超深基坑内坑中坑二次支护工程桩与混凝土悬臂桩交叉作用施工技术

Construction Technology of the Synergy Between Engineering Piles and Concrete Cantilever Piles for the Pit-in-pit Secondary Support in Ultra-deep Foundation Excavation

沈阳宝能环球金融中心项目T1塔楼为在建东北第一高楼,底板由四周到中间厚度分别为2.5,4.2,6.0,7.6,8.4,11.1m,电梯基坑处底板最深达11.1m,板顶标高为-24.650m,基底标高为-30.650m,局部最深电梯井坑底板底面标高为-35.750m。而电梯基坑开挖深度与周边开挖深度相差5.1m,为超深基坑内的深坑中坑,为了土方在开挖过程中坑中坑支护安全稳定性得到保证,本工程在土方开挖过程中采用工程桩和混凝土悬臂桩结合形成排桩支护体系对坑中坑进行支护,而且采用素混凝土承台模替代传统砖胎模,既保证了坑中坑开挖及施工安全,且加快了施工进度。

The Tower 1 of Shenyang Baoneng Global Financial Center which is in construction will be the tallest building in the northeast of China. The thickness of base plate varies from the perimeter to the middle, which is 2.5m, 4.2m, 6.0m, 7.6m, 8.4m with the maximum depth of elevator pit 11. lm. The surface elevation of the plate is -24. 650m, and the bottom elevation is -30. 650m. The surface elevation of the deepest elevator shaft foundation excavation is - 35. 750m. The excavation depth of the elevator shaft is 5. 1 m which is deep pit-in-pit in ultra-deep foundation excavation. To make the safety and stability of pit-in-pit support guaranteed in soil excavation, the project applies engineering pile and concrete cantilever pile which are combined to form row piles support system to support pit-in-pit structure. And plain concrete formwork of cushion cap is utilized instead of traditional brick form, which not only ensures the safety of the excavation but also accelerates the construction progress.