Study On Saturated And Unsaturated Seepage Field Of Landfill Due To Rainfall

Most of the domestic landfill have surface damage and clogging drainage problems,Rainfall directly goes into the landfill and leads to failure of drainage of groundwater;Rainfall also results in transient water pressure in waste landfill site.Transient water pressure in waste landfill site is one of the major reasons causing the instability of waste mass.To understand the distribution characteristics of transient ground water table in the waste landfill site under rainfall conditions and waste dam water load distribution,based on the garbage composition of a waste landfill site located in southwest region of China,laboratory tests were performed to study the permeability of a waste mass with different void ratio,with 2D and 3D seepage field numerical calculation method,the main contents and conclusions are as follows.(1)By studying literature,the works such as summarized the leachate transport in landfill,analysis on mechanism leading to the landfill seepage and damage mechanism are performed.(2)Laboratory tests were performed to study the permeability of a waste mass with different void ratio such as 2.0,2.5,and 3.0 respectively.It shows that the large amount organic components are the reason causing the permeability coefficient and residual water content of waste mass being relatively large.(3)Furthermore,saturated-unsaturated seepage numerical method was employed for better understanding of the distribution,variation of groundwater table and waste dam water load distribution in waste landfill site under rainfall conditions.It shows that the large amount organic components are the reason causing the permeability coefficient and residual water content of waste mass being relatively large.Landfill leachate in the rain before the initial water level(corresponding to the landfill leachate drainage system working state)during the operation of the water level rises due to rainfall infiltration,garbage body pore water pressure and load distribution of dam water important influence.For a small scale valley-type waste landfill site,the water table of leachate will rise rapidly under storm and rainfall long time rainfall conditions and lead to a high level status of transient water pressure.On the aspect of influence on the stability of waste landfill,a long time rainfall condition is worse than a storm rainfall condition in the case of total rainfall quantity is same.(4)Through dynamic analysis of various process of landfill seepage field,water load distribution acting the waste dam for waste dam stability analysis is suggested.