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| Research and Practice on the Scheme of Pre - stressed Pipe Pile Reinforcing Multi - line Railway Subgrade |
| CHEN Xiao - xing, ZHU Hong – wei |
| (The Third Railway Survey and Design Institute Group Corporation，Tianjin 300251 ,China) |
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Abstract Research purposes ： The multi - line subgrade of DK 285 + 400 ?DK 287 + 100 section of Shijiazhuang railway hub on Beijing - Shijiazhuang Passenger Dedicated Line, applies ballastless track on main line and turnout zone. Ballastless track requires strict settlement after construction and is affected as well by the lag of goods line relocation project. So the original scheme for foundation treatment was designed without preloading time. In order to ensure the subgrade construction does not affect the whole opening and operation time of Beijing - Shijiazhuang Passenger Dedicated Line，according to the project period requirements， the reinforcement scheme without preloading was researched，and the practice and verification were carried out.
Research conclusions: ( 1 )Through the comparison of CFG pile raft，bored pile plate and pre - stressed pipe pile raft scheme，using pile raft for reinforcement multi line subgrade has obvious technical，economic and shorter work - period of comprehensive advantages. (2) By using the pile raft foundation，the amount of cushion compression,pile and the stab deformation of the piles can be ignored in the calculation of the settlement calculation of compositefoundation， the amount of compression of the substratum under the pile is only counted，calculation accuracy meets the requirements. (3) Using static pressure method for prestressed pipe pile construction,in case there are thick dense sand stratum，using high pressure water flushing with static pressure construction methods to traverse can meet the design pile depth. (4)Through observation and evaluation ol subgrade settlement，it is recognized that using the pile raft foundation without preloading meet the standard of settlement after construction. (5 ) The research results can provide reference for the foundation reinforcement of the multi line subgrade of passenger dedicated railway line.
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Received: 23 July 2015
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2015, Vol. 32 
