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利用空心圆柱扭剪仪对重塑黄土试样开展一系列复杂应力条件下的试验,对重塑黄土的变形及强度特性进行研究,重点分析剪切过程中剪切方向、中主应力系数等参数的影响。试验结果表明:复杂应力条件下重塑黄土应力-应变曲线基本呈现出加工硬化特性,并可采用双曲线拟合。重塑黄土存在显著的强度各向异性,大主应力方向角为0°时的剪切强度最大,大主应力方向角为45°左右时剪切强度最低。剪切方向和中主应力系数b对重塑黄土强度均有显著的影响:在b=0.25时,试样接近平面应变状态,相应的强度也较高;在b>0时,重塑黄土在π平面内的破坏强度要高于摩尔-库仑强度,与邢义川等提出的破坏条件吻合很好。
A series of experiments under the condition of complex stress were carried out on the remolded loess sample with a hollow cylindrical torsional shear instrument. The deformation and strength characteristics of the remolded loess were studied. The shear direction, the main stress coefficient and other parameters Impact. The experimental results show that the stress-strain curve of the remolded loess shows the work-hardening characteristics under complex stress conditions, and the hyperbolic fitting can be used. The remolded loess has obvious anisotropy of strength, the shear strength is the largest when the principal stress direction angle is 0 °, and the shear strength is the lowest when the principal principal stress direction angle is 45 °. The shear direction and the middle principal stress coefficient b have a significant effect on the strength of remolded loess: at b = 0.25, the sample is close to the plane strain state and the corresponding strength is higher; when b> 0, the remolded loess The failure intensity in π plane is higher than that of Mohr-Coulomb, which agrees well with the destructive conditions proposed by Xing Yichuan et al.