Research on Real-Time Monitoring Technology and Engineering Application for Internal Support Demolition Construction in Foundation Pits: Application Practice in a Deep Foundation Pit of an Urban Commercial Center in Changsha
基坑内支撑拆除施工实时监测技术及工程应用研究 —长沙某城市商业中心深基坑应用实践

摘要

基坑内支撑拆除是深基坑施工周期内风险最高、受力体系转换最剧烈的关键工序，支撑分步卸荷会引发围护结构、 坑内土体、主体换撑结构应力重分布，极易诱发围护墙体侧移、地面不均匀沉降、周边建构筑物及市政管线破损，甚 至引发基坑整体失稳坍塌事故。传统人工定时监测存在数据滞后、频次不足、应急响应慢等短板，无法适配拆撑动态 卸荷施工工况。本文结合基坑监测技术标准要求，剖析拆撑阶段受力变形机理，阐述自动化实时监测系统布设要点、 监测指标与预警机制，结合长沙某城市商业中心深基坑工程论证实时监测应用价值，分析监测数据变化规律与施工联 动管控策略。研究表明：拆撑全过程实时监测可实现变形、内力数据及时采集、超标自动预警，动态优化拆撑施工工 序，有效规避基坑施工安全风险，保障主体结构、周边道路及建筑物和施工人员安全，可为同类深基坑拆撑施工监测 与安全管控提供工程参考。

Abstract

 Internal support demolition in foundation pits is a key procedure with the highest risk and the most drastic transformation of the stress system during the construction cycle of deep foundation pits. Step-by-step unloading of supports can lead to stress redistribution in retaining structures, soil inside the pit, and main structural support-replacement systems, which may easily induce lateral displacement of retaining walls, uneven ground settlement, damage to surrounding buildings, structures, and municipal pipelines, and even overall instability and collapse of the foundation pit. Traditional manual periodic monitoring has shortcomings such as delayed data acquisition, insufficient monitoring frequency, and slow emergency response, making it unable to meet the requirements of dynamic unloading conditions during support demolition. Based on the requirements of foundation pit monitoring technical standards, this paper analyzes the stress and deformation mechanism during the support demolition stage, expounds the layout points, monitoring indicators, and early-warning mechanism of an automated real-time monitoring system, and demonstrates the application value of real-time monitoring through a deep foundation pit project of an urban commercial center in Changsha. It also analyzes the variation patterns of monitoring data and construction-linked control strategies. The study shows that real-time monitoring throughout the support demolition process can realize timely acquisition of deformation and internal force data, automatic warning of threshold exceedance, and dynamic optimization of support demolition procedures. It can effectively avoid safety risks in foundation pit construction and ensure the safety of the main structure, surrounding roads, buildings, and construction personnel, providing engineering reference for monitoring and safety control in similar deep foundation pit support demolition projects.