三峡库区望霞危岩体地质模式及变形破坏过程

Geological model and deformation failure process of the Wangxia unstable rock mass in the Three Gorges Reservoir

危岩体变形破坏预警判据的选择和确定是地质灾害监测预警预报的关键性问题。结合三峡库区望霞危岩体两次发生大面积破坏过程的监测数据和观测资料,采用地质勘察、地球物理勘查对底部采空区及地质结构特征分析,并结合裂缝位移、GPS监测数据分析危岩体后缘主控裂缝T10号缝的变形特征,将其划分为3个变形区段和3个变形演化阶段。研究认为:底部采空区、后缘塌陷坑、岩体节理裂隙、风化凹槽对危岩体变形具有控制性作用,后缘主控裂缝分为性质不同的东段、中段和西段,整体上呈现直角状,在变形程度上由东向西减弱,东段变形牵引中、西段变形,以塌陷沉降为主,伴随向SSW的强烈扩张,新生多条次级裂缝形成阶梯状陷落地貌,显示台阶式渐进后靠变形演化特征。

The selection of warning criterion in the failure deformation process of the unstable rock mass is the critical problem to the monitoring and warning forecast of the geological hazard. By using the monitoring data and observation information in the twice failure deformation process of the Wangxia unstable rock mass in the Three Gorges Reservoir and based on the geological survey,drilling and geophysical exploration data,this paper analyzes the control action by the engineering geological conditions of the mined-out area and the geological structure features. The deformation features of the controlling crack T10 at the back edge are examined according to crack displacement and GPS data. Three deformation areas are divided and three deformation evolution stages are established. The results show that the deformation of the rock mass is controlled by the mined-out area,collapse pits,joints,fractures and weathering grooves. The controlling crack at the back edge is divided into east,middle and west part with different characteristics with the rectangular shape as a whole. The deformation extent decreases from east to west. The deformation in middle and west part were pulled by the east part,with the settlement of the strong expansion to SSW. Ladder shape collapsing landscape was formed by the controlling crack T10 and new multiple cracks,displaying the gradually back deformation evolution features as ladder shape.