水工混凝土损伤的声发射特性演化试验分析

Experimental Study on AE Behavior During Hydraulic Concrete Damage Under Flexural-tensile Condition

通过预置裂缝水工混凝土梁三点弯曲声发射试验研究,分析了水工混凝土三点弯曲受载过程中声发射特性,探究了混凝土力学性能、宏观效应与声发射特性间的相关关系.实验结果表明:混凝土材料在损伤过程的不同阶段,有着不同的声发射模式,具有明显的分阶段特征,在加载初始阶段,由于混凝土内部粗骨料的阻裂作用,使得混凝土内部裂缝呈间歇发展,但达到临界状态后,由于没有更多的能量储存,使得裂缝扩展呈失稳状态,出现连续和迅速的声发射;对于特定范围内的裂缝,其开度与声发射事件数有着强的相关关系,可以通过构建裂缝开度与声发射累计事件数关系数学模型,实现水工混凝土结构裂缝的声发射间接监测和定量评估.

According to the study on three-point bending AE test for pre-cracks hydraulic concrete beams,it analyzes AE properties during three-point flexural loading procedure for hydraulic concrete and investigates the correlation among mechanical properties,macro effect and AE activities of concrete.The test results show that,there are different AE modes in different stages for concrete materials,with definitely characteristics by stages;In the initial stage of loading,as action of crack arrest from internal coarse aggregates in concrete makes the inner cracks of concrete develop intermittent;While after it is up to critical state,as there are no more energy storage,it leads the crack propagate till to unstable state,showing continuous and rapid AE;For the cracks in special scope,there is strong correlation between its opening and AE events.By building mathematical model on the relationship between cracks aperture and AE cumulative events,indirect monitor and quantitative evaluation of hydraulic concrete structural cracks are achieved by means of AE technology.