Analysis Of Long-Term Test Of High-Speed Railway Ballastless Subgrade And Transition Zone

With the rapid development of High-speed railway, based on the deformation control design, comes to a stringent requirement for post-construction settlement of subgrade and long-term deformation induced by train load. Many experts and scholars at home and abroad made a large number of tests and theoretical analysis and get many researchs. But the design life of the high-speed railway embankment structures is100years, currently there is little research serving on the long-term performance of high-speed railway ballastless subgrade and transition section structure. So developing analysis of long-term test of high-speed railway embankment ballastless and transition has Has the application value and engineering significance. Based on the automatic test system foundation of sensor network, we develop a situ site observation of point of Beijing-Tianjin high-speed rail tester and Beijing-Shanghai high speed railway, launched a prototype test site.The Beijing Tianjin inter city railway test spots observed soil embankment horizontal displacement, long-term settlement of soft ground and retaining wall, the fluctuation range of underground water level, moisture content of embankment and foundation, the deformation of the friction plate and the abutment, bedding long-term cumulative deformation in the base pipe of supporting layer and transition plate, track plate and the supporting layer three to the deformation, the adjacent track plate longitudinal relative deformation and some other deformation indexs. This paper also analysis engineering properties of subgrade under long train and the embankment load. Beijing Shanghai high speed railway transition section test spots observed earth pressure on CFG pile foundations, soil between piles and settlement of bridge abutment, long-term settlement of abutment piles CFG pile foundations and soil between piles, relative deformation between bridge abutment and subgrade, long-term compaction sinking of embankment, longitudinal horizontal displacement of bridge abutments and foundation stage, relative between deformation raft foundation and bridge cap, longitudinal differences in deformation between barbed end structure and embankment construction, long-term deformation in friction plate and bridge abutments, relative deformation between concrete footings and abutments, friction plate longitudinal deformation, long-term deformation in transition plate with supporting layer. This paper analysis the response to the long-term mechanical transition structure. The main conclusion is below:(1)The results of the Beijing Tianjin inter city railway test spots is:Volumetric water content of subgrade surface,the subgrade in the top surface of the retaining wall and foundation surface (height above The underground water level) have suffered large in summer, small in winter cyclical changes. Groundwater level of foundation maintain a certain periodic law, shallow in summer, deep in winter. Foundation settlement of long-term cumulative settlement roughly consistent, increases gradually with time but not stable, it is about1.79mm to14.08mm in three years.The gap between friction plate and abutment appear periodic variational regularity like small in summer, large in winter, one-year period the maximum deformation is8.2mm. Vertical deformation increases firstly, it stabilized one and half a year later, the mean after steady is ablut1.2mm～1.65mm. The longitudinal relative deformation between two adjacent track plates appear periodic variational regularity, open in winter and close in the summer, it changes between-0.44mm～0.98mm. Laterally relative deformation orbital plate and the supporting layer increases by time, a maximum is1.19mm, the deformation decreases gradually stabilized after one year. The longitudinal relative deformation value has been increased as time, maximum is about0.89mm. Vertical relative deformation between them suffered large in summer, small in winter cyclical changes, one-year period the maximum deformation is about1.04mm.(2) The results of the point of Beijing Shanghai high speed railway transition section test spots is:Earth pressure on CFG pile foundations, soil between piles increases rapidly with the subgrade construction height increasing. Earth pressure diagonal center of pile is larger than the axial center of the pile in growth rate. Long-term compaction sinking in embankment soil gradually increased over time, the settlement is small, test value after steady is about2.8mm. CFG pile and soil between piles increases rapidly with the subgrade construction height increasing. Horizontal displacement in abutment foundation along the road bridge increases by time, away from the longitudinal abutment embankment foundation, it is away from the subgrade. Relative deformation in raft and pile foundation longitudinally along the road gradually opened, deformation values gradually stabilized after one year. Concrete footings and abutments longitudinally along the road open in winter, close in summer, the maximum difference vertical deformation is0.68mm. Longitudinal differences in deformation of friction plate and concrete base is same as friction plate and bridge abutments in law open in winter and close in summer. Vertical deformation difference of transition plate with supporting layer is relatively small, it change between-0.22～0.09mm.