Research On The Mechanism And Technology Of Rock Burst Control In Datong Coal Mining Area

Rockburst is dynamic phenomenon of coal mine, caused by sudden release of the accumulated elastic energy in the surrounding coal and rock of tunnel and workface.Due to complicated formation mechanism, multiple influencing factors, diverse forms and serious consequence, rock burst has received considerable concern from scholars in rock mechanics theory and engineering field both at home and abroad. It is also a hotspot and difficult point in underground mining. Affected by factors such as geological conditions, property of surrounding rocks, mining order and support method, there is rock burst phenomenon at face and roadway of Datong Mining Area to different degrees, which is a bottleneck bothering safe and efficient production in the mining area. Therefore, research on occurrence mechanism and countermeasures of rock burst against engineering background of rock burst in this area, is of great significance to solution of the problem confronted by Datong Mining Area, strengthening knowledge to its occurrence mechanism and development of prevention and control theory and technology.Based on summary of existent research results, according to actual situation in Datong Mining Area, this article carried out exploratory research to cause and characteristics, occurrence mechanism, monitoring and forecast methods, control measures of rock burst in the area, by comprehensively applying approaches like case study, field measurement, laboratory experiment, theoretical analysis, numerical simulation and field test, concerning mechanism and control of rock burst. The main research contents and results are illustrated as below:1. Studied geological conditions, mining method, support method as well as occurrence of rock burst in four mines of Datong Mining Area in detail, analyzed the cause and summarized basic characteristics of rock burst in this area.2. Obtained basic physical and mechanical property of coal seam in Datong Mining Area with laboratory experiment, and analyzed rupture process and pattern of coal sample, according to its complete stress-strain curve and rupture fracture; field measurement was given to rock stress to obtain its distribution law in this area. Stress distribution in coal seam was obtained with method of theoretical research.3. Built a source mechanism model of coal seam impact "cylinder" according to occurrence and propagation law of coal fracture, and with this model, analyzed occurrence process of friable impact in coal seam; built a mechanical model of overall impact based on stick-slip theory and occurrence structure of coal seam, besides, according to this model, established kinetic equation of the overall impact and carry out solving, received analytical solution of displacement, velocity and acceleration of overall impact. According to bottom board structure and stress characteristics, built fractographic pattern and damage-instability model of bottom board impact, and received conditions of bottom board impact through solving the models. Research on mechanism of coal seam and bottom board impact provided theoretical basis for control of rock burst.4. Proposed a new index forecasting rock burst hazard, "gob ratio", according to occurrence history of rock burst in the field. The "gob ratio" is defined as percentage of gob in total mining area. Statistical result of rock burst in Datong Mining Area was applied to verify feasibility of this index and analyze its internal mechanism in theory. Rock burst monitoring and forecast procedure suitable for Datong Mining Area was proposed by combining "gob ratio" index with traditional monitoring and forecast method, and forecast software was designed to carry out auxiliary process to monitoring data. The research result was successfully applied to predict rock burst at test face.5. The relation between pressure relief and drilling parameters (hole position, hole diameter aperture, and combination mode of holes, etc.) and pressure-relief effect was studied in depth with methods of numerical simulation and theoretical analysis, and on this basis, proposed method of determining drilling and pressure relief basic parameters; research result was proved to be feasible by field application of drilling and pressure relief, which provided theoretical and technical support for effective control of rock burst in Datong Mining Area.6. Region control measures of rock burst in Datong Mining Area were studied:multiple exploitation and design principles of coal seams with burst tendency in this area were put forward according to occurrence mechanism of rock burst; feasibility of preventing rock burst by setting small pillar was studied with methods of theoretical analysis and numerical simulation; anti-scour support method with bolt-anchor cable-anchor net overall support mode was studied with numerical simulation. The comprehensive control measure was applied on the spot, and favorable effect was received.