Study on flow field structure and dust suspension law in tunnel construction drilling process

Abstract

In order to clarify the dust production law of railway tunnel drilling and blasting construction, the flow field structure characteristics and the distribution and migration law of drilling dust production in the tunnel under the condition of press-in ventilation were studied by indoor model test and CFD numerical simulation method. The results show that: 1) The dust concentration on the M axis and R axis gradually decreases with the increase of distance from the face of the face. The dust concentration on the L axis showed a small-large-small trend from the palm surface to the outlet of the hair dryer, and the maximum dust concentration appeared at 1m away from the face of the face. 2) Under the condition of press-in ventilation, the flow field structure can be divided into three parts: jet area, vortex area and reflux area, and the proportion of reflux gradually increases from 54% to 100% after three stages. 3) Large particles of dust mainly settle in the area of 1m from the end of the working face on the return air side, and the particle size of the dust settled on the tunnel floor gradually decreases with the increase of the distance from the face face; Most dust particles can settle or discharge the tunnel within 30s, and the vortex area has an adverse effect on the tunnel dust exhaust and dust reduction.