Investigation of coal burst characteristics under impact loading

Abstract

Under condition of static loading, although the coal seams in some collieries were of weak burst proneness, still there were occurrences of coal bursts. This paper investigates the coal burst proneness under varying impact loading rates, peak impact loads and loading cycles in terms of four indices, i.e., Rc, DT, WET and KE. An acoustic emission (AE) system recorded the coal sample failure and consequently the development of fractures in coal samples was analysed through AE count under different loading conditions. The above mentioned four indices could be directly obtained from the stress vs. strain relationship and are normally used to assess coal burst proneness. The coal burst is a natural process of crack development and energy conversion. The laboratory test results depicted strengthening of coal samples' burst proneness with the increase in loading rate and peak impact load and weakening with the increase in loading cycles. [Received: February 4, 2017; Accepted: November 7, 2017]