Key hydrothermal processes and top-edge erosional failure characteristics of rammed-earth heritage sites under sudden snowmelt conditions

Le résumé fourni par la source

Rammed-earth heritage sites in cold regions are often susceptible to top-edge erosional failure during rapid snowmelt, as the shallow surface layer is weakened and destabilized by the combined effects of thermo-hydro-saline-mechanical actions. This study examines the key hydrothermal processes and the evolution of erosion at the top edge during abrupt snowmelt events. A full-scale, in situ simulation field that replicates the original form and materials of the Beiting Ancient City site in Xinjiang was constructed. By integrating external meteorological monitoring with an internal macro-micro sensing system for heat, moisture, salt, and stress, we investigated the characteristics and controlling factors of top-edge erosional failure in a rammed-earth test wall. The results reveal distinct seasonal stages. During the freezing period, a cold and humid climate facilitates prolonged snow accumulation; rapid warming in early spring triggers swift snowmelt and infiltration, which serve as the critical environmental drivers of erosion. On the shaded slope segment of the wall top, the shallow layer experiences an erosion sequence of “particle migration→undercutting rills→coalesced rills→stripping and deepening”, following a staged pathway of “snowmelt infiltration-migration→freeze-induced expansion→melt-induced loosening →abrupt-melt erosion”. The wall exhibits a typical “top tension-bottom compression” shear failure mode that progresses incrementally each year, with a heightened risk of failure occurring when the mean air temperature exceeds 0 ℃ for two consecutive days and the diurnal temperature range surpasses 15 ℃. These findings provide theoretical support and technical guidance for early warning and conservation strategies addressing erosion and sliding hazards in earthen sites located in cold regions.

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