复杂地质条件和敏感环境中基坑设计实践及关键技术

Design practice and key technology for the foundation pit in complex geology and sensitive environments

上海某国际金融大厦深大基坑项目北侧紧邻运营轨道交通8号线区间隧道,最近处仅7.87 m,南侧与现有世博共同管沟净距2.0~3.0 m,基坑变形控制要求高,周边环境敏感。同时,本项目位于黄浦江畔,场地浅层为典型的淤泥质软土地层,下部为富含承压水粉(砂)土层,且微承压水层与第一、第二承压水层互为连通,止水帷幕无法隔断承压水层,地质条件复杂。设计采用分坑施工、被动区加固、预应力伺服钢支撑系统、抽灌一体化降水方案、超深地下连续墙、跟踪注浆、型钢垫层等技术方案。实测结果表明,区间隧道的最大变形6.52 mm,共同管沟的最大变形15.3 mm,其最大变形均满足变形控制要求,确保了运营区间隧道和共同管沟的安全。

The deep and large foundation pit project of an international financial building in Shanghai is adjacent to the operating rail line interval with the shortest distance of only 7.87 m on the north side,and the clearance of 2.0 to 3.0 m from the pipe ditch of World Expo on the south side.Because of the high sensitivity of the surrounding environment,the deformation control of the foundation pit is quite demanding;meanwhile,the project is located on the bank of the Huangpu River.The shallow layer at the site is a typical silty soft soil layer,while the lower part is a soil layer rich in confined ground water.Moreover,the micro-confined aquifer is connected to the first and second confined aquifers,and the sealing curtain cannot cut off the confined aquifers.All these factors constitute complex geological conditions.Considering the situation,the project adopted various technical measures.The final measurement results showed that the maximum deformation of the tunnel is 6.52 mm,and the maximum deformation of the pipe ditch is 15.3 mm,which meet the deformation control requirements,ensuring the safe operation of the tunnel and the pipe ditch.