高地应力下拉西瓦水电站地下洞室群稳定性分析

Stability analysis of large underground caverns in Laxiwa hydropower plant under high crustal stress

针对黄河流域装机容量最大的拉西瓦水电站地下洞室群高地应力、大跨度和硬岩特点,结合描述硬岩弹脆性破损的岩体劣化模型(RDM)和评价围岩脆性破坏倾向性的局部能量释放率指标(LERR),通过三维有限差分数值方法模拟了地下洞室群开挖全过程,从整体上揭示了拉西瓦水电站地下洞室群分期开挖时围岩变形场、应力场、塑性区、能量释放率的时间演化过程与空间分布特征。另外,通过洞室开挖过程中局部部位出现的几种典型围岩变形破坏模式的跟踪分析表明,厂区高地应力和洞室开挖后重分布应力场的动态调整是围岩发生不同形式变形与破坏的内在机理。其研究结论和认识可为同类高地应力环境下地下工程开挖支护提供有益参考。

The underground caverns of Laxiwa hydropower plant are typical grottos with characters of high crustal stress,big span and hard rock.So,a new hard rock elasto-brittle model named rockmass deterioration model（RDM） is adopted to describe the brittle break of rock and a new rock burst indicator named local energy release rate（LERR） is used to estimate the rock burst tendency.Through the 3D numerical excavating simulation of underground caverns,the typical time evolvement rule and space distribution characteristic of hard rock mechanical performance is gained,which include the deformation field,stress field,energy field and plastic zone.In addition,the analysis of deformation and break mode of cavern wall rock indicates that high crustal stress is the basic inner mechanism of different break and deformation behaviors of rock.The research result is a good reference for similar excavation and support of large underground caverns under high crustal stresses.