# Failure Mode Analysis and Dynamic Response of a Coal Mine Refuge Chamber with a Gas Explosion
## 3 Simulation Results and Discussion
### Failure Mode of Refuge Chamber Structure  
The impact of the destruction occurred in different components of the refuge chamber is analyzed in this study. The front door and the connection of the front door are selected for analysis and its impact on the form and extent of damage that may occur in the refuge chamber. (a) Failure mode I  
The front door is the first structural component suffering the blast shockwave. With the propagation of the shockwave, the peak pressure value of the shockwave is decreased as the energy of the shockwave is absorbed by the refuge chamber. Therefore, the deformation of the front door of the refuge chamber is the most severely deformed structural component. After the application of a strong blast shockwave, remarkable extrusion and dents can be observed in the front door and the largest deformation is found at the center of the front door. In this section, the arrangement of the cabin door stiffeners of the refuge chamber on the influence of the door deformation is analyzed. The deformation of the door with different thicknesses is considered in both cases, which are a door with stiffeners and a door with no stiffeners, as Figure 6 shows. From the comparison charts it can be seen that the effect of stiffeners on the door is obvious. The thickness of the door has minimal impact on the peak deformation. The peak deformation values of the door center with three different thicknesses are in the range of 17-20 mm. Moreover, the peak deformation of the door with no stiffeners is greatly affected by the thickness of the door. The peak deformation of the door with no stiffeners will decrease markedly with the increase of the thickness of the door. The peak deformation values of the door center with three different thicknesses are in the range of 35-62 mm. There is no residual deformation of the door in both cases. The peak deformation values of the door with no stiffeners are a 106%-210% increase over the door with stiffeners. Figure 7 shows the deformation contour of the doors with different thicknesses. Figure 5: Pressure-time curve on different surfaces. (**a**) Front surface; (**b**) Top surface; (**c**) Side surface. Figure 6: Maximum displacement-time curves with different front door thicknesses. (**a**) Door with stiffeners and (**b**) door with no stiffeners. Additionally, the deformation of the door with different forehand plate thicknesses is also considered in both cases, which are the door with stiffeners and the door with no stiffeners, as Figure 8 shows. Similar to the results of the last section, the effect of stiffeners on the door is obvious. The difference is that the peak deformation and the residual deformation of the door are affected by the thickness of the forehand plate, regardless of whether the door has stiffeners. The peak deformation will decrease, marked with the increase of the thickness of the forehand plate. In the case of the door with stiffeners, the peak deformation values of the door center with three different forehand plate thicknesses are in the range of 17-83 mm and the maximum residual deformation is 24 mm. In the case of the door with no stiffeners, the peak deformation values of the door center with three different forehand plate thicknesses are in the range of 35-112 mm and the maximum residual deformation is 34 mm. The peak deformation values of the door with no stiffeners are a 35%-106% increase over the door when reinforced. The maximum residual deformation value of the non-reinforced door is a 42% increase over the door with stiffeners. Figure 9 shows the deformation contour of the doors with different forehand plate thicknesses. The structure of the refuge chamber was in a plastic state. The peak deflection values are already beyond the safety requirement in the \"specifications for mine mobile refuge chambers\" manuscript in China (20 mm or 2% deflection). Thus, failure mode I is the unrecoverable extrusion large deformation. Figure 8: Maximum displacement-time curves with different forehand plate thicknesses.