Heat Hazard Control in High-Temperature Tunnels: Experimental Study of Coupled Cooling with Ventilation and Partial Insulation for Synergistic Geothermal Extraction.

The problem of heat hazard in tunnel engineering has seriously affected the normal work of personnel and machinery. After combining the heat hazard control method of controlling the energy source and blocking the energy transfer, a technical scheme of precise thermal insulation at the working face in concert with geothermal energy extraction is proposed, forming a coupled cooling method of ventilation and partial thermal insulation. By building a scaled model test platform, the temperature field of the working area was analyzed, and the effect of factors, such as with or without a thermal insulation layer, ventilation velocity, and surrounding rock temperature on the cooling limit, was discussed. The feasibility of extracting energy and enhancing cooling through the heat exchange layer was judged. The results show that the partial thermal insulation can effectively weaken the heat dissipation of the surrounding rock and enhance the ventilation and cooling effect, which can reduce the average ventilation limit temperature of the working area by 1.6 °C. The addition of the heat exchange layer can further improve the tunnel environment on the basis of partial insulation, making the cooling limit temperature drop by another 3.1 °C, and the heat exchange layer can work for one year to extract geothermal energy 4.5 × 10 J. The coupled cooling scheme of ventilation and partial thermal insulation is practical and useful, which can provide technical ideas for improving the thermal environment of the tunnel.