Field test and study on construction ventilation of small-radius spiral tunnels

To study the diffusion law of pollutants in spiral tunnel construction, the ventilation parameters, carbon monoxide concentration after blasting, and dust concentration in the spraying process of spiral tunnel construction in Midi Village of Jian (Ge) Yuan expressway in Honghe Prefecture of Yunnan province were measured by the field test method. The results showed that the wind speed along the tunnel decreased with the increase of the distance from the palm surface, and the wind speed had different effects at different air duct hanging positions. The detection results of carbon monoxide concentration showed that the flue gas gradually diffused outwardly with the airflow, the flue gas concentration showed a “rise-peak-decline” at all places beyond the distance from the shotcrete, and the dust concentration along the shotcrete process showed a decreasing trend with the increase of the distance from the face of the gun. The research results can provide a theoretical basis and engineering reference value for numerical simulation and field construction.