摘要
采用楔入劈拉试件几何形式,进行了最大尺寸为1 200 mm×1 200 mm×200 mm混凝土断裂试验.根据试验获得的荷载张开口位移关系曲线,在线性渐近叠加假定的基础上,利用应力强度因子叠加原理计算了双K断裂参数,考虑了当楔形力的竖向分量、自重和支承反力三者不共线时,竖向分量和自重对裂缝尖端应力强度因子的贡献.试验结果表明,当试件高度大于600 mm时,测定的双K断裂参数是与尺寸无关的常数值;当试件高度低于600mm时,测定的双K断裂参数存在尺寸效应.采用边界效应模型分析发现,其尺寸效应与边界对断裂过程区发展的约束作用相关,试件的高度越小,边界的约束作用越强,测定的断裂韧度越小.经边界效应模型修正后,可得到与尺寸无关的常数值.
Wedge splitting fracture tests are performed on concrete specimens with the maximum dimension of 1 200 mm × 1 200 mm× 200 mm. With the load-crack mouth opening displacement curve obtained from tests, based on linear asymptotic assumption, the double-K fracture parameters are calculated by using superposition principle of the stress intensity factor,in which the effect of vertical force and deadweight on the calculated double-K fracture parameters is taken into account when vertical component of wedge force, deadweight and support force are non-colinear with each other. The results show that the confinement of back boundary of specimen to the development of fracture process zone is responsible for the observable size effect on fracture toughness of concrete material. For small specimens with the depth of less than 600 mm, the smaller the depths of specimen are, the stronger the confinement of back boundary is and the smaller the fracture toughness is. Moreover, it is also concluded that the size-independent consistent fracture toughness can be obtained after the consideration of effect of boundary restriction.
出处
《大连理工大学学报》
EI
CAS
CSCD
北大核心
2006年第6期868-874,共7页
Journal of Dalian University of Technology
基金
国家自然科学基金资助项目(重点项目50438010)
国家"973"重点基础研究资助项目(2002CB412709)
关键词
楔入劈拉
双K断裂参数
边界效应模型
混凝土
wedge splitting
double-K fracture parameters
boundary effect model
concrete
