三峡库区巫山县翠屏小区岩溶引起的地质灾害危险性研究

三峡库区移民迁建中发现的岩溶问题是一个重大工程地质问题。巫山县城翠屏小区是较早发现有确切岩溶证据的地方,研究证实小区三叠系嘉陵江组灰岩普遍遭受了强烈的岩溶作用。不同部位具有不同的岩溶特点和强度,在纵向上,从山顶到坡脚岩溶作用有增强的趋势;从地表向深部,有局部强烈岩溶层位。岩溶作用在小区产生了顺坡或顺层延伸的溶洞和深部蜂窝状溶孔。岩溶作用在小区形成了脖颈状溶蚀槽地、槽状谷地、溶蚀台地和与地貌相关的"飞雁状"褶皱、岩溶正断层及帚状密集节理带。岩溶过程中伴随着其他外营力作用,它们的相互耦合形成各种次生岩土体。岩溶轻则引起岩体质量降低,重则可能导致地面不均匀沉降、地裂缝、滑坡、崩塌、泥石流及地面塌陷地质灾害。

The Catastrophic Karstification of the Foundation Limestone in Cuiping Area, Wushan County, Three Gorges Reservoir Region

Karstification recently discovered in the Three Gorges Reservoir region is a vital engineering geological problem.The reliable karst evidence was discovered early in Cuiping area,Wushan County,and the authors' investigation has revealed that the limestone of Triassic Jialingjiang Formation(T1j)in the area generally has suffered strong karstification.There are different features and intensities of karstification in different parts.Longitudinally,there exists intensifying tendency of karstification from the hill top to bottom,and from surface to the depth,there exists local strong karst layer.Many slope-parallel or layer-parallel caves near the surface and beehive-like dissolved holes in depth were generated by karstification in the area.Some karst landforms like neck-shaped karst trough,uvala between two gullies and dissolution tableland,and some structures in connection with the landform such as flying-goose-shaping folds,normal karst faults and brush-shaped close-spaced joint zones were also produced by karstification.The karstification accompanied other exogenous processes,and many types of secondary rockmasses and soils were generated together with the processes.Due to karstification,the quality of rockmass will drop gradually and,what is more,there might occur geo-hazards such as uneven subsidence,fissure,landslide,collapse,mud flow and cave-in.