Research On Mechanical Mechanism Of Fault Activation And Water Inrush From Faults In Mining Floor

The prediction and prevention of water inrush accidents in coal mine has always been one significant subject of safe mining production in china, in which water inrush from faults in floor is one main style. In the process of mining, faults in floor are likely to be activated and link to mining-induced fissures to form water channel, which is one important reason that induces many water inrush accidents in coal mines. In this thesis, different study methods including theoretical analysis, experimental test, numerical simulation and field practice are applied to systematically research the mechanical mechanism of water-inrush with fault activated by mining in floor, and obtain the following innovational results:The permeability property of rock around fault zone is measured by using permeability measurement system for rocks with fissures and broken rocks, which indicates that: compared with common rock with fissures, the permeability of post-peak borken rock and in situ can reach up to 10 to 1000 times of that; the premeability of broken samples is greatly controlled by axial and surrounding pressures. The study results can play an important role in revealing mechanism of water-inrush induced by fault activation.According to the mechanical characteristics of water inrush form faults activated by mining, mechanical model on mechanism analysis of fault activation in mining floor is built, obtaining stress field distribution rule of rock around fault, giving out shear stress criterion for falut activation in floor, analyzing the effect of factors, such as mining deepth, fault dip, fault throw, advance direction, concentration degree of supporting force in working face, on rule of fault activation in floor.Control volume method is applied to build dynamical control equation for water flow in fissures of fault zone, analyzing and presenting the distribution rule of water pressure in fissures; based on this, the propagation characteristics of fissures under the effect of pore pressure in fault zone is studied by using fracture mechanics theory, and give the corresponding criterion for fissure propagation; getting the change rule for effective stress strength of tension-shear compound fissures, compaction-shear compound fissures along with fissure water pressure.Numerical simulation method is also applied to study fault activation in mining floor and characteristics of seepage field, obtaining scope of fault activation as well as change rule for seepage velocity along with fault dip, fault throw, confined water pressure, comparing the difference and similarity on falut activation and seepage characteristics under the two different conditions of normal fault and reverse one, and primarily finding the determination method for water-proof coal pillar under the situation of mining floor with fault above confined water.The research results have been successfully applied in the water inrush prediction and prevention practice of working face with fault in a certain mining area, and created significant social and economic value, which can provide reference for the prevention of water inrush in mining area with the similar engineering condition.There are 119 figures, 26 tables and 177 references in this thesis.