粗粒料在外力作用下存在明显的颗粒破碎特性,研究颗粒破碎过程是当前研究的热点问题之一。基于粗粒料单颗粒破碎机制,考虑单颗粒破碎强度与直径的变化规律,采用非线性接触H-Z模型和密度控制法建立了粗粒料颗粒破碎数值模型。开展粗粒料双轴剪切试验数值模拟研究,并与室内试验结果进行对比分析。研究表明:建立的粗粒料颗粒破碎数值模型能够较好地模拟粗粒料偏应力与轴向应变和体积应变与轴向应变的关系;数值模拟获得的粗粒料颗粒破碎率与室内试验结果基本一致;去除试样制备过程和固结过程引起的颗粒破碎,不同围压条件下的颗粒破碎率归一化后基本重合,且可以近似地采用双曲线函数进行拟合。颗粒破碎率随着围压的增大,逐渐增大,试验级配趋于Einav提出的颗粒破碎的最终级配(分维数等于2.6)
The coarse aggregate can show significant particle breakage characteristics under external force loading. Studying the particle breakage process is one of the research focuses at present. Based on one coarse particle failure mechanism, a numerical model for particle breakage is developed, in which the nonlinear contact H-Z model and a density-control method are introduced and the variation of a single particle breakage strength and diameter are considered. Based on the proposed model, the biaxial shear test of coarse aggregate is carried out and compared with the laboratory test results. It is shown that the proposed particle breakage numerical model can describe well the relationship between deviatoric stress and axial strain, and the relationship between volume strain and axial strain. The particle breakage ratio obtained by numerical simulation is consistent with the results obtained by laboratory test. The normalized particle breakage ratios under different confining pressures are practically coincident, and can be fitted by a hyperbolic curve function without considering particle breakage in sample preparation and consolidation processes. As the confining pressure increases, the particle breakage ratio increases, and the final grading curve of sample coincides with that proposed by Einav, which has a fractal dimension of 2.6.