不同破损位置对膨胀土力学特性影响的三轴试验研究  

A Study on the Effect of Different Damage Locations on the Mechanical Properties of Expansive Soils by a CT-Triaxial Test

作　　者：张雅倩[1] 汪时机[1] 韩毅[1] 程明书[1] 江胜华[1] 

机构地区：[1]西南大学工程技术学院,重庆400716

出　　处：《西南大学学报（自然科学版）》2016年第4期176-180,共5页Journal of Southwest University(Natural Science Edition)

基　　金：国家自然科学基金项目资助(10902091;51208078);中央高校基本科研业务费专项资金资助(XDJK2015C018;XDJK2013C042)

摘　　要：以南水北调中线工程陶岔引水渠坡的膨胀土为研究对象,利用X-Ray CT断层扫描技术机配套使用的CT-多功能土工三轴仪,对不同损伤位置的3组重塑膨胀土样进行控制吸力为50kPa和净围压为100kPa的CT-三轴压缩试验.通过CT扫描设备获得试验过程中土样内部结构的实时演化情况.试验结果表明:不同损伤位置的圆柱孔对土体的强度特性和变形特性有分阶段、不同程度的影响,轴向应变小于11%时,相同损伤面积不同损伤位置的试样的偏应力-轴向应变关系曲线形式基本重合;但当轴向应变大于11%以后,6mm中孔试样表现出与其他两个试样不同的明显的应变软化特征.而体应变-轴向应变关系曲线只在应变小于6%范围内表现出基本相似的变化规律,后阶段6mm中孔试样体变速率加剧.同时在剪切过程中,损伤位置也影响土体内部结构的演变规律,损伤位置越靠近中间的试样其ME值和SD值都将越大.To research the real-time evolution of the internal structure of expansive soils during a triaxial test, three groups of remolded expansive soil samples with different locations of cylindrical pore damage were tested by an X-ray CT-triaxial apparatus, where the soils were taken from the site of the Central Line Project of South-to-North Water Diversion. Then experiments were carried out under controlled suction of 50 kPa, and net confined pressure of 100 kPa. The results indicated that different locations of damage with cylindrical pores had a by-stage and different-degree effect not only on the deformation characteristics but also on the mechanical properties of the soils. That is, when the axial strain was less than 11 ~, the curve variation tendency relationship between deviatoric stress and axial strain had minor differences with the same damage area but different locations~ when the axial strain was over 11~, 6 mm central pore-dam- aged sample showed a strain softening property, which differed obviously from the other two. Moreover, the curve of volumetric strain and axial strain presented a similar effect only within the scope of a strain less than 6%. In the late stage of the test, 6 mm central pore sample＇s volumetric strain rate increased drastically. Furthermore, different initial damage positions had an influence on the evolution of the samples＇ internal structure, that is, when the damage position was closer to the samples＇ centre, the mean value （ME） and standard deviation （SD） were greater.

关 键 词：膨胀土 力学特性 CT-三轴试验 损伤位置 

分 类 号：TU443[建筑科学—岩土工程]