竖井地基固结二维等效分析方法考评
Evaluation of two-dimensional equivalent method for finite element analysis of consolidation by vertical drains
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摘要: 平面应变二维等效分析方法是竖井地基固结有限元分析的主要方法之一。介绍了该法的基本原理,列举了六种具体的二维等效转换公式。然后,以成层土竖井地基算例和未打穿竖井地基算例,分别对不同转换方法的可靠性进行了考评。结果发现:地基土成层性对二维等效方法计算结果的可靠性有较显著影响,而竖井未打穿情况的影响不明显;在本文算例参数取值情况下,各种方法的误差情况差别较大,其最大误差达35%;Chai方法和Tran方法得到的固结度计算结果相对可靠,其最大误差在10%以内。另外还发现,Chai方法考虑的因素较全面,操作过程不受人为因素影响,其计算结果相对可靠且计算效率显著提高,因此值得推广。Abstract: The two-dimensional equivalent method is one of the main approaches for the finite element analysis of consolidation by vertical drains. Summaries and comments about the equivalent methods are firstly carried out based on the existing researches. Then, six equivalent methods, which are widely applied in present, are examined through two numerical examples. The first one is the layered soft soil foundation and the other is the partially penetrated vertical drained foundation. The estimated results show that the parameter values for the layered soil example have significant impact on the reliability of the equivalent methods, while the length of the drain has no significant effect. For the parameter values applied in the examples, errors for the degree of consolidation for different methods vary considerably. The biggest errors reach 35% for different methods. Relatively, the calculated results of Chai's (2001) method and Tran's (2008) method are reliable and the largest errors of the two methods are within 10%. Besides, Chai's equivalent method is worth promoting since the operation of the method is rigorous and has high computational efficient.