Blasting Demolition of Brick Concrete Office Building under Complex Environment

摘要

Blasting demolition about office building with mixed structure in downtown under complicated condition is introduced at this paper. This office building was constructed in I960' s by brick & concrete, and it was reinforced and heightened by steel & concrete in following days. The original building was a fourfloor one, and it was heightened to a six-floor one. All the pillars and walls had inner and outer layers, the inner was constructed with brick & concrete, and the outer was reinforced by 20cm steel & concrete material. And steel tension bars which were radial spaced 6 to 8 meters were used to reinforce the building. Because the building was badly constructed as well as low security, the structure of this building was complicated after reinforcing. The office building is an "L" shape structure, only part of the building in east west will be removed, and the left must be well kept wholly and run orderly. The safety of explosion should be higher than usual due to the more complicated condition meanwhile the building is located at the most prosperous district in downtown. Integrated research and comparing about various operating programmes are executed through field survey and computation. Finally the explosion plan is determined that the building is collapsed in place and fallen in one direct, and there are two explosion gaps in the top and bottom respectively. In order to protect the maintained a one meter wide split is cut between the pre-explosion part and the kept one by man work and machine firstly. And blasting parameters are selected properly by careful survey & design and operation. In the explosion split there are two layers, one is inner one with brick structure and the other is outer one with steel structure. While designing detailed computation and tests are carried out The explosive is loaded in both layers individually and shot delay blasting technique is applied, and the building can be separated extremely to minimize the ground shock, thereby the surrounding construction is protected safely. Close body protection and covering main parts are supplied to avoid flying stone after demolition. This operation receives ideal results and the maintained parts and building nearby are protected effectively. After this demolition valuable experiments are obtained for similar complex structure buildings.