填埋场复合排水系统中最高水位深度的计算

Maximum saturated depth of landfill in drainage system with geosynthetics

现代填埋场排水层或覆盖层设计时,对复合排水系统最大水位深度的准确估算一直都没有获得很好的解决。依据扩展的Dupuit假设形式,导出复合排水系统在自由出流边界条件下的浸润线求解方法。通过与HELP模型,Giroud等以及Qian的计算结果比较,说明本文提出的方法是合理和准确的,在此基础上,进行了算例及多参数分析。对复合排水系统(两层)而言,如果入渗率、排水距离、土工网排水率、上覆砂层渗透系数不是很小,最大水位深度受这些因素的影响非常明显。和单一介质相比,复合排水系统的最大水位深度受坡度的影响很大,在实际的设计中,增加复合排水系统的坡度可以非常有效地减少最大水位深度。

To design cover system or leachate collection systems of a modem landfill, engineers often have to estimate the maximum saturated depth （Dmax） for a drainage system with geosynthetics. Based on the extended Dupuit assumption, a computational solution was presented to calculate Dmax, and the liquid profile for drainage system with geosynthetics underlain a sand layer was provided. By comparison with the results calculated by other methods, the present method was shown to be rational and accurate. By means of parametric analysis, in drainage systems with a sand layer above a geocomposite layer, Dmax was significantly influenced by the inflow rate, drainage distance, transmissivity of the geocomposite and the hydraulic conductivity of the sand when they were not extraordinarily low. It was also found in drainage systems with a sand layer and a geocomposite layer, Dmax was much more sensitive to the slope of the drainage layer than that in a comparable system consisting of two sand layers. It was of great advantage to increase the inclination when geocomposites were applied as a drainage material.