大尺寸饱和混凝土单轴压缩动态性能试验研究

Dynamic Performance of Large Size Saturated Concrete Under Uniaxial Compression Test

为了解饱和混凝土材料的动态特性,开展了大尺寸饱和混凝土在不同应变速率下的单轴压缩试验。试验在大型多功能液压静动力三轴仪上进行,采用300 mm×600 mm圆柱体混凝土试件,得到了大尺寸饱和混凝土的动态力学性能参数,并根据破坏形态分析了其破坏机理。试验结果表明:峰值应力、吸能能力随着应变速率增大而增加,峰值应变、弹性模量随着应变速率的增大整体上增加。根据应力-应变关系的特点,建立了峰值应力前服从Weibull统计分布,峰值应力后服从Lognormal统计分布的损伤本构模型。混凝土破坏形态表现为多个共轭斜面的剪切破坏,根据试件破坏后裂缝开展情况,解释了混凝土破坏剥落原因,并从材料组成、吸能能力等方面分析了其破坏机理。

In order to study the dynamic properties of large size saturated concrete, we carried out uniaxial compres- sion tests under different strain rates. By using large-scale multi-function static and dynamic triaxial test machine, we prepared cylindrical concrete specimens with diameter 300 mm and length 600 mm and obtained dynamic me- chanical properties of the concretes. Then, we analyzed the failure mechanism according to failure shape. Test results show that peak stress and energy absorption capacity increased with the increase of the loading rate, so did peak strain and elastic modulus. On the basis of stress-strain relation, we established a damage constitutive model of concrete. In the model, stress-strain relation conformed with Weibull statistical distribution before peak stress; while after peak stress, the relation conformed with Lognormal statistical distribution. Shear failure at a few conjuga- ted inclined planes were observed . According to crack expansion after specimen failure, we explained the causes of spalling failure of concrete and analyzed the failure mechanism in aspects of material composition and energy ab- sorption ability.