Discrete element modeling of migration and evolution rules of coarse aggregates in the static compaction process

基于离散元的粗集料静压过程的迁移与演化规律（英文）

To investigate migration and evolution rules of coarse aggregates in the static compaction process, an algorithm of generating digital coarse aggregates that can reflect real morphology（ such as shape, size and fracture surface） of aggregate particles, is represented by polyhedral particles based on the discrete element method（ DEM）. A digital specimen comprised of aggregates and air voids is developed. In addition,a static compaction model consisting of a digital specimen and three plates is constructed and a series of evaluation indices such as mean contact force σMCF, wall stress in direction of zcoordinate σWSZZ, porosity and coordination numbers are presented to investigate the motion rules of coarse aggregates at different compaction displacements of 7. 5, 15 and 30 mm. The three-dimensional static compaction model is also verified with laboratory measurements. The results indicate that the compaction displacements are positively related to σMCF and σWSZZ, which increase gradually with the increase in iterative steps. When the compaction proceeds, the digital specimen porosity decreases, but the coordination number increases. The variation ranges of these four indices are different at different compaction displacements. This study provides a method to analyze the compaction mechanism of particle materials such as asphalt mixture and graded broken stone.

为研究粗集料在静止压实过程中的迁移与演化规律,基于离散单元法用不规则的多面体颗粒表示真实集料的形态特征,建立了由粗集料、空隙构成的数字试件,同时,建立了由数字试件及3块板构成的静止压实模型.以平均接触力、轴向应力、空隙率及配位数为评价指标,模拟压实位移为7.5,15与30 mm时粗集料在压实过程中的运动规律,并通过室内试验验证了此模型的可靠性.结果表明:轴向应力、平均接触力随着加载的进行,数值逐渐增加,压实位移与轴向应力、平均接触力正相关;不同压实位移的空隙率随着压实的进行不断减小,而配位数逐渐增大;总体上轴向应力、平均接触力、空隙率和配位数等4个指标在不同压实位移情况下变化幅度不同.研究结果为深入分析颗粒材料如沥青混合料或级配碎石的压实机理提供了一种方法.