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利用空心圆柱扭剪仪对饱和砂土进行了应力主轴固定和偏应力比增大(即定向剪切)、偏应力比不变和应力主轴单调旋转(即纯应力主轴单调旋转)、偏应力比和应力主轴偏转角同时增加、偏应力比和应力主轴偏转角分段增加4个系列的排水剪切试验,着重分析不同应力路径下饱和砂土的变形特性及主应力和主应变增量方向变化规律。试验结果表明,纯应力主轴单调旋转下,主应力增量方向在45°~135°范围内变化,主应变增量方向逐渐偏向主应力方向;偏应力比和应力主轴偏转角同时增加下,砂土变形不断增大,当主应力增量方向????45°时,主应变增量方向与主应力增量方向基本一致,但当????45°时,主应变增量方向逐渐偏离主应力增量方向。当应力状态在偏应力比?≤0.75、应力主轴偏转角?≤45°范围内时,体应变、最大剪应变与应力路径无关,且后期纯应力主轴旋转下砂土变形不受前期加载历史的影响。
The stress distribution of the saturated sand was analyzed by using a hollow cylindrical torsional shear tester. The results show that the stress of the saturated sand increases with the increase of the principal stress and the ratio of the deviatoric stress (that is, the directional shearing), the constant deviatoric stress and the monotonic rotation of the stress spindle And the deflection angle of the stress spindle increases at the same time. The deviatoric stress ratio and the deflection angle of the stress spindle are increased by four series of drainage shear tests. The deformation characteristics and the changes of the principal stress and the principal strain increments of saturated sands under different stress paths are mainly analyzed law. The experimental results show that under the monotonic rotation of the pure stress spindle, the incremental direction of the principal stress changes in the range of 45 ° ~135 °, and the direction of the principal strain increment gradually shifts to the direction of the principal stress; while the deviatoric stress ratio and the stress spindle deflection angle increase simultaneously, As the principal stress increment direction increases by 45 °, the principal strain increment direction basically agrees with the principal stress increment direction. However, when the principal stress increment direction gradually deviates from the principal strain increment direction at 45 ° The main stress increment direction. When the stress state is within the range of deviatoric stress ≤0.75 and deflection angle of the stress main body is less than or equal to 45 °, the body strain and the maximum shear strain are independent of the stress path, and the deformation of the sand under the pure stress spindle rotation is not affected by the previous loading history influences.