Theoretical Analysis And Verification Of Water Inrush Danger In Deep Mining Affected By Local High Confined Water And Multiple Aquifers

With the continuous development of coal seams,the local high confined water in the aquifer and the multi-aquifer in the floor seriously threaten the safe mining of coal.In this paper,the research methods of reference data,theoretical analysis,modeling solution,numerical verification and instance verification are used.Based on the actual situation,the existence characteristics of local high confined water and multi-aquifer in the deep floor are discussed respectively.Their historical formation process and water inrush danger are analyzed.The mechanical models applicable to their mechanism of action are established respectively.The risk of water inrush under the influence of the two is solved and analyzed.Combined with numerical calculations and examples,the analysis,application and verification are carried out,which has certain guiding significance for the prevention and control of deep water inrush under the influence of both.This article has achieved the following conclusions:(1)Based on the previous research results,the characteristics of local high confined water and multi-aquifer in the floor are summarized,and the actual existence and historical formation process are described.The water inrush danger and mode of action are roughly analyzed.Among,local high confined water can be used as a water inrush channel(vertically developed water-conducting collapse column),which can form a water inrush channel(causing damage to the water-bearing rock formation),and all have relative sealing and high water pressure;It is an independent destructive action to the water-bearing strata and has the risk of inducing the large scale surge of water inrush from aquifer;The water inrush from the multi-aquifer floor has singularity,linkage,hysteresis and integrity,and the risk of water inrush is different.The hydraulic effect between aquifers may have no influence,negative influence and positive influence relationship.(2)Based on the theory of "down three zone" and "the key strata",the water-resisting key strata in the floor and the local high confined water area were simplified into the cylinder mechanics model,and the yield failure mechanism of the water-resisting key strata under the role of local high confined water was analyzed.Four critical water pressure formulae for yielding in the water-resisting key strata were obtained.By dividing the critical water pressure values into sections and analyzing the yielding state of the water-resisting key strata in different sections,the water pressure criterion balance equations for the two stages of yielding and breaking of the water-resisting key strata caused by local high confined water were determined.The calculation expression of the remaining water-resisting capacity of the Ordovician top rock layer as water-resisting key strata was obtained.And the formulas for the upper and lower limits of the mining depth were obtained by inverse derivation.Combined with the deep mining practice of Jiulong Mine and FLAC3D numerical method,the mechanics model was validated and applied.And the relevant measures were proposed to prevent the local high confined water disaster,which has important theoretical significance for realizing safe mining of deep coal seam.(3)Based on the theory of "down three zone",the state distribution characteristics of multi-aquifer floor are analyzed,and a mechanical model for evaluating water inrush from deep multi-aquifer is innovatively established.In the model,the mechanical action,hydraulic connection and head loss of multi-aquifer were considered comprehensively,and the classification and analysis of complex water inrush in multi-aquifer can be realized.Through the analysis of the mechanical model,the water inrush conditions and criteria of different water inrush modes are obtained.The water inrush modes of deep multi-aquifer are summarized as four types,namely,single aquifer water inrush,multi-aquifer linkage water inrush,single aquifer lagging water inrush and multi-aquifer linkage lagging water inrush,and the prevention and control measures for each water inrush mode are proposed.The prevention and control principles of water inrush from multi-aquifer are summarized comprehensively as follows:preventing linkage,eliminating hysteresis,preventing water inrush from a single aquifer,focusing on prevention and control,and preventing step by step.Combined with the actual three floor aquifers of the Jiulong Mine in Fengfeng Mining Area,the mechanical model was verified and applied.