| Summary: | Filtration compatibility of base soil and granular filter materials must be addressed in the design of zoned engineered fill structures. The evolution of design practice governing filter compatibility is reviewed, with emphasis placed on the experimental studies that have made the greatest contribution to current guidelines. Design practice governing filter compatibility for cohesionless uniform materials has remained relatively unchanged for the last 70 years. A novel and improved triaxial permeameter is used to test base soil-filter grain size ratios (D₁₅/d₈₅) close to the limit of filter incompatibility. The configuration and operation of the test device are described. Thereafter, data are reported for select combinations of base soil-filter specimens of glass beads that are reconstituted, consolidated and subject to unidirectional seepage flow. Interpretation of the test results addresses the onset of filter incompatibility with reference to independent measurements of change in permeability of the two-layer system and mass loss of the base soil through the filter. A unified framework is presented for interpretation of filter incompatibility, taking into account the influence of stress and hydraulic gradient. The implications of the test results are analyzed and discussed with reference to a confident understanding of base-soil filter compatibility. === Applied Science, Faculty of === Civil Engineering, Department of === Graduate
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