摘要
顶管施工广泛应用于市政工程的隧道开挖作业。针对某地下电缆隧道穿越高架桥桩基的实际工程案例,利用数值模拟方法建立有限元计算模型,研究了沉井和顶管施工对附近土体的扰动以及高架桥桩基的变形、受力等情况。结果表明,沉井和顶管施工会对周围桩基础的应力和变形产生一定影响。在外径12.8 m的沉井施工时,施工引起的土体卸载会使得沉井周围土体产生较大的隆起,最大回弹量为164 mm左右,三个方向(水平x方向、y方向和竖向z方向)的最大变形均出现在沉井上部土体周围,距沉井30 m处的高架桥桩基桩体在x方向(指向沉井方向)上受施工影响较大,桩体顶部产生背离沉井的水平位移,下部逐渐过渡到趋近沉井的水平位移,x方向最大位移量约为1.6 mm,对y方向(垂直于顶管方向)的水平位移影响较小。外径3.6 m的顶管施工过程会使土体在卸载后会出现变形,最大变形出现在顶管底部的扰动土体,变形量为170 mm。在x方向上,四个桩基均表现为桩顶部远离沉井、桩底靠近沉井。在y方向上,桩身的最大水平位移出现在隧道开挖深度处,方向为远离顶管,影响范围为顶管隧道施工处上下15 m。
Pipe jacking is widely used in tunnel excavation of municipal works.Based on the pipe jacking process of a cable tunnel in Tianjin,the finite element calculation model was established.The deformation of soil and the deformation and stress of pile foundation were studied.Results show that both the construction process of open caisson and pipe jacking have an impact on the stress and deformation of the pile foundation.During the construction of open caisson of which external diameter is 12.8 m,soil unloading caused by open caisson causes large uplift of soil around open caisson and the maximum value is about 164 mm.The maximum deformations in three directions including horizontal and vertical directions occur in the surrounding soil of the caisson.The pile foundation of viaduct 30 m away from the caisson is greatly affected by the construction in the x direction(pointing to the caisson direction).The upper part of the pile generates a horizontal displacement away from the caisson and the deeper part gets close to the caisson.The maximum displacement in x direction is about 1.6 mm.This process has little effect on the horizontal displacement in y direction which is perpendicular to pipe jacking.The soil deforms after unloading in the process of pipe jacking of which outer diameter is 3.6 m.The maximum deformation occurs in the disturbed soil at the bottom of pipe jacking,and the deformation is 170 mm.In x direction,all the four piles generate a horizontal displacement away from the caisson at the pile cap and the piles deform close to the caisson at bottom.In y direction,the maximum horizontal displacement of pile occurs at the depth of tunnel excavation and the displacement is away from the pipe jacking.The range of influence is 15 m around the construction site of pipe jacking tunnel.
作者
郭伟
蔡旺
任宇晓
GUO Wei;CAI Wang;REN Yu-xiao(School of Civil Engineering, Tianjin University, Tianjin 300072, China;Key Laboratory of Coast Civil Structure Safety (Tianjin University), Ministry of Education, Tianjin 300072, China)
出处
《科学技术与工程》
北大核心
2021年第22期9598-9604,共7页
Science Technology and Engineering
基金
国家自然科学基金(51878446)
天津市自然科学基金重点项目(18JCYBJC40500)。
关键词
隧道工程
变形
有限元模拟
顶管施工
桩基础
tunnel engineering
deformation
finite element simulation
pipe jacking
pile foundation
