Experimental Study on Acoustic Emission Characteristics of Cemented Waste Rock Backfills with Two Different Structures during Creep Process

The studies on acoustic emission characteristics of cemented waste of rock backfills with two different structures during creep process were carried out by virtue of short-term creep test under different stress levels. The results show that: When two parts of the stone combinations in the test specimens are combined in a minor angle (30 degrees similar to 60 degrees) (type I), under sustained loading without failure, acoustic emission amplitude will increase during steady creep stage with surface crack opening and propagating. When two parts of the stone combinations in the test specimens are combined in a large angle (60 degrees similar to 90 degrees)(type II), under sustained loading without failure, the test specimens show two varied features. On one hand, acoustic emission amplitude will decrease significantly during steady creep stage, with surface crack opening and propagating which will mainly occur during decelerated creep stage. On the other hand, acoustic emission amplitude is rather fluctuating during sustained load stage which leads to separation and drop of parts of the test specimen. One common trait of these two types of test specimens is that, the whole decelerated creep and steady creep stages show relatively stable acoustic emission amplitude before destruction. During accelerated creep stage, acoustic emission amplitudes appear as wave type in type I test specimens with shear fracture and accretion type in type and II test specimens with tensor failure.