富水复合地层地铁深基坑开挖风险分析与对策

Risk Analysis and Countermeasures for Excavation of Deep Foundation Pit in Water-rich Composite Strata

针对富水复合地层地铁深基坑施工风险大但相关研究相对较少的问题,从风险源分析出发,根据广州地铁多年的相关施工经验,归纳富水复合地层中深基坑开挖的特点及风险,提出并介绍"开挖评估、预先封缝、缺陷修复、科学降水、均足回灌、精准测量、及时支撑、快速回筑"的32字施工步序和对策。其中"开挖评估、预先封缝、缺陷修复"强调围护结构自身的完整性及止水能力,"科学降水、均足回灌、精准测量"集中应对富水带来的风险,"及时支撑、快速回筑"确保在复合地层中有序完成高风险的施工过程。32字施工步序和对策以风险预估为基本,应对措施前置为核心,可达到有效控制富水复合地层深基坑施工风险的目的。

The construction risk of deep metro foundation pit in water-rich composite strata is high,and there is little relevant research.Hence,the characteristics and risk of excavation of deep metro foundation pit in water-rich composite strata are summarized based on risk source analysis and construction experience of Guangzhou Metro;and the construction method of"excavation and assessment,pre-sealing,defect repairing,scientific dewatering,uniform and adequate backfilling,accurate measurement,timely support and rapid construction"is proposed and introduced.The above-mentioned method emphasizes the integrality and waterproofing capacity of the retaining structure,rich-water risk and successful completion of high-risky construction procedure.The method takes the risk assessment as the basis and the countermeasure preposition as the core,by doing which the risk of deep foundation pit construction in water-rich composite strata can be effectively controlled.