부산대학교 도서관

A project called MACASTAB (co-financed by the Interreg Mac 2014-20 program) is being developed, by a group of technicians from the Canarias, Azores, Madeira and Cabo Verde archipelagos. This project aims to prepare a methodological guide for the natural risk management produced by the instability of volcanic slopes and talus in Macaronesia archipelagos. One of its tasks is the development of charts that can be applied in the referred archipelagos in order to do an expeditious evaluation of slope stability. Given the specificities of the geology of the Azores and Madeira islands, the charts were supported by limit equilibrium analysis methods (e.g. Morgenstern-Price) applied to slopes whose constitution is predominantly formed by soils (an unusual situation in other archipelagos that are in the project). Results of shear strength parameters obtained for volcanic soils on both archipelagos by triaxial compression tests and direct shear tests are presented. Empirical correlation between friction angle and particle size distribution was found with a coefficient of adjustment of 93%. That correlation shows a relationship between the angle of internal friction of a given material and the percentage of gravel and sand. For the preparation of these charts, several stability analyzes were performed with different scenarios (slope gradient and heights, and shear strength parameters), in order to determine the safety factor of slopes in a simple and fast way in the field.