砂土拱效应滑移面几何轮廓与松动土压力分析  

Geometric Contour of Slip Surfaces and Loosening Earth Pressure in Sand Under Soil-Arching Effect

作　　者：周思危 冷伍明[1,2,3] 聂如松[1,2,3] 李亚峰 狄宏规[4] 陈伟庚 ZHOU Siwei;LENG Wuming;NIE Rusong;LI Yafeng;DI Honggui;CHEN Weigeng(School of Civil Engineering,Central South University,Changsha 410075,China;MOE Key Laboratory of Engineering Structures of Heavy Haul Railway,Central South University,Changsha 410075,China;National Engineering Laboratory for High Speed Railway Construction,Central South University,Changsha 410075,China;Key Laboratory of Road and Traffic Engineering of Ministry of Education,Tongji University,Shanghai 201804,China;China Railway Guangzhou Group Co.,Ltd.,Guangzhou 510088,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中南大学重载铁路工程结构教育部重点实验室,湖南长沙410075 [3]中南大学高速铁路建造技术国家工程实验室,湖南长沙410075 [4]同济大学道路与交通工程教育部重点实验室,上海201804 [5]中国铁路广州局集团有限公司,广州510088

出　　处：《西南交通大学学报》2023年第6期1413-1422,共10页Journal of Southwest Jiaotong University

基　　金：国家自然科学基金(51878666,51978672)。

摘　　要：土拱效应本质上是由于土体内部松动引起的应力转移现象,土体松动过程伴随着滑移面的形成和延展,但目前针对滑移面几何轮廓、松动影响范围以及考虑松动区动态演变对松动土压力的影响等方面的研究尤待深入.利用Trapdoor试验对砂土拱效应滑移面轮廓及演变开展研究,获得滑移面几何轮廓及其演变模式在不同填土高度、活动门下移和宽度以及砂料密度下的表征区别.通过界定滑移面影响范围内松动核心区域,提出基于核心区几何形状的松动应力计算方法.分析松动应力-活动门下移曲线特征,以揭示最大、最小拱状态条件下的曲线特征随填土高度、活动门下移和宽度以及砂密度的变化规律.研究结果表明:1)滑移面轮廓随活动门下移的演化过程为三角形—子弹头形—椭圆形,填土高度越高,活动门宽度越小,初始和次级滑移面轮廓越尖锐;2)初始、次级滑移面高度随活动门下移递增,第Ⅲ级滑移面拐点高度随活动门下移递减,初始、次级滑移面夹角随活动门下移先增后减,第Ⅲ级滑移面上半夹角与下半夹角均随活动门下移递增;3)随着填土高度的增加,松动核心区形状演化过程为三角形—梯形—矩形,核心区高度为填土高度的0.5倍~0.8倍,核心区夹角与核心区面积均随内摩擦角的增加近似线性递减;4)基于核心区面积的松动应力计算方法相比,Terzaghi等方法更具适用性,且其适用于计算低填土试验组的临界应力和高填土试验组的极限应力.研究成果为更精确地描述砂土松动区的位移破坏模式及其界定标准以及松动区稳定性评价提供参考.The soil-arching effect,in essence,is a stress transfer phenomenon triggered by the loosening of the internal structure of the soil.The loosening process is accompanied by the formation and expansion of slip surfaces.At present,research on the geometric contour of slip surfaces,loosening-affected areas,and influence of the dynamic evolution of loosening zones on the loosening earth pressure remains sparse.Therefore,Trapdoor tests were conducted to investigate the contour of slip surfaces and their evolution in sand under the soil-arching effect.In this way,differences in the characterization of the geometric contour of slip surfaces and their evolution modes under different filling heights,downward movements and widths of trapdoors,and sand densities were obtained.By defining a core loosening zone in the area affected by slip surfaces,a calculation method for the loosening stress based on the geometric contour of the core loosening zone was proposed.In addition,the curve characteristics of the loosening stress and downward movement of the trapdoor were analyzed to reveal the changes in curve characteristics with the filling height,downward movement and width of the trapdoor,and sand density under maximum and minimum arch states.The research results show that:1) the contour of slip surfaces evolves from a triangle,to a bullet shape,and finally to an ellipse with the downward movement of the trapdoor.As the filling height gets greater,and the trapdoor becomes narrower,the contour of primary and secondary slip surfaces is sharper.2) with the downward movement of the trapdoor,the height of the primary and secondary slip surfaces increases,while that of inflection points of the level-Ⅲ slip surface decreases.In addition,as the trapdoor moves downward,the angles of the primary and secondary slip surfaces both increase first and then decrease,while the upper and lower half-angles of the level-Ⅲ slip surface both increase.3) the contour of the core loosening zone changes from a triangle,to a trapezoid,and finally to

关 键 词：土拱效应 Trapdoor试验 滑移面轮廓 松动区 松动土压力 

分 类 号：U216.41[交通运输工程—道路与铁道工程]