filled due to the volume shrinkage of the grouting fluid which is 8.40%?9.8%so that the actual grouting capacity is 1.1 times that of the theoretical amount in the poor permeability ground,with the increase of permeability,the grouting volume should be added as well.3?The additional displacement and internal force of adjacent buildings caused by ground displacement have been studied by the analysis of the elastic foundation beam model and the elastic shear-bending beam model both based on the synergistic effect.The results show that buildings with small foundation coefficient and low overall building rigidity can better adapt to the disturbance of shield construction,while the influence of shield construction on the internal force of the structure is obvious for the buildings with large overall stiffness,but the influence on the inclination of the building is small.4?Two-stage method is adopted to analyze the influence of adjacent pile foundation on shield construction,and the study shows that the additional internal force of adjacent pile is sensitive to the space between pile and tunnel.According to the relationship between the additional internal force of pile and the space between pile and tunnel,ground around tunnel has been divided into three regions:strong-influence area?weak-influence area and non-influence area,the division standard was given as well.5?This thesis has studied the microcosmic mechanism of foam modified slag and the influence factors of foam half-life,whose results have been successfully applied to solve the problems relying on backing project.The practice shows that the excavated materials would been massive when the additional water is not enough in mudstone with low water content,resulting in transmission slippage and reducing the drive speed;the plasticity of materials would been obviously improved as well as the drive speed with the increase of the additional water. |
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