Refuse : the fibrous soil

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University of New Brunswick


When refuse is placed in a landfill, it is no longer just a pile of garbage, but it becomes a geotechnical material. It is the soil of the landfill site. Landfills have a side slope and occasionally retaining walls need to be built also. For the soils engineer to have an effective efficient design, the geotechnical properties of this unnatural material should be known. This report is a study of the lateral pressures produced by refuse, under static and dynamic (earthquake) loading, and of the shearing resistance under dynamic loading. Tests were performed at UNB in testing apparatuses designed and built at the same university. The refuse was also sorted and an attempt was made at classifying it with respect to its fibre content. This was not successful because of reasons covered in there report. It has been recommended that more research be done on the sorting of refuse in an attempt to classify the fibre content, or as it is starting to be called, fibrosity. Part of this research could be done on a piece of equipment called the split box. The split box has been calibrated for friction and most of the problems with it sorted out and is ready to be used. The refuse does not behave like a traditional soil with respect to lateral pressures. Where loose sand has Ko value of 0.5 the garbage has a value of 0.3. When in an active state, the refuse will have a Ka of 0. A loose sand's Ka will never reach 0 and most likely will not fall below 0.2. The reason for the lower lateral pressures in the refuse is that there are many fibres in this "soil" and they strengthen it laterally. It was seen that when subjected to cyclic loading the lateral reinforcement did not deteriorate. Tested cyclically in shear, the refuse did not lose it lateral strength. It has been determined that because of its fibrous nature, refuse has very different geotechnical properties from traditional soils.