| Disturbance action cased by coal mining results in rock stratums losing their original mechanical balance.And physical characteristics of adjacent rock stratas have large differences comparatively,which causes the uncoordinated deformation along the level to the buckling and forms a convex lens shape space among adjacent rock stratums.Which called Bed Separation Space(BSS).When the extension of the gateway and its water accumulated to a certain extent,then the lower BSS is broken due to mining action,and the BSS broken make the BSS water(BSSW)to release into the goal along water bursting channel formed by diversion fissure zone.The mining BSSW inrush has become a new form of coal mine roof water inrush which called the roof BSS water inrush.Therefore,it is necessary to study the evolution mechanism of discontinuity water damage for reducing the personnel and property damage.The prediction and determination of BSSW inrush disaster involves complicated physical processes such as damage and failure law of rock,deformation law of rock mass and flow characteristic of separation water and so on.In order to further reveal the evolution law of BSS water inrush,this paper study the chemical composition of roof strata and the physical and mechanical parameters,the damage law of rock,the deformation law of rock as a whole and abscission layer water outburst flood operation system research,though the laboratory test,theoretical analysis,field test,numerical simulation methods,and combination with the delamination area of mine BSSW inrush disasters.The research results are as follows:(1)The differences of chemical composition,physical properties and mechanical properties of rocks in typical BSSW inrush zones are revealed.Rock at different depths was drilled on site in the in typical BSSW inrush zones area for chemical composition identification and mechanical experiments.Analyzing the differences of chemical composition between adjacent rock stratums and the elastic modulus,poisson's ratio and other mechanical parameters.From the micro angle to analyze the influence factors for BSSW inrush,founding that the differences of chemical composition,physical and mechanical properties is the prerequisite for the generation between adjacent rock stratums,the study can provide a simple determine method by geological geology for BSSW inrush disaster.(2)Establishing a rock damage statistical constitutive model based on triaxial confining pressure experiment.Based on statistical strength theory,the continuum damage mechanics and Weibull distribution function,the damage of the rock are divided into load damage and environmental damage and the damage evolution equation is deduced.The Z-P yield criterion is used to as the discriminant criterion of the rock cell broken and according to the confining pressure of rock triaxial experimental peaks experimental data,a rock damage constitutive model describing the process of rock damage under load is established.And through the comparative analysis of the experimental data and theoretical value to verify the reliability of the model.Considering the damage caused by water in rock and taking elastic modulus of damage as damage variable,through analyzing the function relationship between the sandstone saturated time and damage variable,and the function relationship between the environment humidity in carbonaceous mudstone and the damage variable,then deducing a statistical damage constitutive model considering the water influence combining with damage constitutive model of combination without considering water.The study provides the theoretical foundation for the discrimination of roof stratums broken.(3)Putting forward the prediction and determination model of BSS water inrush in goal for analyzing the location of BSSW,volume BSSW of and the characteristics of BSSW during mining.Based on the theory of thin plate and the derived damage constitutive model,and the overburden is simplified as the model of combination rock plate,the expression of the internal force of rock plate described by the disturbance of rock plate is derived.And the Z-P yield criterion is taken as the criterion for judging the failure of rock elements,the mechanical conditions for the formation of BSS are put forward.The BSS prediction and determination process are put forward according to the characteristics of composite rock plate and rock plate theory.Based on the seepage differential control equation of BSS morphology and darcy's law,the volume prediction formula of BSSW is deduced.This study can provide theoretical basis for the prediction of BSSW and the assessment of BSSW disaster.Based on similar simulation experiments,this paper analyzes the distribution characteristics of the water-conducting fracture zone in overlying rock and describes the flow process from formation to inrush of the discontinuity water by using the three flow modes of percolation-fissure flow-gushing water.(4)A three-dimensional water-inrush similar simulation experiment system was developed and used to analyz the evolution law of BSS and the mechanism of BSS water inrush.A three-dimensional water-inrush simulation experiment system has been independently developed,which can simulate three-dimensional coal seam mining and water-inrush disaster,and also can analyze the failure law of roof overburden,the development law of roof isolates and the characteristics of water-inrush.Based on the case of Yuanzigou coal,the development law of BSS,the failure law of coal overburden and the three-dimensional morphology of water-conducting fracture zone are explained.The experiment results show that when the coal seam is mined to 240 m,the water-diversion fissure zone develops to the highest level,and it is located in the conglomerate layer of yijun formation,with a height of 380 m and a fracture production ratio of 23.8:1.The monitoring data show that the separation layer under the conglomerate of luohe formation is the largest,and the existence of the aquifer makes the BSS water appear in the process of coal seam mining,and the BSS water damage can be formed.This study provides a new method for studying the mechanism of separation layer water damage.(5)Putting forward the control measures to reducing BSSW inrush disaster.Based on the rock plate model,two kinds of control measures are put forward.The first prevention measure is drilling some vertical diversion holes on the ground.The other is drilling some vertical diversion holes inclined diversion boreholes.This study provides a reliable reference for the prevention and control of roof layer water damage in actual mine production.There are 119 figures,5 tables and 186 references in this paper. |
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