大型地下洞室岩梁开挖主要工程地质问题及处理措施讨论

Main engineering geological problems and treatment measures of large underground cavern rock beams during excavation

为研究地下洞室岩梁主要工程地质问题及其应对处理措施,通过分析白鹤滩水电站岩梁地质条件、破坏特征、影响因素、不利后果等,对岩梁主要地质问题进行归类,分析产生原因,总结处理措施,研究认为岩梁主要地质问题有围岩变形、卸荷回弹、破裂破坏、松弛破坏、块体破坏、缓倾角软弱结构面影响、陡倾角裂隙影响等,为最大限度的避免不利地质条件影响,应在洞室选址、方案布置时便充分考虑,开挖前详细制定岩梁开挖方案,必要时采取预处理措施,对开挖后发生的围岩破坏,可针对性的采用机械挖除、预应力加固、增加插筋、混凝土修补、设置扶壁墙、固结灌浆、锚索加固等措施。

In order to study the main engineering geological problems and treatment measures of underground cavern rock beams, by analysing the geological conditions, failure characteristics, influencing factors and adverse consequences of the rock beams of Baihetan Hydropower Station, the main geological problems of rock beams are classified, the causes are discussed, and the treatment measures are summarized. The study indicates the main geological problems of rock beams in the clued deformation of surrounding rock, unloading rebound, breakage, relaxation failure, block failure, influence of the slightly inclined weak layer, and influence of high dip angle fissure. In order to greatly avoid the influences of unfavorable geological conditions, full consideration should be given to the site selection and layout of caverns. Before excavation, the excavation plans of rock beams should be worked out in detail, and the pretreatment measures should be taken if necessary. For the failure of surrounding rock after excavation, the relevant measures such as mechanical excavation, pre-stressed reinforcement, additional reinforcement, concrete repair, supporting wall, consolidation grouting and reinforcement prestressed anchor cables should be adopted.