摘要
为提供更为充足的试验数据充实《水工混凝土断裂韧度试验规程》,同时也为研究双K断裂参数的尺寸效应问题,进一步确定进行混凝土断裂韧度试验的最小试件尺寸,方便工程技术人员的实际应用,采用一种新的试验方法即楔入式紧凑拉伸法设计了最大尺寸为1250mm×1200mm×200mm不同高度的6组共36个试件,试验研究双K断裂参数。该方法结合两种常规的楔入劈拉方法和紧凑拉伸法的优点,既消除了楔入劈拉试验中当竖向荷载与双线支承不共线时在裂缝尖端所引起的附加弯矩对双K断裂参数真实值的影响,又克服了紧凑拉伸试件对试验设备刚度要求的问题。试验中沿韧带方向布置电阻应变片,监测裂缝的起裂及扩展过程。通过对不同尺寸的楔入式紧凑拉伸试件的试验研究表明,楔入式紧凑拉伸法是一种操作简单且稳定的断裂试验方法,有望进一步补充现有的试验规程;所测定的混凝土双K断裂参数与试件的尺寸无关,可作为裂缝起裂和失稳的控制阀值来预测预报混凝土结构裂缝的发展状态。
For the purpose of providing sufficient experimental data to support the ＂Norm f or fracture test of hydraulic concrete of China＂ and of getting a better understanding of size-effect of the double-K fracture parameters and then further identifying the minimum specimen depth required for no size-effect double-K fracture parameters of more convenientusage, a new approach of wedge-splitting test on compact tension specimen is attempted. A total of 36 specimens with different sizes, with the maximum size of 1250mm×1200mm× 200mm, are prepared to examine the double-K fracture parameters. This new method has the same advantages of the traditional wedge-splitting methods and compact tension method. It may not only eliminate the influence of the additional moment caused by the noncollinear vertical forces on the true values of double-K fracture parameters, but also weaken the stiffness requirements needed for fracturing a specimen. In addition, in order to monitor crack initiation and development, electric resistance strain gauges are arranged along the direction of the fracture ligament. The experimental results show that this fracture testing method is easy and stable. It is desirable that this modified method can be regarded as a supplement to the current testing specification. Moreover, the results also indicate that the measured double-K fracture parameters,KIC^ini,KIC^unare independent of specimens size. Hence, it is believed that double-K fracture governing parameters can be viewed as the thresholds to predict or estimate crack development.
出处
《土木工程学报》
EI
CSCD
北大核心
2008年第2期70-76,共7页
China Civil Engineering Journal
基金
国家自然科学基金重点项目(50438010)
国家973项目(2002CB412709)
关键词
混凝土
楔入式紧凑拉伸断裂试验
双K断裂参数
尺寸效应
concrete
wedge-splitting test on compact tension specimen
double-K fracture parameters
size effect
