Mechanical Behavior Characteristics and Energy Evolution Law of Coal Samples under the Influence of Loading Rate—A Case Study of Deep Mining in Wudong Coal Mine

Abstract

In order to clarify the mechanical properties and energy changes of coal samples under the influence of mining depth, a mechanical test analysis method to determine that the increase in mining depth increases the loading rate has been developed. Taking the Wudong Coal Mine as an example, a mechanical test analysis of coal samples is carried out. The results show that the surface deformation and failure of coal samples in the loading process presents four stages. That is, the evolution process of ‘complete coal sample’–‘partial failure-failure extension’–‘overall instability’. The maximum temperature of a coal sample when it is destroyed shows an obvious nonlinear increasing trend with the increase in loading rate. With the increase in loading rate, the strength and elastic modulus of coal samples decrease gradually. The cumulative total energy and elastic energy of coal samples are linearly positively correlated with the loading rate. The research results provide ideas for rational control of mining intensity and determination of productivity in steeply inclined thick coal seams for deep mining.