粗粒土抗剪强度的缩尺效应规律试验研究  

Experimental study on laws of scale effects of shear strength of coarse-grained soils

作　　者：蒋明杰 吉恩跃 王天成 栗书亚 朱俊高[4] 梅国雄 JIANG Mingjie;JI Enyue;WANG Tiancheng;LI Shuya;ZHU Jungao;MEI Guoxiong(Laboratory of Disaster Prevention and Structural Safety of Ministry of Education,Guangxi University,Nanning 530004,China;Guangxi Key Laboratory of Disaster Prevention and Structural Safety,Guangxi University,Guangxi University,Nanning 530004,China;Department of Geotechnical Engineering,Nanjing Hydraulic Research Institute,Nanjing 210024,China;Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,Hohai University,Nanjing 210024,China)

机构地区：[1]广西大学工程防灾与结构安全教育部重点实验室,广西南宁530004 [2]广西大学广西防灾减灾与工程安全重点实验室,广西南宁530004 [3]南京水利科学研究院岩土工程研究所,江苏南京210024 [4]河海大学岩土力学与堤坝工程教育部重点实验室,江苏南京210024

出　　处：《岩土工程学报》2023年第4期855-861,共7页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(51878185,52178321,52108309);国家自然科学基金委员会-雅砻江流域水电开发有限公司雅砻江联合基金项目(U1865104);长江水科学研究联合基金重点支持项目(U2040221);广东省海洋土木工程重点实验室开放基金项目(LMCE202103);水利部土石坝破坏机理与防控技术重点实验室开放基金项目(2020ZDK003);广西自然科学基金项目(2021GXNSFBA196091)。

摘　　要：抗剪强度是评价土体稳定性的重要指标,研究缩尺效应对粗粒土抗剪强度的影响,对高土石坝工程土体强度估算有重要的理论意义和应用价值。根据前人的研究,颗粒最大粒径d_(max)和级配结构两部分变化是导致缩尺后试样存在缩尺效应的主要原因,其中级配结构可由级配面积S作为特征参数表示。通过改变试样的d_(max)和S,设计了24组不同级配试样,利用大型直剪仪对各组试样进行直剪试验,从而定量研究颗粒最大粒径和级配结构对粗粒土抗剪强度的影响规律。研究结果表明:粗粒土的抗剪强度指标黏聚力c和内摩擦角φ均表现出随着d_(max)增大而增大的规律,且c和φ均与d_(max)呈对数函数关系;黏聚力c和内摩擦角φ随着S的减小而增大,到达某一特定值后呈略微减小的趋势,并根据相应试验数据分别建立c和φ与S的关系式。最后,基于试验结果建立了考虑缩尺效应的粗粒土抗剪强度的预测模型,并用相关文献试验数据验证了该模型对不同类型粗粒土的适用性。The shear strength is one of the important evaluation indices for the stability of soils.The investigation into the influences of the scale effects on the shear strength of coarse-grained soils has important theoretical significance and application for the strength estimation of soils in high earth-rock dam projects.According to the previous studies,the variations of the_(max)imum particle size d_(max)and gradation structure can be seen as the main reasons resulting in the scale effects,and the gradation structure can be expressed by a characteristic parameter,the gradation area(S).By changing d_(max)or S,24 groups of samples with different gradations of coarse-grained soils are designed.The direct shear tests on all the samples are conducted by a large-scale direct shear apparatus to quantitatively study the multiple influences of the_(max)imum particle size and gradation structure on the shear strength of coarse-grained soils.The results show that the cohesion(c)and the internal friction angle(φ)of coarse-grained soils tend to increase with the increasing d_(max),and thus a logarithmic equation relationship between c/φand d_(max)is proposed.Both c andφtend to increase with the decrease of S,and then decrease slightly after S reaches a certain level.As a consequence,an empirical relationship between c/φand s is established based on the corresponding test results.Furthermore,a new prediction model for the shear strength of coarse-grained soils considering the scale effects is proposed,and the test results in the relevant literatures verify that the proposed model can be applied to different types of coarse-grained soils.

关 键 词：粗粒土 缩尺效应 抗剪强度 颗粒最大粒径 级配结构 

分 类 号：TU441[建筑科学—岩土工程]