Investigation on the effects and mechanisms of nano-ZnO in mitigating frost heave damage of water conveyance structures in cold regions.

The occurrence of frost heave damage in water conveyance channels in cold regions can lead to the deterioration of engineering structures and cause significant water loss during transportation, posing a serious threat to public safety. However, traditional methods to mitigate frost damage, such as replacing foundation soil, become less effective over time as the operational lifespan of the water channels increases, causing recurring frost-related damages. This paper proposes incorporating nano-ZnO into the canal foundation soil to mitigate frost heave damage of the "Yin Da Ru Qin" water conveyance project. Systematic experiments were conducted to assess the effectiveness and underlying mechanisms of this approach. Indoor model tests were first carried out to compare and analyze the differences in frost heave deformation, volumetric water content, and frost depth between the in-situ silt soil (natural silt sampled from the project site without modification) and nano-ZnO-modified soil. The results demonstrate that nano-ZnO addition significantly reduces the frost heave of the soils, with a maximum reduction of 30%. It also inhibits the freezing front's advancement and impedes water migration within the freezing soil. Furthermore, post-test scanning of both the original and modified soils using nuclear magnetic resonance revealed a significant reduction in the unfrozen water content in the modified soil, providing insight into the microscopic mechanisms of how nano-ZnO alleviates frost heave by regulating water migration pathways. This study introduces a novel technical approach and material selection for the anti-freezing design of water conveyance channels in cold regions, offering valuable theoretical and practical support for the development of anti-freezing technologies for engineering structures in extreme climatic conditions.