Hydraulic weakening technology for unsupported top coal at the end of fully mechanized caving face
To address the issue of excessive unsupported top coal length and delayed caving at the end of a fully mechanized caving face, a hydraulic weakening technology for face-end top coal in steeply inclined thick coal seams was proposed based on the coal-breaking and cavity creation method using high-pre...
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| Format: | Article |
| Language: | zho |
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Editorial Department of Industry and Mine Automation
2025-05-01
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| Series: | Gong-kuang zidonghua |
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| Online Access: | http://www.gkzdh.cn/article/doi/10.13272/j.issn.1671-251x.2025020050 |
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| author | DONG Haofu ZHANG Wei SUN Guangjun FU Huijian LONG Zhaoxi LIU Yang LIU Dongliang ZHU Xiaodong |
| author_facet | DONG Haofu ZHANG Wei SUN Guangjun FU Huijian LONG Zhaoxi LIU Yang LIU Dongliang ZHU Xiaodong |
| author_sort | DONG Haofu |
| collection | DOAJ |
| description | To address the issue of excessive unsupported top coal length and delayed caving at the end of a fully mechanized caving face, a hydraulic weakening technology for face-end top coal in steeply inclined thick coal seams was proposed based on the coal-breaking and cavity creation method using high-pressure water jet. Taking the 31123-1 steeply inclined fully mechanized caving face of Dongxia Coal Mine as the engineering background, a mechanical model was established for the unsupported top coal condition at the end of a fully mechanized caving face. Based on the principle of linear superposition, the deflection equation under the combined action of bending moment and shear stress was derived. It was found that the deflection at the free end of the unsupported top coal was greatest, while the fixed end generated the maximum tensile stress due to the peak bending moment, identifying this area as the optimal zone for hydraulic weakening. This study revealed that high-pressure water jets weakened the mechanical connection between the top coal and coal pillar through impact-induced coal fracturing, cavity creation, and fracture propagation. A standardized procedure of "drilling positioning→high-pressure jet coal breaking→rotational cavity creation" was proposed. By combining numerical calculation and field application, this study analyzed the evolutionary patterns of stress distribution in the face-end top coal zone, deformation characteristics of surrounding rock of roadways, and collapse effects of unsupported face-end top coal before and after applying the new technology. The results demonstrated that after hydraulic weakening for coals, the peak values of vertical stress inside the coal pillar and advanced support stress of the working face decreased by 29.6% and 17.4%, respectively. The maximum convergence of the roof-to-floor and rib-to-rib in roadways reduced by 35.8% and 37.8%, respectively, and the unsupported top coal length decreased from the original 10 m to 1 m. |
| format | Article |
| id | doaj-art-644285a8570944b9832123e2e76fc8bc |
| institution | Kabale University |
| issn | 1671-251X |
| language | zho |
| publishDate | 2025-05-01 |
| publisher | Editorial Department of Industry and Mine Automation |
| record_format | Article |
| series | Gong-kuang zidonghua |
| spelling | doaj-art-644285a8570944b9832123e2e76fc8bc2025-08-20T03:33:43ZzhoEditorial Department of Industry and Mine AutomationGong-kuang zidonghua1671-251X2025-05-01515152210.13272/j.issn.1671-251x.2025020050Hydraulic weakening technology for unsupported top coal at the end of fully mechanized caving faceDONG Haofu0ZHANG Wei1SUN Guangjun2FU Huijian3LONG Zhaoxi4LIU Yang5LIU Dongliang6ZHU Xiaodong7Dongxia Coal Mine, Huating Coal Industry Group Co., Ltd., Pingliang 744100, ChinaDongxia Coal Mine, Huating Coal Industry Group Co., Ltd., Pingliang 744100, ChinaSchool of Mines, China University of Mining and Technology, Xuzhou 221116, ChinaDongxia Coal Mine, Huating Coal Industry Group Co., Ltd., Pingliang 744100, ChinaSchool of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, ChinaDongxia Coal Mine, Huating Coal Industry Group Co., Ltd., Pingliang 744100, ChinaDongxia Coal Mine, Huating Coal Industry Group Co., Ltd., Pingliang 744100, ChinaDongxia Coal Mine, Huating Coal Industry Group Co., Ltd., Pingliang 744100, ChinaTo address the issue of excessive unsupported top coal length and delayed caving at the end of a fully mechanized caving face, a hydraulic weakening technology for face-end top coal in steeply inclined thick coal seams was proposed based on the coal-breaking and cavity creation method using high-pressure water jet. Taking the 31123-1 steeply inclined fully mechanized caving face of Dongxia Coal Mine as the engineering background, a mechanical model was established for the unsupported top coal condition at the end of a fully mechanized caving face. Based on the principle of linear superposition, the deflection equation under the combined action of bending moment and shear stress was derived. It was found that the deflection at the free end of the unsupported top coal was greatest, while the fixed end generated the maximum tensile stress due to the peak bending moment, identifying this area as the optimal zone for hydraulic weakening. This study revealed that high-pressure water jets weakened the mechanical connection between the top coal and coal pillar through impact-induced coal fracturing, cavity creation, and fracture propagation. A standardized procedure of "drilling positioning→high-pressure jet coal breaking→rotational cavity creation" was proposed. By combining numerical calculation and field application, this study analyzed the evolutionary patterns of stress distribution in the face-end top coal zone, deformation characteristics of surrounding rock of roadways, and collapse effects of unsupported face-end top coal before and after applying the new technology. The results demonstrated that after hydraulic weakening for coals, the peak values of vertical stress inside the coal pillar and advanced support stress of the working face decreased by 29.6% and 17.4%, respectively. The maximum convergence of the roof-to-floor and rib-to-rib in roadways reduced by 35.8% and 37.8%, respectively, and the unsupported top coal length decreased from the original 10 m to 1 m.http://www.gkzdh.cn/article/doi/10.13272/j.issn.1671-251x.2025020050fully mechanized caving facesteeply inclined thick coal seamtop coal weakeningunsupported face-end top coaltop coal collapsehydraulic coal breaking and cavity creation |
| spellingShingle | DONG Haofu ZHANG Wei SUN Guangjun FU Huijian LONG Zhaoxi LIU Yang LIU Dongliang ZHU Xiaodong Hydraulic weakening technology for unsupported top coal at the end of fully mechanized caving face Gong-kuang zidonghua fully mechanized caving face steeply inclined thick coal seam top coal weakening unsupported face-end top coal top coal collapse hydraulic coal breaking and cavity creation |
| title | Hydraulic weakening technology for unsupported top coal at the end of fully mechanized caving face |
| title_full | Hydraulic weakening technology for unsupported top coal at the end of fully mechanized caving face |
| title_fullStr | Hydraulic weakening technology for unsupported top coal at the end of fully mechanized caving face |
| title_full_unstemmed | Hydraulic weakening technology for unsupported top coal at the end of fully mechanized caving face |
| title_short | Hydraulic weakening technology for unsupported top coal at the end of fully mechanized caving face |
| title_sort | hydraulic weakening technology for unsupported top coal at the end of fully mechanized caving face |
| topic | fully mechanized caving face steeply inclined thick coal seam top coal weakening unsupported face-end top coal top coal collapse hydraulic coal breaking and cavity creation |
| url | http://www.gkzdh.cn/article/doi/10.13272/j.issn.1671-251x.2025020050 |
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