单轴压缩下碳化混凝土的声发射特性

Study on acoustic emission characteristics of carbonated concrete under uniaxial loading

为探明碳化对混凝土细观破坏机制的影响,开展了不同碳化程度混凝土的单轴压缩试验,并记录了混凝土破裂过程中的声发射信号。在细观尺度上,运用矩张量声发射反演算法(CAE方法)对混凝土的破裂过程进行了分析,得到了混凝土破裂过程的b值及破裂机制。结果表明:碳化与未碳化混凝土的声发射特性存在一定区别,主要表现在声发射事件数量及能量随时间分布规律及绝对量值的差异;而碳化程度在一定范围内的混凝土,差异性相对前者而言较小;碳化程度的加深会导致b值的减小,表明碳化程度与微裂纹相互作用强度间为正相关关系;而碳化程度与混凝土微观破裂力学机理并无相关关系,即各种碳化程度下,破裂均以张拉破裂为主。

In order to explore the influence of carbonation on the mesoscopic failure mechanism of concrete,uniaxial compression tests of concrete with different carbonation degrees are carried out,and acoustic emission signals during concrete rupture process are recorded.At the mesoscopic scale,the moment tensor acoustic emission inversion algorithm(CAE)established on the basis of moment tensor theory is used to simulate the concrete fracture process,and the b value and fracture mechanism of the concrete fracture process are obtained.The results show that there are some differences in AE characteristics between carbonized and uncarbonized concrete,which are mainly manifested in the differences in the number and energy distribution over time and the absolute value of AE events.It reveals that the deepening of carbonation degree will lead to the decrease of b value and enhance the interaction of micro-cracks.However,the micro-cracking mechanism has little difference in different carbonized concrete,and the rupture pattern is dominated by tensile one.The experiment results provide a basis for the evaluation of mechanical properties of concrete structures.