含水率对膨润土改性黄土的动力特性研究  

Dynamic Characteristics Study on Bentonite Modified Loess with Water Content

作　　者：刘冬 崔自治[1] LIU Dong;CUI Zizhi(School of Civil and Hydraulic Engineering,Ningxia University,Yinchuan 750021,China)

机构地区：[1]宁夏大学土木与水利工程学院

出　　处：《宁夏工程技术》2019年第4期316-320,共5页Ningxia Engineering Technology

基　　金：国家自然科学基金资助项目（41361024）

摘　　要：结合宁夏同心地区黄土的特点,以含水率为因素,设计单因素试验,应用美国GCTS公司动三轴测试系统控制膨润土掺量、压实度、围压、动剪应力比、频率和循环次数等条件的方法,研究了改性黄土的孔隙压力、轴向应变、应力-应变和滞回阻尼等动力特性。结果表明:孔隙压力随着循环次数的增加而逐渐增大,随着含水率的增大孔隙压力增加速率增大,并且单个周期内孔压的峰值与最小值差值减小;轴向应变随着循环次数的增加逐渐增大,随着含水率的增大而增大,单个循环周期内应变峰值与最小值差值减小;应力-应变曲线(滞回圈)随着循环次数的增加前期逐渐向右移动后期趋于稳定,随着含水率增大其向右移动的幅度增大,且倾斜程度减小;滞回阻尼随着循环次数的增加先迅速减小后缓慢减小,随着含水率增大其衰减的趋势更平缓。综合来看,膨润土改性黄土的含水率为12%时,其动力特性变化最为明显。Combining with the characteristics of the loess in Ningxia region,the moisture content as main factors,the single factor experiment is designed by application of GCTS dynamic triaxial testing system to control the dosage of bentonite,degree of compaction,confining pressure,dynamic shear stress ratio,frequency and cycle times etc.Dynamic characteristics of modified loess including pore pressure,axial strain,stress-strain and hysteresis damping are studied.The results show that the pore pressure increase with the increase of cycles and the pore pressure increases with the increase of water content.But the difference between the peak and the minimum values of pore pressure decreases in a period.The axial strain increases with the increase of both the number of cycles and also the water content with the decrease of the difference between the strain peak and the minimum value in a single cycle.The stress-strain curve(hysteretic loop)gradually moves to the right in the early stage and tends to be stable later with the increase of the number of cycles.Hysteretic damping decreases rapidly at beginning and then decreases slowly with the increase of the number of cycles.In general,when the moisture content of bentonite modified loess is 12%,the dynamic characteristics change most obviously.

关 键 词：膨润土改性黄土 孔隙压力 轴向应变 应力-应变 滞回阻尼 

分 类 号：TU411.8[建筑科学—岩土工程]