高铁预应力管桩桩—网复合地基动力响应研究

Research on the Dynamic Response of Prestressed Pipe Pile Supported and Geogrid Reinforced Subgrade

为评价高铁荷载作用下桩网复合地基的动力响应,以甬台温铁路客运专线预应力管桩桩网复合地基为研究对象,通过Midas/GTS NX建立轨道路堤地基三维有限元分析模型,得到了桩-网复合地基中桩和土的应力变化情况。研究发现:在列车动荷载作用下,预应力管桩主要受轴力作用,轴力峰值出现在桩顶以下3.8 m处,桩身剪力由动荷载强度及入射角度共同决定。桩体竖向动应力峰值沿深度方向先增大后减小,桩体与轨道中心间距越大其竖向动应力峰值越小。土体中的竖向动应力峰值沿深度方向逐渐衰减,由于在桩端位置处桩体与土体的相互作用,桩端处土体动应力峰值出现局部放大现象。

This paper investigated the dynamic response of the pile-net composite foundation under high-speed rail loads.According to the prestressed pile supported and geogrid reinforced subgrade of Yongtaiwen railway passenger dedicated line,a 3 D finite element model was established by Midas/GTS NX to analyze the dynamic responses of the composite foundation submitted to the train loads.The stress changes of piles and soils in the pile-net composite foundation were obtained.The results show that under the dynamic load of the train,the prestressed pipe pile is mainly affected by the axial force,and the peak value of the axial force appears 3.8 mm below the top of the pile.The shear force was depended on the dynamic loads and their incident angles.The larger the distance between the pile and the track center,the smaller the vertical dynamic stress peak.The peak value of the vertical dynamic stress in the soil gradually decreases along the depth direction.Due to the interaction between the pile and the soil at the end of the pile,the dynamic stress peak in the soil appears locally amplified.