China　is　actively　building　urban　utility　tunnels　and　incorporating　gas　pipes　into　the　tunnels.　However,　there　is　a　certain　risk　of　leakage　and　explosion　when　gas　enters　the　tunnels.　If　the　gas　pipe　leaks　and　causes　an　explosion,　this　will　not　only　seriously　damage　the　integrated　tunnel　structure　and　other　pipelines,　but　also　lead　to　a　catastrophic　impact　on　the　surrounding　buildings.　It　is　therefore　necessary　to　study　the　safety　of　urban　utility　tunnels　under　gas　blast　loadings.　In　the　present　work,　based　on　a　completed　gas　explosion　model,　we　investigated　the　blast　loading　characteristics　of　a　typical　utility　tunnel　to　achieve　the　shock　wave　propagation　law　and　distributions　of　the　explosion.　We　also　analyzed　the　effects　of　gas　concentration,　pressure　relief　vent,　and　gas　volume　on　the　shock　wave　load.　By　dimensional　theoretical　analysis,　we　established　a　formula　for　calculating　the　overpressure　peak　and　impulse　for　such　utility　tunnels.　The　research　can　therefore　provide　loading　information　for　the　safety　assessment　and　further　improve　the　antiexplosion　safety　performance　of　utility　tunnels.