基于离散元方法的沥青混合料虚拟三轴剪切试验三维模拟

Three dimensional simulation of virtual triaxial shear test for asphalt mixture based on discrete element method

基于离散元方法建立了沥青混合料的细观力学结构模型,并通过虚拟三轴剪切试验,模拟验证了该模型的合理性.首先,开发了基于方孔筛工作机制的粗集料生成算法,建立了不规则形状的颗粒,使得粗集料的形状控制多样化和精确化.然后,将具有实际纵向分布特征的空隙相引入到沥青混合料的细观结构模型中,取代了传统方法中空隙随机分布的处理模式.结合室内试验和虚拟试验,获取了中高温条件下的沥青砂浆接触本构模型参数.虚拟三轴剪切试验的模拟结果以及对沥青混合料抗剪强度的预测结果验证了建立的细观结构力学模型的合理性,离散元虚拟试件产生的剪切破坏和实际试件破坏形态一致,由虚拟试验得到的抗剪强度和实际结果基本吻合.

A mesoscopic mechanic structure model of asphalt mixture is established based on the discrete element method and validated by using the virtual triaxial shear tests.First,a coarse aggregate generation algorithm is developed based on the working mechanism of the square sieve system,aggregates with irregular shapes are generated,making the shape control of coarse aggregate diversified and precise.Then,the air void phase with actual longitudinal distribution scenario is introduced into the mesoscopic structure model of asphalt mixture,which substitutes the random distribution in traditional methods.The contact constitutive parameters of asphalt mastic at medium and high temperatures are obtained by combing laboratory tests and virtual tests.The simulation results of virtual triaxial shear tests and the predictive results for anti-shear strengths of asphalt mixture verify the reasonableness of the proposed mesoscopic mechanic structure model.The shear damage modes from the laboratory tests and those of the actual specimens are similar,and the shear strengths of laboratory tests generally agree with the actual results.