Avaliação do risco de ruptura em taludes rochosos fraturados hipotéticos utilizando métodos probabilísticos e conceitos da lógica fuzzy

• Ano de defesa: 2022
• Autor(a) principal: Silva Júnior, Jubemar Sabino da
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Taludes (Mecânica dos solos) - Estabilidade; Lógica difusa; Taludes (Mecânica dos solos) - Avaliação de riscos
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/67492

The shear strength parameters used in the stability analysis of heavily fractured rock masses are determined from geomechanical classifications. The GSI (Geological Resistance Index) proposed by Hoek (1994) allows classifying the quality of the rock mass and making estimates for the parameters of shear strength. The GSI value is related to the degree of fracturing and the conditions of the fracture surfaces and can be obtained in two ways: a) through a visual assessment of the rock mass and comparison with the abacus; or b) correlations with the RMR (Rock Mass Rating) geomechanical classification systems or the Q System. Although the GSI is a modern method, the accuracy of the visual assessment depends on the experience and judgment of the specialist involved in the field mapping and the choice of correct region for the GSI. In this work, a procedure will be presented to evaluate the influence of the existing uncertainties in the estimation of the shear strength parameters in the results of the stability analyzes of rock masses by the application of probabilistic methods and concepts of fuzzy logic. For the application of the probabilistic methods and the fuzzy model, a hypothetical natural slope of 50 m was adopted, composed of limestone rock, extremely fractured and with the fracture surface conditions varying from good to moderate. The massif's behavior in terms of global stability was analyzed for heights of 50, 100, 150 and 200 m. Of the four scenarios analyzed using probabilistic methods, only the 200-meter slope presented non-zero failure probability. The performance levels obtained as a function of the rupture probability were bad (5.21%) estimated by the Monte Carlo method and unsatisfactory (8.67% and 8.13%) estimated by the approximate FOSM (First Order and Second Moment) methods. and PEM (Point Estimation Method), respectively. The failure rate estimated for the 200-meter slope by the fuzzy model was 18.61%, equivalent to a dangerous performance level. In addition, the fuzzy model was the only method to point out the possibility of failure for the 150-meter slope, indicating a failure rate of 1.95% (below average). The theory of fuzzy sets is an option with a lot of potential to analyze the possibility of occurrence of failure events in fractured rocky slopes, since it requires less computational time and the database is limited.