Abstract: Aiming at the structural characteristics of masonry residential buildings, taking the gas flash explosion accident in residential buildings in Wafangdian city as the research object, FLACS software was used to model explosive floor in 3D. Gas leakage and explosion were simulated considering injection direction, doors, windows, partitions and other factors. Results showed that, horizontal and vertical leakage have almost no impact on the volume fraction distribution of natural gas, with kitchen volume fraction higher due to hall partition obstructing effect; Room 504 explosion pressure increased sharply at the beginning of explosion, transmitted outward through doors and windows in arc form. Explosion pressure at 400 s was lower than 600 s, with pressure at 600 s explosion greater than brick wall failure pressure of 76 kPa causing structure damage. Research results provide theoretical guidance for accident inversion, stability evaluation of damaged structures and accident prevention.

Key words: masonry residential building, gas leaks, gas explosions, FLACS, simulation