【摘要】 通过对48个试件进行轴拉声发射试验,研究混凝土试件在往复循环拉伸加载条件下Kaiser效应的有效性及其应力范围,探讨混凝土材料中Kaiser效应与Felicity效应的关系,并就Kaiser效应的影响因素进行系统全面的分析。结果表明:混凝土在轴心受拉试验中存在明显的Kaiser效应,其存在的机理是混凝土材料损伤不可逆的结果。Kaiser效应存在的应力上限值约为极限抗拉强度的80%。Felicity比随着相对应力水平的提高而单调下降,当达到较高的应力水平后,Felicity比迅速下降,Kaiser效应衰退,出现Felicity效应。加载速率对混凝土轴拉声发射Kaiser效应基本没有影响;而加载制度、应力水平、卸载后放置的时间以及干湿条件等对混凝土轴拉声发射Kaiser效应产生较大的影响。研究结果为应用声发射技术探讨混凝土拉伸破坏机理奠定基础,同时也为Kaiser效应的工程实际应用提供参考。更多还原

【Abstract】 Acoustic emission tests are conducted on 48 specimens under uniaxial tension loading. The existence of Kaiser effect and the corresponding stress range in the concrete specimens under uniaxial cyclic tension loading are studied. The relationship between the Kaiser effect and the Felicity effect is discussed. The factors that influence the Kaiser effect of the concrete specimens are systemically analyzed. It can be concluded that the existence of Kaiser effect in concrete under uniaxial tension loading is valid. This is the result of the irreversibility of concrete damage. The upper limit of stress level under which Kaiser effect exists is about 80% of the ultimate tensile strength. Felicity ratio decreases monotonically with the increase of stress. When the stress is near the upper limit of stress level, Felicity ratio decreases rapidly, Felicity effect appears and Kaiser effect disappears. The loading rate has no effect on Kaiser effect in concrete. However, the loading pattern, stress level, time delay and wet-dry condition have great effects on Kaiser effect in concrete. The results are useful for explaining the failure mechanism of concrete under uniaxial tension loading and provide a reference for the application of Kaiser effect in engineering practice.更多还原