Natural disasters such as rainstorm,flood and typhoon occur frequently in China in recent years.Blasting technology has been widely used in emergency rescue projects all over the country.In view of the risk of blasting demolition and flood discharge construction of cohesive soil dams in flood season,Chuhe dam blasting demolition project in 2020 it taken as the analysis example.The problem of collapsible collapse in the excavation of cohesive soil embankment under high water level for a long time can be solved by designing a drilling rig with mud suction and soil discharge performance.Through the analysis of four existing models of explosion in soil,the calculation model of blasting cavity volume, i.e.the spherical charge explosion similarity theory model,is suitable for blasting demolition of soil buildings.Based on this model,the blasting cavity volume required for the project is calculated as 160% of the volume of strong throwing blasting charge by blasting tests and the convenience of engineering operation.Combined with the theory of enhanced throwing blasting cavity and the size of the cohesive soil dam,the hole depth is determined as 3.6 m.According to the previous experience of blasting compacted soil,the powder factor,hole spacing and charge amount of enhanced throwing blasting are determined as 0.83 kg/m3,2.5 m and 84 kg/cavity,respectively.Thus the charge amount of cavity expanding is calculated as 0.40 kg.The results show that the semi empirical formula based on the similarity theory of spherical charge explosion can meet the application needs of blasting demolition of soil buildings.It is proved that the construction method of cavity expansion and strong throwing blasting technology based on mud suction and dumping drill is feasible and effective in the demolition of soil buildings in flood control and rescue.