Study On Motion Characteristic And Protection Of Rockfalls On Rock Slope

With fast growth of national economy and the government-led implementation of west development strategy, the input by the state to western regions construction has been used widely in infrastructure and engineering projects. Because of the special geological characteristics in western regions, geological hazards are inevitable in the course of construction, even after projects being put into operation. Especially, the severity of rockfall hazard has come to the fore. Due to the complexity of rockfall motion, its theoretical research is superficial and weak. The researches about trajectory and energy transformation process of the rockfall are both limited at home and abroad. All the problems above have to be settled urgently.In this thesis, rock slope is chosen as the research object. Based on comprehensive methods as theoretical analysis, laboratory test and numerical simulation, the theories and algorithms of rockfall trajectory are presented. The vital influential parameters are analysed systematically and their acquirement methods are also probed into. Rockfall hazard mitigation measures are discussed accordingly.In this paper, the main research contents and the innovative research results are:(1)Through theoretical comparison and analysis, the main parameters that affect the trajectories of the rockfalls are selected, namely, Coefficient of Restitution (RN (Coefficient of Normal Restitution) and RT (Coefficient of Tangential Restitution)), they not only determine the bounce height and distance of the rockfall, but also affect the conversion and loss of the energy. Therefore, the design to prevent the rockfall hazard should pay special attention to them. In addition, the friction angle of the slope plays an important role when the rockfall rolling and sliding on the slope, it should be paid special attention too. (2) A new segmented loop algorithm is put forward based on the summary analysis of existing algorithm of the trajectory and the actual motion of the rockfall, a Rolling Stone, the new algorithm which can be used not only to the jumping phase of the rockfall, but also to the rolling (sliding) phase of the rockfall. Compared with existing algorithm, the new algorithm is simple and clear, easy to use and so on. (3) On the basis of in-depth research and repeated tests, an anti-analysis method is proposed which combines model tests and numerical simulation using, that is, obtained the trajectories of the rockfalls by model tests, and then use numerical simulation to obtain the relevant parameters of the rockfall movement.(4)In the model test, the trajectories are accurately captured from the video of the test frame by frame. (5)On the basis of these findings for the rockfall, through theoretical analysis and numerical simulation, a method is proposed to solve how to choose the best location and height for the prevention of the rockfall hazard, these results will provide the help to the actual design of the rockfall hazard prevention.Focused on the motion characteristics of the rockfall,the mechanisms of parameters effect to rockfall motion and its trajectory shaping process are revealed basically in the studies. Acquirement method of vital influential parameters is given and the energy transformation process is clear. The results and conclusions obtained in the research deepen and enrich content of rockfall hazard prevention theory. The research is essential to guide protection system establishment and determine corresponding engineering protection measures.