Construction Monitoring Of Metro Station Built By Semi-inverse Covered Excavation Method And Numerical Simulation Study

The early21st century, China’s economy is in a stage of rapid growth, at the same time,the process of urbanization is being pushed forword.However, a series of problems such as traffic congestion, environmental pollution reduce the quality of people’s lives and restrict the development of society.Urban metro is an effective measure to solve the problems.Metro is consequent production of the development of great city traffic.It possesses advantages of big load,fast,safe,on time,comfortable and less pollution. However,it might influence the environment and obstruct traffic in the busy streets during the construction. As a result, the cover-excavation method is adopted as an effective solution.In this context, based on May4th square station engineering of Qingdao subway, the main research contents and conclusions of this paper are as follows:(1)This paper analyzes the characteristics and applicable scope of cover-excavation method,covered top-down construction method and covered half top-down excavation method,which convinces the obvious superiority of the cover excavation method. It has been used for a number of engineering construction both at home and abroad.For the May4th square subway station for Qingdao,Using analytic hierarchy process (ahp) makes quantitative calculation and selection of three kinds of construction method.Covered half top-down excavation method is absolutely choosen as the best choice from the comparison of aspects of technology, economy, environment and time limit.(2)There is description about the construction process monitoring work of metro foundation pit retaining structure in detail. Collect and analyze data of the surface settlement horizontal displacement of retaining piles, anchor axial force.The laws of data change were researched. The measured values are under security lines. It shows that structure design is reasonable.(3)The Midas/GTS model of subway station construction process is created. The simulation of the laws of the deformation of the retaining structure of the deep excavation and the comparison of the simulated results and in-situ monitoring results is accomplished. The primary consistence of the simulated results and in-situ monitoring results shows that the model creation, parameter selection and calculation process is correct. Based on the Midas/GTS model, this paper brings up the measures for retaining system optimization design on the basis of deformation contrll.(4)Based on Midas/GTS calculation results, the retaining structure of foundation pit is optimized. And the measures to control deformation of foundation pit are summrized.