Research on anti-cracking measures for concrete face slabs of rockfill dams under coupled thermal stress and settlement deformation

• A multi-field coupled model integrating temperature, stress, and settlement is established to reveal the cracking mechanism of concrete face slabs. • Under coupled loading, significant stress concentration occurs at slab edges, with a maximum tensile stress of 2.73 MPa and edge settlement 20-30% higher than the central area. • The synergistic effect of thermal stress and settlement deformation is quantified, showing the coupled case increases stress by 25-40% compared to single-factor scenarios. • A comprehensive anti-cracking strategy combining material optimization, flowing water curing, and winter insulation reduces thermal stress by 40-50%. • The proposed measures ensured exceptional crack control, with only 12 cracks found on 33,800 m² of the slab, enhancing long-term durability. The concrete face slab is a critical impervious structure in pumped-storage power plants, and its cracking directly affects engineering safety and long-term durability. In practice, face slabs are often subjected to the coupled effects of thermal stress and foundation settlement deformation, making traditional single-factor analysis methods inadequate for accurately revealing the cracking mechanisms. This study establishes a multi-field coupled numerical model integrating temperature, stress, and settlement to systematically analyze the mechanical response and crack development of concrete face slabs under coupled loading. It elucidates how thermal expansion and contraction induced by temperature gradients, combined with mechanical disturbances from uneven foundation settlement, collectively alter the internal stress distribution within the slab. The research indicates that during construction and operation, the slab is significantly influenced by both temperature gradients and uneven settlement, with stress concentration being particularly prominent at the edges. The maximum tensile stress along the slope direction reaches 2.73 MPa, and the settlement at the edges is 20%–30% higher than in the central region. Numerical simulations demonstrate that thermal insulation measures effectively protect the slab against cold waves. Through comprehensive strategies including material optimization, flowing water curing, and winter insulation, thermal stress was reduced by 40%–50%, effectively suppressing crack development. This study provides a theoretical basis and key technical support for the anti-cracking design of concrete face slab dams in cold regions and areas with soft foundations.