STUDY ON FAILURE MECHANICAL CHARACTERISTICS AND DAMAGE CONSTITUTIVE MODEL OF SANDSTONE WITH DIFFERENT NUMBERS OF HOLES

Abstract

THE EXISTENCE OF HOLES IN ROCK IS ONE OF THE KEY FACTORS FOR THE INSTABILITY OF UNDERGROUND ROCK MASS ENGINEERING. COMBINED WITH ACOUSTIC EMISSION EQUIPMENT, UNIAXIAL COMPRESSION TESTS OF ROCK SAMPLES WITH DIFFERENT NUMBERS OF HOLES IN THE ROCK WERE CARRIED OUT. THE RESULTS SHOW THAT WITH THE NUMBER OF HOLES INCREASES, THE VALUE OF PEAK STRENGTH AND ELASTIC MODULUS OF THE ROCK DECREASE. THE ACOUSTIC EMISSION (AE) COUNTS GONE THROUGH STABLE, SLOW INCREASE, A SUDDEN INCREASE AND TOWARDS ZERO FOUR STAGES AND THERE ARE CORRESPONDING TO THE INITIAL COMPACTION STAGE, ELASTIC STAGES, STRAIN HARDENING STAGE AND POST-PEAK STRAIN SOFTENING STAGE OF THE STRESS-STRAIN CURVES APPROXIMATELY. BASED ON THE AE EVENTS, DAMAGE VARIABLES OF ROCKS WERE OBTAINED. THE DAMAGE EVOLUTION PROCESS OF ROCK CAN ALSO BE DIVIDED INTO THREE PARTS, INCLUDING STABLE DAMAGE STAGE, SLOWLY INCREASING DAMAGE STAGE AND SHARPLY INCREASING DAMAGE STAGE. ACCORDING TO DUNCAN MODEL, THE DAMAGE VARIABLE IS INTRODUCED TO OBTAIN THE ROCK DAMAGE CONSTITUTIVE MODEL. NO MATTER IT IS THE PRE-PEAK INITIAL COMPACTION STAGE, THE LINEAR ELASTICITY STAGE, THE STRAIN HARDENING STAGE OR THE POST-PEAK STRAIN SOFTENING STAGE, THE FITTING CURVES ARE IN GOOD AGREEMENT WITH THE TEST CURVES. IT ALSO ILLUSTRATES THE RATIONALITY OF THE DAMAGE CONSTITUTIVE MODEL.