深基坑边塔吊地基加固设计及变形控制分析

随着城市建设地下空间开发需要，深基坑支护工程日益增多。深基坑开挖卸荷作用会引起岩土体应力应变效应，进而诱发周围建(构)筑物地基产生变形。某建筑工程由于施工场地限制，不得不将塔吊基础布置于深基坑围护结构边缘，而塔吊结构的运转荷载会对基坑安全造成隐患，故在基坑开挖前需要对塔吊地基进行加固设计，并对施工过程中塔吊地基变形进行预测。基于工程地质和施工环境等条件，设计锚拉桩支护方案对塔吊地基及基坑围护结构进行加固；并使用Midas GTX NX建立基坑开挖全过程施工工况的有限元模型，对塔吊地基加固前后的变形特征进行数值模拟；后与开挖过程中现场监测数据进行对比分析，评估塔吊地基加固设计方案的可靠性及效果。研究表明，本设计方案采用的支护桩间增设预应力锚索以及增设锚桩、拉梁的整体加固措施对基坑边设置的塔吊地基变形起到良好控制效果。研究成果可为类似深基坑工程支护设计、施工提供借鉴。

Reinforcement Design and Deformation Control Analysis of Tower Crane Foundation beside Deep Foundation Pit

With the development of underground space in urban construction, the number of deep foundation pit supporting projects is increasing. During the excavation of deep foundation pit, the unloading would cause the stress-strain effect of rock and soil, and then induce the deformation of surrounding buildings foundation. Due to the limitation of construction site, the foundation of tower crane has to be placed on the edge of deep foundation pit retaining structure. The operation load of tower crane structure will cause hidden danger to the safety of foundation pit. Therefore, before the foundation pit excavation, it is necessary to reinforce the tower crane foundation and predict the deformation characteristics of the tower crane foundation during the construction process. First of all, based on the conditions of engineering geology and construction environment, this project has designed the anchor pulling pile support scheme to reinforce the tower crane foundation and foundation pit retaining structure. Then, the finite element model of the whole process of foundation pit excavation was established through Midas GTX NX software, and the deformation characteristics before and after the reinforcement of tower crane foundation were simulated. Finally, the numerical simulation results were compared with the field monitoring data in the excavation process to evaluate the reliability of the tower crane foundation reinforcement design scheme. The study shows that the reinforcement design of this project has a good effect on the deformation control of the tower crane foundation. The study results will provide reference for similar deep foundation pit support design and construction.