材料期刊网

采用PFC2D离散元首先生成混凝土基质，然后利用Clump技术形成不同形态的粗骨料混凝土数值模型，分析研究粗骨料含量和形态对混凝土强度和损伤演化的影响。获得以下主要结论：随着粗骨料含量的增加混凝土单轴抗压强度增大，相同含量下三角形粗骨料混凝土的强度最高，其次是五边形粗骨料，圆形粗骨料混凝土的强度最低；粗骨料含量小于50％时，随粗骨料含量的增大弹性模量增速较小，而大于50％时增速较大；混凝土破坏的初始微损伤主要集中在结合面处，圆形粗骨料微裂隙沿着结合面切线方向发展，主控破裂面沿着相邻粗骨料的公切线方向发展，多边形粗骨料微裂隙沿边延伸进入基质，主控破裂面为相邻粗骨料角度基本一致边的微裂隙沿边发展贯通而成。混凝土的损伤演化分为：微损伤的随机分布、微裂隙形成和微裂隙贯通形成破裂面三个阶段，粗骨料含量低时混凝土损伤比较集中，形成明显的主控破裂面，粗骨料含量高时内部损伤严重形成网状损伤裂隙。

Used to PFC2 D discrete element software to generate the concrete matrix , then the Clump technique was used to form different forms of coarse aggregate concrete model .Analyzed the influence of coarse aggregate content and forms on uniaxial compressive strength and damage evolution of concrete . Some main research results are as follows: concrete uniaxial compressive strength increases with the increase of the content of coarse aggregate .At the same content of coarse aggregate , the strength of triangular coarse aggregate concrete is the highest , followed by the pentagon coarse aggregate concrete , circular coarse aggregate concrete strength is the lowest .When the content of coarse aggregate is less than 50%, the growth rate of elastic modulus is lower with the content of coarse aggregate , when greater than 50%, the growth rate higher .The initial micro damage of concrete is mainly concentrated in the interface, micro cracks of circular coarse aggregate concrete develops along the tangent direction of interface, main cracks develops along the common tangent direction of adjacent coarse aggregates , micro cracks of polygon coarse aggregate concrete develops along edge then extend into the matrix , main crack is formed by micro cracks of the basically same angle edges of adjacent coarse aggregates .The damage evolution of concrete is divided into three stages:the random distribution of micro damage , the formation of micro crack and the formation of main crack through the coalescence of micro cracks .There are obvious main cracks formed by the concreted damage when the content of concrete coarse aggregate is lower , while concrete inter damage is serious and forms into network cracks when the content of concrete coarse aggregate is higher .