东非某大型水电工程地下洞室群稳定性研究

Stability analysis of underground cavern group of a large hydropower plant in East Africa

以东非某大型水电站为研究对象,建立地下洞室群的三维数值模型,基于Hoek-Brown破坏准则确定岩体力学参数,采用等效方法模拟系统支护效果,模拟洞室群七层开挖及支护的全过程,分析、对比围岩的变形、二次应力及塑性区等力学响应和整体稳定性。计算表明,Hoek-Brown准则是实用及可靠的;开挖后洞室变形、应力松弛、塑性区深度等均不显著,洞室整体稳定性良好,局部交叉部位需加强支护;采取系统支护后,上述力学响应均明显减弱,表明了支护的有效性;分析结果为后续的设计及施工提供重要依据。

Taking a large scale hydropower plant in East Africa as the research object,a 3-D numerical model of the underground cavern is built.Hoek-Brown Failure Criterion was used to obtain mechanical parameters of rock mass,and an equivalent method was applied to simulate system support effect.The excavation and supporting process of the underground cavern group with seven layers in total is simulated to analyze and compare mechanical conditions such as deformation,secondary stress and plastic zone,as well as the general stability.The numerical analysis results indicate that the Hoek-Brown Criterion is practical and reliable and the deformation,stress relaxation and plastic zone depth are all not significant and the whole cavern group is in good stability situation,while only local intersection parts require reinforced supporting.The above mentioned mechanical responses become lower after system supporting,indicating the supporting is effective.The analysis results provide the basis for following design and construction work.