关键词: 混凝土;单轴强度;骨料形态;损伤演化;PFC数值模拟

Abstract: 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 .

Key words: concrete;uniaxial compressive strength;coarse aggregate forms;damage evolution;PFC numerical simulation