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通过对混凝土施加0.2定围压比,使单轴受压混凝土裂缝发展受到约束,研究了混凝土在接近无裂纹发展状态下的受压力学性能。本文以在MTS815.02岩石电液伺服系统上对不同强度等级的混凝土试件在定围压比为0.2时的单调、循环加卸载受压常规三轴试验为基础,研究分析了0.2定围压比对混凝土受压应力-应变规律的影响和围压对混凝土裂缝发展的限制效果,并根据0.2定围压比下混凝土材料的特殊性能,提出了无裂纹发展状态下混凝土上升段表达式及参数。分析结果表明,0.2定围压比下,各强度混凝土本构关系均表现出了类似金属材料的本构关系,且低强混凝土试件应力-应变的提高幅度优于中强混凝土试件。综上所述,0.2定围压比改善了混凝土在受压时无征兆失效(脆性破坏)的力学性能。
The confining pressure of concrete under uniaxial compression is restrained by applying a confining pressure ratio of 0.2 to the concrete, and the compressive mechanical properties of the concrete under near crack-free development are studied. In this paper, MTS815.02 rock electro-hydraulic servo system for different strength grades of concrete specimens at a constant confinement pressure ratio of 0.2 monotonous, cyclic loading and unloading compression of the conventional triaxial tests based on the analysis of 0.2 fixed pressure Compared with the compressive stress-strain law of concrete, the effect of confining pressure on the development of concrete crack is analyzed. According to the special properties of concrete under 0.2 confining pressure ratio, the expressions and parameters of concrete ascending stage . The analysis results show that the constitutive relation of all kinds of strength concrete shows the constitutive relation of similar metal materials under 0.2 constant confining pressure ratio, and the stress-strain of low-strength concrete specimens is better than that of medium-strength concrete specimens. In summary, 0.2 fixed pressure ratio to improve the compression of concrete without symptoms of failure (brittle failure) of the mechanical properties.