主应力方向角对重塑黄土各向异性的影响研究

Study on influence of principal stress direction angle on anisotropy of remolded loess

为探究主应力轴循环后不同主应力方向角对青海重塑黄土各向异性的影响,对取自青海西宁地区的黄土进行了主应力循环后的定向剪切试验。试验结果表明:主应力方向角对重塑黄土各向异性具有显著影响,不同主应力方向角下重塑黄土的八面体剪应力-应变曲线和偏应力-主应变曲线均表现出很大差异,且不同主应力方向角下土体归一化强度不同;当主应力方向角超过60°时,土样剪切破坏的八面体剪应变变小;土体大主应变曲线的发展趋势与八面体剪应变相似,主应力方向角不超过75°土体中主应变不断向正向发展,主应力方向角为90°时,中主应变有着不同变化趋势,不断向负向发展,土体小主应变的总体变化趋势为负向;重塑黄土归一化强度随主应力方向角增大呈非线性降低,且主应力方向角为90°时土体归一化强度最小。

In order to explore the influences of different principal stress direction angles on the anisotropy of the remolded loess in Xining area of Qinghai Province after principal stress axis cycling, a directional shear experiment is made on the loess from Xining area of Qinghai Province after principal stress cycling. The experiment result shows that the principal stress direction angle has a significant influence on the anisotropy of remolded loess, while the octahedral shear stress-strain curve and the deviatoric stress-principal strain curve of the remolded loess under different principal stress direction angles exhibit great differences with different the normalized strengths of the soil mass under different principal stress direction angles. When he principal stress direction angle exceeds 60°, the octahedral shear strain for the shear failure of soil sample becomes smaller. The development trend of the large principal strain curve of the soil is similar to the octahedral shear strain, while the principal strain in the soil mass with the principal stress direction angle less than 75° continuously develops in a positive direction, while the intermediate principal strain has a different trend and continuously develops in the negative direction when the principal stress direction angle is 90° and the general changing trend of the minor principal strain of the soil mass is negative. The normalized strength of the remodeled loess nonlinearly decreases with the increase of the principal stress direction angle, while the normalized strength of the soil mass is the smallest when the principal stress direction angle is 90°.