铁道标准设计2025，Vol.69Issue(10)：274-279,287,7.DOI:10.13238/j.issn.1004-2954.202506220001
托换柱顶节点自密实微膨胀混凝土试验研究
Experimental Study on Self-Compacting Micro-Expansive Concrete for Underpinned Column Top Joints
摘要
Abstract
In structural extension and expansion projects,cracking frequently occurs at the connection joints between new and old structures on underpinned column tops,mainly caused by insufficient vibration compaction of concrete and shrinkage deformation,which seriously affects structural safety and durability.To solve this problem,the pile foundation underpinning project of the Shenzhen North Station transportation hub complex was taken as a case study.To optimize the mix design of infill materials for underpinned column top joints,the influence of different factors on structural durability was considered.Optimization tests of CaO expansive agent dosage,mineral admixture proportion,and steel fiber content were conducted,and the effects of these factors on the shrinkage-expansion properties and mechanical performance of self-compacting concrete(SCC)were systematically investigated.The effects of the above factors on the workability,expansion rate,compressive strength,and ductility of concrete were analyzed through experiments,and the superiority of self-compacting micro-expansive concrete was further demonstrated by comparative tests.The results showed that when the CaO expansive agent dosage was 15％,the fly ash-to-slag ratio was 2∶3,and the steel fiber content was 0.9％,the prepared self-compacting micro-expansive concrete exhibited optimal comprehensive performance:the 28-day compressive strength reached 59.1 MPa,and the expansion rate was 6 410 με,which could effectively compensate for shrinkage deformation.At the same time,the incorporation of steel fibers significantly improved the toughness of concrete,allowing it to maintain certain ductility after failure,thereby meeting the requirements for seismic resistance and long-term stability of the joints.This mix of concrete possesses high fluidity,micro-expansive properties,and excellent mechanical performance,making it an ideal infill material for underpinned column top joints.The research results provide a feasible technical solution to the connection challenges between new and old structures in similar projects.关键词
铁路运输/混凝土收缩补偿/掺量优选试验/自密实微膨胀混凝土/桩基托换/新旧结构连接Key words
railway transportation/concrete shrinkage compensation/admixture dosage optimization test/self-compacting micro-expansive concrete/pile foundation underpinning/new and old structural connection分类
交通运输引用本文复制引用
邬泽,彭博,彭斌,耶律根迪,高越,李明皓,付艳斌..托换柱顶节点自密实微膨胀混凝土试验研究[J].铁道标准设计,2025,69(10):274-279,287,7.基金项目
国家自然科学基金项目(52578478) （52578478）
广东省基础研究基金项目(2025A1515010671) （2025A1515010671）
深圳市科技计划项目(20240809110122002,20220525163716003) （20240809110122002,20220525163716003）
中铁工程设计咨询集团有限公司重点课题(研2021-12) （研2021-12）
