The Study On The Stress Mechanism And Settlement Regularity Of The High-speed Railway CFG Pile Composite Foundation

Soft foundation problems are often encountered in the high-speed railway construction.Due to the easily ensured construction quality、low engineering cost and short constructionperiod of CFG pile composite foundation, it has been more widely used in the soft foundationtreatment of high-speed railway. However, compared to the construction industry, thehigh-speed railway CFG pile composite foundation is still in the exploratory stage, whosetheoretical research lags far behind the engineering practice.Combining with the CFG pile composite foundation project of the Changsha to Yupingin the Shanghai-Kunming passenger special line, this paper carries out the CFG pilecomposite foundation settlement calculation study. The main contents of this study include:(1) Analyze the reinforcement mechanism of CFG pile composite foundation and studyits core technology mattress layer’s reasonable thickness;(2) Summarize now commonly used composite foundation settlement calculationmethods and analyze their flaws existing in the high-speed railway CFG pile compositefoundation settlement calculation;(3) Combined with CFG pile composite foundation engineering examples and taken fullaccount of the impact of pile body’s upper、lower penetration and positive、negative frictionresistance in the high-speed railway CFG pile composite foundation, this paper puts forward anew type of settlement calculation method and verifies the feasibility of the calculationformula through the contrast analysis of settlement calculated value and observation value;(4）Establish pile-soil contact element constitutive relation model, analyze the influenceof various factors on the CFG pile composite foundation settlement amount using the ANSYSfinite element software, and propose the optimized design scheme.Finally, this paper deduces a new kind of high speed railway CFG pile compositefoundation settlement calculation method and validates its feasibility. It is concluded that thecertain segment of Changsha to Yuping’s CFG pile composite foundation engineering pilespacing can be increased from1.6m to2.0m through finite element simulation analysis on avariety of factors influencing settlement.