富水圆砾层深基坑双排桩变形特性  

Deformation Characteristics of Double-row Pile in Deep Foundation Pit with Water-rich Circular Gravel Layer

作　　者：欧孝夺[1,2,3] 吕政凡 江杰 罗方正[4] 梁亚华 OU Xiao-duo;Lü Zheng-fan;JIANG Jie;LUO Fang-zheng;LIANG Ya-hua(College of Civil Engineering and Architecture,Guangxi University,Nanning 530004,China;Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education,Nanning 530004,China;Guangxi Engineering Research Center for Metallic Tailings Security Prevention and Control,Nanning 530004,China;China Construction Eighth Engineering Division Co.,Ltd.,Nanning 530028,China)

机构地区：[1]广西大学土木建筑工程学院,南宁530004 [2]工程防灾与结构安全教育部重点实验室,南宁530004 [3]广西金属尾矿安全防控工程技术研究中心,南宁530004 [4]中国建筑第八工程局有限公司,南宁530028

出　　处：《科学技术与工程》2021年第13期5484-5490,共7页Science Technology and Engineering

基　　金：国家自然科学基金(51768006,51978179);广西科技计划项目(桂科AB17195035,桂科AB19245018)。

摘　　要：以南宁地铁4号线那洪立交站附属围合区富水圆砾层深基坑为工程实例,对围合区基坑双排桩的桩顶水平位移、桩身水平位移、坑外地表沉降及地下水位进行监测,进而对基坑双排桩支护结构的变形规律进行分析,同时对止水帷幕效果进行评价。结果表明:受基坑开挖及圆砾土性质影响,桩顶水平位移在前期增长较快,受泥岩流变特性影响,停工期的变形呈现一定时间效应;桩身水平位移曲线呈"鼓胀"形,因双排桩刚度大且能够协调自身内力和变形,最大值仅为23.22 mm,桩底处几乎没有产生位移,嵌固稳定性较好;坑外地表沉降曲线受桩侧阻力影响呈"凹槽"形分布,最大值仅为0.12%H(H为基坑深度),基坑开挖对周边地表的影响主要在0.7H范围内的主要影响区;相较于监测起始水位,坑外地下水位最低点为950 mm,表明高压旋喷桩具有良好的止水效果。综合分析在圆砾层中采用双排桩支护结构是可行的,采用高压旋喷桩止水帷幕能满足施工要求。Taking the deep foundation pit of water rich round gravel layer in the enclosure area of Nanning Metro No.4 Nahong Interchange Station as an engineering example,based on the monitoring of the horizontal displacement of the pile item,the horizontal displacement of the pile body,the surface settlement outside the pit and the ground water level,the deformation law and mechanism of the retaining structure with double-row piles were analyzed.At the same time,the effect of water stop curtain was evaluated.The results show that the horizontal displacement of pile top increases rapidly in the early stage due to the excavation of foundation pit and the properties of round gravel soil,and the deformation of the pile body during the stop period shows a certain time effect due to the rheological properties of Mudstone,and the horizontal displacement curve of pile body is"bulging",the maximum value of double-row piles is only 23.22 mm,there is almost no displacement at the bottom of the pile,and the stability of the pile is good,the maximum value is only0.12%H(H means depth of foundation pit),and the influence of excavation on the surrounding surface is mainly in the range of 0.7 H.Compared with the monitoring initial water level,the lowest point of the groundwater level outside the pit is 950 mm,which indicates that the high-pressure rotary jet grouting pile has a good water stop effect.It is feasible to adopt the double-row pile supporting structure in the round gravel layer,and the high-pressure rotary jet grouting pile waterproof curtain can meet the construction requirements.

关 键 词：圆砾层 深基坑 双排桩 变形分析 

分 类 号：TU753[建筑科学—建筑技术科学]