Abstract
In order to study the mechanical properties and energy dissipation of gas coal under dynamic and static loads, the static loading and impact tests of different strain rates were carried out by the testing systems of SZW-1000 microcomputer servo pressure tester and separated Hopkinson pressure bar (SHPB) for gas coal in the Panxie Coal Field in Huainan City. In the test, the influence laws of various loading patterns on mechanical properties, failure characteristics, and energy dissipation of gas coal sample were analyzed. The results showed that the stress-strain curve of coal gas under dynamic load had no micropore compaction stage compared with that under static load. Dynamic compressive strength, dynamic strength growth factor, mixed dynamic elasticity modulus, and dissipation energy were all highly correlated with strain rate, whereas energy dissipation rate was uncorrelated with strain rate. In addition, the gas coal sample with lower strain had small dissipated energy, and it developed a splitting failure mode. With the increase of strain rate, the dissipation energy increased and the crushing degree of gas coal intensified, finally presenting a compressive failure mode. Based on the comparison of dissipated energy densities of different gas coal samples, given the same dissipated energy density, the failure degree of sample under dynamic load was higher than that under static load.
Highlights
With the increase of mining depth in coals, the dynamic phenomena of coal-rock mass intensify increasingly, which threatens the mine safety and high-efficiency production [1, 2]
E separated Hopkinson pressure bar (SHPB) is a technique that is widely used in studying dynamic mechanical properties of coal-rock mass [9,10,11,12,13]
Liu et al [14], Wang et al [15], and Fu et al [16] carried out the impact loading experiments of Furong anthracite under different strain rates to study dynamic characteristics and energy dissipation, loss characteristics, electromagnetic change features, and constitutive model of anthracite sample
Summary
With the increase of mining depth in coals, the dynamic phenomena (e.g., coal and gas outburst and rock burst) of coal-rock mass intensify increasingly, which threatens the mine safety and high-efficiency production [1, 2]. Liu et al [14], Wang et al [15], and Fu et al [16] carried out the impact loading experiments of Furong anthracite under different strain rates to study dynamic characteristics and energy dissipation, loss characteristics, electromagnetic change features, and constitutive model of anthracite sample. For outburst-prone coal as samples, Fan et al [22] investigated the dynamic strength and energy dissipation characteristics laws of coals under different strain rates. Erefore, to guide mining technological revolution and further disclose the occurrence mechanism of dynamic phenomena of gas coal, it is urgent to study mechanical properties and energy dissipation law of gas coal under dynamic loads. The dissipated energy density was analyzed under different loading patterns, aiming to comprehensively understand mechanical differences between static loading failure and dynamic impact failure for gas coal
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