层状反倾-顺倾边坡倾倒变形形成条件及发育规模特征

以往研究中倾倒变形研究在反倾边坡较多而在顺倾边坡中很少，对两种不同结构的边坡形成倾倒体的异同点更是存在较多空白。在总结大量倾倒体实例基础上，对层状反倾和顺倾边坡倾倒变形形成条件及发育规模特征进行了详细研究。结果表明，顺倾边坡若发生倾倒，通常表现为坡高 100 m，边坡坡角 35°，岩层倾角 60°，岩性为薄层或薄层与中层互层的软岩、软硬相间的岩石；反倾边坡当坡角 30°及岩层倾角 30°就可能发生倾倒，其岩性为薄层～中厚层状的软岩、硬岩及具有似层状结构的坚硬岩石均可；提出层状岩质边坡“倾倒临界倾角 ”的概念，对于顺倾边坡， 60°，当 时边坡将可能产生倾倒破坏，当 时边坡通常产生顺层面的“滑移-弯曲”或“滑移-拉裂”型破坏；反倾边坡 30°，当 时边坡才可能演化成明显倾倒变形，当 时边坡不会倾倒或倾倒不明显；对于地质条件基本相同而坡体结构不同的两种边坡，反倾边坡形成的倾倒体无论是发育分布面积还是倾倒深度通常是大于顺倾边坡的，而且一旦形成倾倒体，二者的规模通常是深层的、大型或特大型的；倾倒体的分布面积和倾倒深度均呈现一种随坡高的增加而增加的趋势，坡高 250 m时其分布面积和倾倒深度表现为陡然增加，并且反倾边坡增加幅度大于顺倾边坡。

Characteristics of forming conditions and development scale of toppling in anti-dip and dip stratified slopes

In the past studies, the toppling has much research on anti-dip slope while little on the dip slopes, and lots of vacancies exist in the comparisons of the toppling mass formed by the two bedded slopes with different structures. Based on many instances of toppling mass, characteristics of forming condition and development scale about the toppling in dip and anti-dip slope have been studied in detail. The results show that, if the dip slope toppling, it’s usually characterized by the slope height of 100 m, slope angle 35, strata dip angle 60°, and the slope with soft or alternating soft and hard strata that is thin or thin-middle layer structure. With slope angle of 30° and strata dip angle 30°, the anti-dip slope can appear topping-deformation. And its lithology varies from soft to hard with thin to medium thickness layer structure. The concept of “toppling critical dip ” about the layered rock slope is proposed. As for dip slope, the is about 60°. When , the slope can appear the failure of toppling, while , it usually appear the failure of “slide-bending” or “sliding-tension”. The of anti-dip slope is about 30°. Only when can it evolve into obvious toppling; while , the slope won’t dump or dump slightly. As for the two slopes with basically the same geological condition but different slope structures, the distribution area and the toppling depth of toppling mass formed by anti-dip slope are usually greater than that of dip slope, and once the topping formed; the scale of both are usually deep, large or super-large. Besides, the distribution area and the toppling depth of toppling mass present a trend that they increase with the increasing of the slope height. When the slope height is about 250 m, the distribution area and the toppling depth is increase steeply, and the increasing amplitude of anti-dip slope is greater than that of dip slope.