| Excavation of the subway will have an impact on the surrounding soil. When the settlement gets larger, it may threaten the safety of surrounding buildings. Based on the functions and site environment and geological conditions of subway, the appropriate method should be selected during the subway construction. Due to the different construction methods will have different influences on surrounding environment. The analysis of the influence of different construction methods on surrounding environment is of great significance for subway construction.In this paper, combined with the special "soil-rock" composite geological situation of Changchun area, mechanical behavior of subway guide hole and the surrounding environment were studied according to comparison of Monitoring data and numerical calculations. In addition to the objective factors such as the strata structure, the excavation sequence and excavation footage are also very important factors for influence of subway construction on the surrounding environment. Therefore, the influence of excavation sequence and excavation footage and other construction factors were studied. Finally, the spatial effect of liaison channels and pipelines were studied, and influence laws under different spatial positions were summed up. The main contents and conclusions are as follows:1. The effect on the surrounding environment during subway station construction with PBA method.Firstly, deformation laws of surface subsidence and vault settlement and clearance convergence were analyzed. Secondly, a numerical simulation of effect on the surrounding environment was performed by using FLAC3 D finite element software. Through comparison of different schemes, the scheme can be determined for this project. These results are useful for providing a basis for similar project construction in the future.The study has concluded that:(1) there are "group hole effect" during subway excavation;(2) after the pilot tunnel excavation, venue stress was redistribution, and vertical concentration stress was appeared in the lower side wall of the guide hole.(3) This project should select excavation sequence that the upper layer is prior to lower and the middle is prior to two sides.(4) the measure increasing the spacing between adjacent excavation cave guide or avoiding the adjacent pilot tunnel being adjacent in excavation sequence can weak the sensitivity of "group hole effect".2. The effect on the surrounding environment during contact channel construction with CRD method.Firstly, through the analysis of surface and cave settlement monitoring data, settlement laws in soil and pipeline with CRD method were summed up. Then, a numerical simulation was performed by using MIDAS/GTS finite element software to study the settlement deformation and mechanical behavior of the cross channel during excavation. And on this basis, the factors affecting construction were analyzed and the spatial effects were studied. The study has concluded that :(1) Sphere of influence of the tunnel face is about 15 m.(2) Due to a good support system has been formed after the upper pilot tunnel excavation finished, the impact on surface produced by the lower is little than the impact on surface produced by the upper pilot.(3) The impact on cave surrounding rock and soil caused by excavation is more directly than the surface.(4) Surface settlement caused guide hole construction accounts for 72.4%.(5) Pilot tunnel with cross excavation method will have a little effect on the upper soil.(6) Within the scope of depth in this project, arching effect had not been found in the soil above contact channel(7) When the lines is perpendicular to liaison channel, excavation has the most influence on upper line. |
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