Abstract:

With the increase of global temperature, the ice crystals at the warm frozen soil-concrete interface are easy to melt, resulting in the decrease of ice cementation force, which in turn leads to the deterioration of interface strength and affects the stability of infrastructure. Pseudomonas syringae (P. syringae) can induce the orderly arrangement of water molecules to promote the growth of ice crystals at elevated temperatures. However, research regarding its application in promoting ice film formation at the warm frozen soil-concrete interface and further enhance the interface strength remains notably absent. Therefore, in this paper, nuclear magnetic resonance and direct shear tests were carried out to study the effects of P. syringae concentrations (0, 1 g/L) on the shear stress-horizontal displacement curve, shear strength and strength index of warm frozen soil-concrete interface at 0,−0.5 ℃ and−1 ℃. After the addition of P. syringae, the ice content of frozen soil increased by 38 %, the interfacial cohesion improved by 29.1 %, the interfacial strength increased by 19 %, and the residual strength enhanced by 7 %. Based on the Mohr-Coulomb criterion and the generalized Darcy 's law, the strengthening mechanism of the warm frozen soil-concrete interface under the action of P. syringae can be summarized as follows: the enrichment of P. syringae occurs due to the migration of water towards the interface, which subsequently induces the formation of ice crystals at relatively elevated temperatures. These ice crystals then then fills the pores, ultimately leading to interface interlocking enhancement and a significant improvement in interface strength. This study initially unveils the potential of P. syringae in augmenting the strength of warm frozen soil-concrete interface, thereby offering theoretical underpinnings for the application of P. syringae in the design and construction of infrastructure in warm frozen soil areas.

Key words: warm frozen soil-concrete interface, Pseudomonas syringae, interface ice film, ice bond strength