Research on key technology of coal seam self-ignition and fire extinguishing behind railway tunnel wall

In order to effectively prevent and control the spontaneous combustion of hidden small coal mines in the complex geological structure area of shallow coal seams and the serious threat posed by the spread of fire to the structural safety of railway tunnel, the direct and indirect impact range of small coal mine open fire on the tunnel is accurately delineated through the monitoring means of tunnel lining temperature scanning, geological radar detection and ground drilling verification, At the same time, combined with the geological characteristics of the strong uplift fault-fold structural area and the special requirements for the structural safety of railway tunnel, a fire area treatment scheme based on filling the mining large aggregate isolation material with the construction ground measure hole to build the tunnel isolation strip is formulated.42 measure holes are constructed before and after, focusing on filling the 403-415 m section of the tunnel, with a cumulative filling of 672 t of isolation material.The field application results show that after treatment, the fire situation in the area is greatly restrained, the tunnel lining surface temperature is generally stable below 33 ℃, and the CO concentration is reduced to 9 ppm, which initially achieves the expected goal and effectively prolongs the service life of volcanic tunnel.