Numerical Simulation and Construction Design of Blasting Demolition of Double-cylinder Old Ammonium Nitrate Granulation Tower

In order to demolish a 57 m high double-cylinder ammonium nitrate granulation tower in a complex environment, this study analyzes the structural characteristics of the tower, including its large potential energy and uneven mass distribution. A blasting method was designed with intermediate initiation and sequential detonation towards both sides to achieve a controlled collapse effect through “directional blasting+internal convergence”. The blasting design includes trapezoidal cut notches with strictly controlled perimeter and height. The bottom supporting walls are partially retained, and highly symmetric directional windows were created at specific heights. The demolition was carried out using high-precision nonel detonators combined with delayed initiation inside the holes and external relays outside the holes. Through theoretical analysis and calculations, the final blast notch length was determined as 13.5 m with a height of 3.5 m. To validate the design scheme, LS-DYNA simulation software was used to establish a three-dimensional finite element model of the granulation tower for pre-collapse analysis. Simulation results show that the collapse process takes approximately 8.8 seconds without any significant forward movement or toppling during collapse, indicating that the overall blasting parameters selected in this scheme are reasonable and can achieve the desired demolition effect.