云冈石窟开凿于砂岩地层中,具有极其重要的文物价值,但因长期遭受自然因素影响,风化现象十分严重.针对第9窟诵经道北壁,综合采用微波测湿、显微和X射线荧光等技术开展无损检测,获取岩壁的水分时空分布、溶液化学性质以及砂岩风化特征,并结合环境条件探讨水岩作用影响下的砂岩劣化机理.结果表明,岩壁含水量分布存在时空差异,底部普遍比上部潮湿,降雨导致的空气相对湿度波动会引起浅表层砂岩含水量的明显变化,并且在表面出现水膜覆盖和水滴附着现象;风化砂岩内含有大量可溶盐,壁面水溶液呈碱性,主要化学元素包括Mg、S、Na、Ca、Cl、K,其中Mg、S含量远高于其他元素;风化病害形式以粉状和片状为主,微观结构多为疏松、开裂状态,颜色差异与物质组成有关;干湿循环和化学溶蚀是造成诵经道壁面风化的关键因素.研究成果可为类似的石质文物预防性保护提供数据支持和理论参考.
The Yungang Grottoes, carved into sandstone strata, are culturally significant heritage sites. However, prolonged exposure to natural elements has led to considerable weathering. Focusing on the north wall of the Chanting Corridor in Cave 9,nondestructive testing was performed using a combination of microwave moisture measurement, microscopy, and X-ray fluorescence techniques. This study examines the spatiotemporal distribution of moisture, chemical properties of aqueous solutions, and characteristics of sandstone weathering on the walls. Considering environmental conditions,the study also discusses the deterioration mechanisms of sandstone resulting from waterrock interactions. The results showed that the moisture distribution on the wall exhibited spatial heterogeneity, with the lower regions being consistently more humid than the upper regions. Rainfall-induced fluctuations in the ambient relative humidity significantly affected the moisture content of the shallow sandstone layers, resulting in the formation of continuous water films and droplets on the surface. The weathered sandstone contained a high concentration of soluble salts, and the aqueous solution on the wall exhibited an alkaline nature. The primary chemical elements in the solution were Mg, S, Na, Ca, Cl,and K, with Mg and S concentrations being substantially higher than those of the other elements. Weathering pathologies were predominantly observed in powdery and flaky forms,characterized by porous and fractured microstructures, with color variations due to differences in material composition. Wetting-drying cycles and chemical dissolution emerged as key factors contributing to the weathering of the walls in the Chanting Corridor. These findings provide valuable data and a theoretical basis for both scientific understanding and preventive conservation efforts in similar stone cultural heritage sites.
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