Abstract
A coal‐rock (CR) combined body can be used to simulate structures of coal and rock strata, and its impact‐induced failure characteristic conforms more close to engineering practice. Exploring the mechanical properties and impact energy in a CR combined body contributes to better predictions of rock bursts in coal mines. In the study, the mechanical properties of CR combined bodies with four different inclinations (0°, 15°, 30°, and 45°) of structural planes were measured, and also their failure mechanism was analysed. Based on the theory of particle mechanics, a calculation model for impact energy in a CR combined body with inclinations was established and then verified by using monitored acoustic emission (AE) data. The test results showed that inclination affected mechanical properties and failure characteristics of the CR combined body, i.e., the larger the inclination, the lower the strength and impact energy in the CR combined body and the lower the level of damage. The proposed calculation model for impact energy revealed the mechanical essence of energy accumulation and release of a CR combined body, providing a reference for investigating rock burst in coal mines.
Highlights
Rock bursts in coal mines are a dynamic disaster induced by failure of coal and rock masses and release much energy [1, 2]
The mechanical parameters and impact-induced failure characteristics of coal and rock are generally tested by applying stress on pure coal (PC) and pure rock (PR) specimens; mining spaces are integral structures composed of CR combined bodies
According to the recommendation of the International Society for Rock Mechanics and Stipulations in the Methods for Test, Monitoring, and Prevention of Rock Burst for the coal industry in China, a load-controlled method of testing was adopted. e specimens were subjected to the uniaxial loading test on the electrohydraulic servo universal testing machine, at the loading rate of 0.5 maximum principal stress (MPa)/s (1.25 kN/s) and the frequency of data acquisition of 1000 Hz
Summary
Rock bursts in coal mines are a dynamic disaster induced by failure of coal and rock masses and release much energy [1, 2]. Mechanical properties of coal and rock masses are considered to be the basis for exploring rock bursts in coal mines [3, 4]. The mechanical parameters and impact-induced failure characteristics of coal and rock are generally tested by applying stress on pure coal (PC) and pure rock (PR) specimens; mining spaces are integral structures composed of CR combined bodies. If only PC and PR are separately investigated, structural planes and interaction of coal and rock masses will be ignored, mechanical properties and failure process of PC and PR specimens fail to reflect the actual condition of failure [5]. Exploring the impact-induced failure and energy evolution of a CR combined body is conducive to investigating the generation of rock bursts in coal mines
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