(1. College of Civil Engineering,Tongji University,Shanghai 200092,China;2. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,Tongji University,Shanghai 200092,China;3. School of Engineering,Tibet University,Lhasa,Tibet 850000,China)
Abstract:The self-initiated static-dynamic state catastrophe behaviour is a key step in coal bursts. However,its dynamic processes and triggering mechanism to coal bursts have not been extensively explored and fully understood. Addressing this gap,our study modified the traditional coal-rock combined specimen and the corresponding indoor experimental method,and implemented physical experiments to simulate coal bursts and static brittle failure under quasi-static displacement loading conditions. Additionally,a novel multi-source information monitoring system was developed,enabling the capture of transient changes in both static and dynamic data on a millisecond time scale. With the new developed experimental method,a comprehensive investigation was conducted to explore the catastrophe process,formation mechanisms of the static-dynamic state catastrophe behaviour,as well as its role in triggering coal bursts. Then some novel insights into the mechanism of coal bursts were put forward. As a result,the elastic rebound dynamic behaviour of the surrounding rock during burst events was founded and identified as a key factor in controlling the self-initiated static-dynamic state catastrophic process. Mechanically,this behaviour exerts impact loads on the coal,directly initiating the dynamic process,and thus can be considered as the direct cause of coal burst. Energetically,through elastic rebound,the surrounding rock works on the coal instantaneously and promotes a large amount of elastic energy it stored to converge to the coal,and effectively reduces the time required for instability,and eventually leading to a large enough energy release rate,which is the inherent cause for coal burst.
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