Study On Foundation Reinforcement And Subgrade Post-construction Settlement Control Technologies For Ballastless Track Of High Speed Railway

Ballastless track, due to its advantages of high smoothness and few maintenance and curing,etc, is widely adopted for the trackwork of high speed railways in China. In order to ensure the stability and high smoothness of balastless track structure, the design concept of subgrade engineering has been changed fundamentally, which can be particularly proved by the extremely strict requirements for subgrade post-construction settlement control:not more than15mm for ordinary sections and not more than5mm for transitional section with bridge, tunnel or transverse structures, with the angle caused by uneven settlement not bigger than1‰. The subgrade post-construction settlement control of ballastless track has become one of the crucial and key factors affecting the subgrade engineering solution, investment and operation security, having been paid great attentions to.In combination with the subgrade pilot section of Wuhan-Guangzhou Passenger Special Line, with adoption of comprehensive investigation approaches, in-situ test, etc., the foundation investigation methods and foundation soil characteristics have been studied in this paper. In view of engineering tests, studies have been carried out on the construction technologies and foundation reinforcement effects of loose foundation reinforcement with different measures including adoption of CFG pile, impact compaction, dynamic tamping, tamping replacement, etc. It shows from the testing reports and monitoring data that, the foundation treatment measures of CFG pile, impact compaction, dynamic tamping, and tamping&replacement adopted in accordance to different geological conditions and subgrade design conditions, have all achieved sound reinforcement effect, with post-construction settlement satisfying the requirement for balastless track of high speed railway. Based on the tests, as regard to the subgrade reinforcement and foundation post-construction settlement control for ballastless track of high speed railway, relevant conclusions have been made in this paper, thus sugguestions on further studies have been put forward.