Study On Law Of Ground Surface Deformation In Shallow Tunnel Excavation

With the accelerated process of urbanization, a large number of people flock to thecity which bring large pressure and serious city syndrome, and that caused two majorcongestion problems, one is traffic congestion, on the other hand is the construction ofcongestion. In order to solve these problems, the people began to look into thedevelopment and utilization of underground space. At present a lot of domestic city arebuilt, being built or plan to build the subway, the rapid development caused by theurban underground engineering. Subway excavation will cause settlement of groundmovement leading to varying degrees and displacement. Local the layer moving andsurface deformation exceeds a certain limit, it will cause ground subsidence, pitcollapsed,tunnel destruction, damage to surrounding buildings, underground pipelinedamage and other accidents, it cause serious economic losses and adverse social impact,affecting the normal use and safety of tunnels and surface buildings. Therefore, thecorrect prediction of surface movement and deformation caused by city tunnelconstruction is necessary.Elaborate background and significance of the paper topic; reviews the existingresearch methods and the existing problems at home and abroad based on theoreticalanalysis. Combined with the project example of Beijing Subway Line7Guangqumen toShuangjiu range segment, theoretical analysis subway construction of the miningmethod caused the mechanism and the basic law of surface subsidence. Law of timeeffect and space distribution of surface subsidence in the engineering are obtained fromthe result. PECK formula for the analysis of surface subsidence distribution andLogistic model of time effects were analyzed, Method of solving each parameter offunction is obtained by using the derived theory. And logistic function model is solved using MATLAB programming. Simulation of tunnel construction by using ANSYSsoftware, explored the changes of various artificial controllable factors on the influenceof surface subsidence. The stochastic medium theory has been optimized, simple andeffective optimization prediction formulas are obtained. Actual predicted value iscompared with measured result. The reliability of the prediction result is verified.Conclusion shows: the method for solving function parameters in the model is effective,the calculation results satisfy the accuracy requirement of practical engineering, and wecan use existing information to correction formula. The slower the speed when thetunnel excavation, the smaller the hole diameter, the deeper the buried depth all canreduce surface subsidence and ensure the safety of the tunnel. The optimized method ofrandom medium formula for the ground surface subsidence safety prediction is reliable.