跨地裂缝带高铁路基动力响应及CFG桩地基加固优化研究

以大西客运专线为研究背景,基于动力有限元数值模拟和正交试验设计,研究了地下水位差异和不同地基条件下跨地裂缝带高铁路基的动力响应及CFG桩对地基加固效果的影响,结果表明:路基动应力和加速度响应在地裂缝带处出现较大波动,路堤中动应力沿深度方向衰减近50%,加速度衰减近70%;上、下盘地下水位差导致地基动应力和加速度幅值出现明显差异;CFG桩降低了路堤加速度和路基下部动应力,且动应力降低幅度要大于加速度;对于动应力,桩间距的影响最大,桩长次之,桩径最小;对于加速度,桩间距的影响最大,桩径次之,桩长最小;地基优化加固方案为:上盘桩间距1. 2 m,桩长8. 0 m,桩径0. 3 m;下盘桩间距1. 2 m,桩长16 m,桩径0. 6 m。研究结果可为跨地裂缝带高铁路基设计提供参考。

Study on Dynamic Response of High-speed Railway Subgrade Crossing Ground Fissure Zone and Optimization of Foundation Reinforcement of CFG Piles

Based on the study of the Datong-Xi’an Passenger Dedicated Line,dynamic finite element numerical calculation and orthogonal test design,the dynamic response of high-speed railway subgrade crossing ground fissure zone under different ground water levels and different foundation conditions,and the influence of CFG pile on the reinforcement effect were studied.The results show that the dynamic stress and acceleration fluctuate greatly in ground fissure zone,and the dynamic stress and acceleration inside the embankment decrease by nearly 50%and 70%along the direction of depth respectively.The dynamic stress and acceleration amplitude of the foundation are obviously different due to the different levels of ground water in the hanging wall and foot wall.The CFG piles reduce the embankment acceleration and the dynamic stress at the bottom of the subgrade,and the dynamic stress reduction is greater than the acceleration.For dynamic stress,the influence of pile spacing is the greatest,followed by pile length and pile diameter.For acceleration,the influence of pile spacing is the greatest,followed by pile diameter and pile length.The optimal reinforcement scheme of foundation includes 1.2 m pile spacing,8.0 m pile length,and 0.3 m pile diameter in the hanging wall;1.2 m pile spacing,16 m pile length and 0.6 m pile diameter in the foot wall of ground fissure zone.The results can provide reference to the design of high-speed railway subgrade across the ground fissure zones.