某高层建筑事故的加卸载和变刚度桩基综合处理
Comprehensive treatment of loading and unloading of pile foundation with variable stiffnesses for a high-rise building accident
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摘要: 在分析某高层建筑严重不均匀沉降原因的基础上,制定了该建筑物的综合处理和实施技术方案。为了逆转高速率的沉降和倾斜态势,并促其趋于稳定达到正常使用标准,采取如下四方面处理措施:一是采取一侧卸载减沉,另一侧加载促沉措施;二是采用混凝土钢管桩结合后注浆实施变刚度加固处理;三是断开原已浇注的后浇带,加大沉降较小一侧的基底压力以增沉;四是科学安排施工程序,以发挥综合处理预期效果。最终使建筑物沉降速率由0.8 mm/d降至0.006 mm/d;倾斜由最大2.8‰降至2.28‰,均小于规范允许值。工程的处理实施过程中遇到的一些问题在文中也进行了讨论分析,本文的相关研究成果和加固经验可为类似工程提供参考。Abstract: According to the correct analysis of the reasons for differential settlement of a high-rise building, the integrated reinforcement technologies and measures of the building are established especially. In order to stop the high settlement and inclination ratio and ensure that the deformation of the building meets the standard requirement, the project takes four measures: (1) to unload and reduce settlement at the one side, and to upload and increase settlement at the other side; (2) to take variable stiffness reinforcement by using concrete-filled steel pipe with post-grouting technology; (3) to add the foundation pressure of small-settlement side with post-cast strip cutting method so as to make the settlement be larger; (4) to arrange a scientific and reasonable sequence of construction to realize the expected results. Finally, the settlement ratio of the building decreases from 0.8 mm/d to 0.006 mm/d; the stable tilt value also decreases from 2.8‰ to 2.28‰, which both satisfy the requirements of the national standard. Problems happened during the process of building implementation of the project are also discussed. The research results and strengthening experience may provide reference for similar projects.