Influência da geometria dos blocos e das encostas rochosas na dinâmica de queda de blocos: uma aplicação da teoria do caos

Abstract

Fractured rock mass have several instability mechanisms, among which the falling blocks are the most frequent. This type of instability usually occurs suddenly and without previous signs of movement, it may cover large volumes of material and involve high values of energy and speed. The great development and improvement of the study methodologies of this phenomenon has provided a great advance in its understanding and analysis, enabling mitigation projects more consistent with the reality of the problem. However, a better understanding is still needed concerning the factors that governing these events and how they manifest themselves. Therefore, Ignacio (2019) proposed and applied in her research a new perspective of analysis using the theory of chaos and obtaining satisfactory results. This theory deals with nonlinear dynamic systems, which have as their main characteristic a high sensitivity to the initial conditions, what makes them unpredictable in the long term practice, a remarkable aspect in the rockfall phenomenon. This dissertation aims to study the phenomenon of block falling using chaos theory. More precisely, it proposes to analyze the influence of block and rocky slopes geometry on the fall dynamics, from the probability distributions of final blocks location obtained through numerical simulations for sixteen proposed scenarios. Each scenario is formed by the combination of four distinct cross section and four different block geometry, which range in hexagonal and square shapes and rounded and vivid edges. The research results indicate that chaos theory can be used in the rockfall phenomenon analysis, however, suggesting that the formation of weakly or strongly chaotic behavior does not depend only on the type of geometry presented by the profile of the slope and the unstable blocks, but also on their mutual interaction, which gives this phenomenon aspects of difficult comprehension.