非均等固结条件下饱和软黏土体应变特性试验研究

Experimental investigation on volumetric strain of saturated soft clay under anisotropic consolidation

研究土料的动力特性对土石坝抗震设计具有指导作用。以卢旺达某水电站心墙黏土为工程依托,开展了一系列复杂初始固结条件下循环排水三轴试验,研究了固结比K_(c)、有效围压σ′_(c)和循环加载剪应变幅值γ_(a)对土体累积体应变ε_(vd)的影响。研究结果表明:小应变幅值循环加载条件下,ε_(vd)与γ_(a)线性相关,相同固结条件下ε_(vd)/γ_(a)发展均具有良好的一致性;σ′_(c)与K_(c)对体应变的影响与土体结构性相关,σ′_(c)与K_(c)越大,相同振次下体应变越小。另外,试验结果表明,Martin等提出的体变增量模型能较好地描述本试验中软黏土的体变发展。

The study on dynamic characteristics of earth material has guiding meanings to seismic design of earth rock dams.In this study,aiming at clay core wall of an abroad hydropower station,a series of cyclic drainage triaxial tests on the soft clay under anisotropic consolidation was conducted.The effects of consolidation ratio K c,effective confining pressureσ′_(c)and cyclic shear strain amplitudeγ_(a)on soil volumetric deformationεvd were investigated.The results show that theεvd is linearly related toγa under cyclic loading with small magnitude strain,and the development ofε_(vd)/γ_(a)under the same consolidation conditions are in good agreement.The influences from K_(c),andσ′_(c)on theε_(vd)is associated with the soil microstructure.The larger theσ′_(c)and K_(c)are,the smaller theεvd will be under the same vibration number.The test result demonstrates that the incremental volume variation model proposed by Martin adequately describes the volumetric deformation of the soft clay in this test.