The forward thrust of the chimney demolition by directional blasting determines the collapse range and the threshold of collapse impact vibration of the chimney.In order to find the forward thrust mechanism of the directional toppling of chimney,mechanical analysis was conducted by considering three touchdown postures of a reinforced concrete chimney,which leads to the calculation formulas for the forward thrust distance and collapse range of the directional blasting of the chimney.At the same time,the characteristics of the ground impact vibration induced by the chimney collapse was analyzed to verify the accuracy and reasonableness of the previous theoretical derivation based on engineering examples.The research results show that the established theoretical model can describe the chimney forward thrust process very well.And the calculation result can provide a reference for the safety protection design of similar blasting projects due to its conservation.In addition,it is more reasonable to use criterion 1 as the mechanical basis when the chimney has a forward thrust because it is difficult to accurately obtain the friction coefficient of the supporting parts in actual demolition projects.And it is also more reliable to study the impact vibration of the chimney on the basis of the forward thrust analysis.