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Mechanical properties and acoustic emission characteristics of karst limestone under uniaxial compression

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Document pages: 14 pages

Abstract: Firstly, the wave velocity of karst limestone with different initial microstructure and water content is detected by i-rpt ultrasonic detector. Then, the acoustic emission under uniaxial compression is tested by RMT-150B rock testing machine and ds2-16b acoustic emission system. The mechanical properties and acoustic emission characteristics of rock during failure are obtained. In this paper, the relationship between stress-strain and acoustic emission characteristics is studied in detail. The results show that: (1) for samples with many primary cracks and defects, the wave velocity in dry state is greater than that in natural state. From the natural state to the saturated state, the wave velocity tends to increase. For the samples with good integrity, the wave velocity increases with the increase of water contentent. (2) In the dry state, the samples presented tension failure. In saturated state, the samples presented tension-shear failure. For samples with cracks and good integrity, samples showed brittle failure. For samples with many corrosion pores which showed ductile damage under natural and saturated state, the spalling phenomenon was enhanced under saturated state. (3) With increasing of water content, the peak stress and AE peak reduced dramatically. In brittle failure, AE peak could be considered a sign of failure. In ductile failure, AE activity decreased gradually with the decrease of stress. (4) The mechanical properties and AE characteristics corresponding to four main fracture propagation types were also discussed.

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