The performance of small-scale model piles jacked into calcareous sand and tested under cyclic axial loadings is presented in this paper. The calcareous sand beds used for the tests have been prepared from reconstituted soil that has been consolidated under different overburden pressures using a test vessel of special design. The study is focused on the accumulation of permanent displacement of the piles under both uniform and nonuniform amplitude cyclic loadings. A numerical analysis is employed to predict the cyclic behavior of the model piles, using input parameters derived from the experimental results. Comparisons between the measured and predicted results show reasonable agreement.

Solute breakthrough curves for a 0.01-M NaCl solution permeated through two compacted test specimens of processed kaolin soil are measured at two volumetric flow rates (2.65 × 10 ⁻⁴ cm ³ /s and 2.65 × 10 ⁻⁵ cm ³ /s) using a flow pump system. Regression analyses of the effluent solute concentrations with two analytical models resulted in hydrodynamic dispersion coefficients D ranging from 1.49 × 10 ⁻⁶ cm ² /s to 3.95 × 10 ⁻⁶ cm ² /s for chloride and from 2.11 × 10 ⁻⁶ cm ² /s to 8.74 × 10 ⁻⁶ cm ² /s for sodium indicating that diffusion dominated the transport process in the two column tests. The effluent electrical conductance values measured immediately after sampling also tend to reflect the dominance of diffusion on the solute migration process. An observed decrease in effluent pH from between 4.8 and 5.5 during permeation with distilled water to about 4.5 during subsequent permeation with the NaCl solution is consistent with Na ⁺ for H ⁺ exchange at relatively low pH previously reported for studies involving kaolinite soils. The results of this laboratory study tend to confirm previous field studies that indicate diffusion-dominated transport at the low flow rates common in fine-grained barrier materials.

A model for the behavior of fully saturated normally consolidated and overconsolidated marine clays subjected to uniform cyclic strain-controlled and staged cyclic loading under simple shear conditions is proposed. Staged cyclic testing with several levels of different uniform cyclic strains was used to simulate a clay response similar to the one that occurs during true irregular cyclic loading during earthquakes, ocean storms, and other natural cyclic loading phenomena. The model incorporates cyclic degradation, cyclic pore-water pressure generation, and cyclic threshold shear strain defined as the cyclic strain amplitude below which neither significant (positive or negative) pore-water pressure develops nor significant degradation occurs. The model was verified by staged cyclic direct simple shear testing of five marine clays. Practical applications of the model are addressed.

A constitutive model for soils and interfaces involved in creeping natural slope is proposed. It is based on the hierarchical single-surface plasticity and viscoplasticity approaches and allows for factors such as elastic, plastic and creep strains, normal stress, and stress-path effects. The model is calibrated from a series of laboratory triaxial tests for soils obtained from the field site at Villarbeney Landslide, Switzerland, simple shear tests for interfaces, and simple shear creep tests for both. It is verified with respect to the laboratory tests used for finding the parameters and independent tests not used in finding the parameters. The model is implemented in a two-dimensional finite-element procedure, which is then used to back-predict observed field behavior at two locations at the Villarbeney Landslide. Typical comparisons between finite-element predictions and field data show that the proposed modeling procedure provides highly satisfactory correlations for the field situations considered herein.

Essential to the development of rate-type, elastoplastic constitutive models to describe the stress-strain behavior of any soil is knowledge concerning magnitude and direction of plastic strain upon application of an incremental stress. A series of stress-probe experiments are performed on a granular material with the objective of developing some understanding of these aspects. Triaxial sand specimens, loaded initially to different specified states of stress, are subjected to incremental stress probing in different directions, and the corresponding strain responses are measured. The results indicate that while the behavior approximately conforms to the theory of plasticity for stress states close to the failure line, it deviates from it for stress states close to the isotropic axis.

A field test was conducted to determine if freeze-thaw cycles cause increases in hydraulic conductivity in the field, as has been observed in laboratory tests. A test pad of compacted clay was instrumented for monitoring temperatures and climatic conditions and partially insulated. The measurements indicated that up to 10 cycles of freeze-thaw occurred in the uninsulated portion of the test pad whereas no freezing occurred in the insulated portion. Hydraulic-conductivity tests were conducted before and after winter to determine if changes in hydraulic conductivity occurred as a result of winter exposure. In situ hydraulic-conductivity tests showed that the overall hydraulic conductivity was similar in the insulated and uninsulated portions of the test pad before and after winter. No change in overall hydraulic conductivity occurred in the uninsulated region because the depth of frost penetration was only 30% of the thickness of the test pad. However, tests on block specimens collected from near-surface soil that underwent freezing and thawing increased in hydraulic conductivity by a factor of 50–300. Similar increases in hydraulic conductivity were measured using laboratory freeze-thaw tests.

Concern has been expressed about the bearing capacity of hydrated geosynthetic clay liners (CGLs), with respect to the possibility of thevarious products decreasing in thickness and thereby sacrificing their lowas-manufactured hydraulic conductivity properties. This experimental studyshows that, with adequate cover soil placement before loads are applied, thispossibility can be avoided. Traditional design of the cover soil thicknesswith respect to anticipated loadings, followed by proper installationprocedures, should be followed when utilizing GCLs.