高速铁路CFG桩网复合结构设计参数分析

采用数值分析方法,依托京沪高速铁路徐沪段CFG(Cement Fly-ash Gravel)桩复合地基处理方法,分析了有无桩帽、不同桩长、不同桩间距等设计参数的桩网结构在高速列车荷载作用下对路基高度4.15 m的地基动力响应的影响,为高速铁路CFG桩复合地基的设计提供理论依据。结果表明,地基面(碎石垫层以下)动位移与有无桩帽、桩长、桩间距有关。无桩帽比有桩帽的位移大7.8%;随着桩长增加30%,70%,120%时,地基面最大动位移分别减小10.4%,19.6%,25.9%。随着桩间距增加0.8,2,2.5D(D为桩径)时,地基面最大动位移分别增加8%,12.4%,23.4%。地基面动应力的大小与有无桩帽、桩间距有关;在持力层相同的情况下,与桩长基本无关。在该文地质条件下,桩土动分担比与地基面桩、桩间土处的动位移呈正比。

An Analysis on Design Parameters of CFG Pile-net Composite Structure of High-speed Railway

With numerical analysis method,based on CGF（Cement Fly-ash Gravel） pile-net composite structure treatment of Xuzhou-Shanghai section in Beijing-Shanghai high-speed railway,the paper analyzes the influence of design parameters pile-net composite structure of cap or non-cap,different pile length,different pile space under high-speed train load on ground dynamic response with the embankment height of 4.15m,which provides theoretical basis for design of the CGF pile-net composite foundation.The results show that the dynamic displacement of soil foundation is related to cap,pile length and pile space.The dynamic displacement of non-cap structure is 7.8% larger than that of cap structure.The maximum dynamic displacement is decreased by 10.4%,19.6%,25.9% when the length of pile increases by 30%,70%,120%.The maximum dynamic displacement is decreased by 8%,12.4%,23.4%,when the space of pile increases by 0.8d,2d,2.5D.The dynamic stress of soil foundation is greatly related to the style of cap and pile space.However,the length of pile has little effect on it.In this geological condition,the dynamic load bearing ratios of soil and pile is directly proportional to the soil foundation dynamic displacement in pile and soil.