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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。
Based on the method of CFG (Cement Fly-Ash Gravel) composite foundation treatment of Xuhu Section of Beijing-Shanghai high-speed railway, the pile-net structure with or without design parameters such as pile cap, different pile length, different pile spacing and so on, The effect of train load on the dynamic response of subgrade with a height of 4.15 m provides a theoretical basis for the design of CFG pile composite foundation of high-speed railway. The results show that the dynamic displacement of foundation surface (below the gravel cushion) is related to the presence or absence of pile cap, pile length and pile spacing. The displacement of the pile with no pile cap is 7.8% larger than that with the pile cap. The maximum dynamic displacement at the pile foundation decreases by 10.4%, 19.6% and 25.9% respectively when the pile length increases by 30%, 70% and 120%. As the pile spacing increases by 0.8, 2 and 2.5D (D is the pile diameter), the maximum dynamic displacement of the foundation surface increases by 8%, 12.4% and 23.4% respectively. The magnitude of dynamic stress on foundation is related to the existence of pile cap and pile spacing. In the same situation of holding layer, it has nothing to do with pile length. Under this geological condition, the dynamic load ratio of pile and soil is proportional to the dynamic displacement of soil between foundation piles and piles.