Abstract: In order to predict the maximum leachate depth in landfill drainage layer and determine the significance of its influening parameters,the following research work is carried out.Firstly,an analytical solution to leachate depth along drainage layer is obtained during leachate infiltration based on the extended Dupuit assumption;the distribution law of leachate depth along drainage layer is analyzed with different leachate infiltration intensity.Then,orthogonal design method is used for comparing the effectiveness of the five main parameters influencing maximum leachate depth,which are leachate infiltration intensity,permeability coefficient,horizontal drainage distance,layout slope as well as water head at the drainage blind ditch ,and the most influential parameters for changing maximum leachate depth are obtained.The variance analysis gives the degrees of impact for each parameter on the maximum leachate depth.The results show that:(1) the analytical solution of leachate depth obtained above considers the actual hydraulic state of the drainage blind ditch in the drainage layer more reasonably,and the distribution characteristics of leachate depth are accurately described;(2) leachate infiltration intensity and horizontal drainage distance have significant impact on the maximum leachate depth in the landfill drainage layer.The findings will facilitate the optimization of design parameters of landfill drainage layer and the prevention of landfill instability caused by high leachate depth.

Key words: landfill, drainage layer, maximum leachate depth, influencing parameters, variance analysis