Determinação do índice de refração vertical, utilizando visadas reciprocas e simultâneas: análise de sua aplicação no cálculo do desnível utilizando nivelamento trigonométrico

Determination of the vertical refractive index, using reciprocal and simultaneous views: analysis of its application in calculating the unevenness using trigonometric leveling

Abstract

The safety and operational efficiency of dams are crucial aspects for their use. However, monitoring these structures faces several challenges. In the context of dam monitoring, the use of total stations has been a practice for controlling the movement of monitoring points. However, atmospheric refraction can introduce significant errors into the measurements performed, affecting the accuracy and reliability of the results. With this in mind, in this work a study was carried out at the hydroelectric power generation plant called Jaime Canet Junior, to analyze the effects of atmospheric refraction in determining unevenness, using data obtained by the first order geometric leveling method. Using the trigonometric leveling method equation, the value of the local refractive index was calculated, reciprocally and simultaneously, between three pillars located on the banks of the dam and in three different periods of the day. After this calculation, the behavior of the refractive index was analyzed, its relationship with local atmospheric conditions and the difference in level between pillars P1, P2 and P3 and two monitoring points located on the crest of the dam, called CG01 and CG02. Analyzing the unevenness values ​​obtained through trigonometric leveling, using the calculated refractive index (k), in each period and for each line of sight, it is possible to see that the unevennesses show improvement in most cases compared to k = 0 ,13. However, this same behavior was not observed for the differences in level obtained from Pillar 3 (P3 – CG01; P3 – CG02), located downstream of the dam. It is estimated that this phenomenon occurred due to the high humidity in the area, due to fog, caused by the flow of water through the spillway, which had three gates open.