Abstract: When a large-scale fire occurs in a Chinese spirits warehouse, the leakage of Chinese spirits can create flowing flames that encircle the unignited ceramic jars, forming a circular pool fire restricted by the jars. Under the intense heat of the flames, these jars can easily shatter, leading to secondary accidents. This paper presents a series of experiments on the thermal effects of circular oil pool fires on ceramic jars with varying water capacities. We investigate the evolution characteristics of flame morphology under conditions of jar rupture, as well as the patterns and distribution of cracks that occur after the jars break. Furthermore, we calculate the critical thermal stress load for fracture based on the maximum temperature difference at the moment of initial rupture. The results indicate that the flame morphology of pool fires in large ceramic jars differs significantly from that in small jars during rupture. The water capacity of the jars has a minor effect on the total length, density, and distribution of cracks following rupture. In experiments with small jars, most cracks are concentrated in the lower half of the total height of the jars. In contrast, the lower half of the walls of large jars experiences initial rupture, often leading to extensive cracking or even collapse. The locations of the critical maximum temperature difference at which rupture occurs in both small and large jars align with the distribution of crack zones. A quantitative analysis of the critical thermal stress load due to temperature differences in the jar walls reveals that when the thermal stress load in small jars is below 14.9 MPa, rupture does not occur. At a thermal stress load of 30.9 MPa, the probability of rupture is 20%. When the load reaches 44.5 MPa, the probability increases to 80%, and above 56.9 MPa, all jars will rupture. For large jars, the critical thermal stress loads in two experiments were found to be 19.9 MPa and 10.9 MPa, respectively.

Key words: ceramic jar, Chinese spirits warehouse fire, circular pool fire, thermal stress load