混凝土在动态双向压力作用下的强度和变形特性

Strength and deformation characteristics of concrete under dynamic biaxial loading

在大型液压伺服混凝土静动三轴试验系统上对立方体试件进行不同应变速率下的压缩试验,系统研究了混凝土在双向压应力状态下的动态强度和变形性能,两轴向加载的比例为1:0,1:0.25,1:0.5,1:0.75,1:1五个级别,加载速率分别为10-5,10-4,10-3,10-2/s四个量级。试验表明:随着应变速率提高,任一应力比例下混凝土的极限强度均有提高,应变速率每增加一个量级,混凝土剪切破坏面相对低应变速率下的破坏面提高2%～10%;弹性模量随着应变速率的增加也有增加的趋势;应力-应变曲线的线性段随着应变速率的增加明显扩展,非线性段的弯曲程度减弱;应变速率对双向应力状态下的双向破坏模式影响不大。

Compressive tests on cubic specimens were conducted at different strain rates using a servo-hydraulic multiaxial testing machine.Considerable emphasis was laid on the dynamic strength and deformation properties of concrete in biaxial stress state.The lateral pressure was kept in proportion to the main axial load with the ratio of 0：1,0.25：1,0.5：1,0.75：1 and 1：1 respectively at the strain rate ranging from 10^-5/s to 10^-2/s.From the test results it is revealed that the dynamic strength is enhanced with the increasing of strain rate.The shear failure envelope is enlarged by 2 %–10 % in case of the strain rate increasing by one order of the magnitude compared with that under static loading.The modulus of elasticity also increases with the increasing of strain rate.The linear part of the stress-strain curves tends to extend as far as strain rate increases,while the curvature of the nonlinear part tends to diminish.Moreover,strain rate has little influence on the fracture modes of specimens in biaxial stress states.