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针对郑西客运专线湿陷性黄土地基的工程特点,采用有限元方法对黄土地区路堤荷载作用下长短桩复合地基的作用性状进行分析.分析中,桩体与土体均采用理想弹性—塑性模型进行模拟,屈服准则采用D ruker-prager屈服准则,运用生死单元技术模拟路堤分级加载.采用“逐步缩进法”取值,分别研究桩体各参数对长短桩复合地基作用效果的影响,并分析其影响程度.分析结果表明:短桩对提高地基承载力的效果并不明显,主要用于消除上层湿陷性黄土的湿陷性;提高长桩变形模量可以有效地提高地基承载力减小基础沉降.因此,针对不同的地基土,优化长短桩桩型的选择,既可以达到处理要求,也可以提高经济效益.
According to engineering characteristics of collapsible loess foundation in Zheng-Xi Passenger Dedicated Railway, the finite element method is used to analyze the effect of long-short pile composite foundation under embankment load in loess area, and the ideal elastic-plastic model The yield criterion is Druker-Prager yield criterion, and the life-and-death element is used to simulate graded loading of embankment. The influence of pile parameters on the effect of long-short pile composite foundation is studied by using “progressive indenting method” The analysis results show that the effect of short piles on bearing capacity of foundation is not obvious, which is mainly used to eliminate the collapsibility of upper collapsible loess; to increase the deformation modulus of long piles can effectively improve the bearing capacity of foundation So as to reduce the foundation settlement.Therefore, for different foundation soils, the optimization of the length and the length of the pile type selection, both to meet the processing requirements, but also can improve economic efficiency.