Study Of Influence To The Vertical Displacement Of Tunnel At The Bottom Of Excavation In Port Land

Along with the development of national economy, all kinds of constructions are carried into execution. Many constructions come down to the influence to neighborhood in process of excavation. So, the analysis of excavation is a basic and important problem which decide the construction successful or not and should be attached importance.In the thesis, firstly the excavation itself and its design, construction, surround shield and soil reinforce is presented simply. Secondly, present status of the excavation study at home and abroad are reviewed and summarized. And present status of the study about vertical displacement at the bottom of excavation is showed. Thirdly, the theory of the analysis for the excavation and calculation model of soil are introduced and summarized. Finite unit method and finite difference method are included in the theory, and viscoelastic-plastic model is mainly referred in introduction of calculation model of soil. In the thesis, the infection of the dividing of the soil parts and layers, and its space and time sequence in excavation was analyzed, it shows that:1. Analysis from the two-dimension method view for the time effect shows that:The ultimate displacement of excavating periphery soil first and center second above tunnels is less and better than excavating sequence that center soil first and center periphery second. Calculation results also show that displacement curve of excavating periphery soil first and center second is smooth, center soil first and center periphery second has abrupt change and it is bad for displacement and establishment control of tunnel.2. Simulation based on excavation of Shanghai M8 runnel Huaihai Road station used finite difference method to calculate and analyze the space and time effect of part divided excavating. The mainly result is as follows:1) Contrast the biggest displacement of calculate results and practice records, displacement of calculate results is about 2.2 times of practice records. Considering lots of engineering measures can not be reflected in simulation, the results is reasonable and our model is acceptable.2) Considering the space and time effect of part divided in excavating above the Metro tunnel, the time of soil excavating and the bottom exposed should be less when space effect is inconspicuous, it is good for reducing upheave.3) When excavating width of block of the third layer along tunnel above tunnel increasing to 6m from 3m and excavation time not shorten, calculation results of upheave on the same position increase 2%. If excavation time is shorten, the increment is less.3. success of excavation at Shanghai M8 tunnel Huaihai Road station shows that, through effective engineering measures, controlling displacement of tunnel and ensuring its security, excavation above Metro tunnel is doable.