深基坑开挖过程中多阶微型钢管桩受力性状试验研究  

Experimental study on mechanical behaviors of multi-stage micro steel pipe piles during deep foundation pit excavation

作　　者：张立 白晓宇[1] 孙林娜[1] 张鹏飞 闫楠[1] Zhang Li;Bai Xiaoyu;Sun Linna;Zhang Pengfei;Yan Nan(School of Civil Engineering,Qingdao University of Technology,Qingdao 266520,China;The Second Construction Limited Company of China Construction Eighth Engineering Division,Jinan 250014,China)

机构地区：[1]青岛理工大学土木工程学院,山东青岛266520 [2]中建八局第二建设有限公司,济南250014

出　　处：《工程勘察》2023年第10期7-11,21,共6页Geotechnical Investigation & Surveying

基　　金：国家自然科学基金资助项目(51778312);山东省自然科学基金重点项目(ZR2020KE009);山东省博士后创新项目(201903043)。

摘　　要：为了探究微型钢管桩在深基坑开挖过程中的受力性状,在青岛地铁某车站开展现场试验,采用多阶微型钢管桩复合预应力锚索(杆)作为支护结构,对第一阶外排桩进行内力测试,研究不同开挖工况下桩身弯矩的分布特征与变化规律,揭示开挖深度对微型钢管桩承载性能的影响机制。研究表明:外排桩桩身弯矩呈“波浪型”分布特征;桩身反弯点位于预应力锚索位置附近,正负弯矩极值点位于两道锚索之间;基坑开挖至第三阶时,即开挖深度超过23m,桩身弯矩增幅较大;处于上部土层的微型钢管桩桩身以背土面受拉为主,嵌入下部岩层的微型钢管桩桩身以迎土面受拉为主。研究结果可为完善土岩组合基坑设计理论提供参考,对类似工程实践具有指导意义。In order to investigate the mechanical behaviors of micro steel pipe pile in the process of deep foundation pit excavation,the field tests are carried out in a station of Qingdao Metro.The project adopts the multi-stage micro steel pipe pile composite prestressed anchor cables(bars)as supporting structure,and carries out the internal force tests in external row piles on the first stage.The distribution characteristics and variation rules of the pile bending moment under different excavation conditions are studied to reveal the influence mechanism of excavation depth on the bearing performance of the micro steel pipe piles.The study results show that the pile bending moment presents a wavy distribution characteristic.The reverse bending point of pile body is located near the position of the prestressed anchor cable and the extreme point of positive and negative bending moment is located between two anchor cables.When the foundation pit is excavated to the third stage,that is,the depth of excavation exceeds 23m,the internal force of the pile increases significantly.The micro steel pipe pile body in the upper soil layer is mainly strained on the back side,while the micro steel pipe pile body embedded in the lower rock layer is mainly strained on the face of the earth.The study results could provide the reference for improving the design theory of soil-rock combination foundation pit and have guiding significance for similar engineering practice.

关 键 词：深基坑 微型钢管桩 开挖深度 弯矩 现场试验 

分 类 号：TU473[建筑科学—结构工程]