Abstract: Sandstone grottoes, a typical type of grotto, face varying degrees of weathering from long-term exposure to natural environments and human activities. Previous studies generally have typically used single-parameter detection techniques to evaluate the degree of weathering of sandstones grottoes. However, these single indicators often fail to fully reflect real weathering conditions. To address this limitation, we conducted simulated weathering experiments under different environmental conditions and prepared sandstone samples with varying degrees of weathering. Several indicators, including mass, ultrasonic velocity, magnetic susceptibility, and chemical element content, were used to characterize the samples. Based on the analytic hierarchy process (AHP) and principal component analysis (PCA), a comprehensive multi-indicator assessment of the degree of weathering of the grotto sandstones was conducted from both subjective and objective perspectives. The results showed that the comprehensive weathering scores obtained by the AHP and PCA methods were highly consistent for sandstone samples with different weathering types and degrees. Compared to single-parameter detection indicators, the comprehensive method proposed in this study exhibited a stronger correlation with the actual weathering process of sandstone, providing a reliable approach for accurately assessing the degree of weathering in sandstone grottoes.

Key words: sandstone grottoes, non-destructive testing, weathering assessment, analytic hierarchy process, principal component analysis