Numerical Study on Blasting Demolition Scheme Optimization of High-rise Chimney in Complex Environment

In order to realize the blasting demolition of 62.8 m high brick structure chimney in complex environment, various demolition options which fully consider the structure of the chimney and the surrounding environment were compared in the case of insufficient space for collapse on the east, west and north sides. After analysis, one-way and two-way folding blasting options were initially selected to blast and demolish the chimney. The circular angle of the upper and lower notch was designed as 220°. The lower notch was set as 2 m high at 0.5 m from the bottom of the chimney, while 30 m from the bottom of the chimney located the upper notch which parameters need to be simulated and optimized. ANSYS/LS-DYNA finite element analysis software was used to compare the collapse effect of the preliminary scheme, and it was calculated that the one-way folding blasting did not meet the demolition requirements, so the two-way folding blasting was selected. Then the chimney collapse process was simulated with the upper cut height of 1m, 1.5 m and 2 m and the delay times of 0.5 s, 1 s, 1.5 s, 2 s and 2.5 s between the upper and the lower cut. After analyzing the collapse process and the distribution range of the blast pile of the chimney under different working conditions, it was determined that the best folding effect with a small collapse space happened when the upper cut height was 1m and the delay time was 1 s. Furthermore, safety measures which were related to blasting vibration and flyrock protection were designed. The blasting effect showed that the chimney collapsed smoothly according to the designed direction during the blasting process, and no damage occurred to the surrounding buildings(structures). The overall blasting demolition effect was good enough to meet the expected goal. It can provide a reference for related scholars and demolition projects.