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路堤荷载下长短桩加固黄土地基影响因素的分析

ISSN号：1672-7029
期刊名称：《铁道科学与工程学报》
时间：0
分类：TU473[建筑科学—结构工程;建筑科学—土工工程]
作者机构：[1]兰州交通大学土木工程学院,甘肃兰州730070
相关基金：国家自然科学基金资助项目(41562014);长江学者和创新团队发展计划项目(IRT1139)

关键词：长短桩, 复合地基, 现场试验, 数值模拟, 承载特性, 影响因素, long-short pile, composite foundation, field test, numerical simulation, bearing characteristics, influence factors

中文摘要：

黄土高原地区，有关路堤荷载下长短桩复合地基工作特性的研究较少，相关经验也较为缺乏。为更好地了解这种复合地基的桩土共同作用状况，结合实际工程，运用MIDAS/GTS有限元软件，分析桩长、桩间距和下卧层刚度对复合地基工作性状的影响。研究结果表明：在一定范围内，桩长和下卧层刚度的增加、桩间距的减小均能起到减小沉降的作用；由于负摩阻力的存在，长短桩的桩身应力最大值出现在桩顶以下一定深度处，当长桩为18m，短桩为8m时，长桩桩身应力最大达1831.7kPa；长(短)桩的桩身应力随短(长)桩长度的增加而减小；长桩桩土应力比随长桩长度、桩间距和下卧层刚度的增加呈先增加后稳定的趋势；短桩桩土应力比随短桩长度的增加而增加，随桩间距的增加而减小，随下卧层刚度的增加则呈先增加后稳定的趋势。因此，长短桩复合地基应在满足沉降及承载力要求的前提下，选取最经济的桩长、桩间距并使长桩桩端尽量支撑在较坚硬的持力层上。本文研究成果对长短桩复合地基的设计和施工均有一定的参考价值。

英文摘要：

The study and relevant experience on working mechanism of long-short pile composite foundatio nunder embankment is rare in loess plateau. In order to understand the interaction of piles and soil, combined real project with MIDAS/GTS, the influence of pile length, pile spacing and stiffness of substratum on composite foundation are studied in this article. The main results are as follows: the increase of pile length and substratum stiffness, the decrease of pile spacing can reduce the settlement within certain limits. Because of the negative skin friction, the maximum stress of long-short pile composite foundation appears at a certain depth near the top of pile.When the lengths of long and short pile are 18 m and 8 m, the maximum stress of long pile is 1 831.7 kPa. The stress of long/short pile decreases with the increase of the short/long pile length. With the increase of long pile length, pile spacing and substratum stiffness, the pile soil stress ratio of long pile increases at first, and then maintain stable. The pile soil stress ratio of short pile increases with the increases of its’ length, but decreases with spacing, while increases at first, and then become stable with substratum stiffness. Therefore, when the required settlement and bearing capacity are meeting, the length and spacing should be designed on the basis of the project cost and the tip of pile should support on the harder bearing layer. These results have reference value for the design and construction of composite foundation with long and short piles.

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