At midnight on January 21, 2017, in the city of Hanko, Hubei Province, China, 19 high-rise buildings were demolished in a domino effect. This is one of the largest high-rise demolition projects in China to date.
19 Buildings Reduced to Dust in an Instant
Within 10 seconds, these buildings were reduced to a pile of dust. The entire demolition process took place over an area of 15 hectares, with clouds of dust and smoke spreading across the sky.
According to Mr. Wang Xuguang, an expert in China, this project utilized explosive demolition techniques instead of traditional dismantling methods. A total of 5 tons of explosives were strategically placed at 120,000 points throughout the building area.
Jia Yongsheng, the project manager, stated that they strictly controlled the impact of the explosion to avoid affecting nearby railways and public facilities.
China demolishes 19 buildings in 10 seconds. (Source: CGTN).
Explosives as a Catalyst
According to How Stuff Works, the concept of explosive demolition is quite simple: If the supporting structure of a building is removed at a specific point, referred to as point A, the portion of the building above point A will collapse onto the section below it.
If the upper section is heavy enough, it will strike the lower section with sufficient force to bring down the entire building. The explosives serve only as a catalyst in the demolition process. What causes the building to fall is gravity.
Explosives are placed at different levels of the building to ensure that the structure collapses at multiple points. When everything is planned and executed correctly, the total damage from the explosives and falling debris will be enough to completely bring down the structure, leaving only a pile of rubble.
Explosives serve only as a catalyst in the demolition process.
To safely demolish a building, the construction team must outline every factor related to the explosion beforehand. The first step is to examine the architectural blueprints of the buildings to determine how they are interconnected. Next, they conduct site visits to document important structural details on each floor.
Once all necessary data is collected, the construction team decides which explosives to use, where to place them within the building, and calculates the timing for the detonations. In some cases, they may create a 3D model on a computer to simulate the detonation’s results in a virtual environment.
The main challenge in this technique is controlling the direction in which the buildings collapse. Ideally, the construction team aims to have the building fall toward an area with no obstructions.
Detonating a building is akin to cutting down a tree. To topple a building to the north, the explosives on the northern side of the building are detonated first.
The construction team may also use steel cables to anchor the columns in the building, allowing them to be pulled in a specific direction as they break apart.
It can take up to six months to survey the building’s structure and prepare for the explosion.
According to BBC News, the demolition technique requiring buildings to collapse on their own must be executed by highly skilled experts and involves a meticulous preparation process.
It can take up to six months to survey the building’s structure and prepare for the explosion. However, in densely populated areas, explosive demolition techniques are generally not permitted.
In some locations, buildings near city centers are often dismantled manually from the top down.
Additionally, in 2008, a Japanese company implemented the “Cut and Lower” technique. By starting from the bottom, the construction crew removes a floor, then lowers the entire building down with jacks, floor by floor, allowing all work to be conducted safely at ground level.
