Research On The Overhead Excavation Technology Under High Filling Railway Embankment In Subsidence Area

Based on the background of culvert repairing or reconstruction under high railway embankment, this thesis presents an excavation method with 3-span support system under embankment without transportation interruption. The theory analysis and numerical simulation are used to study the excavation slope stability. The relative facts that influence the slope stability are analyzed by a 3D numerical model. The reinforcement methods are proposed which can insure the slope stable during excavation. The research results are used in a engineering. The main results in this study are following.(1) A 3-span support system is proposed which can be used in culvert repairing or reconstruction engineering under high railway embankment without transportation interruption.(2) The ballast collapses firstly during excavation with the face collapse. Grouting reinforcement can be used which can raise the slope stability efficiently and economically. The reinforcement zone need to be larger than the potential slip surface of the slope. When the height of the slope is less than 8m and the inclination is less than 1:1, the embankment slope filled by coal spoil is stable. When the height of the slope is 10 m and the inclination is less than 1:1.2, the embankment slope filled by coal spoil is stable. When the height of the slope is 12 m, the embankment slope filled by coal spoil is unstable with the usual inclination, and the reinforcement must be used. Two methods can be used. The one is grouting reinforcement in coal spoil. And the other one is the upper half part with retaining and the lower part with sloping.(3) The sloping excavation has little influence on the first and second platform with large width of the embankment.(4) The manual digging piles in slope contribute little to the safety factor of the slope. The length of the piles in side span slope need to be 1m more than the depth of the potential side surface.(5) The 3-span support system presented in this thesis is efficient in engineering practice, and can insure the stability of the embankment slope and the safety of the railway transportation.