寒区引水隧洞低温相变温度场-渗流场耦合模型及其数值模拟研究

Study on Temperature-Seepage Field Coupling Model and Its Numerical Simulation for Diversion Tunnel in Cold Area under Low Temperature and Phase Transition

针对寒区引水隧洞围岩冻胀的多场耦合问题,考虑低温相变对岩体温度场和渗流场的影响,结合低温冻结条件下围岩的温度场-渗流场耦合模型,采用有限元法对新疆某电站引水隧洞工程围岩的冻结过程进行分析,研究低温相变条件下隧洞围岩温度场和渗流特性的变化规律。研究结果表明:在长期的冻结过程中,围岩内部形成了冻结区与未冻结区;随着冻结时间的持续,冻结锋面向围岩内部推移,岩体冻结深度和冻结范围不断增大。含水岩体在冻结过程中,水分由未冻结区向冻结区迁移,其渗流速度在冻结缘处达到最大,为1.359×10^(-4)m/s,在未冻结区渗流速度较小,为4.1×10^(-6)m/s。

In view of the multi-field coupling problem of surrounding rock frost heave of diversion tunnel in cold area, the finite element method is employed to analyze the freezing process and the variation laws of temperature field and seepage characteristics of surrounding rock for the diversion tunnel of a hydropower station in Xinjiang. In the study, the influences of low temperature and phase transition on temperature and seepage fields of rock mass are considered and the temperature-seepage field coupling model is used. The results show that the frozen area and no frozen area are formed in surrounding rock during long-time freezing process, and with the increase of freezing time, the freezing thickness and freezing range of surrounding rock are increasing. Due to the segregation potential, the water in water-bearing rock mass is transferred to frozen area from nofrozen area during freezing period. The seepage flow velocity is increased to maximum of 1.359×10^-4 m/s at frozen edge, and is reduced to minimum of 4. 1×10^-6 m/s at no-frozen area.