三级配大骨料混凝土双轴抗压性能试验分析

利用自行研制的大型混凝土静、动三轴试验系统，完成了5种应力比、4种应变率、3种含水状态（干燥、自然、饱和）的三级配大骨料混凝土双轴动态抗压试验。试验研究了含水率对三级配大骨料混凝土动态极限抗压强度的影响，并在此基础上提出考虑含水率影响的大骨料混凝土动态破坏准则。研究表明，饱和混凝土试件在高应变率下的强度明显提高，而在低应变率下强度则有所降低。在相同应变率下，极限抗压强度在应力比为1∶0.5时达到最大值。影响三级配大骨料混凝土试件破坏形态的主要因素为应力比，其动态极限抗压强度随含水率的增大而增大，而静态极限抗压强度随含水率的增大而减小；单轴受压状态下的变形明显小于双轴受压，试件的峰值应变随应变率的增大而减小。

Experimental analysis of compressive properties of three-graded large aggregate concrete under biaxial compression

By using a large static and dynamic electro hydraulic servo controlled testing system, the dynamic compressive tests of three graded large aggregate concrete with three kinds of water content (i.e. dry, natural and fully saturated) are carried out under different stress ratios (1:0, 1:0.25, 1:0.50, 1:0.75, 1:1.00) and strain rates (10-5/s, 10-4/s, 10-3/s, 10-2/s). In the test analyses, the effects of water content on the biaxial dynamic compressive strength of the three-graded large aggregate concrete are studied. A dynamic compression failure criterion of the large aggregate concrete is proposed. The experimental analysis results show that the compressive strength of the saturated concrete increases at the high strain rate, and decreases at the low strain rate. Comparing with the uniaxial compression, the compressive strength reaches the maximum value at the stress ratio of 1:0.5. It is found from experimental studies that the major factor influencing the failure pattern of the three-graded large aggregate concrete is the stress ratio. The dynamic ultimate compressive strength increases with an increase in water content, while the static ultimate compressive strength decreases with an increase in water content. The specimen under the uniaxial compression has less deformation than that under the biaxial compression, and the peak strain of the specimen is found to increase with the decrease of the strain rate.