Research On Deformation Risk Control Of Tunnel Excavation Of Separate Island Station Group

With the continuous increase in the development rate of urbanization in China,especially since the 20 th century,the increase in urban size and population growth has resulted in insufficient urban road capacity.In order to cope with the normalization of traffic congestion,cities across the country have begun to vigorously promote urban rail construction.With the increasing scale of the subway,various complex engineering problems will appear in the construction.The number of existing engineering cases is small,and a relatively complete system has not been formed to solve the construction of special subway stations.The research in this paper is based on the special station form of the separated island station,and the risk control measures for the internal and external deformation of the tunnel excavation of the group tunnels.It is helpful for the follow-up to solve the construction problems in the background of similar projects.The selection of control measures has great reference significance.In this paper,the main research object is the underground excavation of the group of tunnels in the special station with separated islands,and the deformation laws of the tunnels during the construction process are studied.The tunnels mainly focus on the clearance convergence of each channel,the analysis of the settling laws of the vaults,and the deformations outside the tunnels.Concentrate on the analysis of the changing laws of surface subsidence.By discussing the influencing factors of group tunnel construction deformation and risk control concerns,combined with an actual subway construction site in Wuhan Metro,the theoretical and actual analysis and data comparison are made.This paper uses ABAQUS finite element software for three-dimensional numerical simulation modeling.With actual engineering as the background,the software is used to simulate the basic law of construction deformation inside and outside the tunnel during the whole process of single-tunnel excavation,comparing the differences between simulation and actual engineering,and analyzing the reason for the difference.Afterwards,collect and sort out the on-site monitoring data of the existing 6 connection channels.According to the on-site measurement data,it is mainly divided into two aspects: inside and outside the cave.It is classified and summarized in detail according to 3 construction methods and 3different strata.Combined with actual construction conditions,comparative analysis by situation.Finally,according to the analysis of the deformation law of the tunnel excavation construction obtained in the above chapters,combined with the specific conditions of the site construction,targeted safety risk control measures are proposed from three angles to effectively control the magnitude and rate of construction deformation and reduce the construction risk.Analyze the results based on the control measures taken at the construction site: most of the ground settlement values are controlled within 70% of the allowable value,a small amount is within 70% to 90%,and the deformation values in the cave are all within 80%,and all monitoring data does not exceed the 100% allowable value phenomenon.It is concluded that the proposed safety risk control measures have a certain degree of effectiveness,and have practical engineering reference for the construction of isolated island group tunnels.