Laboratory Research Of Clogging Of Landfill And Analysis Of Maximum Liquid Depth In Landfill Drainage Layers Under Clogging Conditions

Leachate collection and drainage systems of landfills at home and abroad are generally prone to lead clogging presently, resulting in high leachate level, which have become an international problem. It has important practical significance to study the landfill drainage layer clogging mechanism, calculate the maximum liquid depth in drainage layers under clogging conditions, reduce the clogging effect and optimize drainage system design.To solve the problem, the status and methods on clogging research and related field, laboratory test data at home and abroad were summarized in this paper. Combined with the latest understanding of the mechanism of clogging, experiment program was developed in view of temperature, particle size, geotextile such three factors and combination of them. Experiment instruments were created and long-term experiments were conducted. The experiments are now in progress.From a preliminary analysis of test results (about 300 days), it showed that the drainage porosity of coarse-grained group and fine-grained group was divided into two parts:the porosity of coarse-grained group is larger and would be gradually less with time; the porosity of fine-grained group is smaller and would also be gradually less with time. It can be seen that particle size is the dominant factor in clogging. There is no obvious difference in drainable porosity for the test equipments with the same particle size under different temperatures. For the test equipments with the same temperature and geotextile, the drainage porosity of coarse-grained group is larger than the fine-grained, have better effect on anti-clogging, and the reduction rate is the same as the fine-grained group's (about 10%), but the absolute reduction is more than the fine-grained group's because of more space occupied by clogging material. For the tests with the same temperature and particle size, there seems not obvious with or without geotextile on drainage porosity. The change of chemical composition of each group is about the same.On the basis, combining with the previous research of our team and the latest international progress, a simplified model was obtained in this paper which can reflect the development of clogging. Method of calculating the maximum liquid depth in drainage layers which was based on the maximum liquid depth clogging model was proposed. Comparing with the steady and transient results, it shows that no clogging results are in accordance with the transient results, which all tend to the steady results. And the clogging must be considered when clogging is seriously which may affect the liquid depth markedly. Parameters analysis shows that the greater previously (the smaller later) the hydraulic conductivity the longer the drainage distance the faster the infiltration rate the higher the concentration, the more seriously the impact of clogging on liquid depth. Design suggestions were proposed for improving the drainage system performance.Finally, from the experimental and numerical analysis results, reducing clogging and optimizing drainage system design suggestions were proposed in order to ensure the landfill running sanitary and safe in the design, construction, landfill, operation and other various stages.