Influence Of Different Excavation Methods On Surface Settlement In Shallow Tunnel

In recent years,with the rapid development of urbanization in China,the scale of the city is expanding,and the traffic pressure on the ground is more and more heavy.Subway lines are generally built in densely populated area.In order not to affect the traffic and buildings on the ground,only the tunnel excavation method can be used in the excavation process.The surface settlement is a very important reference factor in the shallow buried excavation engineering,and the current situation of the project can be roughly understood by the cumulative amount and rate of surface subsidence.In this paper,the principle and the general method of shallow buried excavation method are introduced.And the development of the research on the influence of surface subsidence is introduced.The main part of the article is to analyze the actual monitoring data and numerical simulation.Combined with the actual engineering data and monitoring data of Wenyanglu Station,using theoretical analysis and numerical simulation method combined with MIDAS/GTS construction process simulation.Draw the following conclusions by analysis of different excavation methods on the influence of surface subsidence:1.In practical engineering,the standard pipeline settlement monitoring points should be arranged in the area where the pipeline deformation is strict;2.In the longitudinal direction of the tunnel,the influence range of the excavation face is about 3 times the diameter of the tunnel,and the influence is more than twice the diameter of the tunnel,and the influence is the largest in the range of 1 to 1.5 times the diameter of the tunnel.The law of lateral settlement is consistent with the Peck formula,and the normal distribution of the settlement trough;3.In this paper under similar engineering conditions,using different excavation scheme on the influence of surface subsidence in ascending order: double wall pilot method,CD method,single side heading method,step method,full face excavation method.The settlement value bench excavation way than CD method and the single side wall heading around 50% more.It is not suitable to adopt the full face excavation method in the case of the tunnel cross section similar to the project;4.In the process of tunnel excavation,the stress of the support system is mainly located at the side of the shoulder and the invert of the tunnel section.