深基坑工程地下水位突涨问题分析及处理

Analysis and Treatment of Sudden Rise of Groundwater Level in Deep Foundation Excavation Engineering

长安九里768地块写字楼项目基坑设计深度为24.55m,根据前期地质勘察报告显示,地下水水位埋深在37.3~38.7m,因此基坑施工时未考虑降排水措施。在地下室施工阶段,永定河开始进行生态补水工作,受此影响,地块范围地下水水位大幅上涨,基坑内出现渗水,坑内积水深度最高达5.82m,极大影响基坑边坡安全,并且影响后续施工。针对该突发情况,采用围堰分仓排水的方式降低坑内积水水位,再通过浇筑水下混凝土对肥槽封底,排干积水后立即进行防水及肥槽回填施工,最大程度保证基坑安全性。

The design depth of the foundation excavation of the 768 block office building project in Jiuli,Chang’an is 2455m.According to the previous geological survey report,the groundwater level is buried at 373~387m,so the drainage measures were not considered during the foundation excavation construction.During the construction phase of the basement,Yongding River began to carry out ecological water replenishment.Affected by this,the groundwater level of the block area rose sharply,water seepage occurred in the foundation excavation,and the depth of water was up to 582m,which greatly affected the safety of the foundation excavation slope and the subsequent construction.In view of this sudden situation,separate cofferdam drainage is used to reduce the water level in the excavation,and then the bottom of the fertilizer tank is sealed by pouring underwater concrete.After draining the water,waterproof and fertilizer tank backfill construction are carried out immediately to ensure the safety of the foundation excavation to the maximum extent.