Creep tests in Daivões dam

Abstract

This paper summarises the most relevant aspects of the design and installation of the laboratory and in-situ setups used to determine the dam concrete deformability over time. These experimental setups aim at determining the modulus of elasticity for different ages and the creep function for the concrete used in the construction of Daivões dam. The laboratory setups have the advantage of carrying out the experimental work under relatively controlled conditions, whereas the in-situ setups (commonly referred to as creep cells) allow these studies to be performed under the dam actual conditions, i.e. real thermo-hygrometric conditions. The creep laboratory setup used in this work uses a rigid frame as the reaction structure and a closed hydraulic circuit which controls the applied pressure on a flat jack on the base of the concrete specimen. The strains were measured with a deflectometer, on the face of the specimens. Creep cells are composed of specimens of concrete with embedded strainmeters, installed in the body of a concrete dam (embedded in the dam concrete) during its construction, with a hydraulic flat jack underneath. During the elastic modulus and the creep tests, while the jack introduces a given compressive stress in the specimen, the embedded strain gauges measure the subsequent strains, instantly or over time, for the modulus of elasticity or creep assessment, respectively. This paper presents the main deformability concrete test results obtained from both experimental setups, in-situ and laboratory, and a preliminary estimate of the creep function. Some of these results have already been used as an input to evaluate the dam structural behaviour during the first filling of the reservoir.