桩承式路堤土拱演化的二维钢棒相似土模型试验  

2D Model Tests of Soil Arching Evolution in Piled Embankments Using Steel Rod Analogical Soil

作　　者：芮瑞[1] 张龙[1] 孙义[1] 徐路畅 夏元友[1] 

机构地区：[1]武汉理工大学土木工程与建筑学院,湖北武汉430070

出　　处：《中国公路学报》2017年第10期8-16,共9页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(51208403);武汉理工大学国家级大学生创新创业训练计划资助项目(20151049706038);湖北省自然科学基金项目(2016CFB469);武汉市城建委科技计划项目(201639)

摘　　要：为了解桩承式路堤的变形类型与土拱效应随桩间土下沉的演化规律,并为参数取值提供参考,开发了可考虑桩承式路堤多个单元相互影响的多沉陷门(Multi-trapdoor)试验装置,考虑填料高度H、桩间净距s-a与桩径参数a,进行了1组随桩间土下沉的土拱演化模型试验。试验采用椭圆钢棒相似土作为填料,将采用砂填料的平面应变试验简化为二维试验条件,消除了前后挡板摩擦力的影响。通过粒子图像测速技术获取了填料随桩间土下沉过程的全场变形,利用自制荷载板精确地测试了填料底面的桩土荷载分布,得到不同参数组合下的桩承式路堤土拱变形类型和桩土应力比变化规律;同时利用试验结果总结了3种演化模式的适用条件。结果表明:钢棒相似土能够很好地模拟实际砂填料的平面应力-应变特性,桩承式路堤土拱效应存在三角形扩展型和等沉面型2种主要的演化模式,与三角形扩展模式相比,等沉面模式路堤表面无差异沉降,土拱效应发挥程度高,且桩土应力比随桩间土下沉降低比例较小,另一种塔形升高模式可以看作三角形扩展型向等沉面型转变的一种过渡模式;低路堤桩承式路堤宜调整桩土截面尺寸以提高相对填料高度H/(s-a),使得路堤变形进入等沉面模式。In order to reveal deformation patterns of piled embankments and soil arching evolution during the settlement of the soil,and provide references for parameter selection of piled embankments,a multitrapdoor test system,in view of interactions between multiple elements in the piled embankments,was developed. The series of trapdoor tests were conducted in consideration of the filling height（ H）,net spacing（ s-a） and width（ a） of the piles. Soil arching evolution during the settlement of the soil was observed. Steel rod analogical soil was used as the filling to meet the two-dimension experiment conditions. The effect of the friction on both the front and back plates was eliminated during the test.Particle image velocimetry（ PIV） technique was adopted to achieve the whole deformation and several load cells were used to measure the load distribution under the filling. The deformation patterns of the soilarching and the pile-soil stress ratio by dint of different parameters were obtained. The results show that the steel rod analogical soil can accurately simulate the stress-strain behaviors of the soil at the plane. There are two main soil arching evolution patterns of piled embankments,namely,triangular expanding pattern and equal settlement pattern respectively. Compared with the triangular expanding pattern,there is no differential settlement on the embankment surface in the equal settlement pattern. With high soil arching effect,the stress distribution ratio goes on with its trends of a slight decrease. Another tower-shaped evolution pattern can be considered as the transitional pattern between the triangular expanding pattern and the equal settlement pattern. In addition, the application conditions of three evolution models are summarized according to test results. It can be concluded that the relative filling height H/（ s-a） of low piled embankments increases through adjusting section sizes of pile-soil,with the purpose of entering the equal settlement pattern.

关 键 词：道路工程 桩承式路堤 沉陷门试验 土拱效应演化 钢棒相似土 

分 类 号：U416[交通运输工程—道路与铁道工程]