Study On The Structure And Property Of Expandable Bolt

Bolt bolting is a reinforce technique used in geographical engineering. In the recent decades, it has an increasing application for its special supporting effect, simple manufacture and installation technique, wide utilization and low cost. Now, it is extensively applied not only in mining engineering, but also in metallurgy, Hydro and Power, Rail and Road, construction engineering and so on. So it has a good application in future.In this paper, the author discussed a new bolt, called the expandable bolt, which is quite different from the bolts commonly used now. It has a new structure and special bolting mechanism, and has overcome the shortage of common bolts and the problem of bolts fitting badly to soft rock and large deformation tunnel. Besides its light weight and easy installation, it is also an organic combination of rigidity and flexibility, expansion and continuous friction. So the study has both an important academic meaning and engineering meaning, as well as good social and economic values.Firstly, the author gathered and analyzed the wall rock's moving mechanism and bolt bolting theories, and on the basis of analyses obtained the performance required by rock bolting. After thinking over the exploit condition and referring to the successful design example, the design parameters of expandable bolt, such as the bolt length, bolt diameter and so on, are determined elementarily. Secondly, the author investigated the mechanical and chemical character of polymer, steel plate, and determined selectively the structure, building material and manufacture methods of the expandable bolt. Thirdly, the author utilized the theoretical analyses methods on materials mechanics and elasticity mechanics etc., to compute the bolt's stress and deformation, in order to guide bolt design and manufacturing. Finally, the author did a series of experiments to test the expandable bolt's performance, validate its structure and building material, and proof its bolting effect. Through the theoretical analyses and experiments, the failure modes of expandable bolt were obtained, which lays a theoretical foundation to engineering application. The theoretical analyses, numerical computations and experimental results show that: the expandable bolt can support the wall rock effectively and overcome the shortages of fitting badly to soft rock and large deformation tunnel of common bolts. Its structure is reasonable and its performance is credible.During completing this research, the author found that the expandable bolt research deals with the material science, mechanics, geographical engineering and several other courses, and the research is a hard work. In the influences of the performance, usage, manufacture, price and many other factors, the study is insufficient, and further researches on theory and experiment are needed.