Application Of Shallow-Buried Tunnel Excavation In Construction Of Beijing Subway

With the rapid development of our country's economy and society,traffic congestion and vehicle jam are common in large and medium-sized cities of our country.The urban traffic congestion is perplexing the government and the common people.However,in many cities with large population density,the per capita construction land is only about 50m2,but the urban construction land is crowded,and it is difficult to arrange more public roads.In addition,the living standard of the people is improving day by day,and the number of private cars is increasing.The contradiction between the rapid growth of motor vehicles and the limited urban road capacity is increasingly prominent,and the development of underground track is the main trend of urban traffic development.In the construction of urban rail transit,shallow excavation is a widely used construction method,especially in the excavation of large section.It is of great significance to study and summarize the application of shallow excavation method in subway construction in order to effectively control tunnel deformation,ground subsidence and eliminate hidden safety hazards such as collapse.In order to sum up the application of shallow excavation method in the construction of large section of Beijing Metro,this paper takes the excavation of Pingle Yuan Station-Jiulongshan Station(hereafter referred to as Ping-9)section of Beijing Metro Line 14 as the research object.Ping-Nine section for the excavation section,the first double-row line crossing line interval.The total length of the section is 693.02 meters,which contains 15 different sizes of sections and 39 change points of the sections,in which the external diameter of the B section is 15.05 meters,which is the highest in the country.In construction,all the methods involved in shallow excavation include ring excavation with reserved core soil method,step method with CD method with CRD method,double sidewall pit guide method and so on,and it also includes triplex arch.Based on the theoretical foundation of shallow buried excavation and combined with engineering practice,this paper summarizes the application of shallow buried excavation method in the construction of large section of subway tunnel,and provides empirical basis for the construction of large section with shallow buried excavation method.In addition,the monitoring measurement can be used as an important link and means for effectively avoiding the risk accidents,and provides a strong reference for the reasonable adjustment of the construction process,parameters and support strength and type during the construction process of the shallow-buried underground excavation method.Therefore,in order to effectively control the deformation of the tunnel and the settlement of the surrounding surface and eliminate the hidden troubles such as collapse,the paper summarizes and analyzes the monitoring measurement in the construction at the same time.