长短桩在湿陷性黄土中作用机理的数值分析

Numerical Analysis of Long-short-pile Composite Foundation in Collapsible Loess Area

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.

In view of collapsible loess foundation in Zhengzhou-Xi＇an passenger-dedicated lines,this paper analyses the properties of long-short-pile composite foundation under the embankment load with finite element method to reach load transmission on pile in long-short-pile composite foundation,Mohr-Column elasto-plastical constitutive model for soil and piles.The multi-stage filling by using life and death element technology is stimulated.It shows that the influence of parameter of long pile on long-short-pile composite foundation is more than the influence of short pile.The results are used to improve and to establish the long-short-pile computation theory for the subsidence of composite foundation with practical distinct meanings.