Experimental Investigation on the Deformation Characteristics and Mechanical Behaviors of Tectonic Coal under Complex Unloading Confining Pressure

Deyi Gao; Shuxun Sang; Shiqi Liu; Wenkai Wang; Hang Mo

LAPSE:2023.10575

Published Article

LAPSE:2023.10575

Experimental Investigation on the Deformation Characteristics and Mechanical Behaviors of Tectonic Coal under Complex Unloading Confining Pressure

Deyi Gao, Shuxun Sang, Shiqi Liu, Wenkai Wang, Hang Mo

February 27, 2023

Abstract
Conventional and cyclic unloading tests with different unloading rates were conducted to study the influences of unloading patterns and rates on the deformation characteristics and mechanical properties of tectonic coal. The results demonstrate that, under continuous unloading, a lower unloading rate promotes an increase in the circumferential strain but inhibits increases in axial strain. A lower unloading rate was found to be able to promote volume expansion under the cyclic unloading path, and the axial, circumferential, and volume strains increased stepwise with the unloading levels, but the increment of the strains decreased with the number of cycles in the same unloading level. It was easier for tectonic coal to reach the elastic limit by a low speed unloading rate when the unloading level was small, and volume dilatation was promoted when the unloading level was large. In both unloading patterns, the tangential modulus and the Poisson ratio were proportional to the unloading rate. Compared with continuous unloading, the cyclic unloading pattern was found to have a significant delaying and inhibiting effect on damage expansion, and thus higher mechanical strength and more structurally stable tectonic coal responses were observed.

Record ID

LAPSE:2023.10575

Keywords

deformation characteristic, mechanical behavior, tectonic coal, unloading confining pressure

Subject

Energy Systems

Suggested Citation

Gao D, Sang S, Liu S, Wang W, Mo H. Experimental Investigation on the Deformation Characteristics and Mechanical Behaviors of Tectonic Coal under Complex Unloading Confining Pressure. (2023). LAPSE:2023.10575

Author Affiliations

Gao D: Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, China University of Mining and Technology, Xuzhou 221008, China; School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221008, China
Sang S: School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221008, China; Carbon Neutrality Institute, China University of Mining and Technology, Xuzhou 221008, China; Jiangsu Key Laboratory of Coal-Based Greenhouse Gas Control [ORCID]
Liu S: Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, China University of Mining and Technology, Xuzhou 221008, China; School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221008, China; Carbon Neut
Wang W: Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, China University of Mining and Technology, Xuzhou 221008, China; School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221008, China
Mo H: Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, China University of Mining and Technology, Xuzhou 221008, China; School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221008, China

Journal Name

Energies

Volume

16

Issue

4

First Page

1889

Year

2023

Publication Date

2023-02-14