杂填土地层深基坑微型桩-锚-撑组合支护体系受力特性原位试验  

In-situ test on force characteristics of miniature pile-anchorsupport combination support system for deep foundation pits in miscellaneous soil strata

作　　者：郝增明 闫楠[1] 白晓宇[1] 张立 张启军 林西伟 HAO Zengming;YAN Nan;BAI Xiaoyu;ZHANG Li;ZHANG Qijun;LIN Xiwei(School of Civil Engineering,Qingdao University of Technology,Qingdao 266520,China;Qingdao Yegao Construction Engineering Co.Ltd.,Qingdao 266022,China)

机构地区：[1]青岛理工大学土木工程学院,山东青岛266520 [2]青岛业高建设工程有限公司,山东青岛266022

出　　处：《中南大学学报（自然科学版）》2024年第2期755-773,共19页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51778312,51708316);山东省自然科学基金重点项目(ZR2020KE009);山东省泰山学者项目(tsqn202306234)。

摘　　要：为深入研究杂填土地层深基坑桩-锚-撑组合支护体系受力特性,依托青岛市某深基坑工程开展微型桩-锚-撑原位试验,分析不同开挖工况下双排微型钢管桩桩身弯矩与预应力锚索轴力的演化规律,揭示该支护体系下前、后排桩的受力性状、预应力锚索应力分布特征,探讨邻近建筑物、基坑暴露时间及钢支撑拆除对该支护体系内力的影响。研究结果表明:1)在基坑开挖过程中,前排桩在受力中起主导作用;当开挖至基底时,桩身最大正、负弯矩极值呈现增大趋势,且极值点不断下移,开挖面以上桩身弯矩均呈正“S”型分布。2)开挖深度增加引起开挖面上、下1.0 m范围内桩身弯矩显著增大,前排桩桩身的反弯点分别位于钢支撑下方0.5 m、开挖面位置。3)在开挖过程中,锚索轴力沿埋深方向呈现减小趋势,锚固段前端1.5 m之后的轴力基本不变或呈微小波动。4)锚索锚固段应力高度集中在锚固段前端4.0 m以内的区域,约为锚固段长度的44%,锚固段末端基本未产生轴力,可对该段长度进行优化处理。5)邻近建筑物对微型钢管桩桩身受力影响较小;随着基坑暴露时间增加,桩身弯矩呈微小增长趋势;钢支撑拆除后,前排桩的弯矩变化集中在0.38H~0.96H(H为基坑开挖深度)。6)桩-锚-撑组合支护体系能够较好地限制基坑变形,选择合理的支撑预应力是该类基坑设计的关键。In order to investigate the stress characteristics of the deep foundation pit pile-anchor-support combined support system in plain fill soil layers,in-situ tests on micro piles,anchor cables,and supports were conducted,relying on a deep foundation pit project in Qingdao City.The evolution laws of bending moment of double-row micro steel pipe piles and axial force of pre-stressed anchor cables under different excavation conditions were analyzed.The stress characteristics of front and rear row piles and the stress distribution of pre-stressed anchor cables in this support system were revealed.The influences of adjacent buildings,exposure time of foundation pit,and removal of steel supports on the internal forces of the support system were discussed.The results show that:1)During the excavation process of the foundation pit,the front row piles play a dominant role in bearing the load.As the excavation reaches the base,the maximum positive and negative bending moment values of the pile body increase,and the extreme points continuously move downward.The bending moments of the pile body above the excavation surface are distributed in a positive"S"shape.2)Increasing excavation depth significantly increases the bending moment of the pile body within 1.0 m above and below the excavation surface,and the inflection points of the front row piles are located 0.5 m below the steel support and at the excavation surface position,respectively.3)During the excavation process,the axial force of the anchor cables decreases along the burial depth,and the axial force after 1.5 m from the front end of the anchor segment remains basically unchanged or shows minor fluctuations.4)The stress in the anchor segment is highly concentrated within the first 4.0 m from the front end of the anchor segment,which accounts for about 44%of the length of the anchor segment.The anchor segment end does not generate axial force,and this length can be optimized.5)The influence of adjacent buildings on the stress of micro steel pipe piles is small.With the

关 键 词：杂填土地层 深基坑 微型钢管桩 锚索 钢支撑 原位试验 

分 类 号：TU473[建筑科学—结构工程]