【摘要】 以陕西武功地区原状黄土为对象,在不同含水率与不同初始平均主应力下进行动扭剪三轴试验,研究了预剪应力作用下原状黄土动剪切模量与阻尼比的变化规律。结果表明:原状黄土动剪切模量随动剪应变变化的整体趋势并未因存在预剪应力作用而发生改变;存在预剪应力作用时,含水率与初始平均主应力对原状黄土动剪切模量的影响程度降低;含水率与初始平均主应力对预剪应力作用下原状黄土的初始动剪切模量具有显著的影响;存在预剪应力作用时原状黄土的阻尼比随动剪应变的增大先减小而后缓慢增大,其值总体上在0.20～0.35之间;现有的半对数坐标进行直线方程拟合的方法已不再适用于存在预剪应力作用时原状黄土阻尼比的计算;含水率对原状黄土阻尼比随动剪应变变化规律的影响呈现出含水率越大、阻尼比越大的趋势;初始平均主应力对原状黄土阻尼比随动剪应变变化的影响规律不明显。更多还原

【Abstract】 The dynamic torsional shear triaxial tests are carried out on undisturbed loess of Wugong(Shaanxi province) under different water contents and different initial average principal stresses conditions;and the changing laws of dynamic shear modulus and damping ratio of undisturbed loess under pre-shearing stresses are obtained.Results show that the general trend of the changing law of dynamic shear modulus of undisturbed loess does not change with the changing of the dynamic shear strains under the condition of pre-shearing stresses.The degrees of effects of water content w and initial average principal stress pm0 on the dynamic shear modulus of undisturbed loess reduce under the condition of pre-shearing stresses.Water content w and initial average principal stress pm0 have significant influences on the initial dynamic shear modulus of undisturbed loess under the condition of pre-shearing stresses.Damping ratio λ of undisturbed loess under the condition of pre-shearing stress first decreases with the increase of the dynamic shear strain,and then increases gradually.In general,the values of the damping ratios are between 0.2 and 0.35.The existing method of using semilogarithmic coordinates to fit the line equation is no longer applicable to the calculation of the damping ratios of undisturbed loess under the condition of pre-shearing stresses.The effects of w on λ-γd relations of undisturbed loess show a trend that the higher w,the larger λ.The laws of effects of pm0 on λ-γd relations of loess are not obvious.更多还原