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Aimed at the stability of surrounding rock in Pingdingshan Coal Mine, took a typical deep roadway with joint fissured surrounding rock as study object, used discrete element numerical simulation, simulated the deformation and failure mechanism of surrounding rock, and the control technologies of joint fissured surrounding rock roadway were proposed. The results show that the tensile failure appears at vault and two side-walls and in the middle of floor at first. Then, the shear failure appears at spandrel and two base angles. The failure zone extends into the deep area until the roadway is instable. According to the in-situ monitor data, it is concluded that the stress in anchor and cable tends to be stable after supporting for two months, as well as the horizontal convergence, vault subsidence and floor heave. It means that the supporting technology works and the stability of soft surrounding rock in deep rock roadway is controlled. [ABSTRACT FROM AUTHOR]

In order to study the distribution of dust particle matter (including PM2.5) in coal workface, the concentration of total dust, PM10 dust and PM2.5 dust were measured with the dust concentration tester during the mining process in all roadways of Coalface 91324 that is the comprehensive mechanized coal face at a coal mine in Jincheng city. The results were analyzed and show that the total dust concentration is at its maximum 5 m downwind of the coal cutter while PM10 and PM2.5 dust fluctuates heavily in the coalface; the concentrations of three kinds of dust (the total dust, PM10 dust and PM2.5 dust) increase gradually and reach their maximum values at 330 m, then decrease slowly in the auxiliary return roadway. The concentration of these three kinds of dust fluctuates within the low concentration range in the main return roadway. In the main return roadway and auxiliary roadway the maximum levels of PM2.5 dust are 56.087 mg/m³ and 180.39 mg/m³ respectively. The PM2.5 dust is above the limit of ambient air quality. These findings provide the parameters for modifying the standard of dust testing and prevention. [ABSTRACT FROM AUTHOR]