Aplicação do método geofísico de eletrorresistividade e de ensaios geotécnicos para análise de integridade e estabilidade de uma barragem de terra

Abstract

The studies that investigate the safety conditions of geotechnical structures are based on investigations of possible causes associated with the decrease in the stability of the rock masses. With scientific advancement, over time, many methodologies have been developed and others have been improved, establish more careful tools for the analysis and monitoring of structures of the most varied sizes. Earth dams intended for water reservoirs play a very important role for society, especially those intended for the supply and maintenance of cities. The construction of these dams must be based on technical criteria and standards of execution in order to avoid risks of rupture or overflow of the water level. In addition, monitoring and periodic studies are fundamental, considering that pathologies may arise during the lifetime of the dam. With this in mind, the present study aims to evaluate the geological and geotechnical conditions of the massif of a small earth dam, located in the municipality of Caçapava do Sul (RS). The evaluation was carried out through a combination of geotechnical soil tests, geophysical investigation and stability analysis. Technical visits were made to the dam site, investigative geophysical profiles were performed using the electroresistivity method, and soil samples were collected for geotechnical tests such as grain size, liquidity limit and direct shear. The slope stability analysis was produced using the Simplified Bishop's and Simplified Janbu's methods using Rocscience's Slide2 software version 2021. The parameters used in the modeling were based on the most critical results, under natural conditions, obtained from geotechnical soil tests and technical parameters of the rock mass geometry. Thus, through the results obtained, the proposed methodology proved to be satisfactory. The results obtained from the geophysical investigations showed no warning anomalies, except for the region located in possible contact between the natural ground and the concrete spillway. Regarding the factor of safety, the model generated from the Janbu method did not show the minimum value required in the current standard and, for this reason, it is advisable that further studies be conducted on site.