Study On Failure Properties Of Water Bearing Rock Under Internal Pressure Under Impact Load

With the development of the times,the demand for mineral resources in natural resources is increasing,but in the process of mineral resources exploitation,it is also accompanied by a series of problems,and the stability of underground goaf areas is a very critical issue in the process of safe production.In this paper,taking the Dolomite Mine in the south of Chengnan,Chenzhou,Hunan Province as the background,the basic mechanical parameters of the rock are obtained by taking field samples from the Dolomite Mine,and then using indoor experiments.Combined with the RMR rock mass classification system,the Dolomite Mine in Seongnam was evaluated,and the stability of the roof of the goaf was analyzed by mathews stability diagram method.According to the mine background and its data,the relationship between the strength of the ore column and its aspect ratio is studied,and the stability of the ore column in the mining area is analyzed and evaluated.Finally,flac^3D software was used to simulate and analyze the stability of the goaf of the Dolomite Mine in the south of the city,and the research content and conclusions were as follows:（1）Through the investigation of mine geological data,the basic conditions of hydrogeology,engineering geology,environmental geological conditions and mining status of the Dolomite Mine in the south of the city are understood,and the status quo and structural parameters of the 8 goaf areas of the mine are counted in detail.（2）Samples were taken from the dolomite mine in the south of the city,and indoor experiments were conducted to obtain its basic rock mechanical parameters.The Hoek-Brown criterion is applied to convert the rock mechanical parameters to obtain the basic mechanical parameters of the rock mass.Combined with the RMR rock mass classification system,the evaluation results of the surrounding rocks in the south of the city are good,which provides a data basis for the numerical simulation analysis of the stability of the subsequent goaf area.（3）The stability of the roof of the 8 goafs was evaluated by using the Mathews stability diagram method,and the top plates of the 6^#and 7^#goafs were stable,and the roofs of the other 6goafs were in a state of destruction.The stability of the ore column is analyzed by using the area bearing theory,and the stable state of the ore column is judged according to the critical safety factor of the ore column of 1.5.Among them:Pillar 13 of the 8^#Goaf is in a state of destruction,the level is IV.;the 1^#Goaf Column 3 and the 2^#Goaf No.8 column are in a more unstable state,the level is III.;the 4^#Goaf No.12 pillar is in a relatively stable state,the status level is II.;other ore columns are in a stable state,the level is I.（4）Using the"three belts"theory to estimate the safe mining depth,the calculation results show that the water-conducting fissure zone of the 1^#and 2^#goaf areas will be channeled to the fourth aquifer,and the water-conducting fissure zone of the 3^#,4^#,5^#,6^#,7^#,and 8^#goaf will not be channeled to the fourth aquifer.The theoretical analysis and derivation of the air impact disaster caused by the large-scale roof of the goaf shows that when the area of the roof rises and falls reaches more than 5%of the area of the roof of the goaf,the pressure and wind speed caused will endanger the safety of downhole operators.（5）The numerical simulation results of the 1^#-8^#goaf show that the 8 goafs have plastic yield units,but the plastic failure of the 2^#,5^#,8^#goaf and the displacement of the top plate are relatively large and are in a relatively unstable state,and the rest of the goaf is in a stable state.The goaf zones 2^#,5^#and 8^#with the possibility of instability are discussed from the stress field,displacement field and plastic zone respectively,and the treatment scheme using artificial ore columns is proposed.