双轴受压混凝土动态力学特性及破坏准则研究

利用动静力三轴试验机进行不同加载速率、不同侧向压力下300 mm立方体混凝土的抗压试验，并对所得试验数据进行力学参数分析，在此基础上，建立考虑动态加载速率的K-G破坏准则并对其适用性进行了验证。验证分析结果表明:应变速率越低，侧压对混凝土峰值应力的增益作用越明显；混凝土峰值应变随应变速率增加，大致呈先减后增趋势；峰值应变随侧压的增大而增大, 侧压对峰值应变的影响在应变速率较低时更明显；随应变速率的增大，混凝土弹性模量呈先增后减趋势；侧压对混凝土弹性模量的影响不明显；建立的改进后的K-G准则对动态双轴受压模型描述效果好，而且该模型同时也适用于100和300 mm混凝土立方体的单向和双向应力状态。

Dynamic mechanical properties and failure criteria of concrete under biaxial compression

The compression tests of 300 mm concrete cubic specimen under different lateral pressures and different loading rates are carried out by using a dynamic and static triaxial test machine, and the mechanical parameters of the test data are analyzed. On this basis, the K-G failure criterion considering the dynamic loading rate is established and its applicability is verified. The results of validation analysis show that the lower the strain rate is, the more obvious the effect of lateral pressure on the peak stress of concrete is; the peak strain of concrete decreases first and then increases with the increase of the strain rate; the peak strain of concrete increases with the increase of the lateral pressure, and the effect of the lateral pressure on the peak strain is more significant when the strain rate is low; the elastic modulus of concrete increases first and then decreases with the increase of strain rate; and the influences of the lateral pressure on the elastic modulus of concrete is not significant. The improved K-G criterion is more effective in describing the dynamic biaxial compression model, and the model can also be used to verify and analyze the uniaxial and biaxial stress states of 100 mm and 300 mm concrete cubic specimens.