Experimental Study On Acoustoelectric Effect Of The Combination Concrete Under Uniaxial Compression

Combination concrete has similar characteristic with coal and rock, that is discrete and heterogeneity. And combination concrete has a good controllability. So study deformation failure process when under load and the law of acoustic signals of combination concrete, is of great significance to further reveal the characteristics of unstable failure and law of acoustoelectric response of coal and rock medium,and improve the accuracy and reliability of forecast the coal and rock dynamic disasters by using acoustoelectric monitoring technology.Acoustoelectric experiment system was established for combination concrete during deformation and fracture under uniaxial compression, three different intensity of concrete and concrete with built-in piece of potential samples was made. Then tested different combinations such as double units(a concrete sample is a unit, the same below)、2′2 units、2′2′2 units of concrete under uniaxial compression, analyse combination concrete damage characteristics under uniaxial compression by I-scan stress distribution system,and recorded surface potential, internal potential and acoustic emission signals of combination concrete during deformation and fracture. Finally analyse characteristics of combination concrete deformation and fracture and rules of acoustoelectric response. The results show as follows:(1) The stress distribution of combination concrete under uniaxial compression is not uniform. The Stress Concentration Region first appeare in the interface of strong and weak units. The combination of concrete failure fracture when the weakest unit occur deformation and completely, and surface of the unit shows macroscopic cracks. At the same time, combination of concrete still own a certain carrying capacity because that deformation and fracture of greater intensity unit are not complete. Micro-crack of combination concrete eventually develop into fracture after development and evolution during deformation and failure.(2) There are obvious distribution characteristics of potential of each unit during deformation and fracture. Before the peak load, potential of the units at the same column change in the same direction, surface potential of the unit adjacent may increase with the increase of load growth in positive or negative direction. After peak of load process, the symmetry of surface potential between adjacent units disappear, namely converge trends. This performance is more obvious in the internal potential curve. Before the peak and near peak the internal potential of units at the same column are in the same direction.(3) Generation of acoustic emission of combination concrete in the loading process is related to the formation and propagation of sample crack. The complexity of the curve trend of acoustic emission of combination concrete during deformation and fracture is gradually increased with the increase of sample size, complexity of combination.(4) Failure modes of the combination concrete under uniaxial compression are mainly tensile and shear tension damage. The piezoelectric effect and charge separation under non equilibrium stress plays a main role in the concrete specimens damage produced free charge...