Abstract: The unsaturated hydraulic characteristics of wasted soil is the basis for predicting and evaluating the migration and distribution of leachate in landfills. Based on the aerobic ecological restoration project of the Beiyangqiao Waste Landfill in Wuhan, an on-site pumping water injection test was carried out, and the effects of using different theoretical methods on the calculation results of permeability were compared in this paper. It was inverted by monitoring the water level change data of the pumping test and unsaturated hydraulic characteristics of wasted soil. The results show that the saturated permeability coefficients of the obsolete landfills tested in the field test are all in the order of 10?6?10?5 m/s, and different test methods have little effect on the saturated permeability coefficient test results. According to pumping test results, it is inferred that the pumping influence radius is about 15 m, and the single well flow rate is 0.3 m3/h; the average residual water content of the wasted soil is 27%, which is larger than the measured value from indoor tests. The air intake value of the wasted soil is 2 kPa and the pore size distribution index is 1.20. The results are similar to the indoor test results. The on-site pumping test can not only directly evaluate the water conductivity of the garbage, but also accurately estimate the effective soil-water characteristics of the waste with the help of numerical inversion methods, which provides a new method for obtaining unsaturated hydraulic characteristic parameters.

Key words: landfill, waste, permeability, soil-water characteristics, numerical inversion