Abstract
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°~60°) (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°~90°)(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.
Highlights
In order to minimize the loss and improve resource recovery, artificial pillars are used to replace the roof support or hanging rock of original pillar in many rare and precious metal mines
1) When two parts of the stone combinations in the test specimens are combined in a minor angle (30°~60°), under sustained loading without failure, acoustic emission amplitude will increase during decelerating creep transiting to steady creep with surface crack opening and propagation
2) When two parts of the stone combinations in the test specimens are combined in a large angle (60°~90°), under sustained loading without failure, the test specimens show two variation features
Summary
In order to minimize the loss and improve resource recovery, artificial pillars are used to replace the roof support or hanging rock of original pillar in many rare and precious metal mines. Artificial pillars are the most important supporting structure for safe mining If they are damaged in complex externally mechanical environment of underground mining, it will cause the roof caving, upper and lower strata movement, and even induces deep mining rock burst, forms a serious threat to the mining safety. Acoustic emission(AE) monitoring technology which can be used as a qualitative or quantitative description of Evolution of micro cracks in concrete materials under external loads[2~6], and prediction of the catastrophe has been gradually applied to solid waste of cemented filling body stability monitoring and forecasting. The results were valuable for the prediction of instability of cemented waste of rock backfills
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