Experimental research of the AE responses and fracture evolution characteristics for sand-paraffin similar material

The research for the features of similar material mechanics, the law of acoustic emission (AE) responses and fracture evolution characteristics can reflect the regularity of deformation, stress and fracture of coal and rock, revealing the evolution mechanism of dynamic disasters. We studied the mechanical properties of loaded sand-paraffin (SP) samples associated with different mixture ratio and the damage evolution of internal cracks based on AE. Results show that (1) with the increase of paraffin content, mechanical parameters of SP samples including compressive strength, elastic modulus, tensile strength, Poisson's ratio and internal friction angle show the overall upward trend, while failure pattern transitions to wedge splitting type and brittle shear failure from extrusion powder flexible broken; (2) the AE test can reflect the internal damage degree of SP samples and law of its space-time evolution. Along with the load increase, the AE response can be divided into three stages: slow growth, rapid growth and saturation, while also the damage variable reduces first then increases rapidly and grows slowly at last; (3) using the quadratic polynomial fitting, fragment expressions of damage evolution mechanism of SP are obtained. Based on Weibull distribution, we get the AE parameters (cumulative pulses) coupling mechanical parameters (stress and strain) expression, which fits better with the experimental data. By studying the mechanical parameters, the main failure form, AE response characteristics and its internal damage evolution rule, the paper evaluate the mechanical properties of the SP material from the macroscopic appearance to the microscopic mechanism, which provides the scientific basis for better selection and matching the material of analog simulation. (C) 2016 Elsevier Ltd. All rights reserved.