全级配混凝土随机骨料二维模型生成的块体切割方法

A method for generating two-dimensional random aggregate model of fully-graded concrete: Block cutting method

混凝土细观力学数值模拟分析所得到的结果与混凝土实际力学性能之间的差异大小,在很大程度上取决于所采用的混凝土骨料模型是否合理.目前,混凝土随机骨料的二维模型生成算法以生长法为主,所生成的骨料几何形态具有较大的局限性,且不便于推广应用至三维问题.研究并提出了一种新的随机骨料二维模型生成方法——块体切割法.首先,引入一组随机平面,并假定其方向及位置符合某种概率分布;然后,基于瓦拉文公式推导出随机平面的相关参数的概率密度函数;最后,通过随机平面切割初始块体,得到不同料径和形状的随机骨料.算例分析结果表明,本方法能够生成符合级配要求的随机骨料,可进一步推广至三维问题.

The difference between results from numerical simulation of mesomechanical analysis of concrete and the actual one is mostly dependent on whether the concrete aggregate model is reasonable.Currently,the generation algorithm of two-dimensional random concrete aggregate model is mainly based on grown method.However,there are a lot of limitations on the aggregate＇s geometry which is generated by that method.Moreover,it is not easy to be extended to three-dimensional problems.This paper proposed a new generation algorithm of two-dimensional random concrete aggregate model,namely block cutting method.There are three steps for this method： first drawing a set of random plane,assuming its direction and position in line with a certain probability distribution;then reducing relating parameters of the probability density function of the random plane based on a Walaraven formula;finally,cutting the initial block with the random plane in order to obtain random aggregate of different sizes and shapes.The results of example analysis indicate that the method proposed is able to generate the random aggregates which meet the distribution requirements of particle size;and furthermore it can be extended to three-dimensional problems.