软土深基坑分段施工效应三维有限元分析

 时空效应在软土地基深基坑工程的实践中已经被证实，分段施工是时空效应理论在实际工程中应用的有效措施，但其应用多带有经验性，缺乏有效的理论指导。提出考虑分段施工效应的深大基坑支护结构三维全过程计算方法，编制三维有限元程序，结合典型算例，详细比较考虑分段施工效应与不考虑分段施工效应时，基坑支护结构、支撑系统的受力及变形性状的差异，从理论上验证采用分段施工技术是控制软土地基上深基坑变形的有效措施。最后，将该方法应用到某实际深基坑工程，计算与实测数据的对比表明，该方法适用采用分段施工的复杂深基坑工程。

THREE-DIMENSIONAL FINITE ELEMENT ANALYSIS FOR EFFECTS OF STEP CONSTRUCTION ON DEEP SOFT SOIL FOUNDATION PITS

Time-space effects have been validated with a lot of soft soil deep foundation pits. Step construction during the excavation is an effective way for the application of the theory of time-space effect，though those applications are somewhat experiential. A method to analyze behaviors of deep foundation pits considering the effects of step-by-step construction is proposed. A 3D finite element program based on the model is developed. The method is used to analyze the deformations and inner forces in the retaining piles and the struts of a typical excavation case. The numerical results are compared with the results that not considering the construction effects. It is also proven that step construction is an effective way to control displacement of deep foundation pits in soft soil. Finally，the method proposed here is used to analyze an actual deep pit project in Hangzhou. The analytical results are compared with the measured data. It is indicated that the suggested method can be well used to simulate the complex excavation process of foundation pits.