Non-destructive testing and temperature distribution of coal mine roadway lining structure under exogenous fire

In order to study the thermal damage of concrete lining under exogenous mine fire conditions, the temperature and P-wave velocity distribution of naturally ventilated concrete roadway lining are investigated through an experiment using a 1/10 reduced-scale roadway model. In this experiment, the lining is composed of concrete cubes, the temperature is monitored with thermocouples installed inside and outside the specimens, and the velocity of concrete specimens is measured before and after the fire. Through the analysis of the results, it is found that the temperature is almost symmetrically distributed on the inner surface of sidewall lining, which corresponds to the stratification of smoke. Moreover, the temperature reaches its maximum value on the inner surface of the lining structure and gradually decreases outward from the inner surface. In addition, the decrease of the P-wave velocity of the concrete is closely related to the fire temperature, while the variation of the P-wave velocity can reflect the damage degree of the concrete lining and thus indicate structural damage and changes in mineral content. Finally, the damage characteristics obtained can provide a basis for the design of roadway linings.