基于0.2定围压比状态下的约束混凝土性能研究

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。

On the Restrained Concrete Performance Under the 0.2 Constant Surrounding Pressure Ratio Condition

Mechanical properties of compression of concrete in a state of nearly no-crack propagation were experimentally studied by exerting 0.2 constant surrounding pressure ratio to prevent the crack from growing in a uniaxially compressed concrete. Based on monotonously cyclic loading-unloading compression experiments with 0.2 surrounding pressure ratio for different strength grade concrete, regular triaxial tests were carried out by using MTS 815.02 rock electro-hydraulic servo system. The influence of surrounding pressure ratio on the compression stress-strain relation and the restriction effect of surrounding pressure on the damage growth were analyzed. Meanwhile, according to the concrete special performance under 0.2 constant surrounding pressure ratio condition, the expression and parameters of concrete at an ascent stage were proposed in this paper. Analysis results show that under 0.2 constant surrounding pressure ratio condition, concrete with different strength grades exhibits constitutive relation similar to metal materials' relation, and stress-strain relation improving range of the lower grade concrete specimens is better than that of middle grade concrete. In a word, 0.2 constant surrounding pressure ratio improves the mechanical properties of no symptom failure (brittle failure) for compressed concrete.