非饱和砂土−混凝土界面剪切强度试验研究  

Experimental study on the shear strength of unsaturated sandy soil-concrete interfaces

作　　者：杨明辉[1] 王文筱 邓波 YANG Minghui;WANG Wenxiao;DENG Bo(School of Civil Engineering,Hunan University,Changsha 410082,China;School of Civil Engineering,University of South China,Hengyang 421001,China)

机构地区：[1]湖南大学土木工程学院,湖南长沙410082 [2]南华大学土木工程学院,湖南衡阳421001

出　　处：《铁道科学与工程学报》2022年第2期409-418,共10页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(51678230)。

摘　　要：土-结构界面的剪切强度是分析土与结构相互作用的重要参数。通过GCTS压力板仪测定砂土SWCC曲线,用Geotest摩擦-剪切仪开展非饱和砂土与不同粗糙度混凝土界面的32组大型直剪试验,探讨基质吸力及界面粗糙度对界面剪切强度和剪胀性状的影响。试验结果表明:基质吸力和净法向应力对非饱和砂土-混凝土界面的硬化、软化以及剪胀特性有显著影响。随着吸力的增大,非饱和砂土−混凝土界面的表观摩擦角均呈增大趋势,而界面总黏结力呈先增大后减小趋势。界面基质角δb随吸力的增大而减小,且其强度包络呈现非线性特性。界面峰值抗剪强度趋势与界面粗糙度有关,随着粗糙度的提高,界面抗剪强度呈增大趋势。在试验现象的基础上,充分考虑剪胀角对表观摩擦角的影响,提出了一种非饱和土抗剪强度的修正公式,并与试验结果对比验证该模型的合理性。The shear strength of soil structure interface is an important parameter to analyze the interaction between soil and structure.In this paper,GCTS pressure plate extractor wasused to measure SWCC curve of sand soil,and 32 groups of large-scale direct shear tests werecarried out by Geotest friction-shear apparatus between unsaturated sand soil and concrete interface with different roughness.Furthermore,the effects of matric suction and interfacial roughness on interfacial shear strength and dilatancy werediscussed.The experimental results show that matric suction and net normal stress have significant effects on the hardening,softening and dilatancy of unsaturated sandy soil-concrete interface.With the increase of suction,the apparent friction angle of unsaturated sand concrete interface increases,while the total interfacial bond strength increases at first and then decreases.The interfacial matrix angleδb decreases with the increase of suction,and its strength envelope presents nonlinear characteristics.The trend of peak shear strength is related to the roughness of interface.As the roughness increases,the shear strength of interface tends to increase.Finally,based on the experimental phenomena and by fully considering the influence of dilatancy angle on apparent friction angle,a modified formula for shear strength of unsaturated soil was proposed,and the rationality of the model was verified by experimental results.

关 键 词：非饱和砂土 混凝土界面 吸力 抗剪强度 剪胀性 

分 类 号：TU411.7[建筑科学—岩土工程]