Optimization Of The Reasonable Coal Pillar Size In Large Mining Height Face Of Ting Nan Coal Mine

Determination of reasonable coal pillar width is key for ensuring safety production of large mining height face. Taking the determination of large mining height face and coal pillar in the second panel of Ting Nan Coal Mine as the engineering background, Theoretical calculation, field measurement, numerical simulation and similar materials simulation had been used to analysis the coal pillar systematically. It’s mostly contents as follows:Firstly, based on analyzing the basic geologic conditions, the failure regularity of current 30 m coal pillar under the effect of mining was systematically studied by using the method of field stress monitoring, studies have shown that when one side of the coal pillar in goaf, about 3 m in width of fractured zone near the goaf was found, and 18 m in width of low stress zone was realized; when the whole pillar was located in goaf, more than 15 m in width of stability region in the middle of the pillar; the results of gateway detection have shown that the width of current 30 m coal pillar is too large, and optimizing the section of coal pillar has certain feasibility. Though field measurement, the section scope of coal pillar initially identified as 5.2~13m. In addition, from the perspective of coal recovery ratio, tunnel support and safety mining under water body, the rationality of cutting along goaf and with thin pillar has been demonstrated; based on analyzing the principle of cutting along goaf and with thin pillar; the limit width of coal pillar was calculated as 6.12 m with limit equilibrium theory. And the lateral stress distributions, as well as the pillar stress evolution law, the elastic-plastic region variation, and the roadways deformation law of 9 different coal pillar that width of 4m, 5m, 6m, 7m, 8m, 9m, 10 m, 11 m, 12 m were studied systematically by numerical simulation; the reasonable width of coal pillar in large mining height face was determined as 10 m. Finally, though analyzing the correlation between overburden failure evolution and pressure distribution of coal pillar, the reasonableness and reliability was verified by using similar materials simulation.Papers of the research results provide theoretical basis for the large mining height face coal pillar size design in the second panel of Ting Nan Coal Mine, and under similar conditions of coal pillar size design has the certain reference value.