In multi-seam mining,the interlayer rock strata between the upper coal seam(UCS)and the lower coal seam(LCS)appear damage and strength weakening after mining the UCS.Ground stability control of the gob-side entry reta...In multi-seam mining,the interlayer rock strata between the upper coal seam(UCS)and the lower coal seam(LCS)appear damage and strength weakening after mining the UCS.Ground stability control of the gob-side entry retaining(GER)under the gob with close distance coal seams(CDCS)is faced with difficulties due to little attention to GER under this condition.This paper focuses on surrounding rock stability control and technical parameters design for GER under the gob with CDCS.The floor rock strata damage characteristics after mining the UCS is first evaluated and the damage factor of the interlayer rock strata below the UCS is also determined.Then,a structural mechanics model of GER surrounding rock is set up to obtain the main design parameters of the side-roadway backfill body(SBB)including the maximum and minimum SBB width calculation formula.The optimal SBB width and the water-to-cement ratio of high water quick-setting material(HWQM)to construct the SBB are determined as 1.2 m and 1.5:1.0,respectively.Finally,engineering trial tests of GER are successfully carried out at#5210 track transportation roadway of Xingwu Colliery.Research results can guide GER design under similar mining and geological conditions.展开更多
The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the...The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the backfill wall, we propose a mechanical model on the structural effect of a soft-hard backfill wall using theory analysis, physical experiments and a numerical simulation. The results show thatChe deformation of the structure of the soft-hard backfill wall is coordinated with the roof and floor. The soft structure on the top of the backfill wall can absorb the energy in the roof by its large deformation and adapt to the given deformation caused by the rotation and subsidence of a key rock block. The hard structure at the bottom of the backfill wall can absorb the strong supporting resistance from the top surrounding rock. The soft structure on the top protecting the hard bottom structure by its large deformation contributes to the stability of the entire backfill wall. An application indicated that the stress in the backfill wall effec- tively decreased and its deformation was significantly reduced after the top coal remained. This ensured the stability of the backfill wall.展开更多
In order to determine the rational width of backfill in the goaf-side retained roadway, the deformation failure mechanism of surrounding rock in retained roadway is studied in the use of theoretical analysis, numerica...In order to determine the rational width of backfill in the goaf-side retained roadway, the deformation failure mechanism of surrounding rock in retained roadway is studied in the use of theoretical analysis, numerical simulation, etc., when the width of backfill is different. The results show that: with the increase of backfill width, the roof deformation above the backfill decreases; the outside of backfill obviously suffers from greater stress compared to the inner side of backfill; the damage firstly appears in the intersection of top backfill and roof; the plastic failure area is mainly distributed in the roof and floor of inside the roadway; 2 m wide backfill in the goaf-side retained roadway can meet the requirements of roadway deformation. Based on the original combination support of "anchor-mesh-belt-lock" in the haulage-track roadway, the study also considers the reinforced support of "anchor-mesh-belt" above the backfill, and 50 m ahead of working face, and 200 m behind the working face. This kind of support achieves a good result. The roadway deformation of field measurement shows that it can satisfy the need of the next working face.展开更多
基金financial support from the National Natural Science Foundation of China(Nos.51804111,51974117,51904102,and 52074117)Natural Science Foundation of Hunan Province(No.2020JJ5194)the Postgraduate Scientific Research Innovation Project of Hunan Province(No.CX20200991)。
文摘In multi-seam mining,the interlayer rock strata between the upper coal seam(UCS)and the lower coal seam(LCS)appear damage and strength weakening after mining the UCS.Ground stability control of the gob-side entry retaining(GER)under the gob with close distance coal seams(CDCS)is faced with difficulties due to little attention to GER under this condition.This paper focuses on surrounding rock stability control and technical parameters design for GER under the gob with CDCS.The floor rock strata damage characteristics after mining the UCS is first evaluated and the damage factor of the interlayer rock strata below the UCS is also determined.Then,a structural mechanics model of GER surrounding rock is set up to obtain the main design parameters of the side-roadway backfill body(SBB)including the maximum and minimum SBB width calculation formula.The optimal SBB width and the water-to-cement ratio of high water quick-setting material(HWQM)to construct the SBB are determined as 1.2 m and 1.5:1.0,respectively.Finally,engineering trial tests of GER are successfully carried out at#5210 track transportation roadway of Xingwu Colliery.Research results can guide GER design under similar mining and geological conditions.
基金Financial supports for this work, provided by the New Century Excellent Talents in University (No.NCET-05-0480)the Research Fund of the State Key Laboratory of Coal Resources and Mine Safety of CUMT (No.09KF06)the Scientific Research Fund of CUMT (No.OA090239)
文摘The stability of a backfill wall is critical to implement gob-side entry driving technology in which a small coal pillar is substituted by a waste backfill wall. Based on features of surrounding rock structures in the backfill wall, we propose a mechanical model on the structural effect of a soft-hard backfill wall using theory analysis, physical experiments and a numerical simulation. The results show thatChe deformation of the structure of the soft-hard backfill wall is coordinated with the roof and floor. The soft structure on the top of the backfill wall can absorb the energy in the roof by its large deformation and adapt to the given deformation caused by the rotation and subsidence of a key rock block. The hard structure at the bottom of the backfill wall can absorb the strong supporting resistance from the top surrounding rock. The soft structure on the top protecting the hard bottom structure by its large deformation contributes to the stability of the entire backfill wall. An application indicated that the stress in the backfill wall effec- tively decreased and its deformation was significantly reduced after the top coal remained. This ensured the stability of the backfill wall.
基金Financial support for this work was provided by Chinese National 863 High Technology Plan (No. 2012AA062101)the Priority Academic Program Development of Jiangsu Higher Education Institutions (No. SZBF2011-6-B35)the Graduate Students Innovation Fund of Colleges and Universities in Jiangsu Province (No.CXZZ12_0950)
文摘In order to determine the rational width of backfill in the goaf-side retained roadway, the deformation failure mechanism of surrounding rock in retained roadway is studied in the use of theoretical analysis, numerical simulation, etc., when the width of backfill is different. The results show that: with the increase of backfill width, the roof deformation above the backfill decreases; the outside of backfill obviously suffers from greater stress compared to the inner side of backfill; the damage firstly appears in the intersection of top backfill and roof; the plastic failure area is mainly distributed in the roof and floor of inside the roadway; 2 m wide backfill in the goaf-side retained roadway can meet the requirements of roadway deformation. Based on the original combination support of "anchor-mesh-belt-lock" in the haulage-track roadway, the study also considers the reinforced support of "anchor-mesh-belt" above the backfill, and 50 m ahead of working face, and 200 m behind the working face. This kind of support achieves a good result. The roadway deformation of field measurement shows that it can satisfy the need of the next working face.
