明挖地铁配套的深基坑开挖卸载的计算与设计

Calculation to the Excavation of Deep Foundation Pit Supporting the Open Excavation Subway Engineering

以厦门轨道交通1号线杏锦路站基坑支护工程为案例,运用有限元和理正深基坑设计软件,通过数值模拟结果分析基坑开挖坑底回弹的规律和不对称开挖对地铁工程的影响.研究发现,离基坑边越远、开挖越深,坑底土体回弹越明显;土体不对称开挖产生土体偏压,桩前塑性区范围与基坑开挖深度成正比,且在土体偏压一侧比另一侧明显.为保护地铁工程结构的功能性和安全性,可采用排桩+预应力锚索结合排桩+内支撑支护方案,解决基坑整体稳定性和变形控制问题;可采用土方分层分段分块、均匀、对称的开挖方案,减少土体偏压对支护结构的影响.

According to Xiamen Subway Line 1 Xingjin Road Station excavations case, the finite element and the Leading deep foundation software are employed to establish a numerical analysis model to simulate and analyze the rules of pit bottom rebound and the asymmetric excavation on subway engineering. The study found that the farther from the side of foundation and the deeper excavation, the more obvious to the soil rebound; Asymmetric soil excavation produces bias , the soil plastic zone before the pile is proportional to the depth of excavation, and the soil bias side is more obvious than the other side. For the protection of subway excavation engineering structure functionality and security, row piles with prestressed anchor and row piles with inner brace can be used in combination to solve the overall stability of foundation and deformation control issues, excavation scheme of the sub block and uniform and symmetrical earth moving can be used to reduce the impact of bias on the soil of supporting structure.