Abstract: Under the conditions of complicated temperature boundaries and operating environments of a high concrete gravity dam in Southwest China, it is usually difficult to directly measure its internal temperature distribution and long-term stress state. In this study, we develop a two-dimensional finite element model of the dam?foundation system, based on monitored temperature data, reservoir water level records, and plumb line displacements, and tested in a case study of Monolith 17 of the Jinghong gravity dam. The operating temperature field is calculated through fitting temperature boundary conditions at the upstream and downstream dam surfaces, and validated using the monitored internal temperatures of the dam. And, we calibrate the elastic modulus of dam concrete using a back-analysis of the displacement measurements. On this basis, the stress distribution during operation is numerically simulated. The results show that reservoir water temperature in front of the dam exhibits obvious stratification along the same elevation; Upstream face temperature is mainly controlled by reservoir water, and the internal temperature field of the dam is generally stable. The calculated horizontal displacement of the monolith in the streamwise direction agrees well with variations in air temperature, but shows no obvious correlation with the reservoir stage. We also find that the majority of the dam concrete is in compression, while under low-temperature conditions, small tensile stress zones appear locally in the upstream dam face layer above the water level. It is revealed that Monolith 17 is in a stable working state during operation, and thermal action is a key factor affecting the deformation and local stress distributions of the monolith.

Key words: gravity dam, finite element analysis, temperature field calculation, parameter back-analysis, stress calculation