Study On The Instability Criterion Of Blasting Demolition About Frame Structure

As a special way of demolition, blasting has been wildly used and its technology has becoming more and more mature. However, its theory has still fallen behind the practice seriously, which has been confirmed by several unsuccessful blasting cases at home and abroad in recent years. Hence, the most important task at present is to study the theory of blasting demolition about buildings, especially the instability criterion of blasting demolition about frame structure as soon as possible. And the technologies of blasting demolition should be made to set free from empirical calculation in order to reduce the venture of the blasting demolition of building and increase the reliability of blasting scheme. Therefore it is indispensable to develop blasting technology based on a lot of consummate theories and great knowledge and construct strictly the design system of blasting demolition.In this paper, the instability criterion of blasting demolition in different collapse techniques of frame structure has been studied in the name of the blasting height of pillar. Firstly, the collapse models of frame structure are classified into autochthonous and directional collapse blasting in the light of the characteristics and different effects of blasting demolition; other models are the mixtures of these two types. Secondly, a feasible pillar blasting height calculation model based on some correlative study methods is put forward. Thirdly, this paper gives analysis on instability criterion of frame structure in autochthonous and directional collapse blasting. The former is that degree of freedom is larger than zero; the latter is that projection of center of gravity on frame structure deviates from the touchdown point of collapsing building. Also, calculating formulas of them have been deducted respectively. Finally, the research findings of this paper have achieved great success in practice, it proves which are right and could guide the blasting demolition practice, what is more, provide a scientific theoretical basis for the design and construction of blasting demolition.