Optimization Design Study Based On The Settlement Control Of High-speed Railway CFG Pile Composite Foundation

With the constant speed increase of China’s high-speed railway, roadbed stability is required to improve, and the subgrade settlement control has become a key factor affecting the speed. How to make the settlement after construction to achieve the requirements of less than15mm becomes a new topic in front of the researchers. As a means of soft ground treatment, CFG pile composite foundation has many characteristics, like less settlement, high bearing capacity, fast stablity, and short-period project, etc. It has been widely used in treatment of soft foundation of such high-speed railways as Beijing-Tianjin Intercity Rail Transit, Wuhan-Guangzhou High-speed Railway and Beijing-Shanghai High-speed Railway with350km/h, and tremendous economic and social benefits have been achieved. This paper relies on the Jinan West Railway Station CFG pile composite foundation of Beijing-Shanghai high-speed railway, through on-site testing, theoretical analysis and numerical analysis, systematically researched and analyzed of Jinan West Railway Station of CFG pile composite foundation settlement rules and optimal design, the main research and analysis results are as follows:1. Through on-site testing and data processing, we analyse Jinan West Railway Station CFG pile composite foundation settlement law. In the case of different subgrade section width, the total settlement of the foundation from the settlement of the substratum, accounting for more than90%; Significant basin of settlement appeared in the central location of CFG pile reinforcement area; Settlement after construction almost within the requirements.2. In the CFG pile composite foundation settlement calculation, conventional calculation method and Boussinesq-Mindlin combined method are respectively applied, and then both the calculation results are compared to the field measurement results, Boussinesq-Mindlin combined method is closer to field measurement results, it verifies that Boussinesq-Mindlin combined method used in CFG pile composite foundation settlement calculation is more reasonable.3. Combination of the station composite foundation layout, ANSYS software is used to establish a numerical analysis model, and numerical simulation results with the measured data were compared to verify the accuracy of the measured data, at the same time paved the way to further optimize the design. 4. The optimimation design principles and ideas of CFG pile composite foundation are briefly introduced. Combined with Jinan West Railway Station Composite Foundation unreasonable, characteristics for subgrade uneven settlement, subgrade settlement after construction is as criteria, to optimize the impact analysis of each parameter; finally the advices of the station CFG pile composite foundation design optimization are proposed.