Synergistic degradation effects of environmental factors on dam concrete: Experimental insights and constitutive model

Abstract

The constitutive properties of dam concrete under environmental influences are critical for evaluating the reliability of hydraulic structures. To address this issue, referring to the concrete mix proportions of high-arch dams in Southwest China, several groups of wet-screened concrete were prepared to investigate the evolution of the mechanical and constitutive properties of dam concrete under the combined influence of multi-environmental factors. Based on meteorological data in Southwest China, a long-term deterioration test system was designed, which coupled temperature and humidity cycling (THC) and salt spray erosion (SSE). In the initial stage, the generation of swelling products led to a slight increase in both mechanical properties and dynamic elastic modulus. As the deterioration period progressed, the expansion of micro-cracks and the degradation of hydration products gradually occurred within the microstructure, leading to stages of both slow and accelerated performance decline. The peak stress and the initial elastic modulus in the constitutive curve showed similar evolutionary trends. The results indicated that the synergistic deterioration effects of THC-SSE were significant, especially adjacent to the surface. THC directly facilitated mass loss and micro-crack development, thereby accelerating SSE. A detailed assessment of the loading capacity of dam concrete was conducted through energy analysis. Furthermore, the proposed model accounts for the characteristics of internal damage distribution in concrete drawing on the homogenization theory. And a novel perspective is provided for investigating constitutive models of concrete with non-uniform internal damage fields. Herein, the experimental and modeling findings provide essential data and theoretical support for the design and evaluation of dam concrete exposed to long-term complex environments.