三级配混凝土及湿筛混凝土单轴动态拉伸性能试验研究

考虑大骨料特性的混凝土动态拉伸性能研究是混凝土坝抗震特性研究的一个突出问题.进行了大坝迎水面常用的三级配混凝土及湿筛混凝土在10-5、10-4、10-3、10-2 s-1四种应变速率下的单轴动态直接拉伸强度试验.试验采用尺寸为250mm×250mm×400mm和150mm×150mm×300mm的棱柱体试件.试验测得不同应变速率下试件的单轴动态拉伸应力和应变.基于试验数据探讨了三级配混凝土及湿筛混凝土的破坏形态、单轴抗拉强度、峰值应力点的应变随应变速率的变化规律.此外,还建立了三级配混凝土与相应湿筛二级配混凝土的动态强度关系.试验结果可为混凝土大坝、海洋平台等的抗震设计提供理论依据.

Experimental study of uniaxial dynamic tensile properties of three-graded concrete and wet-screened concrete

The study of the dynamic tensile properties of concrete, which considers large aggregate size effect, is an essential issue when studying the seismic properties of concrete dams. Uniaxial dynamic direct tensile tests of three-graded concrete and wet-screened concrete used for the upstream face of dam are carried out under 4 different strain rates, which are 10 -5 , 10 -4 , 10 -3 and 10 -2 s -1 . Dimensions of prismatic specimens are 250 mm×250 mm×400 mm and 150 mm×150 mm×300 mm. The uniaxial dynamic tensile stress and strain under different strain rates are measured in the process of tests. Based on the test data, the variation rule of the strain at peak stress, uniaxial tensile strength and the failure patterns are studied. Some formulas relating to dynamic strength between three-graded concrete and its wet-screened two-graded concrete are proposed. The experimental results can provide the reference for the seismic design of concrete dams and offshore platforms.