某电站地下厂房硐室群分阶段开挖数值模拟

摘要

Based on the engineering geological conditions and excavation design of the underground powerhouse in the project,3D finite element software ANSYS was applied to the model and FLAC-3D was applied to simulate on the excavation process of underground powerhouse. The distri-bution character of the stress field,displacement field and plastic zone in the excavation process were studied based on the fitted inversion of three dimensional initial in situ stress fields. The result shows that the high value of the maximum main stress appears in the excavation concentration of underground cavern group and the high value of maximum main stress base overlap with the high value of displacement. The cavern floor’s rock mass may appear high value of displacement due to unloading.%根据某电站地下厂房工程地质条件和开挖设计方案，采用ANSYS有限元软件进行三维地质建模，并以地应力实测结果为参照反演分析初始地应力场，在此基础上进行地下硐室群分阶段开挖数值模拟计算，进而分析硐室群开挖过程中分步开挖对围岩应力场、位移场和塑性破坏特征的影响。结果表明：受硐室集中开挖影响，最大主应力的高值出现在地下硐室群开挖集中部位，硐室拐角处也易出现应力集中；岩体开挖后围岩卸荷回弹，围岩最小主应力局部呈减小趋势；地下硐室围岩位移的高值与最大主应力高值部位基本重合，主厂房和主变洞开挖跨度大，在边墙中部可能出现较大的位移值，硐室底板围岩同样可能因卸荷回弹而出现较大的位移值。