Concrete dams: thermal-stress and construction stage analysis

摘要

During the process of concrete hardening, temperature profiles show gradual non-linear distributions due to the generation of heat development by cement hydration. At early ages, this distribution can have an influence on crack evolution, especially in mass concrete such as that used in gravity dams. It is thus important to study the factors affecting the amount of heat generated in the hydration process and minimise it as much as possible to prevent the generation of undesired cracks through the dam's body. Coupled thermal-stress finite-element analysis, which also considers the stages of construction, has been performed on a concrete gravity dam (Muzdalifa dam, KSA) to determine the impact of changing the time intervals in concrete placing schedule on the thermal/stress response of the dam. The significance of time, material and environmental factors has been scrutinised: the investigated parameters were the concrete casting construction schedule, the cement content and the ambient temperature. The investigation also explored the effect of introducing water pipe cooling system on the generated temperature and induced stresses, and then recommends an effective scheme for pipe cooling.