复杂地质隧道进口危岩稳定性评价及防治措施

基于某隧道进口处3处危岩单体，详细进行野外调查、勘查、测绘，查明危岩的自然环境、水文和工程地质条件、危岩特征及变形破坏模式。分析形成危岩的内外因素，认为危岩形成的内因是活动断裂、地层岩性和地貌条件，外因是风化作用和大气降水。并采用定性分析及结合计算模型定量评价危岩的稳定性，危岩体在天然工况下处于基本稳定状态，暴雨和地震工况下处于欠稳定-基本稳定状态。根据危岩体的发育特征、破坏模式及隧道洞口的建设条件，采用清危、镶补凹腔、回填洞穴、锚固、封闭注浆的防治措施。

Stability Evaluation and Controlling Measures of Dangerous Rock at Entrance of Complex Geological Tunnel

Based on three dangerous rock monomes at the entrance of a tunnel, the field investigation, exploration and mapping are detailed. The natural environment, hydrologic and engineering geological conditions, the characteristics of dangerous rock and the mode of deformation and failure are identified, and the internal and external factors of the formation of dangerous rock are analyzed. It is considered that the internal cause of the formation of dangerous rocks is active fault, formation lithology and landform conditions, and the external cause is weathering and atmospheric precipitation. The stability of dangerous rock is evaluated quantitatively by qualitative analysis and calculation model. The analysis concludes that dangerous rock is basically stable under natural conditions, and understable to basically stable under rainstorm and earthquake conditions. According to the development characteristics of the dangerous rock mass, the failure mode and the construction conditions of the tunnel entrance, the prevention and control measures such as clearing the dangerous rock mass, inserting and filling the cavity, backfilling the cave, anchoring and sealing grouting are adopted.