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Natural gas is extensively used as a clean energy source in cities and industries; consequently, there are associated risks of accidental explosions. To reduce the hazards associated with natural gas explosions, it is important to study the inherent laws of natural gas blast loads in unconfined spaces and establish load models. Using experiments on natural gas explosions in unconfined spaces, this study demonstrates the influence of natural gas concentrations, propagation distances, and gas volumes upon explosion loads. A new load model was proposed for the overpressure–time history curves of natural-gas explosions in an unconfined space. A comparison with the empirical model indicated that the predictive effect was superior to that of previous models, such as the TNT equivalent model and the TNO multi-energy model.

Due to the influence of many factors, the overpressure–time history load model of vented gas explosions is difficult to describe and is not conducive to further structural design. Based on vented gas explosion test data, this paper obtains three typical overpressure-time history curves and puts forward a new semi-empirical model— double hump model that considers gas concentration and venting pressure, and gives a formula for peak pressure and overpressure–time history model. The scientificity of the model is then verified by the total impulse in the load. The model is able directly reflect the load characteristics, provide reference for calculating key parameters of a vented gas explosion and provide information on the structural response under the load. The model thereby has the potential to help reduce the impact of gas explosion disasters.