| Qingdao is located in the upper,soft,and lower,hard formation area,and many subway stations in the city are located in the granite.In view of the complex diversity of Qingdao strata,the builders proposed the method of constructing the two-lining arch cover on the basis of the original traditional arch cover method.The two-lining arch cover jumping method refers to a method according to which the earthwork of the upper part of the station is excavated in the step method after the excavation of the step method or the next door method.The two-lining arch cover is a relatively novel form of excavation and support,especially in the underground station with the underground excavation hall separation structure,and the stability of the surrounding rock during the excavation process still needs to be further studied and demonstrated.Taking Jiangsu Road Station of Qingdao Metro Line 4 as the research object,this paper analyzes the data indicators of surrounding rock stress,surface settlement,clearance convergence and arch settlement,and discusses the safety and applicability of second-lining arch vault method in subway construction.This article mainly completes the following work:By creating the finite element numerical calculation model of the subway station method,the station excavation process is simulated according to the construction step,and the change rules of the surrounding rock stress,surface settlement and arch settlement of the station with the construction process.Second,relying on Qingdao line 4 Jiangsu line arch vault excavation engineering example,through the excavation of the station surrounding rock stress,surface settlement,arch settlement data site monitoring,analysis of the excavation caused by the station surface subsidence,the hole clearance convergence and station arch subsidence data consistent with the data trend of simulation calculation.Finally,through the problems found in the construction process,the optimization construction of the two-lining arch cover jump warehouse method under the large-section hall and platform separation structure is proposed,so as to provide the direction for the subsequent optimization design and construction scheme of similar projects.From the above work:(1)confirmed through simulation calculation and site construction that the construction of the two lining arch vault method is feasible in subway construction;(2)verified that the construction parameters of the primary branch,second lining and disassembly selected in the paper are applicable to the upper soft and lower hard strata of Qingdao Metro.(3)through the actual demolition length of the warehouse jump method,concluded that the 11.3m demolition can be realized in the arch door of the large section dark excavation station,breaking through the previous example of 6m demolition. |
