长江三峡水库区危岩分类及宏观判据研究

危岩是三峡水库区主要地质灾害之一，约30，000余个位于陡崖或陡坡上。河流或沟谷强烈下切产生的岸坡岩体卸荷作用、软硬相间的岩层组合（如砂岩、泥岩）以及高强度的降雨或较大的日温差变化是三峡水库区危岩形成的基本条件，其破坏具有突发性、致灾具有毁灭性。目前将危岩分为滑塌式、倾倒式及坠落式3类，体现了危岩失稳破坏的主要模式。现场可识性不强、力学机理不明确，降低了危岩治理的针对性及有效性。据此，文章提出了现场易识性、力学机理明确性和失稳模式预判性的危岩分类原则，并将危岩分为单体危岩和群体危岩两大类。单体危岩分为压剪-滑动型危岩、拉剪-倾倒型危岩、拉裂-坠落型危岩及拉裂-压剪坠落型危岩；群体危岩分为底部诱发破坏型危岩及顶部诱发破坏型危岩。分析了各类危岩的基本特点；从陡崖（坡）断面形状、主控结构面、主控结构面走向与陡崖（坡）走向之间的组合关系以及岩性等方面构建了危岩分类宏观判据，经万州太白岩50余个危岩的现场验证，利用这些宏观判据判识的危岩与实际相符。

Classification and identify of perilous rock in the area of the Three Gorges Reservoir

As one of main geologic disasters in the area of the Three Gorges Reservoir,about 30,000 perilous rock sites on cliffs or steep slopes.Basic conditions for perilous rock to develop in the area classify as strong unloading agent by cutting of river or ravines,lithological composition with weak or hard feature such as sandstone and mudstone,violent precipitation,and obvious variation of temperature day and night.Rupture of perilous rock is abrupt while calamity is catastrophic.Hitherto,three types of perilous rocks are classified as sliding,topping and falling,which are difficult to identify in fields and haven't distinct signs of mechanism so that such the classify system are not easy to be used in stabilization projects.In present paper,the authors provide three criteria: easy identification in-situ,clear-cut mechanism and pre-judgment of fracture model,with general classify : single and aggregate.Further,the single perilous rock is classified as sliding perilous rock under pressure-shear,toppling perilous rock under tension-shear,falling perilous rock under tension and falling perilous rock under tension-pressure-shear,while the aggregate perilous rock is classified as both perilous rock-triggered by top block fracture and perilous rock-triggered by bottom block fracture.The features of each category have been described.In view of section outline of cliff or steep slope,feature of control fissure,relation of orientation between control fissure and cliff or steep slope,and lithofacies,the authors found macro-criterions to identify perilous rock in fileds.These macro-criteria are checked with 50 perilous rocks at Taibaiya,Wanzhou.