真三轴应力下混凝土的动态力学性能及破坏准则

为研究混凝土结构处于复杂应力状态下的静动态力学特性，进行了不同应力比及加载速率下的真三轴压缩试验。对混凝土的强度特性和变形特性展开了深入分析，并基于八面体应力空间建立了考虑应变速率效应的真三轴动态破坏准则。结果表明:真三轴受压下的混凝土极限抗压强度随着应力比的增大而增大。随着应变速率的增加，应力比较低时，混凝土的极限抗压强度逐渐增大；应力比较高时，极限抗压强度先减小后增加。随着应变速率的增加，侧向变形曲线的破坏峰值点更明显；随着应力比的增大，侧应力较大方向上的变形越来越小。基于八面体应力空间建立的真三轴动态破坏准则表达式中包含3个率效应参数，经验证与试验数据吻合较好。

Dynamic mechanical properties and failure criteria of concrete under true triaxial stress

The true triaxial compression tests under different stress ratios and different loading rates are conducted to study the static and dynamic mechanical properties of concrete structures under complex stress conditions. The variations of concrete’s compressive strength and deformation characteristics are examined in depth. Based on the octahedral stress space, the true triaxial dynamic failure criterion of the concrete considering the rate effect is established. The results show that the ultimate compressive strength of concrete under true triaxial compression increases with the increase of stress ratio. At lower stress ratio, the ultimate compressive strength of concrete gradually increases with the increase of strain rate; at higher stress ratio, the ultimate compressive strength of concrete decreases firstly and then increases. The deformation on the lateral compression surface changes from compression failure to tensile failure in a shorter time with the increasing strain rate, and the deformation becomes smaller and smaller in the direction of greater lateral pressure with the increasing strain ratio. The expression of the true triaxial dynamic failure criterion based on the octahedral stress space contains three rate-effect parameters, which is verified to be in good agreement with the experimental data.