Roof breaking and dynamic evolution of energy field in thick coal seam working face

Abstract

In order to solve the problems of significant increase of bearing pressure and energy accumulation in front of the working face when the basic roof of the working face in deep and thick coal seam is broken, this paper takes 5301 fully mechanized top coal caving face of a mine as the engineering background, the evolution law of roof breaking, advance abutment pressure and energy field in the process of working face advancing was obtained through field micro-seismic monitoring and abutment pressure in front of working face, combined with three-dimensional numerical simulation, and the influence of advance breaking of basic roof on dynamic evolution of energy field was revealed. Research results show that when the basic roof is fractured, the rotating movement of the broken rock beam causes the coal body to be destroyed between the fracture line and the coal wall of the working face, resulting in the energy release of the coal body within 18 m in front of the working face, and the elastic energy density decreases from 55 kJ to 28.5 kJ. With the increase of the separation amount between the basic roof and overburden, the supporting point of the basic roof to the upper rock stratum moves forward to the position beyond the fault line, and the peak of the supporting stress moves forward to about 20-25 m in front of the coal wall, and the corresponding coal outside the fault line (22-90 m in front of the coal wall) can release the accumulation of elastic strain energy (the total increase of energy is 176.2 kJ). The energy peak increased from 80.15 kJ to 136 kJ, and the energy concentration coefficient reached 2.94.

Keywords

• deep dynamic disaster
• micro-seismic monitoring
• roof fracture
• numerical simulation
• energy evolution