考虑骨料尺寸的混凝土岩石边界效应断裂模型  

BOUNDARY EFFECT FRACTURE MODEL FOR CONCRETE AND GRANITE CONSIDERING AGGREGATE SIZE

作　　者：管俊峰 王强[1] HU Xiaozhi 白卫峰 姜斌 

机构地区：[1]华北水利水电大学土木与交通学院,河南郑州450045 [2]西澳大学机械与化学学院 [3]北京科技大学材料科学与工程学院,北京100083

出　　处：《工程力学》2017年第12期22-30,共9页Engineering Mechanics

基　　金：国家自然科学基金项目(51779095;51679092);澳大利亚国家基金项目(DP0346198);郑州市科技攻关项目(153PKJGG111);河南省高等学校青年骨干教师资助计划项目(2013GGJS-084)

摘　　要：该文比较了边界效应模型(BEM)和尺寸效应模型(SEM)在研究材料断裂性能方面的不同。提出了由处于准脆性断裂状态的三点弯曲试件的峰值荷载P_(max),同时确定材料参数——断裂韧度K_(IC)与拉伸强度f_t的理论与方法。由于实验室条件下混凝土试件高度W与骨料最大粒径d_(max)的比例W/d_(max)约为5~20,试件的非均质性明显,破坏为准脆性断裂控制。因此,区别于以连续介质力学为基础的应用于准脆性断裂研究的力学模型,该文研究将骨料最大粒径d_(max)引入相应的断裂模型解析表达式中,由参数组合β·d_(max)来计算结构峰值状态对应的裂缝扩展量,通过离散参数β的不同取值,实现了对材料参数——断裂韧度与拉伸强度的准确预测。基于不同学者的相同尺寸W而不同初始裂缝长度α_0,以及相同初始缝高比α_0/W而不同尺寸W的几何相似的砂浆、混凝土及岩石类材料试件的试验成果(骨料最大粒径d_(max)从1.2 mm^40 mm变化),验证了所提理论与方法的合理性。The application of boundary effect model （BEM） and size effect model （SEM） on fracture behavior of materials were compared. A theory and the associated method for determining the material constants （fracture toughness Kic and tensile strength fi） were proposed using experimental peak loads Pmax from three-point-bend （3-p-b） specimens with quasi-brittle fracture controlled. The ratio of 3-p-b concrete specimens size W to maximum aggregate size dmax under laboratory conditions is around 5 to 20. These concrete specimens are heterogeneous, where quasi-brittle fracture is dominant. In contrast to the fracture mechanical models those are based on continuum mechanics and applied to quasi-brittle fracture, the maximum aggregate size dmax was introduced in the analytical formula of the proposed fracture model. The stable crack growth corresponding to the peak load of these specimens can be evaluated based on parameter combination β·dmax, and precisely predict results can be obtained by using different values of discrete number β. The validity of the theory and the proposed method has been confirmed by test results from different scholars, including mortar, concrete and granite material （dmax=1.2 mm to 40 mm）, linked with same specimen size W but with different initial crack length a0 and geometrically similar or with a same ratio of initial crack length to specimens size a0/Wbut different W.

关 键 词：准脆性断裂 骨料粒径 断裂韧度 拉伸强度 边界效应 尺寸效应 

分 类 号：TU528.1[建筑科学—建筑技术科学] TU501