循环荷载下不同裂隙方向饱和原状膨胀土动力特性试验研究  

Experimental study on dynamic characteristics of saturated undisturbed expansive soil with different fissure orientations under cyclic loading

作　　者：高志傲 孔令伟[1,2] 王双娇 黄珏皓 赵浩武 GAO Zhiao;KONG Lingwei;WANG Shuangjiao;HUANG Juehao;ZHAO Haowu(State Key Laboratory of Geomechanics and Geotechnical Engineering Safety,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Science,Beijing 100029,China;School of Automation,Central South University,Changsha 410083,China)

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程安全全国重点实验室,湖北武汉430071 [2]中国科学院大学,北京100049 [3]中国科学院地质与地球物理研究所页岩气与地质工程重点实验室,北京100029 [4]中南大学自动化学院,湖南长沙410083

出　　处：《岩土工程学报》2025年第4期736-748,共13页Chinese Journal of Geotechnical Engineering

基　　金：国家重点研发计划资助项目(2019YFC1509901)。

摘　　要：裂隙方向是导致膨胀土力学特性各向异性的重要原因之一,为探究裂隙倾角对土体的动力特性的影响,以安徽淠史杭灌区不同裂隙倾角的原状膨胀土(α为0°,22.5°,45°,67.5°,90°)为研究对象,采用GCTS动静真三轴仪对土体进行单向循环荷载试验。研究裂隙倾角、围压和不同动应力幅值对膨胀土累积塑性应变、动弹性模量及阻尼比变化特征的影响。试验结果表明:随着循环荷载幅值增大,同一裂隙角度试样的累积应变不断增加,所研究的5个裂隙角度中,α=67.5°试样将产生更大的累积塑性应变。在低围压下裂隙角度对土体临界动应力幅值影响较大,其各向异性特征显著,随着围压增大,土体各向异性减弱。随着裂隙角度的增大,试样动弹性模量呈现出先减小后增大的趋势,在α=67.5°时,试样动弹性模量最小,循环振动荷载幅值增大到临界动应力时,动弹性模量加速减小;根据阻尼比随振动次数的变化特征,提出了能够考虑其衰减速率、初始阻尼比和稳定阻尼比特征的表述模型,并分析了动应力幅值和围压对裂隙膨胀土阻尼比变化的影响。研究结果对揭示动荷载下裂隙膨胀土力学特性的各向异性,确保膨胀土地区铁路路线和轨道交通的安全运营具有重要意义。The fissure orientation is one of the important factors contributing to the anisotropy of mechanical properties of expansive soil.To explore the influences of inclination angle of fissures on the dynamic properties of soil,using the undisturbed expansive soil with different inclination angles of fissures(α=0°,22.5°,45°,67.5°and 90°)in the PiShihang Irrigation Area of Anhui Province as the research object,the unidirectional cyclic load tests are carried out on the soil by using the GCTS dynamic and static true triaxial instruments.The effects of fissure inclination,confining pressure and different dynamic stress amplitudes on the characteristics of the cumulative plastic strain,dynamic elastic modulus and damping ratio of expansive soil are studied.The test results show that as the amplitude of cyclic loading increases,the cumulative strain of the samples with the same fissure angle increases continuously.Among the studied five fissure angles,the sample withαof 67.5°produces greater cumulative plastic strain at each amplitude of cyclic loading.Under low confining pressure,the fissure angle greatly influences the critical dynamic stress amplitude of the soil,and its anisotropy characteristics are significant.As the confining pressure increases,the anisotropy of the soil weakens.With the increase of the fissure angle,the dynamic elastic modulus of the sample shows a trend of decreasing first and then increasing.Whenα=67.5°,the dynamic elastic modulus of the sample is the smallest,and the dynamic elastic modulus decreases rapidly when the amplitude of the cyclic vibration load increases to the critical dynamic stress.According to the characteristics of the damping ratio changing with the number of vibrations,an expression model considering the characteristics of the attenuation rate,initial damping ratio and stable damping ratio is proposed,and the influences of dynamic stress amplitude and confining pressure on the variation of damping ratio are analyzed.The research results are of great significance for r

关 键 词：膨胀土 裂隙方向 循环荷载 累积塑性应变 动剪切模量 阻尼比 

分 类 号：TU43[建筑科学—岩土工程]