三峡库区岩溶景区危岩破坏模式及稳定性——以重庆天生三桥深秀洞陡崖危岩为例

天生三桥景区深秀洞陡崖存在16处危岩,严重威胁到深秀洞下方水幕电梯和两侧栈道工程的安全。通过现场勘测和理论分析的方法,研究了危岩基本特征和破坏模式,进一步采用定性与定量相结合的方法对危岩稳定性进行综合评价。研究结果表明:天生三桥景区深秀洞陡崖危岩发育,其形态多样、规模不等,破坏后影响范围大、后果严重;危岩破坏模式主要表现为滑移式、倾倒式和坠落式三种;采用RMR法对陡崖岩体稳定性进行评价,陡崖岩体属于Ⅳ级,岩体质量为差岩体;采用赤平投影分析对陡崖岩体稳定性进行评价,岩体受结构面切割严重,裂隙L1、L4和多组组合交线为不稳定结构;对危岩稳定性进行定量评价,计算出危岩介于稳定与欠稳定状态之间,但在暴雨工况下,危岩大多处于欠稳定状态。研究成果可为后期危岩防治提供一定的科学依据和理论支撑。

Study on Failure Mode and Stability of Dangerous Rock in Karst Scenic Spot of Three Gorges Reservoir area:Taking Shenxiu Cave Cliff Dangerous Rock of Tiansheng Sanqiao in Chongqing as an Example

:There were 16 dangerous rocks on the cliff of Shenxiu cave in Tiansheng Sanqiao scenic spot, which seriously threatens the safety of the water-curtain elevator and the plank road works under the Shenxiu cave. Through the methods of site survey and theoretical analysis, the basic characteristics and failure mode of dangerous rock were studied, and the combination of qualitative and quantitative methods was used to comprehensively evaluate the stability of dangerous rock. The results show that dangerous rock on the cliff of Shenxiu cave in Tiansheng Sanqiao scenic spot were well developed, which have various shapes and different scales. After destruction, the impact scope was large and the consequences were serious. The failure mode of dangerous rock can be divided into three types which are slipping, toppling and falling. The stability of cliff rock blocks were evaluated by RMR method. The rock blocks belong to grade IV and its quality is poor. The stability of cliff rock blocks was evaluated by stereographic projection analysis. The rock blocks was severely cut by structural planes, and fissures L1, L4 and the intersection lines of multiple combinations were unstable structures. Quantitative evaluation the stability of dangerous rock, and the dangerous rock is calculated to be between stable and unstable, but under the condition of rainstorm, dangerous rock was mostly in unstable state. The research results provide a certain scientific basis and theoretical support for the prevention and control of dangerous rock in the later period.