Analysis Of Land Subsidence Characteristics And Influencing Factors Of Beijing Rail Transit New Airport Line

The new airport line is Beijing's second rail transit,the North from Cao qiao,and the South to the North terminal of the new airport.It is a high-speed railway passenger passage connecting Beijing City to the Daxing New Airport.In the plain area,the railway passes through the land subsidence area of Lixian-Yufa in Daxing area of Beijing from south to north,which is greatly affected by the land subsidence and poses a threat to the normal operation of the high-speed railway.Therefore,the development history and present situation investigation,characteristic analysis,influence factor analysis and formation mechanism research of regional land subsidence along the railway are carried out.Based on the progress of the first phase project of Beijing New Airport Line,this paper comprehensively analyzes the development history of land subsidence and groundwater exploitation along the new airport line.On this basis,the land subsidence area of Lixian-Yufa,which is crossed by the new airport line high-speed railway,is selected as the research object.According to the monitoring results of each compression layer obtained by the land subsidence monitoring station and the groundwater monitoring results of the layerwise mark standards,the deformation characteristics and genetic mechanism of the ground subsidence are studied.The compressive contribution value of different horizons to land subsidence and the deformation characteristics of layered soil are analyzed.It is concluded that the main compression horizon of ground subsidence in the study area changes with the change of the main mining layer of groundwater,and the shallow,middle,and deep strata show obvious viscoelastic-plastic deformation characteristics in general.Regression analysis method is used to study the relationship between land subsidence and regional groundwater dynamics,the thickness of cohesive soil and compression,and good positive correlation is found.The physical properties of cohesive soil and the law of soil compression deformation are analyzed.It is concluded that the deformation of shallow cohesive soil is obviously higher than that of deep soil under the same pressure.The research results of this paper provide a theoretical basis for the normal construction and safe operation of the first phase project of the new airport line,and have certain practical significance and application value.