温州软黏土不排水真三轴试验的研究

摘要

利用英国GDS真三轴仪,针对原状温州软黏土进行恒定小主应力σ3下不同中主应力系数b的固结不排水试验。在三维应力状态下,研究不同中主力条件下黏土的强度变形特性,利用相同应力路径下主应力旋转对比试验反映土的各向异性特性。研究结果表明：在轴向压缩( TC)试验中,随着加载的进行,偏应力逐渐增大并趋于平稳；并随中主应力系数b呈现先增大后减小的趋势,b=0．8时出现峰值；广义剪应力峰值呈现先增大后减小的趋势,峰值在0．6~0．8之间；轴向压缩试验( TC)加载过程中；当b=0．4时,中主应变接近为0,可视为平面应变情况；在b=0．4~1．0之间时,剪缩效应受中主应力系数b影响较明显；b=1．0时,轴向压缩( TC)试验破坏强度高于轴向拉伸( TE)试验的破坏强度,其应力应变响应有显著不同；在π平面上,Lade-Duncan准则对试验点的拟合精度优于Mohr-Coulomb准则和Matsuoka-Nakai准则。%A series of consolidated undrained true triaxial tests on Wenzhou undisturbed soft clay samples with different b values under constant minor principal stressσ3 are carried out through the GDS true triaxial apparatus. Under the three dimensional stress state,the strength-deformation characteristics of clay in the different conditions of intermediate principal stress will be researched, as well the anisotropy features taking advantage of the principal stress rotation experiments. The test results show:in the axial compression ( TC) test, the shear of deviatoric stress increased gradually and leveled off, as the intermediate principal stress coefficient b increases, the shear stress peak value showed a trend of increases at first then decreases; The generalized shear stress peak value showed a trend of decrease after the first increase, the peak value between 0. 6 ~ 0. 8;When b=0. 4, the intermediate prin-cipal strain is close to 0,which can be treated as plane strain condition;When b Between 0. 4 and 1. 0, the shear shrinkage effect affected by the principal stress coefficient b distinctly;when b=1. 0 , the failure strength in Axial compression ( TC) test is higher than that of axial tensile ( TE) test, which the stress and strain response is signifi-cantly different;the fitting precision of the results in theπplane is close to Lade-Duncan criterion, which is better than that of Mohr -Coulomb criterion and Matsuoka -Nakai criterion.