【作者】 何海健； 刘维宁； 项彦勇； 王霆；

【Author】 He Haijian, Liu Weining, Xiang Yanyong, Wang Ting(School of Civil Engineering & Architecture, Beijing Jiaotong University, Beijing 100044)

【机构】 北京交通大学土木建筑工程学院；

【摘要】 地铁施工对邻近既有构(建)筑物的影响问题是城市轨道交通建设中的常见问题。本文以工程实例为背景,抽象出几何模型,采用数值试验的方法,建立了三维弹性有限元模型,分别分析了地铁施工对邻近单桩和群桩的影响方式和影响水平,分析中考虑了桩-土之间的相互作用。计算分析表明:1)对邻近单桩而言,桩端与隧道水平轴线的相对位置、桩基与隧道中心线之间的水平距离等因素对桩基反应(沉降、侧移和摩阻力等)的影响很大,距离隧道较近的短桩情形受隧道开挖引起的反应较大,在隧道施工中应加强保护;2)对邻近群桩,群桩效应对减小开挖引起的群桩反应起到一定的积极作用,由于群桩效应,距离隧道较远的单桩内力会有一定程度的减小;3)承台在减小开挖引起的群桩反应中发挥了一定的作用,但显著增加了桩基顶部的弯矩;4)群桩中距离隧道较近的桩基在一定条件下会产生较大的轴向拉力,这对桩基受力会产生不良影响。更多还原

【Abstract】 It constitutes a common problem that urban tunneling exerts negative influences on nearby existing structures. With the detailed case published in the foreign literature as the background, this paper addresses the approach for formulating 3-D elastic FEM models to efficiently simulate the effect of the metro tunneling on the adjacent single pile and pile groups respectively, in the analysis, the interaction between the piles and the soil is considered. The analyses indicate that: 1) from the studies of nearby single pile, the position of the pile tip regarding the tunnel horizontal axis and the distance of the pile axis from the center of the tunnel are two main factors which strong influence the pile responses (such as vertical displacement, lateral displacement, skin friction and so on), and the responses of the short pile which is very near the tunnel are more considerable than the others, which requires strong protective measures during the tunnel construction. 2) as to nearby pile groups, we find that group effect does some positive function on the responses of pile groups, and due to its influ ence, a high reduction of the internal forces will be got in the piles which are farther away from the tunnel. 3)from the studies of nearby single pile and pilegroups in a same model, we learn that the pile cap will make some importance in reducing the responses of pile groups induced by tunneling, but at the same time, it will increase the moment of the piles in the group markedly. 4) piles which are more near the tunnel in the groups may produce quite big axial tension, which has bad effect on pile’s bearing capacity.更多还原