荆江大堤盐卡险段地下水渗流场模拟研究

SIMULATION ON SEEPAGE FIELD OF UNDERGROUND WATER IN YANKA DANGER SECTION OF JINGJIANG GREAT EMBANKMENT

采用美国地质调查局(USGS)的Visual Modflow软件,通过对荆江大堤荆沙市盐卡险段不同水位条件下以及在高水位下(10和13 m水头差)不同处理模式(存在天窗模式、改变人工填土渗透系数模式、减压井模式和防渗墙模式) 的模拟,结果表明:(1) 在高水位下,减小人工填土的渗透系数可明显减少渗透破坏。(2) 当存在渊塘或天窗时,减压井对防止管涌发生有更为明显的效果。(3) 防渗墙对防止渗流破坏也有一定的作用,防渗墙深度达到中间的粘土层(20 m的深度),能达到彻底治理险情的效果。

The Yanka section of the Jingjiang Great Embankment on the north bank of the Yangtze River is one of the zones with piping hazard in flooding seasons. Seepage fields of ground water at different river water levels are simulated by using the software of Visual Modflow developed by US geological survey. Different treatment models,such as models of presence of scuttle,seepage-proof walls,pressure-reducing wells and chaning the seepage coefficiency of artificial filling,are studied at high water levels. The results show that (1) a decrease in seepage coefficiency of artificial filling will reduce the seepage damage significantly in the high water level,(2) reducing of pressure wells has significant effect on preventing piping if ponds or scuttles are present,and (3) seepage-proof walls are effective against seepage damage if the walls reach the clay layer in the middle (about 20m in depth).