Abstract Rainfall scour and broader surface erosion pose persistent threats to loess slopes on the Chinese Loess Plateau, and these hazards are further aggravated in seasonally frozen regions where dry–wet (DW) alternation and freeze–thaw (FT) cycling coexist. Microbially induced calcite precipitation (MICP) offers an environmentally sustainable option for near-surface stabilization; however, existing studies have mainly emphasized strength improvement under single environmental actions or short-term exposures, and the comparative durability of MICP-treated loess under DW, FT, and their combined dry–wet and freeze–thaw (DWFT) cycling remains insufficiently quantified. Here, untreated and MICP-treated loess specimens were exposed to 3, 5, and 10 cycles of DW, FT, and DWFT. Disintegration, micropenetration, rainfall scour, and scanning electron microscopy (SEM) tests were conducted to evaluate deterioration in near-surface mechanical resistance and erosion resistance. At matched cycle numbers, deterioration consistently followed DWFT > FT > DW, evidenced by earlier stabilization at higher disintegration ratios, larger cumulative soil loss, and the greatest reduction in penetration resistance under DWFT. The regime dependence was distinctly stage-specific: FT cycles caused a pronounced early drop that subsequently moderated, whereas DW alternation produced a more progressive weakening; their sequential action promotes crack connectivity and moisture infiltration, thereby intensifying freeze-related disruption and accelerating overall damage evolution. MICP mitigated degradation across all regimes by suppressing disintegration and cumulative soil loss and by retrading near-surface strength decay. After 10 DWFT cycles, MICP reduced the disintegration ratio from 96.5% to 82.2%, increased penetration resistance by 30.9%, and decreased cumulative soil loss by 25.2% relative to untreated loess. SEM further indicated the regime-dependent cementation degradation mechanism, with DW favoring surface etching and partial dissolution accompanied by crack reopening, FT promoting interfacial debonding and bridge fracture driven by frost-heave-related opening, and DWFT accelerating both pathways while most strongly enhancing pore–crack connectivity. These results identify DWFT as the most critical durability scenario for surface reinforcement of loess slopes in cold-arid regions. Even after 10 DWFT cycles, MICP still reduced the disintegration ratio by 14.3%, increased penetration resistance by 30.9%, and decreased cumulative soil loss by 25.2%, indicating a measurable near-surface durability benefit under the most adverse tested condition.
Zhang et al. (Tue,) studied this question.