Research on Control Mechanism and Application of Sequenced Instability of Section Key Stratum in Short Wall Continuous Mining
Author:Wang Shu Li
Supervisor:zhang kai zhi
With reducing and exhausting of coal resources,it is imperative to mining and using boundary coal.The paper aiming at large area hanging roof,collapse and vibration of short-wall mining,taking Shendong mining area as an engineering background,put forward short-wall continuous mining with full roof falling.Using theoretical analysis,laboratory experiments,numerical simulation and field monitoring to analyze and verify the feasibility of sequenced instability of section key stratum.Research fracture and movement of overlying strata and spatial structure evolution;analyze failure form and stress distribution of coal pillar and design control technology to keep roof falling safety.Realize the key strata "mining before and fractured later",and "collaps but no hazard".The main conclusions as follows:(1)Short-wall continuous mining with full roof fallingBased on analyzing fractured forms of key strata of short-wall mining,which including single section movement,several sections movement and single section stable-large area hanging roof,put forward continuous short-wall mining with full roof falling to control large area hanging roof and reduce collapse degree.Putting section key strata regard as a control unit,and key strata-coal pillar as one system to design reasonable length of section and width of isolated coal pillar.Leaving no coal pillar and keeping key strata stable in one section and movement in next section.(2)Sequenced instability of section key stratumBased on the theory of thin plate analyze the changing of limited span of key stratum to establish principles of design reasonable section length.According to coal pillar separation of elastic-plastic and Mises criteria establish principles to design reasonable coal pillar width,which including the minimum width keeping key strata stable mining single section and the maximum width keeping key strata-coal pillar fractured and broken synchronously mining next sections.Finally,taking the highest abutment pressure as link,establish basic principles of sequenced instability of section key stratrum systemly.(3)Fracture and movement of overlying strataResearch fracture and movement of overlying strata,and spitial structure evolution by simulated experiments,Which main including stable of key strata-coal pillar during mining single section and several sections,failure form and broken process of coal pillar between sections,spatial structures evolution of key strata and the secondary movement mechanism of high and thick hard key strata.(4)Stress distribution and evalution of coal pillarEstablishing two structures’ numerical calculation model,analyze stress distribution of block and isolated coal pillar mining single and several sections.Analyzing the distribution of elastic-plastic zone,combining with the evalution of highest abutment pressure,analyze and verify the stability of coal pillar and key strata.(5)Control technology and applicationControlling immediate and main roof by linear support and blasting,to reduce hanging roof area and collapse degree,keep mining space safety.Designing Arc-shaped bulkhead to anti-shock caused by fracture of key strata calculating the pressure,width of wall.Research results and control technology used in Shendong mining area successfully.