橡胶颗粒-砂混合物三轴CD剪切试验研究

Study on Shear Characteristics of Rubber-Sand Mixtures by Triaxial CD Tests

对6种围压7种不同质量配比的干燥橡胶颗粒-砂混合物（橡胶砂）进行三轴CD试验，研究不同配比不同围压对橡胶砂的强度特性、偏应力-轴向应变曲线和体应变-轴向应变曲线特性的影响。试验结果表明：橡胶颗粒质量分数为0%~30%时，有利于改善砂颗粒的剪切强度特性；在10%附近时，内摩擦角出现最大值；在20%附近时，其粘聚力出现最大值。橡胶砂的偏应力-轴向应变曲线特性在橡胶颗粒质量分数低于50%时，与纯砂类似，表现出双曲线特性；不低于50%时，与纯橡胶类似，表现出近似线弹性，且由双曲线模型拟合得到的橡胶砂模型参数（如峰值偏应力、初始切线模量以及破坏比）随围压的增加而增加，随橡胶颗粒含量的增加而减少。橡胶砂的体应变-轴向应变曲线特性在橡胶颗粒质量分数不高于20%时，与纯砂类似，有先剪缩后剪胀的特点；高于20%时，表现出单调剪缩的特性，橡胶颗粒含量越大，剪缩越明显。

Conducted triaxial CD tests on 7 different proportions of dry rubber-sand mixtures under six confining pressures. Studied the effects of proportions and confining pressures on properties of shear strength, deviatoric stress-axial strain curves and volumetric strain-axial strain curves of rubber-sand mixtures. The results indicate that： it is beneficial to improve the shear strength properties of sand when the mass fraction of rubber particles is 0%~30%; the angle of internal friction appears the maximum value near to 10% mass fraction; the cohesion appeared the maximum value near 20%. The characteristics of the deviatoric stress-axial strain curves of the rubber-sand mixtures are similar to that of pure sand when the mass fraction is less than 50%, exhibiting hyperbolic curves, and when the mass fraction is no less than 50%, the mixtures are similar to pure rubber particles, exhibiting linear elastic. The rubber sand model parameters（such as the peak deviator stress, initial tangent modulus and failure ratio） obtained from hyperbolic model fitting increase with confining pressures increment and decrease with rubber content increment. The characteristics of volumetric strain- axial strain curves of the mixtures are similar to pure sand when rubber mass fraction is not over 20%, exhibiting contraction followed by dilatation, and above 20%, it appears the characteristics of monotonic shearing shrinkage, and the rubber particle content is more, the shear shrinkage is more obvious.