土工织物散体桩复合地基路堤土拱效应研究

摘要

In the aim of investigating the soil arching of geotextile-encased stone columns,we established a three-di-mensional finite element model of geotextile-encased granular columns composite foundation under embankment load to analyze the influences of geotextile stiffness,column spacing and embankment height.Results indicated that the ratio of geotextile modulus to soil modulus which induced the start of soil arching was 20.The modulus ratio had little effect on soil arching after reaching 67.The height of soil arching increased linearly until the height of em-bankment reached 5 times of net spacing and then remained constant.The required height for a complete soil arc-hing increased with the increase of net spacing.When net spacing reached twice the pile diameter,the height of soil arch remained stable.Moreover,with the increase of embankment height,the soil arch rate decreased gradually. When the height of embankment reached 1 .7 times of net spacing to form complete soil arch,the soil arching rate did not change anymore.Compared with numerical results,we found that the results calculated by the three-dimen-sional soil arching method proposed by Hewlett and Randolph are the closest to the numerical results,and we sug-gest to use this method for design.%为研究土拱织物散体桩的土拱效应，采用三维有限元软件建立了路堤荷载下土工织物散体桩复合地基模型，分析了筋材刚度、桩间距和路堤高度3个主要因素的影响。结果表明：土工织物散体桩的起拱筋土模量比为20，当筋土模量比达到67后，筋土模量比对土拱效应影响不大；土拱高度在路堤高度达到5倍桩净间距之前呈线性增长，之后土拱高度将不随路堤高度变化；随着桩净间距增加，形成完全土拱所需的高度也在增大，当桩净间距达到2倍桩径后，土拱高度将不再变化；随着路堤高度的增加，土拱率逐渐减小，当路堤高度达到1．7倍桩净间距形成完全土拱后，土拱率不再发生变化；与数值计算结果对比发现，由Hewlett 和Randolph 提出的三维土拱计算方法与数值计算结果最为接近，建议采用这种方法进行设计。