This work presents a comprehensive coupled thermal-hydro-mechanical model to explore the frost heave mechanism of the concrete-lined canal under a freeze–thaw environment. Unlike previous models that regard concrete as a homogeneous material, this model considers concrete a porous medium and considers the effect of the concrete pore structure, as well as the water content, ice content, and ice-water phase transition, on the mechanical deformation of the canal. Firstly, based on the theories of unsaturated soil mechanics, thermodynamics, and poroelasticity, the thermal-hydro-mechanical coupling equations of the soil under the freeze–thaw condition are established. Then, based on the theories of thermodynamics, poroelasticity, and permeability mechanics of porous media, the thermal-hydro-mechanical coupling equations of the concrete under the freeze–thaw condition are established. Finally, the freeze–thaw simulation of a canal is carried out and compared with the referred indoor model test, in which the evolution behavior of temperature, frost depth, and frost heave deformation of the canal are studied. The results show that the freezing process of the soil foundation is a unidirectional process that develops from the surface to the bottom, and the thawing process of the soil foundation is a bidirectional process that thaws from the surface and bottom to the center. The frost heave deformation of the soil foundation at the 1/2~1/3 slope height area is the largest, which may easily lead to frost heave damage to the concrete lining in this area. The frost heave deformation of the canal obtained by the numerical simulation is consistent with the experimental results, which illustrates the validity of the established model for predicting the frost heave deformation of concrete-lined canals.

For the risk assessment of flood defense, a comprehensive understanding of risk factors affecting dike failure is essential. Traditional risk assessment methods are mostly based on experts’ experience and focus on just one type of failure mode of flood defensive structures. The risk resources, including the analytical factors and non-analytical factors, were summarized firstly according to the general experience of dikes. The uncertainty of the resources that affect dike safety can be quantified by membership degree. Hence, a fuzzy influence diagram based on fuzzy mathematics was proposed to assess the safety of the dikes. We evaluated the multi-failure modes at the same time by a fuzzy influence diagram. Taking a dike as an example, the expected value of the dike failure was 6.25%. Furthermore, the chance of damage to this dike was “very unlikely” according to the descriptive term of the Intergovernmental Panel on Climate Change (IPCC). The evaluation result was obtained as a probabilistic value, which enabled an intuitive perception of the safety of the dikes. Therefore, we provided some reasonable suggestions for project management and regular maintenance. Since the proposed method can account for uncertainties, it is well suited for the risk assessment of dikes with obvious uncertainties.