孟加拉某基坑工程地连墙安全评估及加固处理  

Safety assessment and reinforcement treatment of diaphragm wall of a foundation pit project in Bangladesh

作　　者：李焕君 张寒 李冰[1,2,3] LI Huanjun;ZHANG Han;LI Bing(State Key Laboratory of Building Safety and Built Environment,Beijing 100013,China;Institute of Foundation Engineering,China Academy of Building Research,Beijing 100013,China;National Research Center for Building Engineering Technology,Beijing 100013,China)

机构地区：[1]建筑安全与环境国家重点实验室,北京100013 [2]中国建筑科学研究院地基基础研究所,北京100013 [3]国家建筑工程技术研究中心,北京100013

出　　处：《建筑结构》2022年第12期139-147,共9页Building Structure

基　　金：中国建筑科学研究院青年基金课题(20216022331030043)。

摘　　要：孟加拉某基坑局部探挖后发现开挖范围内的地连墙普遍存在大面积露筋、混凝土夹渣、少筋等严重缺陷。为全面调查地连墙缺陷范围及程度,在基坑大面积开挖前,对地连墙进行了一系列质量检测和安全评估工作。通过检测发现存在混凝土质量缺陷的地连墙主要集中在基坑西南侧,此处回填土深度7~10m,地连墙施工未采取槽壁加固措施,混凝土灌注期间发生塌孔;此外,所施工地连墙均未按设计图纸配筋,受力钢筋缺少39%;导致地连墙承载力大幅度降低。根据以上安全评估结果,结合工程实际情况,对地连墙的加固处理方法进行了创新,采用以地连墙为板、H型钢为次梁、支撑腰梁为主梁的空间结构加固体系,使工程得以顺利推进。最后通过计算和实测变形结果的对比进一步验证了加固方案的可行性。After excavating the local part of the foundation pit in Bangladesh, it was identified that there are serious quality defects on the diaphragm wall, such as large-area exposed steel reinforcement, concrete slag inclusion and less steel reinforcement. In order to detect the defect area as well as the degree of defect quality for the diaphragm wall, a series of quality inspections and safety assessments were carried out prior to the full excavation of the foundation pit. Through these quality inspections, it was found that the concrete quality defects on the diaphragm wall are mainly located in the southwest of the foundation pit, where the backfill-soils have a depth of 7 ~ 10 m. The trench wall was not reinforced during the construction of diaphragm wall, and thus the hole might be collapse during the post-pouring of the concrete. Additionally, the reinforcement of the constructed diaphragm wall was not conducted according to the design drawings that the percentage of longitudinal steels is about 39% less than the designed reinforcing bars, which results in a significant reduction of the bearing capacity of the diaphragm wall. Based on the results of safety assessments as well as by considering the actual situation of this project, a novel treatment approach for reinforcing the diaphragm wall was developed, by which the space structure reinforcement system is used as the plate, the H-section steel as the secondary beam and the supporting waist beam as the main beam, so that the project could be processed successfully. Finally, the feasibility of the reinforcement scheme was verified by comparing the calculated and measured results of deformation.

关 键 词：基坑工程 地连墙 质量缺陷 质量检测 安全评估 加固处理 

分 类 号：TU47[建筑科学—结构工程]