酸雨水化学损伤加剧粉砂质泥岩崩解机制研究

酸雨区泥质岩崩解相对于非酸雨区显著增强，但其机制尚有待进一步研究。以酸雨条件下水化学损伤的形成及其发展特性入手，选取典型酸雨区攀枝花市机场滑坡粉砂质泥岩，进行不同pH值条件下（pH=7、5、3）的耐崩解性试验。通过测定试验后崩解液离子成分变化、观察酸雨作用前后粉砂质泥岩薄片镜下特征、分析试样崩解破坏模式，探究酸雨水化学损伤加剧粉砂质泥岩崩解的细观机制；引入比表面积增量指标表征崩解残留物破碎程度，定量评价酸雨水化学损伤对粉砂质泥岩崩解的加剧效果。研究结果认为，粉砂质泥岩酸雨水化学损伤主要源于特定矿物的溶蚀，为其崩解劣化提供额外路径；随着崩解液pH值降低，粉砂质泥岩水化学损伤增强，崩解路径增多，崩解破坏模式发生转化，崩解残留物愈发破碎；采用比表面积增量指标可良好反映崩解残留物的破碎程度，崩解残留物愈破碎，比表面积增量指标值越大，粉砂质泥岩崩解程度越高。结论可为酸雨地区岩土体工程性质评价及加固设计提供理论参考。

Mechanism of silty mudstone slaking aggravated by acid rain-induced chemical damage

Slaking of mudstone in acid rain area is significantly stronger than that in non-acid rain area, and the slaking mechanism needs to be studied. Based on the formation and development characteristics of hydro-chemical coupled damage under acid rain, this paper took a landslide at Panzhihua city airport as an example, which is in a typical acid rain area. Silty mudstone rock samples located in the sliding zone were selected and processed. After that, a series of slaking experiments was comparatively carried out under different pH conditions. In order to explore the micro-mechanism of acid rain-aggravated slaking behavior of silty mudstone, we adopted a series of analytical methods, including analyzing cation composition changes in different pH slaking fluids, observing micro-structure change of samples before and after acid rain treatment as well as analyzing slaking failure modes of silty mudstone. Finally, an index named specific surface area increment index was introduced to reflect the impacts of acid rain-induced chemical damage on slaking behavior of silty mudstone. The results highlight that: the acid rain-induced chemical damage in silty mudstone was mainly caused by the dissolution of specific minerals, which provided extra paths for the slaking of silty mudstone. With the decrease of pH value of slaking fluid, the acid rain-induced chemical damage of silty mudstone increased, the slaking paths increased, the slaking failure mode changed, and the slaking residues were broken into finer fragments. The specific surface area increment index could well capture the fragmentation degree of slaking residuals. The more breaking the slaking residuals, the higher the specific surface area increment index, and the greater the slaking degree of silty mudstone. Conclusions of this paper provide theoretical reference for the evaluation of geotechnical engineering properties and reinforcement design in acid rain areas.