颗粒介质剪胀、软化特性的直剪试验研究  

Direct Shear Test on Dilatancy And Softening Properties of Granular Media

作　　者：姜雨 陆勇[1] 邓衍博 胡笑竹 JIANG Yu;LU Yong;DENG Yanbo;HU Xiaozhu(School of Civil Engineering,Suzhou University of Science and Technology,Suzhou 215000)

机构地区：[1]苏州科技大学土木工程学院,江苏苏州215000

出　　处：《土工基础》2021年第1期76-80,共5页Soil Engineering and Foundation

基　　金：江苏省高校自然科学研究面上项目(15KJB170017);江苏省建设系统科技项目(2017ZD204);苏州科技大学科研基金自然科学项目(ZL2873);国家自然科学基金项目(51508369)。

摘　　要：颗粒介质的宏观力学行为特征与其微观组构演化密切相关,涉及孔隙比、颗粒形态、颗粒破碎以及各向异性等因素的交叠影响。采用DRS-I型超高压直剪试验系统对3种不同粒径的钢球进行0.4~12 MPa法向压力下的直剪试验,避免颗粒形态、颗粒破碎及各向异性的交叠影响,进而单独分析峰值强度、残余强度与孔隙比演化的关联性,以期为揭示颗粒介质的细观力学机制提供参考。结果表明:1)落雨法制得的圆球颗粒介质普遍呈现剪切软化特性,剪切过程中存在明显的峰值应力和残余应力;2)峰值强度随围压增大呈现出一定程度的减小趋势,与孔隙比变化斜率的极值相对应;3)残余强度基本不受颗粒粒径、围压的影响,对应着孔隙比的稳定值即临界状态;4)采用Rowe剪胀方程能够较好地描述颗粒介质的强度特性与体变特性的关联性。Particle is one of a large number of media forms and is widely existed in the nature.Particles are widely used as engineering materials,such as dam rockfills,railway ballasts,and foundation backfills.The macro-mechanical behavior of granular media is closely related to its micro-structural evolution.It involves the overlapping effects of factors such as porosity ratio,particle morphology,particle fragmentation,and anisotropy.Analyzing the independent influence of each factor reveals that the macro-mechanical behavior of granular media is an important way of mechanism.In the investigation,the DRS-I type ultrahigh-pressure direct shear test system was used to perform direct shear tests on steel balls with three different particle sizes under normal pressures ranging from 0.4 to 12 MPa to avoid the overlapping effects of particle morphology,particle fragmentation and anisotropy.The correlation of peak strength,residual strength and porosity evolution was analyzed separately,in order to provide a reference for revealing the meso-mechanical mechanism of granular media.The results show that:1)the spherical granular media prepared by the falling rain method generally exhibits shear softening characteristics,and there are obvious peak stresses and residual stresses during the shearing process;2)the peak intensity shows a certain degree of decrease as the confining pressure increases the small trend corresponds to the extreme value of the change slope of the porosity ratio;3)the residual strength is basically not affected by the particle size and the confining pressure,corresponding to the stable value of the porosity ratio,that is,the critical state;A good description of the correlation between the strength characteristics of the granular media and the volume change characteristics.

关 键 词：颗粒介质 软化 剪胀 直剪 

分 类 号：TU432[建筑科学—岩土工程]