Abstract:In response to the frequent problem of temperature cracks in the strongly constrained parts of mass concrete in water conservancy and hydropower projects, its cause mechanisms are revealed and a dynamic feedback-based preventive control system is constructed. Relying on the piers and silos section of a gravity dam at a water conservancy hub in Southwest China, the collaborative analysis is carried out by jointly adopting adiabatic temperature rise tests, distributed optical fiber temperature measurement, vibrating strain acquisition and 3D temperature-stress coupling finite element modeling. The result shows that compared with the pure ordinary Portland cement system, the ternary cementitious system of low-heat cement combined with fly ash and slag powder can reduce the peak adiabatic temperature rise of the structure by approximately 22%. Compared with the natural curing method, the collaborative mode of intelligent water supply and double-layer flexible insulation can compress the maximum temperature difference between the inside and outside of the structure from 26.3 ℃ to 14.2 ℃, and reduce the crack occurrence rate from 12.5% to 0.8%. At the same time, the dual mechanisms of self-constrained shallow fractures on the surface and strongly constrained deep fractures in the bedrock are quantitatively distinguished. The constraint degree index is upgraded from a static parameter to a dynamic feedback variable to form a three-in-one anti-cracking technical path of materials, processes and regulation, which significantly enhances the long-term service performance of mass concrete structures in water conservancy and hydropower projects.
