TOPOGRAPHIC MONITORING OF A WATER TANK IN THE WIDENING WORKS OF EIXO NORTE-SUL HIGHWAY IN LISBON

Abstract: A monitoring necessity for a water tank in Lisbon originated in the widening work of the Eixo Norte-Sul highway, which involved excavation near the tank. As the excavation could affect the tank’s safety and the water supply service, the owner (EPAL – Empresa Portuguesa de Águas Livres) and the employer (EP – Estradas de Portugal) agreed on the installation of a topographic monitoring system. This paper describes the processes in the topographic monitoring of the water tank, and stresses the importance of the installed system. The use of the sub-system for vertical displacement determination as a warning system is also focused. Due to the complexity of the works and an unexpected behaviour of the structure, the integration of the results of the topographic monitoring with the geotechnical instruments was critical in the analysis, understanding and validation of the results. 1