摘要
接触面剪切带的细观变形特征是研究结构物与土体相互作用的核心问题。为探明砂土-混凝土接触面剪切带变形特征,利用大型直剪仪开展砂土-混凝土接触面直剪试验,采用灌砂变形标记法实测砂土变形,依据标记线剪应变沿竖向的变化特征对砂土变形区域进行划分。在此基础上,研究粗糙度、法向应力和密实度对砂土-混凝土接触面剪切带细观变形特征的影响规律。研究结果表明:1)砂土可分为非剪切区、过渡区和应变集中区,应变集中区仅存在剪切面之上。2)规则型接触面的上剪切带厚度均值为33D_(50),远大于下剪切带9D_(50)和“光滑”接触面剪切带厚度20.4D_(50)。3)密实度对剪切带及其过渡区厚度的影响微弱,而粗糙度对其影响显著;法向应力、密实度对应变集中区厚度影响有限,应变集中区厚度随粗糙度的增大近似线性增大;应变集中区长度随粗糙度的增大先增大后减小,随密实度的增大近似线性增大,随法向应力增大而减小。4)随剪切位移增大,上剪切带厚度不断增大而下剪切带厚度先增大后保持基本不变,应变集中区的长度增大,但剪切位移对应变集中区厚度的影响有限。5)获得归一化剪切带厚度取值h_(t)/D_(50)与D_(50)的关系,在有限元模拟规则型结构与砂土的相互作用时,建议砂土体细化网格单元的范围不小于最大剪切带厚度37D_(50)。研究成果深化了砂土-规则型接触面剪切带变形特征的认识,可为大粗糙度、带肋桩的承载变形特性的精细化有限元模拟分析提供重要参考和依据。
The meso-deformation characteristics of shear bands are a core issue of the interaction between soil and structural materials.A series of interface direct shear tests were carried out using a large-scale direct shear apparatus to investigate the meso-deformation characteristics of the sand-concrete interface.Thus,the shear deformation of the sand was measured by using sand filling deformation marking method,and the deformation area of the sand was divided according to the change characteristics of the shear strain along the vertical direction of the marking line.On this basis,the influence of surface roughness,normal stress,and soil density on the mesodeformation characteristics of the shear zone were investigated.The results of the interface direct shear tests are summarized as follows.(1)The deformation zone can be divided into non-strain,transition,and strain concentration zones,and the strain concentration zone is observed only above the shear plane.(2)The average thickness of the upper shear band on the structural interface was 33D_(50),which is much greater than that of 9D_(50) for the lower shear band and 20.4D_(50) for the smooth interface shear band.(3)The influence of soil density on the thickness of the shear band and transition zone is slight,while the effect of roughness is significant.The normal stress and soil density have limited influences on the thickness of the strain concentration zone,and the thickness of the strain concentration zone increases approximately linearly with roughness.The length of strain concentration zone initially increases and then decreases with increasing roughness.Further,its length increases linearly with increasing soil density and decreases with increasing normal stress.(4)With the increase of the shear displacement,the upper shear band thickness increases continuously,while the lower shear band thickness first increases and then remains stable.The strain concentration zone length increases and its thickness slightly changes with increasing shear displacement.(5)The relationship between normalized shear zone thickness and D_(50) was obtained.It is suggested that the range of soil refinement grid elements should not be less than the maximum shear zone thickness of 37D_(50).The research results can deepen the understanding of the deformation characteristics of the sand-regular contact surface shear zone and provide an important reference and basis for the refined finite element method simulations of the bearing capacity and deformation characteristics of the rough and ribbed piles.
作者
杨奇
吴亚飞
陈琛
邓煜晨
徐方
阮波
YANG Qi;WU Yafei;CHEN Chen;DENG Yuchen;XU Fang;RUAN Bo(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;School of Civil Engineering,Xiangtan University,Xiangtan 411105,China)
出处
《铁道科学与工程学报》
EI
CAS
CSCD
北大核心
2024年第2期613-625,共13页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(51978672)
中国铁路设计集团有限公司课题(总-2022土建103)
上海局杭州铁路枢纽指挥部横向科研课题(2023-122,2021-50)
湖南铁院土木工程检测有限公司检测研究基金资助项目(HNTY2021K09)。
关键词
砂土-混凝土接触面
大型直剪试验
灌砂标记法
剪切带
细观变形
sand-concrete interface
large scale direct shear test
sand filling marking method
shear band
mesodeformation
