A typical county for traditional village conservation in China is Songyang County. It is renowned for its ancient rammed earth dwellings, which exhibit a unique microclimate and possess significant historical value. However, high precipitation and acid rain under the subtropical monsoon climate have caused severe surface erosion, including cracking and spalling. This study focuses on traditional rammed earth dwellings in Chenjiapeng Village, Songyang County, combining field surveys, experimental analysis, and microscopic characterization to systematically investigate erosion mechanisms and protection strategies. Techniques, such as drone aerial photography, X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and microbial diversity detection, were employed to elucidate the anti-erosion mechanisms of gray-green biological crusts on rammed earth surfaces. The results indicate that algal crusts enhance surface compressive strength and shear resistance through macroscopic coverage (reducing raindrop kinetic energy and moisture retention) and microscopic extracellular polysaccharide-cemented soil particles forming a three-dimensional network. However, acidic environments induce metabolic acid release from algae, dissolving cementing materials and creating a surface protection-internal damage paradox. To address this, a transparent film-biofiber-acid inhibition layer composite biofilm design is proposed, integrating a biodegradable polylactic acid (PLA) mesh, algal attachment substrates, and calcium carbonate microparticles to dynamically neutralize acidic substances, achieving synergistic ecological protection and cultural heritage authenticity. This study provides innovative solutions for the anti-erosion protection of traditional rammed earth structures, emphasizing environmental compatibility and sustainability.

Inner dumps formed by mining activities were prone to soil erosion. Slope improvement is an effective means to control soil erosion and ecological restoration. However, little research has been done on the effect of improver application methods on the effectiveness of amendments. This paper combined similar theory to build an indoor inner dump model, used simulated rainfall tests and microstructural analysis to investigate the erosion resistance and water retention of the inner dump under different methods of PAM. The results showed thattrace source erosion and side erosion didn't occur in the inner dump model without PAM applied. Spreading PAM powder granules and spraying PAM gum liquid could reduce the internal earth pressure and pore water pressure of the inner dump to rainfall. Spraying PAM gum liquid could form a uniform film that can more effectively prevent rainfall infiltration. The carboxyl groups generated by the reaction of PAM and water could enhance the adhesion of clay minerals in the inner dump. The hydrogen bonds in the PAM gum liquid could connect water molecules, thereby forming interlocking soil particle aggregates, which enhance the anti-erosion ability of the inner dump. Spreading PAM powder granules and spraying PAM gum liquid can reduce the porosity of the improved soil, but spraying PAM gum liquid could reduce the porosity by 56.44%, which can effectively reduce water loss and had the best water retention. Therefore, spraying PAM gum liquid had better anti-erosion ability, which could lay the foundation for the ecological restoration of the inner dump.