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Failure and Instability Characteristics of Coal-Rock Parting-Coal Structures with Rough Discontinuities
https://orcid.org/0000-0002-7439-8256
Abstract The characteristics of energy liberation, crack propagation, and shear slip during the process of failure and instability of coal-rock parting-coal structures (CRCS) with rough discontinuities were studied using numerical simulations and field microseismic (MS) observations. The influences of the joint roughness coefficient (JRC) of the discontinuities on the failure and instability characteristics of CRCS were also compared and analysed. Field observations were in good agreement with the numerical simulations. The following main conclusions are proposed: (1) the concentration of contact force first appeared at the obvious convex areas of the discontinuities, and crack propagation and slip along discontinuities developed gradually. The instability of slip increased gradually with stress loading/or unloading and there was clear periodic instability during slip of discontinuities; (2) the shear slip trend of discontinuities promoted the development and concentration of shear cracks near the rough areas, and then local slip near failure zones unlocked and induced the expansion of cracks into coal/rock. Among these, the unlocking or sudden increase in shear slip along rough discontinuities easily induced MS events with higher magnitude and source radius; (3) there was a key area for unlocking a slip along the rough discontinuities, which was usually located in an area with a high degree of concave convex, and the unlocking of shear slip easily induced an extremely high vibration velocity of coal/rock. Additionally, with the increase in the roughness of discontinuities, both the instantaneous and overall instability of the composite structure gradually increased; and (4) field observations confirmed that the higher concentration stress induced frequent fracture and shear slip of CRCS under mining disturbance, and the different stress tension and pressure areas were generated along the advancing of working face owing to the difference in shear slip along rough discontinuities. This work is a supplement to our previous studies on the failure and instability characteristics of CRCS with smooth discontinuities, which can be more helpful for understanding the mechanism of coal-rock dynamic disasters triggered by slip and instability of CRCS near coal seam bifurcations in coal mines.
Highlights Evolution characteristics of stress, crack and shear slip of coal-rock parting-coal structures with rough discontinuities were studied.Shear-slip unlocking conditions of rough discontinuities between coal and rock parting were researched.Unlocking or sudden increase in shear slip along rough discontinuities promotes development and expansion of cracks.Field investigations confirmed the shear slip and stress differential distribution characteristics in coal seam bifurcation zone.
Failure and Instability Characteristics of Coal-Rock Parting-Coal Structures with Rough Discontinuities
https://orcid.org/0000-0002-7439-8256
Abstract The characteristics of energy liberation, crack propagation, and shear slip during the process of failure and instability of coal-rock parting-coal structures (CRCS) with rough discontinuities were studied using numerical simulations and field microseismic (MS) observations. The influences of the joint roughness coefficient (JRC) of the discontinuities on the failure and instability characteristics of CRCS were also compared and analysed. Field observations were in good agreement with the numerical simulations. The following main conclusions are proposed: (1) the concentration of contact force first appeared at the obvious convex areas of the discontinuities, and crack propagation and slip along discontinuities developed gradually. The instability of slip increased gradually with stress loading/or unloading and there was clear periodic instability during slip of discontinuities; (2) the shear slip trend of discontinuities promoted the development and concentration of shear cracks near the rough areas, and then local slip near failure zones unlocked and induced the expansion of cracks into coal/rock. Among these, the unlocking or sudden increase in shear slip along rough discontinuities easily induced MS events with higher magnitude and source radius; (3) there was a key area for unlocking a slip along the rough discontinuities, which was usually located in an area with a high degree of concave convex, and the unlocking of shear slip easily induced an extremely high vibration velocity of coal/rock. Additionally, with the increase in the roughness of discontinuities, both the instantaneous and overall instability of the composite structure gradually increased; and (4) field observations confirmed that the higher concentration stress induced frequent fracture and shear slip of CRCS under mining disturbance, and the different stress tension and pressure areas were generated along the advancing of working face owing to the difference in shear slip along rough discontinuities. This work is a supplement to our previous studies on the failure and instability characteristics of CRCS with smooth discontinuities, which can be more helpful for understanding the mechanism of coal-rock dynamic disasters triggered by slip and instability of CRCS near coal seam bifurcations in coal mines.
Highlights Evolution characteristics of stress, crack and shear slip of coal-rock parting-coal structures with rough discontinuities were studied.Shear-slip unlocking conditions of rough discontinuities between coal and rock parting were researched.Unlocking or sudden increase in shear slip along rough discontinuities promotes development and expansion of cracks.Field investigations confirmed the shear slip and stress differential distribution characteristics in coal seam bifurcation zone.
Failure and Instability Characteristics of Coal-Rock Parting-Coal Structures with Rough Discontinuities
https://orcid.org/0000-0002-7439-8256
Abstract The characteristics of energy liberation, crack propagation, and shear slip during the process of failure and instability of coal-rock parting-coal structures (CRCS) with rough discontinuities were studied using numerical simulations and field microseismic (MS) observations. The influences of the joint roughness coefficient (JRC) of the discontinuities on the failure and instability characteristics of CRCS were also compared and analysed. Field observations were in good agreement with the numerical simulations. The following main conclusions are proposed: (1) the concentration of contact force first appeared at the obvious convex areas of the discontinuities, and crack propagation and slip along discontinuities developed gradually. The instability of slip increased gradually with stress loading/or unloading and there was clear periodic instability during slip of discontinuities; (2) the shear slip trend of discontinuities promoted the development and concentration of shear cracks near the rough areas, and then local slip near failure zones unlocked and induced the expansion of cracks into coal/rock. Among these, the unlocking or sudden increase in shear slip along rough discontinuities easily induced MS events with higher magnitude and source radius; (3) there was a key area for unlocking a slip along the rough discontinuities, which was usually located in an area with a high degree of concave convex, and the unlocking of shear slip easily induced an extremely high vibration velocity of coal/rock. Additionally, with the increase in the roughness of discontinuities, both the instantaneous and overall instability of the composite structure gradually increased; and (4) field observations confirmed that the higher concentration stress induced frequent fracture and shear slip of CRCS under mining disturbance, and the different stress tension and pressure areas were generated along the advancing of working face owing to the difference in shear slip along rough discontinuities. This work is a supplement to our previous studies on the failure and instability characteristics of CRCS with smooth discontinuities, which can be more helpful for understanding the mechanism of coal-rock dynamic disasters triggered by slip and instability of CRCS near coal seam bifurcations in coal mines.
Highlights Evolution characteristics of stress, crack and shear slip of coal-rock parting-coal structures with rough discontinuities were studied.Shear-slip unlocking conditions of rough discontinuities between coal and rock parting were researched.Unlocking or sudden increase in shear slip along rough discontinuities promotes development and expansion of cracks.Field investigations confirmed the shear slip and stress differential distribution characteristics in coal seam bifurcation zone.
Failure and Instability Characteristics of Coal-Rock Parting-Coal Structures with Rough Discontinuities
Liu, Yang (author) / Lu, Cai-Ping (author) / Zhang, Xiu-Feng (author) / Guo, Ying (author) / Song, Chun-Hui (author) / Wang, Chao (author)
2022
Article (Journal)
Electronic Resource
English
BKL:
38.58
Geomechanik
/
56.20
Ingenieurgeologie, Bodenmechanik
/
38.58$jGeomechanik
/
56.20$jIngenieurgeologie$jBodenmechanik
RVK:
ELIB41
Study on the Failure and Instability Mechanism of Coal–Rock Parting–Coal Structures under Unloading
| Springer Verlag | 2024