Mining causes stress redistribution and stratum movement.In this paper,a numerical model was built according to the geological conditions in the 12th coal mine in Pingdingshan city to study the strata movement and the...Mining causes stress redistribution and stratum movement.In this paper,a numerical model was built according to the geological conditions in the 12th coal mine in Pingdingshan city to study the strata movement and the evolution of stress when mining two overlapping longwall panels,named panels#14 and#15.The strata close to the mined panel move directly towards the gob,while the strata that are farther away swing back and forth during the mining process.The directed movement and swinging can break the transverse boreholes for gas extraction;a surface borehole should not be within the range of directional movement.The stress evolution suggested that the mining of the lower panel#15 after the upper panel#14 would further increase the de-stressed range,while the stress concentration around the mined panel would be increased.Hard strata usually carry a greater stress than adjacent rocks and soft coal seams.The stress in a hard stratum increases greatly,and the stress decreases greatly in the coal seams below the hard stratum.This study supplies a reference for similar coal mines and is useful for determining the de-stressed range and transverse borehole arrangement for gas extraction.展开更多
As China＇s energy strategy moving westward, the surface movement and deformation characteristics due to high-intensive coal mining in the windy and sandy region become a research hotspot. Surface movement observation...As China＇s energy strategy moving westward, the surface movement and deformation characteristics due to high-intensive coal mining in the windy and sandy region become a research hotspot. Surface movement observation stations were established to monitor movement and deformation in one super-large working face. Based on field measurements, the surface movement and deformation characteristics were obtained, including angle parameters, subsidence prediction parameters, etc. Besides, the angle and subsidence prediction parameters in similar mining areas are summarized; the mechanism of surface movement and deformation was analyzed with the combination of key stratum theory, mining and geological conditions. The research also indicates that compared with conventional working faces, uniform subsidence area of the subsidence trough in the windy and sandy region is larger, the trough margins are relative steep and deformation values present convergence at the margins, the extent of the trough shrink towards the goaf and the influence time of mining activities lasts shorter; the overlying rock movement and breaking characteristics presents regional particularity in the study area, while the single key stratum, thin bedrock and thick sand that can rapidly propagate movement and deformation are the deep factors, contributing to it.展开更多
When mining metal mines with steep structure planes by the caving method,there is a mechanical model in which the horizontal stress on the rock mass is simplified as a column before surface subsidence.The model is use...When mining metal mines with steep structure planes by the caving method,there is a mechanical model in which the horizontal stress on the rock mass is simplified as a column before surface subsidence.The model is used to deduce critical support load and limiting column length for a given horizontal stress and support pressure.Considering the impact of the column effect,a method is proposed to determine the movement of the ground and caving area in a mine.After surface subsidence,the horizontal stress on a surrounding rock mass can be simplified to a cantilever beam mechanical model.Expressions for its bending fracture length are deduced,and a method is given to determine its stability.On this basis,an explanation for the large ground movement and subsidence scope was given.A case study shows that the damage effect of column and cantilever beam is significant for ground movement in metal-ore mine,and an appropriate correction value should be applied when designing for its angle of ground movements.展开更多
基金the National Key R&D Program of China(No.2016YFC0801402)the National Natural Science Foundation of China(No.51874291).
文摘Mining causes stress redistribution and stratum movement.In this paper,a numerical model was built according to the geological conditions in the 12th coal mine in Pingdingshan city to study the strata movement and the evolution of stress when mining two overlapping longwall panels,named panels#14 and#15.The strata close to the mined panel move directly towards the gob,while the strata that are farther away swing back and forth during the mining process.The directed movement and swinging can break the transverse boreholes for gas extraction;a surface borehole should not be within the range of directional movement.The stress evolution suggested that the mining of the lower panel#15 after the upper panel#14 would further increase the de-stressed range,while the stress concentration around the mined panel would be increased.Hard strata usually carry a greater stress than adjacent rocks and soft coal seams.The stress in a hard stratum increases greatly,and the stress decreases greatly in the coal seams below the hard stratum.This study supplies a reference for similar coal mines and is useful for determining the de-stressed range and transverse borehole arrangement for gas extraction.
基金Financial supports for this work, are provided by the National Natural Science Foundation of China （NSFC） ＆ Shenhua Group Corporation Limited key support project of the coal joint fund （U1361203） and NSFC under Grant No. 41501562. Thanks are also due to some participants for rendering assistant cooperation during studies.
文摘As China＇s energy strategy moving westward, the surface movement and deformation characteristics due to high-intensive coal mining in the windy and sandy region become a research hotspot. Surface movement observation stations were established to monitor movement and deformation in one super-large working face. Based on field measurements, the surface movement and deformation characteristics were obtained, including angle parameters, subsidence prediction parameters, etc. Besides, the angle and subsidence prediction parameters in similar mining areas are summarized; the mechanism of surface movement and deformation was analyzed with the combination of key stratum theory, mining and geological conditions. The research also indicates that compared with conventional working faces, uniform subsidence area of the subsidence trough in the windy and sandy region is larger, the trough margins are relative steep and deformation values present convergence at the margins, the extent of the trough shrink towards the goaf and the influence time of mining activities lasts shorter; the overlying rock movement and breaking characteristics presents regional particularity in the study area, while the single key stratum, thin bedrock and thick sand that can rapidly propagate movement and deformation are the deep factors, contributing to it.
基金Project(51274188)supported by the National Natural Science Foundation of China
文摘When mining metal mines with steep structure planes by the caving method,there is a mechanical model in which the horizontal stress on the rock mass is simplified as a column before surface subsidence.The model is used to deduce critical support load and limiting column length for a given horizontal stress and support pressure.Considering the impact of the column effect,a method is proposed to determine the movement of the ground and caving area in a mine.After surface subsidence,the horizontal stress on a surrounding rock mass can be simplified to a cantilever beam mechanical model.Expressions for its bending fracture length are deduced,and a method is given to determine its stability.On this basis,an explanation for the large ground movement and subsidence scope was given.A case study shows that the damage effect of column and cantilever beam is significant for ground movement in metal-ore mine,and an appropriate correction value should be applied when designing for its angle of ground movements.
