In order to investigate the coupled enhancement effects of shock wave and temperature generated by thermobaric explosives in confined spaces, internal explosion experiments were conducted with 100−400 g charges in a confined building space. Pressure sensors and thermocouples were employed to obtain the explosion pressure and temperature data at different locations within the confined space. The experiments revealed the evolution characteristics and propagation patterns of the shock wave and temperature field produced by the thermobaric explosive. The results show that the temperature generated by the internal explosion of the thermobaric explosive exhibits significant secondary heating and prolonged duration characteristics. A decay model for the initial peak temperature based on the scaled distance was established. The TNT equivalence coefficient of the shock wave from the internal explosion of the thermobaric explosive exhibits a concave hyperbolic trend with increasing scaled distance. At a scaled distance of 1.7 m/kg^1/3, the TNT equivalence coefficient of the shock wave overpressure reaches a minimum value of 1.43, indicating that this position is the turning point where the energy from aerobic afterburn combustion exerts a significant effect on the peak overpressure. A two-stage prediction model for the peak overpressure was established, describing the contributions of non-ideal detonation and the aerobic afterburn effect of aluminum powder to the shock wave in different regions. Based on the pressure rise caused by the expansion of detonation products and the temperature rise due to afterburn combustion, a quasi-static pressure prediction model for the internal explosion of thermobaric explosives was established. Taking the quasi-static pressure of the 100 g charge as the reference, the quasi-static pressures for the 200, 300, and 400 g charges increased to 2.27, 3.21, and 4.18 times the reference value, respectively, showing a nonlinear growth under the coupled effect of detonation product expansion and afterburn temperature rise.

To investigate the propagation characteristics of blast shock waves and the thermal effects of fireballs in tunnel explosions involving thermobaric explosives, numerical simulations were conducted using OpenFOAM. The simulation accuracy was validated through comparative analysis with experimental data from tunnel explosion tests. The effects of axial distance along the tunnel and explosive mass on shock wave propagation characteristics and fireball thermal effects were systematically studied. The results demonstrate that under identical charge mass conditions when the axial distance exceeds 1/3 of the equivalent tunnel diameter, the attenuation of shock wave overpressure peak and planar wave formation distance remain independent of axial position. After planar wave formation, the impulse increases with axial distance before stabilizing. At the same axial explosion distances, the planar wave formation distance increases with explosive mass. Post planar wave formation, the attenuation pattern of the shock wave overpressure peak remains unaffected by charge mass. In contrast, the impulse exhibits a growth trend proportional to the increase in charge mass. Under the influence of the tunnel portal energy dissipation effect (tunnel effect), explosion-induced fireballs exhibit a consistent propagation tendency toward the proximal tunnel portal. The confinement imposed by tunnel walls restricts the lateral expansion of the fireball perpendicular to the tunnel axis while facilitating the formation of a high-temperature tip along the longitudinal axis. Especially, the temperature distribution along the tunnel axis maintains axial symmetry despite directional propagation biases. A fitting formula was established to characterize the relationship between the maximum axial propagation distance of explosion fireballs at different temperatures and the explosive mass, enabling the prediction of axial spread limits for fireballs at specific temperatures in typical thermobaric explosive detonations within tunnel-confined environments.