A novel two-layer composite geomembrane lining structure to mitigate frost damage in cold-region canals: Model test and numerical simulation

The canal is crucial for water diversion projects, but it is susceptible to frost damage. To address this, a two-layer composite geomembrane lining structure (TLCGLS) was proposed that regulates the interaction between canal lining and frozen soil. Model tests were conducted to investigate its anti-frost heave effectiveness. Considering the interaction among the lining, two-layer composite geomembranes (TLCGs), and frozen soil, a canal frost heave model with heat-water-mechanical coupling was developed. The influence of canal cross-section shapes and TLCGs arrangements on anti-frost heave performance and mechanism of TLCGLS were discussed. Results show that TLCGLS reduces uneven frost heave degree and compressive/tensile strains of the lining by 35%, 29%, and 28% respectively. During melting, it rapidly reduces frost heave, tangential deformation, and strain with minimal residual effects. TLCGLS demonstrates strong resetting ability and excellent anti-frost heave performance. It is particular suitable for arc-bottomed trapezoidal canals. However, excessive reduction in friction between TLCGs weakens arching effect of the bottom lining, increasing tensile stress and safety risks. TLCGLS with geomembrane-geotextile contact exhibits superior anti-frost heave performance, mitigating compressive stress by over 50% while meeting design requirements for tensile stress. These findings provide a theoretical basis and technical solution for mitigating frost damage in canals.