旱涝急转条件下土石坝渗流特性分析与安全控制

为分析旱涝急转条件下土石坝的渗流特性,基于非稳定饱和—非饱和渗流理论及其有限元方法,分析了长江中下游某粘土心墙坝在旱涝急转期间不同库水位上升速度下瞬时浸润线、等势线、渗透坡降等渗流要素的变化特性,建立了渗透坡降与库水位上升历时的经验关系,通过库水位上升速度判断坝体渗透安全性能,并计算了渗流安全控制条件下的临界库水位上升速度。结果表明,旱涝急转期间,随着水库水位抬高、上升速度增大,土石坝渗流场呈现规律性变化;利用库水位上升速度评价坝体渗流安全性能,对于旱涝急转条件下坝址区合理分洪调洪措施制定等具有重要意义。

Seepage Characteristic Analysis and Safety Control of Earth-Rockfill Dam under Conditions of Abrupt Alternation of Drought-Flood

For analysis of seepage characteristics of earth-rockfill dam under conditions of abrupt alternation of drought-flood, based on the seepage theory of unsteady saturated-unsaturated and its finite element method, the change characteristics of different seepage elements, such as transient saturation line, equipotential line and gradient, of a clay core dam in the middle and lower reaches of the Yangtze River under drought-flood abrupt alternation with different rising velocities of water level were analyzed. Empirical relationship between seepage gradient and duration of rising water level was established. The seepage safety of the dam was judged by the rising velocity of water level. The results show that during the abrupt alternation of drought-flood, with the water level as well as its velocity increasing, the seepage field of the dam changes regularly. To judge the seepage safety of the dam with rising velocity of water level has the vital practical significance of making reasonable measures for flood management.