Experimental study on vented explosion overpressure of methane/air mixtures in manhole.

•A full-scale experiment system was established to investigate the manhole explosion.•The effects of methane concentration, ignition location and cover weight on the peak overpressure were studied.•The results showed that there were two peaks in overpressure histories caused by manhole explosion.•When the methane concentration was 10%, the peak overpressure generated by explosion was the largest.•The peak overpressure increased with the depth of ignition position and the weight of manhole cover.