锦屏二级水电站裂隙岩体渗流-应力耦合分析

Seepage-Stress Coupling Analysis of Fractured Rock Body in the Jinping Second-cascade Hydropower Station

如何准确地了解和预测隧洞周围裂隙岩体的渗流-应力耦合行为对锦屏二级水电站深埋高压引水隧洞的设计和施工有着重要意义。锦屏山裂隙岩体的渗透系数的空间非均质分布利用随机连续模型生成。通过顺序指示模拟方法生成的随机连续场随后被导入有限元程序进行两场耦合分析。计算结果表明,随机连续模型能够较好地预测锦屏二级水电站隧洞开挖过程中地下水的最大入渗率。渗透系数的空间变异性使得隧道开挖后围岩应力有明显的非连续性,对裂隙介质的耦合过程起着重要作用。同时,雨季降雨对隧道支护系统有着重要影响。补给水将引起外水压力短时升高,衬砌上的负荷增加,其弯矩增加了近22%。

How to accurately understand and forecast the seepage-stress coupling function of the fractured rock body surrounding tunnel is significant for the design and construction of deep buried high-pressure tunnel of Jinping Second- cascade Hydropower Station. The spatial uneven distribution of the seepage coefficient of the fractured rock mass in Jinping Mountain was produced by the stochastic continuum model. The stochastic continuum field that was generated with the sequential indicator simulation method was introduced into finite element program for coupling analysis. The calculation results showed that the stochastic continuum model can give a better prediction of the maximum infiltration rate of underground water in the excavation of tunnel of Jinping Second-cascade Hydropower Station. The spatial variability in permeability plays an important role in the coupled hydro-mechanical processes of the fractured rock mass and induces a discontinuous distribution of principal stresses. It is also found that water recharge can affect the mechanical behavior of the support and increase the load on the liner. The results indicated that the moments on the liner increase by 22% after the water recharge.