藏东南砂层路堑分层开挖下钻孔桩响应研究  

Research on Response of Bored Pile under Stratified Excavation of Sand Layer Cutting in Southeastern Tibet

作　　者：郭在旭[1] 向俐蓉[1] 刘会娟[1] 孙晓[1] GUO Zaixu;XIANG Lirong;LIU Huijuan;SUN Xiao(China Railway Eryuan Engineering Group Co.,Ltd.,Chengdu 610031,China)

机构地区：[1]中铁二院工程集团有限责任公司,成都610031

出　　处：《高速铁路技术》2020年第5期51-56,共6页High Speed Railway Technology

基　　金：四川省科技计划(2019YFG0460)。

摘　　要：为研究砂层路堑分层开挖条件下,钻孔桩植筋挡墙的力学响应特征,本文结合拉萨至林芝铁路建设,开展了设置钻孔桩植筋挡土墙支挡的路堑的分层开挖模拟。结果表明:(1)在分层开挖条件下,桩后边坡产生了一定程度的下滑,桩前地基也出现了不同程度的隆起变形,但此类隆起变形属于砂层的卸荷回弹,对工程正常使用影响小;(2)各工况下,钻孔桩桩身弯矩沿桩深方向均呈单峰曲线变化,且随着砂层的开挖,桩身弯矩峰值点由浅层逐渐向地基深层方向发展;桩身剪力沿桩深方向均呈反“S”型变化,且随着砂层的开挖,桩身剪力正、负峰值点均向地基深处发展;(3)土层开挖造成钻孔桩向路堑临空面发生挠曲变形,且变形量逐渐增大,向临空侧的水平位移最大值位于桩顶;(4)挡土墙与钻孔桩通过钢筋连接后,挡土墙的水平位移一般都大于钻孔桩的水平位移,连接钢筋以受拉为主。本文研究成果可为高原砂层铁路路堑的设计与施工提供参考。In order to research the mechanical response characteristics of bored pile planting-bar retaining wall under the condition of stratified excavation of sand layer cutting,in combination with the construction of the Lhasa-Nyingchi railway,the stratified excavation simulation of cutting with bored pile planting-bar retaining wall support is simulated in the paper.The results show that:(1)Under the condition of stratified excavation,the slope behind the pile slides to a certain extent,and the foundation in front of the pile also heaves and deforms in different levels,but the heave and deformation belong to unloading rebound of sand layer and have little influence on the normal use of the construction.(2)Under all working conditions,the bending moment of bored pile body changes in a unimodal curve along the pile depth direction,and with the excavation of sand layer,the peak point of bending moment of pile body gradually develops from shallow layer to deep layer of foundation;the shear force of pile body changes in reverse"S"shape along the direction of pile depth,and with the excavation of sand layer,the positive and negative peak points of shear force of pile body develop to the deep layer of foundation.(3)The excavation of soil layer causes the flexural deflection of the bored pile to the free face of cutting,and the deformation gradually increases.The deformation of maximum horizontal displacement to the free face is located at the top of the pile.(4)After the retaining wall and the bored pile are connected by steel bars,the horizontal displacement of the retaining wall is generally greater than that of the bored pile,and the connecting steel bars are mainly in tension.The research results in the paper can provide a reference for the design and construction of railway cutting in plateau sand layer.

关 键 词：藏东南 砂层路堑 分层开挖 钻孔桩 响应 

分 类 号：U416.13[交通运输工程—道路与铁道工程]