Experimental and numerical studies of the blast-induced overbreak and underbreak in underground roadways

Hong, Z; Tao, M; Cui, X; Wu, C; Zhao, M

Experimental and numerical studies of the blast-induced overbreak and underbreak in underground roadways

Hong, Z Tao, M Cui, X Wu, C

Zhao, M

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Publisher:: Elsevier
Publication Type:: Journal Article
Citation:: Underground Space (China), 2023, 8, pp. 61-79
Issue Date:: 2023-02-01

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Field	Value	Language
dc.contributor.author	Hong, Z
dc.contributor.author	Tao, M
dc.contributor.author	Cui, X
dc.contributor.author	Wu, C https://orcid.org/0000-0001-6786-7934
dc.contributor.author	Zhao, M
dc.date.accessioned	2023-03-26T21:33:21Z
dc.date.available	2023-03-26T21:33:21Z
dc.date.issued	2023-02-01
dc.identifier.citation	Underground Space (China), 2023, 8, pp. 61-79
dc.identifier.issn	2096-2754
dc.identifier.issn	2467-9674
dc.identifier.uri	http://hdl.handle.net/10453/168418
dc.description.abstract	Overbreak and underbreak are the crucial problems during the blasting excavation of underground tunnels owing to their effects on the construction costs and operational safety. A critical challenge facing overbreak and underbreak control is the difficulty in developing guidelines with respect to various and complex engineering conditions. In this study, a series of field measurements of overbreak and underbreak using the FocusS 150 laser scanner were performed in a deep roadway of the Kaiyang phosphate mine, China. The distribution and extent of the overbreak and underbreak surrounding the roadway contour were accurately analyzed in accordance with the collected point cloud data. Subsequently, a simplified three-dimensional model was established to simulate the blasting excavation of pre-stressed roadway using the explicit dynamic analysis code LS-DYNA. A comparison of numerical and measurement results revealed that the proposed model was a reliable tool to simulate the overbreak and underbreak induced by blasting excavation. Thereafter, the influences of uncontrollable geological factors such as in situ stress conditions and controllable blasting factors including contour hole spacing (S), charge concentration (β) and decoupled coefficient (ζ) as well as stemming were further numerically investigated. The simulation results indicated that the lateral pressure coefficient significantly affected the distribution pattern of the overbreak and underbreak, while the stress magnitude contributed to their extents. Moreover, a comparison of the simulation findings and the field measurement data indicated that the minimal extents of the overbreak and underbreak corresponding the optimal contour blasting results were obtained at S = 0.70 m, β = 0.9 kg/m and ζ = 2.5, respectively. Furthermore, the contour blastholes stemmed with sand created smaller damage to the periphery rock mass of roadway and enhanced the utilization efficiency of explosive energy. The research findings of this study provide important implications for similar blasting excavation projects.
dc.language	en
dc.publisher	Elsevier
dc.relation.ispartof	Underground Space (China)
dc.relation.isbasedon	10.1016/j.undsp.2022.04.007
dc.rights	info:eu-repo/semantics/openAccess
dc.title	Experimental and numerical studies of the blast-induced overbreak and underbreak in underground roadways
dc.type	Journal Article
utslib.citation.volume	8
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology
pubs.organisational-group	/University of Technology Sydney/Faculty of Engineering and Information Technology/School of Civil and Environmental Engineering
pubs.organisational-group	/University of Technology Sydney/Strength - CBI - Centre for Built Infrastructure
utslib.copyright.status	open_access	*
dc.date.updated	2023-03-26T21:33:19Z
pubs.publication-status	Published
pubs.volume	8

Abstract:

Overbreak and underbreak are the crucial problems during the blasting excavation of underground tunnels owing to their effects on the construction costs and operational safety. A critical challenge facing overbreak and underbreak control is the difficulty in developing guidelines with respect to various and complex engineering conditions. In this study, a series of field measurements of overbreak and underbreak using the FocusS 150 laser scanner were performed in a deep roadway of the Kaiyang phosphate mine, China. The distribution and extent of the overbreak and underbreak surrounding the roadway contour were accurately analyzed in accordance with the collected point cloud data. Subsequently, a simplified three-dimensional model was established to simulate the blasting excavation of pre-stressed roadway using the explicit dynamic analysis code LS-DYNA. A comparison of numerical and measurement results revealed that the proposed model was a reliable tool to simulate the overbreak and underbreak induced by blasting excavation. Thereafter, the influences of uncontrollable geological factors such as in situ stress conditions and controllable blasting factors including contour hole spacing (S), charge concentration (β) and decoupled coefficient (ζ) as well as stemming were further numerically investigated. The simulation results indicated that the lateral pressure coefficient significantly affected the distribution pattern of the overbreak and underbreak, while the stress magnitude contributed to their extents. Moreover, a comparison of the simulation findings and the field measurement data indicated that the minimal extents of the overbreak and underbreak corresponding the optimal contour blasting results were obtained at S = 0.70 m, β = 0.9 kg/m and ζ = 2.5, respectively. Furthermore, the contour blastholes stemmed with sand created smaller damage to the periphery rock mass of roadway and enhanced the utilization efficiency of explosive energy. The research findings of this study provide important implications for similar blasting excavation projects.

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http://hdl.handle.net/10453/168418