长江巫峡岸坡座滑式危岩稳定性研究——以望霞座滑式危岩为例  

On the stability of slide type crag in Wu gorge bank slope, Yangtze River:A case study in Wangxia

作　　者：何潇[1,2] 陈洪凯[2] 赵鹏 刘丽[4] 

机构地区：[1]西南大学地理科学学院,重庆400715 [2]重庆交通大学岩土工程研究所,重庆400074 [3]重庆市地质灾害防治工程勘查设计院,重庆400715 [4]重庆交通大学水利水运工程教育部重点实验室,重庆400074

出　　处：《中国岩溶》2013年第4期411-418,共8页Carsologica Sinica

基　　金：西南大学中央高校基本业务费专项(XDJK2012C031);重庆交通大学水利水运工程教育部重点实验室暨国家内河航道整治工程技术研究中心开放基金(SLK2012B02)

摘　　要：通过对长江巫峡望霞座滑式危岩调查研究表明,在川东平行岭谷一系列平行展布的背斜山、向斜谷的窄岭宽谷地貌格局控制作用下,长江巫峡横石溪背斜岸坡近水平的灰岩与页岩、泥岩软硬互层结构为座滑式危岩的孕育提供了有利条件;对危岩软弱基座矿物成分X-Ray衍射的结果表明,绿泥石、云母、蒙脱石等层状结构硅酸盐矿物含量较高,其抗剪强度低,容易产生滑动,易沿主控结构面方向形成潜在破坏面,导致岩体整体剪出,发生座滑破坏。根据危岩发育机理,将三峡地区座滑式危岩破坏过程归纳为四个阶段,即:拉裂阶段、扩展阶段、失稳阶段和后期破坏阶段;并基于极限平衡理论和岩体结构理论,推导了座滑式危岩破坏的两组结构面的应力表达式,建立了座滑式危岩稳定性分析的力学模型。将该方法运用到望霞座滑式危岩案例计算表明,天然状况下危岩稳定系数为1.19,属于基本稳定岩体;在饱和状态下,随后缘裂隙充水高度的增加其稳定系数递减,当裂隙充水高度为10m时,稳定系数为1.15,当裂隙充水高度为20m时,稳定系数为1.07。Crag is one of the major geologic disaster in the Three Gorges Reservoir Region,forming serious threaten to human life and property and to the navigation safety of the river way of the Three Gorges Reser-voir Region.As the slide type crag,accounting for 60 %-70 % of the total crags,it is of significant mean-ing to get clear the failure mechanism of the slide type crag for scientific forecast,prophylaxis and treatment in the Three Gorges limestone area.In this study,it is found that under the control of the geologic structure of paralleled anticline ridge and syncline valley in east Sichuan,the crag is quite developed in the horizontal interbed of limestone and shale or mudstone at the Hengshixi anticline ridge bank slope.The X-Ray diffrac-tion analysis on the soft foundation mineral of the crag rock indicates that the chlorite,mica and montmoril-lonite have high layered silicates minerals,low shear strength,thus is easy to slide along the potential failure surface in the direction of the major structural surface and leading to the whole rock body sliding down.Ac-cording to the failure mechanism of the failure process is divided into 4 phases in the paper,i.e.the phases sliding fissure emerge,tensile crack expand,unstable rock sliding and disintegration of rock body.Further-more,the stress expression of two groups of structural plane that forming the slide is derived in the paper and the mechanical model for analyzing the crag’s stability is established.This method is applied in the ana-lyses on the stability in Wangxia unstable sliding rock,and the results show that the stability coefficient is 1.1 9 under natural conditions ,which belongs to the basic stable rock mass.While,the stability coefficient decreases subsequently as the water head in fissures increases under saturated condition.The research result is helpful to improve our knowledge on stability calculation of the unstable rocks with soft foundations in the Three Gorges area.

关 键 词：望霞座滑式危岩 破坏机理 稳定性分析 岸坡 长江三峡 

分 类 号：TU457[建筑科学—岩土工程]