南龛石窟砂岩风化特征及剥落病害发育机理研究  

WEATHERING CHARACTERISTICS AND DEVELOPMENT MECHANISM OF THE DETACHMENT PATTERN IN THE SANDSTONE HERITAGE,NANKAN GROTTO

作　　者：张雪凝 李雪梅 凌斯祥 巫锡勇 王逢睿 王捷 ZHANG Xuening;LI Xuemei;LING Sixiang;WU Xiyong;WANG Fengrui;WANG Jie(Faculty of Geosciences and Environmental Engineering,Southwest Jiaotong University,Chengdu 610756,China;Nankan Grotto Research Institute,Bazhong 636001,China;Northwest Research Institute Co.,Ltd.of China Railway Engineering Corporation,Lanzhou 730099,China)

机构地区：[1]西南交通大学,地球科学与环境工程学院,成都610756 [2]南龛石窟研究院,巴中636001 [3]中铁西北科学研究院有限公司,兰州730099

出　　处：《工程地质学报》2024年第6期1963-1972,共10页Journal of Engineering Geology

基　　金：国家自然科学基金项目(资助号:42077271,42377198);国家文物局重点科研基地课题(资助号:2020ZCK110)。

摘　　要：经过长期的岩石风化,南龛石窟砂岩文物发生了严重的风化病害,亟须进行保护性研究。为了探明南龛石窟砂岩风化特征及剥落病害的发育机制,对取自南龛石窟上、下两层岩层的新鲜岩样和风化岩样进行了矿物成分综合分析、化学组成分析、黏土矿物分析及扫描电镜测试。结果表明:上、下层砂岩矿物的微观形貌及风化行为基本一致,主要包含方解石溶蚀、黑云母氧化、长石蚀变及黏土矿物膨胀4个过程,这4个矿物微观风化行为的协同作用是南龛石窟剥落病害发育的内在机制。岩石矿物成分含量的差异,尤其是方解石、黑云母、长石的含量,以及风化后形成的黏土矿物的含量,是造成4类不同的剥落病害差异性发育的根本原因。方解石、黑云母、长石及黏土矿物的含量越高,岩石更易发育颗粒状剥落和鳞片状剥落病害。反之,鼓包胀裂和片状剥落病害更易发育。南龛石窟上、下岩层的剥落病害发育具有差异性:鼓包胀裂和片状剥落主要发育在下层浅黄色砂岩表面,颗粒状剥落和鳞片状剥落主要发育在上层灰白色砂岩表面。这可归因于上层灰白色砂岩的黏土矿物和黑云母含量高于下层砂岩,导致其风化过程中会产生更多的裂隙,且上层灰白色砂岩的颗粒粒径略小,从而形成了风化行为更为破碎的颗粒状剥落和鳞片状剥落。从微观矿物蚀变的角度揭示了南龛石窟砂岩表层剥落病害的发育机理,研究结果对南龛石窟剥落病害治理有借鉴意义。The Nankan Grotto had undergone severe weathering over long geological timescales.To elucidate the deterioration mechanisms of sandstone in the Nankan Grotto,we collected rock samples for TESCAN integrated mineral analysis,chemical composition analysis,clay mineral composition analysis,and scanning electron microscope test.The results showed that the micro-weathering behaviors of minerals in the upper and lower sandstone strata were the same,including the dissolution of calcite,the alteration of feldspar,the expansion of clay minerals,and the oxidation of biotite.The micro-weathering processes of these minerals were the internal mechanism of detachment pattern in the Nankan Grotto.The higher the contents of calcite,biotite,feldspar,and clay minerals,the more likely the rock is to develop disintegration and scaling patterns.On the contrary,blistering and fragmentation patterns are more likely to develop when these contents are lower.The blistering and fragmentation patterns mainly developed in the lower light yellow sandstone,while the disintegration and scaling patterns mainly developed in the upper gray sandstone.The different deterioration in the upper and lower strata can be attributed to the higher contents of clay minerals and biotite in the upper gray sandstone.Our research revealed the development mechanism of detachment pattern in the Nankan Grotto from the perspective of microscopic alteration of the minerals.The research results can provide theoretical reference for the conservation of Nankan Grotto.

关 键 词：砂岩石窟 微观风化 矿物蚀变 剥落病害机理 

分 类 号：P642.3[天文地球—工程地质学]