复合地层稳态渗流水头损失计算模型试验研究

Calculation model test study on water head loss in composite stratum under steady-state seepage

研究预测复合地层渗流过程中水头损失变化规律与简化计算,针对不同类型的复合地层进行稳态渗流条件下的水头损失简化计算模型试验。结果表明,复合地层渗流过程水头损失明显受到地层交替分布影响;粗粒土复合地层按照渗透系数较大的土层向渗透系数较小的土层方向连续渗流,水头损失大小采用达西定律简化计算;渗透系数小的粉质黏土层若是位于复合地层的上层或是中层,可能出现渗流的不连续,甚至是水头的消失,水头损失大小由渗透系数最小的地层控制简化计算;位于大厚度粉质黏土层下的饱水地层,水头损失从粉质黏土层临界面以下土层进行重新简化计算。

In order to study and predict the change law and simplified calculation of head loss in the process of seepage in composite stratum,the simplified calculation model of water head loss under steady-state seepage conditions was carried out for different types of composite stratum.The results showed that the water head loss was obviously affected by the alternate distribution of stratum.The coarse-grained soil composite strata had continuous seepage in the direction of the soil layer with a large permeability coefficient to the soil layer with a small permeability coefficient,and the head loss was simplified and calculated by Darcy’s law.If the soil layer with low permeability is located in the upper or middle layer of the composite stratum,it will lead to the discontinuity of seepage flow in the composite stratum,and even the disappearance of water head.The water head loss was simplified by the stratum with the lowest permeability.In the water-saturated stratum located under the large thickness silty clay layer,the head loss was resimplified from the soil layer below the critical interface of the silty clay layer.