Time-Settlement Behavior of Processed Refuse. Part I: Mathematical Model for Solid Waste Settlement

摘要

The material investigated in this study is municipal refuse which has been processed in a hammer mill to produce a relatively fine-textured material in which the constituents are uniformly mixed. Such a material offers several advantages from an operational point of view, so that it is likely that the milling process will come into widespread use in the future. This material, in contrast to that of conventional sanitary landfill, lends itself to study and analysis because of its relative homogeneity. To model the time-settlement behavior of this material a generalized time-pore pressure dissipation relationship is combined with a rate process function which describes secondary consolidation to produce two simultaneous equations, one of which is non-linear. This model includes the effects of finite strains, biological and chemical activity, time variations in saturation, and large creep displacements. Functions are proposed to relate the instantaneous geometry and saturation to the instantaneous permeability, and the instantaneous geometry to the instantaneous compressibility. These are tentatively quantified using previously published data on the behavior of peat, which like the material studied is composed primarily of cellulose. The effects of the possible partial saturation on the stress distribution and compressibility are discussed. Under conditions of total saturation, constant compressibility-permeability ratio, small strains, and no changes due to biochemical activity, the model reduces to the classical Terzaghi case.