超高心墙坝非稳定渗流三维有限元分析

水库蓄水和放空过程对土石坝渗流安全产生重要影响,300 m级超高心墙坝渗控方案是筑坝关键技术难题之一。结合300 m级砾石土心墙堆石坝工程,通过建立整体三维有限元模型,模拟大坝运行过程中水库蓄水和放空过程,分析库水位变化条件下心墙等区域的浸润面和渗透坡降变化,研究水位变化速率对坝体渗透稳定性的影响。数值模拟结果表明,蓄水时随着库水位的升高,自由面在心墙内形成陡降并自上游侧向下游侧不断发展。蓄水历时越短、水位上升速率越快,心墙内形成的浸润面越陡。放空时随着库水位的下降,心墙内水位下降有所滞后,自由面在心墙内形成凸形面。放空历时越短、水位下降速率越快,心墙内形成的凸形浸润面落差越大。

Unsteady seepage analysis of super-high core wall dams using 3D finite element method

The processes of reservoir impoundment and emptying have important impact on seepage safety of earth-rock dams. The seepage control is one of the key technical problems for 300 m-level super-high core wall dams. To investigate the effect of change rate of water level on the seepage stability of dams, a three-dimensional (3D) finite element model for a 300 m-level gravel-soil core wall rock-fill dam is established. The seepage processes of reservoir impoundment and emptying are simulated, and the change of seepage surface and seepage gradient of core wall are analyzed. The simulated results show that the seepage surface has a steep drop in the core wall and continues to develop from the upstream to the downstream when the water level rises during the impoundment. The faster the water level rises, the steeper the seepage surface in the core wall. When the reservoir is be emptying, the seepage surface in the core wall lags behind with the reservoir water level, and the free surface has convex shape. The faster the water level drops, the greater the difference of the convex seepage surface forms in the core wall.