裂隙岩体非恒定渗流场与弹性应力场动态全耦合分析

COMPLETE COUPLING ANALYSIS OF TRANSIENT FLUID FLOW AND ELASTIC STRESS IN FRACTURED ROCK MASSES

为更真实地反映在环境条件变化以及施工过程等因素作用下渗流场和变形场的行为规律,在裂隙岩体介质小变形的假定下,基于不可压缩水流在复杂应力状态作用下的裂隙岩体介质中运动的一般方程,建立两场动态全耦合的有限元数值模拟方法。在耦合分析中采用统一域混合模型模拟渗流场,对弹性变形场的模拟则采用多裂隙岩体介质和离散裂隙介质分别模拟的方法。对建立的耦合模型采用四自由度全耦合法结合有限元数值方法直接求解,对无压流中自由面的处理则采用固定网格法中的改进初流量法。最后针对水库裂隙岸坡算例,进行能模拟水库蓄水加载过程的静态、动态耦合有限元分析,揭示水库蓄水过程中裂隙岸坡位移场和渗流场的基本变化规律。分析结果表明,考虑蓄水过程中渗流的动态效应时,将会使水库岸坡产生较大的差异沉陷,从而对岸坡的稳定性产生不利影响,对于缓慢蓄水过程可以近似作为静态问题处理。

In order to reflect the actual behavior of the seepage field and deformation field during the environment change and construction processes, the basic equations and finite element expressions for complete coupling analysis of transient fluid flow and elastic stress are developed according to the assumption of small deformation and incompressible fluid flow in complicated fractured rock masses. A unified hybrid media model is used to simulate the seepage field： and both the equivalent continuum media model and the discrete media model are adopted to simulate the elastic deformation field. The coupled equations are solved directly by use of the four-freedom complete coupled method with FEM. And the modified initial flow method is adopted to deal with the free surface of unconfined seepage. Finally, the above method is applied to the fractured rock bank slope of a reservoir. Both the static and dynamic coupled processes of seepage field and stress fields are simulated during the rising of water level in reservoir, and the variations of both the displacement field and the seepage field are studied. The result shows that the dynamic action of water flow for quick rising can lead to a great difference in the settlement of the reservoir bank slope and reduce the bank slope stability; but slowly rising process can be solved as the static problem.