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Tests were conducted to determine the variation of water content and pore water suction for compacted clayey soils. The soils had varying amounts of clay fraction with plasticities ranging from low to high plasticity. The unsaturated soil behavior was investigated for six conditions, covering a range of compactive efforts and water contents. The experimental data were fit to four commonly used models for the water content-pore water suction relationship. Each model provided a satisfactory fit to the experimental data. However, the individual parameters obtained from the curve fits varied significantly between models. The soil water characteristic curves (SWCCs) were more sensitive to changes in compaction effort than changes in compaction water content. At similar water contents, the pore water suction increased with increasing compaction effort for each compaction condition and soil type. For all compaction conditions, the lowest plasticity soils retained the smallest water content and the highest plasticity soils retained the highest water content at a specified suction. In addition, SWCCs for soils compacted in the laboratory and in the field were similar. DOI: 10.1061/(ASCE)1090-0241(2002)128:9(733) CE Database keywords: Soil compaction; Soil water; Soil conditions.

ABSTRACT: This investigation was conducted to determine the effects of temperature and moisture on the shear strength of a double nonwoven geosynthetic clay liner (GCL) and a high-density polyethylene textured geomembrane (T-GM) interface for municipal solid waste landfills. Interface direct shear tests were conducted at normal stresses representative of cover liners (10, 20 and 30 kPa) and bottom liners (100, 200 and 300 kPa). Tests were conducted at temperatures of 2, 20 and 40°C (cover liner) and 20 and 40°C (bottom liner); and at moisture contents of as-received (19%), 50 and 100%. Both peak and large-displacement (50 mm) shear strength parameters were determined. For cover liners, temperature was determined to have a greater influence on interface shear strength than moisture content, whereas bottom liner shear strength was influenced more by moisture than temperature. Measured interface shear strengths varied by up to 54% with temperature and up to 43% with moisture content. Interface friction angles were greatest at 20°C for both cover and bottom liners. Variations in the interface shear strength parameters were attributed to geosynthetic damage including surface texture of the geomembranes (quantified with optical interferometry) and bentonite extrusion. Overall, results of this testing programme indicated that both peak and large displacement GCL/T-GM interface shear strengths were influenced by temperature and moisture content representative of field service conditions. [ABSTRACT FROM AUTHOR]

Authors' thank discussants for their careful consideration of authors' article. Each discussant provides additional insight into the experimental procedure and results presented in the article. As described in the article, each model provides an acceptable fit to the measured soil retention data, with the sum of squared residual for all cases falling within a relatively narrow range. In all cases, except for soil 3 at wet of optimum modified compaction effort, the FX5 model provides a slightly better fit to the data.