渗透溶蚀作用下帷幕性态对坝基渗流的影响

Effect of Initial Behavior of Curtain on Seepage Flow of Dam Foundation under Osmotic Dissolution

帷幕是影响大坝工程安全的重要因素之一,其防渗性能在坝基水渗透溶蚀作用下会发生衰减。为研究帷幕初始性态不同时,对运行一段时期后帷幕耐久性及坝基渗流量的影响,首先建立了渗流场、化学场以及固相介质孔隙度等多场耦合模型,然后考虑帷幕整体性变化和局部存在薄弱部位两种情况。前者通过局部敏感性分析,结果表明不同阶段各性态的影响大小有所不同,在初始阶段,透水率>深度>宽度,而在运行10年后,表现为透水率>宽度>深度;对于后者,模拟结果表明,坝基水对薄弱部位的侵蚀速率会明显加快,待该区域内帷幕的可溶性组分全部溶蚀后,继续向该部位上下两侧扩展,从而加速了整个帷幕的溶失。基于以上研究可为具体工程实际中帷幕设计提供科学指导。

Curtain was one of the important factors affecting the safety of dam engineering. Its impervious performance is weakened under the action of seepage dissolution of dam foundation water. In order to study the influence of different initial behavior on curtain durability and seepage flow of dam foundation after a period of operation, a multi-field coupling model of seepage field, chemical field and pore structure of solid medium is built up firstly. Then the two situations including overall change of curtain and the existence of weak parts locally are considered. Local sensitivity analysis of the former one shows that the influence of different characteristics is different in different stages. At the initial stage, the effect of the permeability is largest and then the depth and the width. While after 10 years of operation, the order changed to the permeability, the width and then the depth. As for the latter, the simulation results show that the dissolution rate in the weak parts is significantly accelerated. Then it continued to expand to the upper and lower sides of this part after all the soluble components of the curtain in this region are dissolved, which accelerated the dissolution of the whole curtain. Based on the above research, it could provide scientific guidance for curtain design in specific engineering practice.