高速铁路CFG桩桩板复合地基工后沉降数值模拟

Numerical Simulation on the Post-Construction Settlement of CFG Pile-Slab Composite Foundation in High-Speed Railway

基于典型段体积元,建立三维有限元模型,通过数值模拟计算分析高速铁路CFG桩桩板复合地基工后沉降（简称＂工后沉降＂）及其影响参数。结果表明：桩底部处有明显的下刺入现象,桩顶由于褥垫层较薄且其模量较大而使刺入不明显;桩长的增加可以有效减小工后沉降,它是决定工后沉降大小的主要参数之一;当桩体模量达到10 GPa时,若再继续增大,对工后沉降的影响不大;在3-6倍桩径范围内,桩体间距宜取较大值作为设计桩体间距,在此设计间距范围内工后沉降变化不大,且方便施工,节约造价;一定厚度（0.2-0.4 m）和模量（120-200 MPa）的褥垫层可以有效调节桩体的刺入现象,减小工后沉降的发生;钢筋混凝土板模量对工后沉降的影响与桩体模量相同,其厚度不宜小于0.4 m;路堤高度不是决定工后沉降的主要参数。

Based on typical volume element and 3D FEM model established, this paper is intended to analyze the post-construction settlement of high-speed railway CFG pile-slab composite foundation and its affecting parameters by means of numerical simulation. The results prove that there is evident downward punching in the bottom of the pile while in the top of the pile there is less evident upward punching due to the minor thickness and large modulus of cushion. The increase of pile length, working as one of the main decisive parameters to affect the settlement, can effectively decrease the post-construction settlement. When the pile modulus greater than 10 GPa keeps increasing, it will exert minor decreasing effect on the post-construction settlement. Within the range of the pile diameter 3 to 6 times wide, it is advisable to set the space between the piles by wider pile diameter range in that there are no significant changes of the post- construction settlement within this set space. Furthermore, it helps to cut down the cost and facilitate the construction. Cushion of certain thickness （0.2~0.4 m） and modulus （120-200 MPa） can effectively regulate the punching of pile and reduce post-construction settlement. Reinforced concrete slab with its suggested thickness no less than 0.4 m works on post-construction settlement the same way as pile modulus does. The embankment height is not the main decisive parameter for post-construction settlement.