深基坑双排桩结构受力变形机理及其计算模型研究

近年来,为了适应国内城市地下工程建设蓬勃发展带来的地下工程密集化、复杂化等方面的需要,深基坑开挖时双排桩围护结构因具有侧向刚度大、控制变形能力强、施工快速等特点在各种大型深基坑工程中得到了较为广泛的推广和应用。但实际设计过程中,由于该结构的变形机理与计算模型尚未有统一的理论,其设计方法比较杂乱,存在一定程度的保守设计。依托南京梅子洲青奥城地下空间工程及其现场监测数据,采用有限元计算模型对近年来在地下工程中逐渐得到推广使用的双排桩围护结构的变形机理、土压力分布规律等进行探讨和研究;在此基础上,结合与目前广为应用的理正双排桩模型和新规范双排桩模型的对比分析,研究并提出更吻合实际的、精确反映结构变形和力学特性的双排桩围护结构的修正设计计算模型,该模型架构清晰,准确性高,贴近实际工程设计,可以大力推广应用于双排桩结构的计算分析。

Research on Mechanism and Computation Model of Deep Foundation Pit Double-row Pile Structure

In recent years,the double-row piles structure is widely promoted and applied in deep foundation pit to meet the needs of intensive and complicated underground projects due to its high lateral stiffness,less deformation and quick construction and the vigorous development of urban underground engineering construction. However,in practical design,there is no unified design method and there exists a certain degree of conservative due to the lack of standard theory to match the structure deformation mechanism with calculation models. With Nanjing Meizizhou Qingao city underground space engineering program and field monitoring data,the deformation mechanism and soil pressure distribution law of double-row pile retaining structure are studied, which is gradually promoted and used in underground engineering field in recent years with finite element computation model. On the basis of this,a practical and reasonable corrected computation model of double-row pile retaining structure is recommended after the comparison and analysis of the widely used Lizheng and Xinguifang double-row pile models. This model structure is featured by clearness,high accuracy,and practical application in engineering design. The model can be easily applied in computation and analysis of double-row pile structure.