STATISTICAL and STRUCTURAL IDENTIFICATION TECHNIQUES IN STRUCTURAL MONITORING OF CONCRETE DAMS

Large dams are monitored both for boundary conditions control (temperature, rainfall, water level, etc.) and for structural response (i.e. displacements, rotations, pore pressures, etc.). Gathered data are useful for safety evaluation of dam performance, mainly if current measures are compared to the whole string of recorded data by means of statistical and structural identification tools. The proposed procedure allows an analytical interpretation of the measures and, after the identification of suitable parameters, is useful to check the regular behaviour of the structure. In the paper, some hollow buttress gravity dams, built in Italy some decades ago, have been considered, comparing temperature change, reservoir water level and the horizontal upstreamdownstream displacement of each buttress, generally given with an acceptable degree of accuracy by pendulum instruments. Two different procedures have been compared: a statistical approach and a structural identification technique, the latter based on numerical models of the structure to assess the elastic Young modulus. This parameter can be a useful indicator of the structural integrity and can also be used to compare different buttresses of the same dam or different dams of the same type. The structural identification technique shows better results in predicting the crest displacement.