| 摘要: |
| 为了解带裂缝混凝土在轴拉荷载作用下的力学特性和在变幅循环荷载作用下声发射Kaiser效应，设计了3种带不同初始缝长的混凝土轴向拉伸试验，详细分析了初始缝长对混凝土轴拉强度、断裂韧度、弹性模量等力学参数和声发射Kaiser效应的影响。结果表明：随着初始缝长的增加，混凝土弹性模量保持不变，断裂韧度逐渐增加，轴拉强度与初始缝长呈线性递减关系；在变幅循环荷载作用下，混凝土表现出明显的Kaiser效应，随着荷载水平的提高，Kaiser效应逐渐减弱；当缝高比小于0.4时，Kaiser效应随初始缝长的增大逐渐增强； Kaiser效应本质上是由混凝土内部损伤程度决定的。此外，混凝土轴拉强度的大小会影响其在低荷载水平作用时声发射信号的强弱，据此可判断混凝土试件强度的高低。 |
| 关键词: 混凝土 轴拉强度 断裂韧度 声发射 Kaiser效应 |
| DOI： |
| 分类号:TV32.1 |
| 基金项目:国家重点研发计划资助项目（2016YFC0401902）；国家自然科学基金重点项目(51739008)；国家重大科研仪器研制项目(51527811) |
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| Experimental studies on mechanical properties and Kaiser effect of concrete with cracks under axial tensile stress |
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HU Yuquan1, HU Shaowei2, HUANG Yiqun3
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1.College of Civil and Transportation Engineering, Hohai University, Nanjing;2.Nanjing Hydraulic Research Institute, Nanjing;3.College of Mechanics and Materials, Hohai University, Nanjing
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| Abstract: |
| In order to clarify the influences of cracks on the mechanical properties of concrete under the uniaxial tensile loads and the Kaiser effect of the acoustic emission under variable amplitude cyclic tension loads, three kinds of axial tensile specimens with different crack lengths have been tested to study the influences of the initial crack length on the axial tensile strength, fracture toughness, elastic modulus and the Kaiser effect. The research results indicate that the elastic modulus remains constant, the fracture toughness increases gradually, and the tensile strength decreases linearly with the increase in the cracking length of the concrete specimens. Under the cyclic loads with variable amplitude, the concrete specimens show obvious Kaiser effect, and the Kaiser effect is gradually weakened with the increase of the load level. When the crack-depth ratio is less than 0.4, the Kaiser effect increases with the increase of the initial crack length of the concrete specimens. The Kaiser effect is essentially determined by the degree of the internal damage of concrete specimens. In addition, the strength of concrete specimens under the axial tension will affect the activation intensity of the acoustic emission signal at the low load level. Based on this, the strength change of the concrete specimens can be judged. |
| Key words: concrete axial tension strength fracture toughness acoustic emission Kaiser effect |
