Longwall Top-Coal Caving Mechanism and Cavability Optimization with Hydraulic Fracturing in Thick Coal Seam: A Case Study

Zhaohui Wang, Yuesong Tang and Hao Gong
Additional contact information
Zhaohui Wang: School of Energy and Mining Engineering, China University of Mining and Technology, Beijing 100083, China
Yuesong Tang: School of Energy and Mining Engineering, China University of Mining and Technology, Beijing 100083, China
Hao Gong: School of Energy and Mining Engineering, China University of Mining and Technology, Beijing 100083, China

Energies, 2021, vol. 14, issue 16, 1-17

Abstract: Longwall top-coal caving mechanisms and cavability optimization with hydraulic fracturing are analysed in this study. Based on the geological and geotechnical conditions of the Dongzhouyao coal mine, it is revealed that top-coal failure mechanisms are dominated by both compressive and tensile stresses. Ahead of the face line, shear failure initiates at the lower level of the top-coal and propagates to the upper level. Compressive stress-induced damage leads to obvious deterioration in tensile strength, causing the onset of tensile failure in the top-coal behind the face line. Accumulated plastic strain (APS) is selected as a top-coal cavability indicator. The cavability degrades gradually at the higher elevation of the top-coal while it is greatly strengthened as the top-coal approaches closer to the face line. In a thick coal seam without hydraulic fractures, the maximum APS occurs at the middle section of the face length in the Longwall top-coal caving (LTCC) panel. After hydraulic fracturing, top-coal cavability is significantly enhanced. But the spatial distribution of the APS transitions from uniform to non-uniform type due to the existence of hydraulic fractures, causing great variety in the cavability along the panel width. With increasing fracture intensity and fracture size, the failure zone expands significantly ahead of the longwall face, which means the cavability becomes increasingly favourable.

Keywords: longwall top-coal caving; failure mechanism; top-coal cavability; stress path; hydraulic fracturing (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View complete reference list from CitEc
Citations: View citations in EconPapers (1)

Downloads: (external link)
https://www.mdpi.com/1996-1073/14/16/4832/pdf (application/pdf)
https://www.mdpi.com/1996-1073/14/16/4832/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:14:y:2021:i:16:p:4832-:d:610563

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().