The basic characteristics of explosion, propagation characteristics of blast wave and the associated relationship of flame wave are presented to get rational repairing scheme for shield segment after explosion disaster. The explosion flame and blast wave are the main factors to the dangerous degree decision during natural gas explosion; and the damage effect of blast wave is the most dangerous. The trinitrotoluene (TNT) equivalent is calculated under condition of tunnel full of gas; the internal overpressure distribution of segment is simulated by imitated static method, by which the segment deformation can be calculated; the segment deformation calculated is couples to monitoring data to verify the accuracy of the simulation results. The results can provide guidance for rational tunnel repairing works and similar disasters in the future.