English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

In order to further explore the relationship between the excavation speed and the damage of surrounding rocks and dynamic manifestation, the stress paths of unloading confining pressure and loading axial pressure were designed based on the changes in the roadway surrounding rock stress in this study. Additionally, the mechanical properties and energy evolution law of the coal body were investigated under various unloading rates. As the unloading rate increased, the mechanical properties of the coal body including the failure strength, the confining pressure, the axial strain, and horizontal strain tended to decrease at the rupture stage, while the volume strain and the elastic modulus increased, indicating that the rupture form evolved from the ductile failure to brittle failure. Regarding the energy, the axial pressure did positive work while the confining pressure did negative work, with the total work and the stored elastic strain energy decreasing. In addition, with the increase of the dissipation energy, the elastic strain energy conversion rate decreased linearly, indicating that the high unloading rate increased the possibility of dynamic disasters induced by the instantaneous brittle rupture of the coal body. On the other hand, due to the low releasable elastic strain energy stored in the coal body, the strength and probability of subsequent dynamic manifestation of coal body destruction were reduced. Therefore, increasing the excavation speed in a controllable way can benefit the safety of mining.

An Investigation on the Impact of Unloading Rate on Coal Mechanical Properties and Energy Evolution Law