橡胶砂力学性能的三维离散元数值模拟

为揭示橡胶砂混合料强度特性、偏应力-轴向应变曲线及体应变-轴向应变曲线的变化规律，利用颗粒流软件，对三轴压缩状态下橡胶砂混合料的力学特性进行了三维离散元数值模拟，从宏观、微观两方面分析质量配比、粒径比和围压对橡胶砂力学及变形特性等方面的影响。分析结果表明：当ω(橡胶)<10%时，橡胶砂表现出类砂力学特性，即先剪缩后剪胀，应力-应变曲线呈软化型，当ω(橡胶)≥20%时，橡胶砂表现出类橡胶力学特性，试样单调剪缩，应力-应变曲线呈硬化型。随着橡胶含量的增加，橡胶砂应力-应变曲线峰值降低。胶砂粒径比对橡胶砂应力-应变关系存在一定的影响，主要表现为随着平均粒径比的增大，体应变增大，应力-应变曲线降低，抗剪强度减小。随着围压的增加，低橡胶含量的橡胶砂剪胀和应变软化特性得到抑制，而高橡胶含量橡胶砂剪缩和应变硬化特性增强。混合料抗剪强度的降低主要归因于软橡胶颗粒的加入所引起的橡胶砂试样刚度损失，而其膨胀反应受到抑制的原因是橡胶颗粒容易被挤压而产生体积收缩。

3D Discrete Element Numerical Simulation of Mechanical Properties of Rubber Sand Mixture

In order to reveal the change law of the strength characteristics, deviator stress-axial strain curve and volume strain-axial strain curve of the rubber sand mixture, the particle flow software is used to perform three-dimensional discrete element analysis on the mechanical properties of the rubber sand mixture under triaxial compression. Numerical simulation analyzes the influence of mass ratio, particle size ratio and confining pressure on the mechanical and deformation characteristics of rubber sand from both macroscopic and mesoscopic aspects. The analysis results show that when the rubber content is less than 10%, the rubber sand exhibits sand-like mechanical properties, that is, the first shear shrinkage and then the dilatancy, and the stress-strain curve is softened. When the rubber content is greater than or equal to 20%, the rubber sand exhibits rubber-like mechanical properties, specimens are monotonously shrunk, and the stress-strain curve is hardened. With the increase of rubber content, the peak value of the stress-strain curve of rubber sand decreases. The particle size ratio of mortar sand has a certain influence on the stress-strain relationship of rubber sand. The main manifestation is that as the average particle size ratio increases, the volume strain increases, the stress-strain curve decreases, and the shear strength decreases. As the confining pressure increases, the dilatancy and strain softening properties of low rubber content rubber sand are suppressed, and the shear shrinkage and strain hardening properties of high rubber content rubber sand are enhanced. The decrease of the shear strength of the mixture is mainly attributed to the loss of stiffness of the rubber sand sample caused by the addition of soft rubber particles, and the reason why the expansion reaction is inhibited is that the rubber particles are easily squeezed to produce volume shrinkage.