灰岩地区陡高边坡危岩的形成与破坏模式——以金佛山国家级风景区甑子岩为例  

Formation and failure mode of unstable rock masses on steep slope in limestone area:A case study of Zengzi cliff in the national scenic spots of Jinfo mountain

作　　者：杨健 唐红梅[1] 周福川 Yang Jian;Tang Hongmei;Zhou Fuchuan(Institute of Geotechnical Engineering,Chongqing Jiaotong University,Chongqing 400074,China)

机构地区：[1]重庆交通大学岩土工程研究所,重庆400074

出　　处：《工程勘察》2023年第11期1-8,80,共9页Geotechnical Investigation & Surveying

基　　金：国家自然科学基金资助项目(51678097,5137821).

摘　　要：我国西南部及三峡库区灰岩地区陡高边坡广泛分布缓倾层状岩层,本文以重庆南川金佛山甑子岩危岩带为例,分析了灰岩地区缓倾层状陡崖危岩的破坏类型并进行了稳定性评价。通过对重庆市金佛山甑子岩危岩带内的现场调研发现:区域内共有33处危岩,危岩破坏类型可分为塑流—拉裂破坏、弯曲倾倒破坏、压裂座溃破坏和压剪座滑破坏四种,分别占7%、54%、25%和14%,并概化出相应的地质模型和力学模型;甑子岩两级陡崖的危岩带广泛分布,硬质灰岩和软质页岩、泥岩交互沉积,呈现“上硬下软”的二元地层结构特征;侧向卸荷和塑流拉裂作用将高陡边坡切割为两组近正交的竖向深大裂隙,控制着危岩的形态和规模,并决定其受力模式和破坏类型,是缓倾层状陡崖崩塌演化的内部机制。研究灰岩地区缓倾层状陡崖危岩的形成与破坏机制,可为该类陡崖危岩崩塌灾害的有效防治提供科学依据。Layered cliffs with gentle dip angle are widely distributed on steep and high slopes in the limestone areas of southwestern China and Three Gorges Reservoir area.Taking the Zengzi cliff in Jinfo mountain as an example,in this paper,the failure types of layered cliff with gentle dip angle in limestone area are analyzed and its stability is evaluated.Through field investigation,it is found that there are 33 unstable rock masses in unstable rock masses zone of Zengzi cliff in Jinfo mountain,Chongqing.The failure types can be divided into four types,i.e.plastic flow-fracture failure,plate toppling failure,tower-shaped fracturing-induced slumping fragmentation and sliding failure of compression shear seat with the proportions of 7%,54%,25%and 14%,respectively.The corresponding geological model and mechanical model are generalized.Unstable rock masses zone of two-stage cliffs in Zengzi cliff are widely distributed,and hard limestone and soft shale-mudstone are deposited interactively,showing a binary stratigraphic structure of upper hard and lower soft.Lateral unloading and plastic flow fracturing cut the high and steep slope into two groups of nearly orthogonal vertical deep fractures,which control the shape and scale of unstable rock masses and determine its mechanics mode and failure type.It is the internal mechanism of the collapse evolution of the layered cliff with gentle dip angle.Study on the formation and destruction mechanism of layered cliff with gentle dip angle in limestone area can provide scientific basis for the effective prevention and control of such unstable rock mass collapse disaster.

关 键 词：危岩破坏类型 缓倾角 层状陡崖 形成机制 

分 类 号：P642.21[天文地球—工程地质学]