荆江大堤杨家湾险段地下水渗流场特征的模拟研究

采用美国地质调查局(USGS)的Visual Modflow软件,通过对荆江大堤监利县杨家湾险段不同水位条件下的模拟和在高水位下(10 m水头差)不同处理模式的模拟(减压井模式、防渗墙模式、压浸模式和改变人工填土渗透系数模式、渊塘模式),结果表明:(1) 人工填土的性质对渗透破坏的影响显著;(2) 减压井有利于降低含水层中的水头,但由于减压井中的混合水位为地表高程,与同点无减压井条件下基本相同,其出流带的减压效果不显著;(3) 由于该剖面防渗墙处岩层的渗透性较小,与防渗墙体的渗透性差异不大,防渗墙的作用不明显;(4) 当存在渊塘或天窗时,渊塘及其周边是发生渗透破坏的重点区域,可以通过减压处理防止渗透破坏。

SIMULATION ON SEEPAGE FIELD OF UNDERGROUND WATER IN YANGJIAWANG,A DANGEROUS PIPING ZONE IN THE JINGJIANG GREAT EMBANKMENT

The seepage field of underground water in Yangjiawang of Jianli county,one of the dangerous piping zone in flooding season,on the north bank of the Yangtze River,is simulated for different water levels of the Yangtze River and different treatment models,such as model in different water levels,model of pond in high water level,model of seepage-proof walls,model of reducing-pressure wells,model to control soak and model in changing the seepage coefficiency of artificial filling,with the software of Visual Modflow developed by US geological survey. The simulation results show that the decrement of the seepage coefficiency of artificial filling will reduce the seepage damage significantly in high water level,and the reducing-pressure wells are of significant effect to prevent the bank from piping if ponds or scuttles are present.