乌东德水电站左岸地下主厂房围岩支护效果分析

Analysis on the Effect of Surrounding Rock Support for the Main Underground Powerhouse on the Left Bank of Wudongde Hydropower Station

地下洞室围岩支护效果检验分析对于地下工程运行具有重要意义.本文在围岩监测分析基础上,采用FLAC 3D对乌东德水电站左岸地下主厂房洞室开挖过程与支护效果进行数值模拟,通过对比分析位移场、应力场及塑性区等基本场与围岩变形监测数据的变化特征,定量评价围岩支护效果.分析结果表明,围岩支护效果显著,尤其是对顶拱围岩的位移变形遏制十分有效:支护后,顶拱累计位移量值最大下降幅度达96.4%,边墙累计位移值下降幅度达18%~25%,且变形趋于稳定;边墙拉应力逐渐减小,局部拉应力逐步变为压应力,缓解了应力集中效应,量值最大下降幅度达32.89%;边墙部位塑性区深度减小,范围缩小,塑性区深度下降50%;支护前后边墙的累计位移值的一致性说明了边墙围岩的自承能力较顶拱围岩强,且实际施工对边墙的支护是及时的.

The inspection of the supporting effect of the surrounding rock of the underground chamber is of great significance for the operation of the underground engineering.In this paper,based on the monitoring and analysis of surrounding rock,FLAC 3D is used to simulate the excavation process and supporting effect of the main underground powerhouse on the left bank of Wudongde Hydropower Station.The supporting effect of surrounding rock is evaluated quantitatively by comparing the variation characteristics of displacement field,stress field and plastic zone and the monitoring data of surrounding rock deformation.The results show that the effect of surrounding rock support is significant,especially for the displacement and deformation control of the surrounding rock of the crown.After the support,the maximum value of the cumulative displacement of the crown decreases by 96.4%,and the cumulative displacement of the side wall decreases by 18%-25%,and the deformation tends to be stable.The tensile stress of the side wall gradually decreases,and the local tensile stress gradually changes into the compressive stress,which alleviates the stress concentration effect.The maximum decline range is 32.89%.The depth of plastic zone in the side wall decreases,the range decreases,and the depth of the plastic zone decreases by 50%.The consistency of the cumulative displacement value of the side wall before and after support indicates that the self-supporting capacity of the side wall surrounding rock is stronger than that of the crown surrounding rock,and the actual construction of the side wall support is timely.