土体水力滞后对土石坝初次蓄水渗流场的影响

在土石坝的蓄水过程中,坝料的持水特性和渗透函数的不同会对坝体渗流场产生很大的影响。因此,对土坡的降雨入渗和土石坝的蓄水渗流场的分析应采用土-水特征吸湿曲线及相应的渗透函数。基于砾石土料的土-水特征曲线的实测结果,采用饱和-非饱和渗流有限元方法对不同程度各向异性的均质土坝初次蓄水过程中由脱湿和吸湿曲线计算所得的渗流场进行对比分析,探讨采用脱湿曲线代替吸湿曲线计算带来的影响。结果表明由脱湿曲线计算的孔隙水压力和体积含水率均明显高于由吸湿曲线计算的结果,渗透性的各向异性程度对坝体中的水力滞后性无明显影响。因此,在入渗分析时若采用脱湿曲线取代吸湿曲线会高估坝体中的孔隙水压力和含水率,低估非饱和区的吸力。

Impact of the Hydraulic Hysteresis of Soil on the Seepage Field in Embankment Dams during Initial Reservoir Filling

Variety of water retention and permeability function has great impact on the seepage in embankment dam during reservoir filling. Therefore, the wetting curve of the soil-water characteristic and corresponding permeability function should be used in the seepage analyses for the rainfall infiltration of soil slopes and reservoir filling of the embankment dams. Based on the measured soil-water characteristic curves of the gravelly clay and saturated-unsaturated seepage finite element method, comparison analyses have been conducted for the seepage in the homogeneous dam with different seepage anisotropy using drying and wetting curves of soil-water characteristics and corresponding permeability functions to investigate the impact of replacing wetting curve by drying curve on analysis results for seepage. The results show that the pore-water pressures and the volumetric water contents calculated by drying curves are evidently bigger than those calculated by wetting curves. The variety of the seepage anisotropy has no evident impact on the hydraulic hysteresis in the dam. Therefore, the pore-water pressure and water content in the dam would be overestimated and the suction in unsaturated zone would be underestimated if the wetting curves were replaced by the drying curves in infiltration seepage analysis.