地铁列车荷载作用下地铁车辆段桩承式复合地基动力响应数值分析

Numerical Analysis on Dynamic Response of Pile-supported Composite Foundation in Metro Train Depot under Metro Train Load Effect

为探讨软土地基经桩体加固后,地铁列车荷载作用下地铁车辆段轨道下部结构的复合地基动力特性及分布规律,采用有限元显式动力学方法,分析比较了广州地铁某车辆段轨道下部软基区域经桩体加固前后以及桩体模量对土体动力特性的影响。数值分析结果表明:(1)经桩体加固后,土体的振动加速度比无桩体加固时衰减更快,土体的动应力幅值有所减小,且土体动应力随桩体模量的增大而减小;(2)土体动应力随横向距离和深度方向变化过程中,局部区域呈现先增大再减小的趋势,说明桩顶和桩底附近出现了应力集中现象;(3)软黏土的动应力幅值和振动加速度幅值沿深度方向先快速衰减,后衰减趋于稳定,说明计算动力附加沉降时主要考虑软土浅层区域。

In order to discuss the dynamic characteristics and distribution law of the composite foundation of track substructure in the metro train depot under metro train load effect after the soft soil foundation is reinforced by the piles,the finite element explicit dynamics method is used to analyze and compare the effects of pile reinforcement and pile modulus on the soil dynamic characteristics in the lower soft foundation area of track in a metro train depot of Guangzhou.The results of numerical analysis show that(1)after reinforced by piles,the vibration acceleration of the soil will decay faster than that of no-pile reinforced.And the dynamic stress amplitude of the soil also decreases.The dynamic stress of the soil decreases with the increase of the pile modulus.(2)During the changing process with the lateral distance and depth,the soil dynamic stress in some area tends to increase first and then decrease,which illustrates that the stress concentration occurs near the top and bottom of the pile.(3)The dynamic stress amplitude and vibration acceleration amplitude of soft clay first decay rapidly along the depth direction,and then the attenuation tends to be stable,which indicates that the shallow area of soft soil is mainly considered when calculating the dynamic additional settlement.