The evaluation analysis on the airborne dust regional pollution of the anchor drilling operation in the tunnel.

Abstract

The anchor drilling operations generate massive airborne dust particles in the tunnel heading face that raises the pneumoconiosis morbidity and explosion risk. In this paper, a full-scale tunnel physical model is constructed to study the effect of the wind velocity and drilling site position on the airborne dust regional pollution scope based on the actual anchor drilling craft. The research indicates that the four extensive vortex areas keep the dust suspension at 14m from the heading face and make the deposition dust particle refloat. The average respirable dust rate reaches the maximum value at section 5m and presents a gradual decline as the dust particle migrates along the outlet direction. Raising the wind velocity contributes to alleviating the airborne dust pollution in the anchor drilling operation. As the wind velocity increases from 3 to 24m/s, the high dust concentration area and number higher than 200mg/m3 pose overall decrease trends, and the average dust concentration displays a linear decrease until 26.14-58.65mg/m3 around the anchor worker head. Moving the drilling site positions closer to the exhaust air duct aggravates the airborne dust pollution in the front breathing zone. As the anchor drilling operation switches from the return air side to the supply air side, the dust concentration area ascends by 59.4-84.4% in the personnel respiratory space.