红砂岩地层大型车站深基坑桩锚支护结构变形分析

Deformation Analysis of Pile-Anchor Supporting Structure in Deep Foundation Pit of Large Station in Red Sandstone Strata

结合江西省赣州市赣州西站预留地铁车站深基坑工程,对红砂岩地层深基坑桩锚支护的桩顶水平位移、深层水平位移、锚索轴力和地表沉降进行现场监测分析。结果表明:桩顶水平位移、深层水平位移、锚索轴力和地表沉降时空效应显著,基坑中部变形大于坑角,长边大于短边,且从中部向坑角逐渐减小;桩体水平位移曲线呈两头小、中间大的"弓"形,最大位移出现在桩体埋深1/2~2/3处,与锚索最大轴力所在位置的深度一致;锚索轴力随基坑深度变化呈类抛物线形分布,轴力损失和增长主要发生在基坑开挖阶段;坑外的地表沉降主要呈凹槽形分布,最大沉降发生在距坑边8.5 m左右处;基坑周围地表最大沉降值与深层最大水平位移之间存在着较为明显的线性关系。

Based on the reserved deep foundation pit project of Ganzhou West Railway Station in Ganzhou City,Jiangxi Province,the horizontal displacement of pile top,the deep horizontal displacement of pile,the axial force of anchor cable and ground settlement of deep foundation pit supported by the pile-anchor supporting structure in red sandstone strata are monitored and analyzed.The results show that the horizontal displacement of pile top,the deep horizontal displacement of a pile,the axial force of anchor cable and ground settlement are obvious in temporal and spatial effects.The horizontal displacement curve of the pile body shows a“bow”,which is small at both ends and large in the middle,and the maximum displacement occurs at 1/2~2/3 of the buried depth of the pile,which is consistent with the depth of the maximum axial force of the anchor cable.The axial force of anchor cable distributed in parabolic shape along with the depth of foundation pit.The ground settlement outside the pit is mainly distributed as“grooves”,with the maximum settlement point occurring about 8.5 m away from the pit edge.There is an obvious linear relationship between the maximum ground settlement value and the maximum deep horizontal displacement of a pile.