Numerical simulation of radon ventilation optimization in filling stope of trackless Z-shaped roadway

In order to study the laws of radon reduction ventilation in a stope with trackless Z-shaped filling method, the actual geometric structure, ventilation parameters, and radon exhalation rate of the exposed surface of this type of stope are determined. The air flow rate distribution, average radon concentration and the volume proportion exceeding the stipulated limit in stopes of different heights were studied by CFD method for the direct ventilation structure and the improved structure with adjustable air curtain. The results show that: 1) For the existing ventilation structure, with the increase of the height of the stope, the air flow rate into the workspace of the stope gradually decreases, and is lower than the required value for radon reduction in the stope, resulting in the average radon concentration in the stope greatly exceeding the stipulated limit. 2) For the improved structure with an adjustable air curtain at the upper mouth of the Z-shaped ramp, the air flow rate can be effectively allocated to the workspace of the stope, and the average radon concentration and the volume proportion exceeding the stipulated limit can be reduced. 3) Based on the numerical simulation results, the relation between the air flow rate of the workspace and the total air flow rate, the height of the stope, and the area ratio of adjustable air curtain to ramp is established, which provides a reference for optimizing the air flow rate distribution of radon reduction ventilation by adjusting the area ratio of adjustable air curtain to ramp.