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Wall-mounted swirling ventilation is a new type of system in mechanized excavation faces with a dust suppression performance that is closely related to the blowing-to-suction flow ratio. Physical and simulation models were developed according to the No. C103 mechanized excavation face in the Nahe Coal Mine of the Baise Mining Bureau, Guangxi Province to optimize the blowing-to-suction flow ratio for wall-mounted swirling ventilation. Both the k-ε turbulence model and the discrete phase model were utilized to simulate airflow field structures and dust concentration distribution patterns at various blowing-to-suction flow ratios. The results suggest that higher blowing-to-suction flow ratios increase the airflow field disturbance around the working face and weaken the intensity of the axial air curtain. On the other hand, both the intensity of the radial air curtain and the dust suppression effect are enhanced. At a blowing-to-suction flow ratio of 0.8, the wall-mounted swirling ventilation system achieved the most favorable dust suppression performance. Both the total dust and respirable dust had their lowest concentrations with maximum efficiencies of reducing both types at 90.33% and 87.16%, respectively.

Abstract. In order to find out the serious and long plagued leakage problems related to the seepage cut-off wall of Nanmenxia Reservoir, used the introduced British Groundvue series of Ground Penetrating Radar equipment, field test and verify work were implied, leakage location and path were determined. The results showed that the seepage cut-off wall of dam foundation is well, its thickness is around 0.50m, but it has the horizontal distance of about 3m away from the current grouting platform, which may be one important cause that the previous grouting effects are bad. This provided important support for the Reinforcement Project of Nanmenxia Reservoir.