Study on Acoustic Emission Characteristics of a Semirigid Base of Dense Skeleton Type during Complete Uniaxial Compression Tests

Abstract

Acoustic emission testing of semirigid base specimens subjected to uniaxial compression was performed by a mechanical testing machine and AE system to find the AE criterion of the uniaxial compressive failure process of the semirigid base of dense skeleton types. AE counts, cumulative AE energy, and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:mi>b</mml:mi></mml:mrow></mml:math>-value were discussed. Results indicated that the AE parameters could reflect the failure process of semirigid bases of dense skeleton types. The failure process mainly underwent three stages that were divided based on AE parameters into initial stage of development, stable growth stage, and unstable stage. The knees of the AE parameter curve were at 25% and 85% of the ultimate load. The variation of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mrow><mml:mi>b</mml:mi></mml:mrow></mml:math>-value could indicate the stress and be a precursor to the failure of the specimens. In general terms, a<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M3"><mml:mrow><mml:mi>b</mml:mi></mml:mrow></mml:math>-value greater than 3.5 indicates that specimens are at the initial stage of development. A<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M4"><mml:mrow><mml:mi>b</mml:mi></mml:mrow></mml:math>-value between 1 and 2 indicates that the specimens are at the stable growth stage. If the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M5"><mml:mrow><mml:mi>b</mml:mi></mml:mrow></mml:math>-value seems to fluctuate and increase, the specimens are at the unstable stage. Moreover, the AE parameters indicated that attaching sensors to the waist of specimens was superior to that at other locations of a specimen.