Model Test Of Deformation Of High-Speed Railway Bridge Foundation Overlying Mined-Out Area

In recent years, with the continuous construction of high-speed railway, many railway lines cross coalmines and the goaf. The presence of goaf roadway is bound to have a certain impact on the deformation of the bridge foundation of high-speed railway. Therefore, it is necessary to research the deformation of high-speed railway bridge foundation overlying the goaf roadway.In this dissertation, based on the GuanShanDi bridge of Hefei-Fuzhou high-speed railway, the deformation regularity of the bridge foundation above the mined-out area of high-speed railway is studied by model test The specific contents and the achievements of the research are as follows:(1) The pile’s axial force of the bridge gradually decreases from the top of the pile to the bottom. At the same section of the piles, the axial force of the piles enlarges with the increment of load. The axial force on the top of the pile which is in the center of the cap is maximum; The axial force of the piles which go through the goaf roadway is a certain value in the roadway.(2)The skin friction of piles is first increment and then turns to decrease. At the same section of the piles,it enlarges with the increment of load; the skin friction of piles which go through the goaf roadway is zero.(3)At the beginning of loading, stresses of both soil among piles and pile top will increase rapidly for a while. But when the load increases to1850N, the increase of stress of soil among piles is reduced and the increase of stress of pile top is enlarged. The sharing ratio of the pile-soil load increases with the increment of load, but the extent of increasing gradually gets small.(4) The settlement of the cap and the soil among piles increases with the increment of load. The central soil settlement of two piles is slightly larger than that of four piles. The settlement at the roof of the goaf roadway increases as the increment of load. The soil settlement above the goaf roadway is greater than that of other places. The settlement of parts of the cap located on the goaf roadway is greater than that of other parts of the cap.