The anti-seepage and absorption ability of clay layer are main factors influencing landfill liner working performance.A 1D convection-dispersion model was proposed to analyze the influence of permeability coefficient

diffusion coefficient

infiltration intensity

and absorption ability on the breakthrough time and leaching quantity.A 2D numerical model considering soil stratification

inhomogeneity

underground water motion and macro-dispersivity was introduced to reflect practical complex conditions

and parameter sensitivity analysis was conducted.The results show that keeping a relatively low leachate head is of great importance to obtaining well anti-seepage performance and durability of clay liner. The permeability coeffisient of clay liner varies within extensive range because of variation in material character and quality control during construction and the breakthrough time decrease sharply when the permeability coefficient increase by one order of magnitude.A nearly linear relation between breakthrough time and retardation factor can be obtained when the permeability keeps constant.Underground water can severely influence the transportation and distribution of pollutant.The results show that pollutant transport occures mainly in vertical direction when the water level is low.The pollutant concentration in lower layer soil and underground water is much lower because of intense absorption in unsaturated soil above the water level.