任意形状混凝土骨料的数值模拟及其应用

Numerical simulation of concrete aggregates with arbitrary shapes and its application

提出了平面二维、空间三维任意形状混凝土骨料的模拟方法。通过一次性形成所有同级骨料的基骨料,再对所有的基骨料进行随机延拓,生成任意形状的随机骨料。提出的算法避免了逐个投放效率低、生成的骨料含量低的缺点。三维骨料任意形状的模拟中,假定同一级配中的骨料粒径呈正态分布,建立了以体积为标度的凸型骨料的生长模式和骨料凸性条件,根据多面体的每个面的面积是否大于限定面积,确定该面是否需要延拓,同时以延生点与延伸面以外的所有边界面组成的体积都应该大于零作为凸性限定条件。采用体积和测试法进行骨料的侵入判别。在此基础上研制了相应的二维骨料、三维骨料随机投放软件2D-RAS和3D-RAS。生成的数值混凝土二维骨料含量可达65%以上,三维骨料含量可达55%左右,基本可以满足全级配混凝土的生成需要。最后还对三维混凝土任意骨料形状的弯拉梁的破坏过程进行了初步研究,得出任意多面体骨料试件的极限承载力要大于圆球骨料试件,任意多面体骨料试件所对应的位移相对较大等结论。

A practical method for 2-D and 3-D modeling of concrete aggregates with arbitrary shapes is presented. In this method the basic aggregates of the same grade are generated once only and randomly extended to generate aggregates with arbitrary shapes. In 3-D modeling, the sizes of aggregates of the same grade is assumed in Gauss distribution. The extension mode and convexity condition of the added aggregates are established according to the constraint that the surface area of polyhedron must be smaller than the limited area and the volume of aggregates outside of the extended surface must not be zero. The aggregates intersections are checked by the test of the sum of aggregates volumes. Corresponding software 2D-RAS and 3D-RAS are developed. It is found that, by means of this method, the aggregate content to be generated in 2-D simulation may reach 65% and will be about 55% in 3-D simulation, which can meet the requirement of full-gradation concrete simulation. The failure processes of specimen for bending test with different aggregates shapes are numerically simulated. The results indicate that critical load capacity of the specimen with arbitrary polyhedron shape aggregates is greater than that of random spherical aggregates, and the deformation of the former is greater than that of the latter.