Study On Occurrence Condition And Prevention Of Support Crushing And Water Inrush Disaster During Mining Under Unconsolidated Confined Aquifer

There is a layer of unconsolidated confined aquifer with high water pressure which forms with unconsolidated sand and grit at the bottom of thick quaternary topsoil in some east china north china coalmine. In recent years, some coalmines have occurred several accidents as supports crushing and water inrushing when mining under such unconsolidated confined aquifer. Take Wanbei Qidong coal mine as an example. It exist unconsolidated confined aquifer at the top of bedrock with thickness of35to50meters and water pressure3to4million Pa. Science mining from2002year, it has happened17accidents as supports crushing and water inrush, and has caused a serious threat to coal mine production safety and significant economic losses. Further research on occurring condition and disaster prevention skills of support crushing and water inrush accident during mining under unconsolidated confined aquifer were studied totally by theoretical analysis, numerical simulation, physical simulation, field measurements etc.According to theoretical and simulated experiment research, we reveal the mechanization of support crushing and water inrush disaster during mining under unconsolidated confined aquifer. The key strata within a certain condition are prone to compound breakage under the effect of load transfer of the unconsolidated confined aquifer, which is the basic reason of support crushing and water inrush disaster. The influence law of characteristic of unconsolidated confined aquifer, key stratum structure and primary key stratum structure stability to the support crushing and water inrush disaster. Larger the skeleton granule diameter is, better the property of flowing and replenishment is, larger the load transfer quotient is, it easily makes the key stratum compound breakage. While under the large load transfer of the unconsolidated confined aquifer, smaller the overburden thickness and larger the first key stratum above coal seam is, more easily the overburden forms compound single key structure, especially existing thick and strong rock in10times mining height, which is prone to caused support crushing and water inrush disaster. The key stratum is usually in an unstable condition and water flowing fracture develops anomaly and connect to the aquifer, which caused water inrush disaster.Aim to realize safe mining under unconsolidated confined aquifer, form a technical route of'dangerous area detecting, water level warning, real-time regulate and control' Forecasting method of dangerous area of support crushing and water inrush disaster and retaining safety coal and rock pillar are put forward according to occurrence condition of support crushing and water inrush disaster. Put forward roof pre-blasting based on location of key stratum and high resistance support to preventing support crushing and water inrush disaster before mining. Using the connected effect between water level variation of loose unconsolidated confined aquifer and roof weighting of working face, the forecasting method using descending speed of groundwater level for support crashing and water inrush disaster was put forward, And using support quality monitoring and mining velocity regulate and control during mining to prevent support crushing and water inrush disaster.Research results of condition and prevention of support crushing and water inrush disaster during mining under unconsolidated confined aquifer have being used successfully at NO.6130and7121working face in Qidong coal mine, which realizes the safe mining, retrieve a loss of12,700,000Yuan and create economic benefits of78,628,000Yuan. Achieve remarkable social and economic benefits.This paper contains83Figures,22tables and171references.