Extensive overview of soil constitutive relations and applications for geotechnical engineering problems.

A state-of-the-art review has been conducted in this work on soil constitutive modeling, which has emphasized on: soil type, ground-water conditions, loading conditions, structural behavior, constitutive relation discipline, and dimensions. By extension also, the soil constitutive applications were reviewed on the bases of: single discipline dealing with soil mechanical properties constitutive modeling which included slope stability problems, bearing capacity, settlement of foundations, earth pressure problems, soil dynamics, soil structure interaction, thermal and hydrological conditions; bi-discipline (coupled problems) which solve problems related to thermomechanical (freeze/thaw conditions), smoothed particle hydrodynamics (SPH) and hydromechanical (consolidation, collapse and liquefaction) conditions in soils and rocks and multi-discipline constitutive models which solve complex problems related to thermo-hydromechanical (THM) conditions in soils and rocks. This work has shown that smoothed particle hydrodynamics (SPH) and hydromechanical (HM) models, which belong to bi-discipline or coupled conditions are better suited for geotechnical applications, generally, while thermo-hydromechanical (THM) models, which belong to multi-discipline are better suited to solving freeze/thaw and thermal piles problems and these are proven with high performance and flexibility.

Understanding the microstructure, mineralogical and adsorption characteristics of guar gum blended soil as a liner material.

Guar gum blended soil (GGBS) offers potentially advantageous engineering characteristics of hydraulic conductivity and strength for a soil to be used as a liner material. Characterization techniques such as X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy and scanning electron microscope were used to examine the mineral composition, functional groups and morphological changes in the unblended soil (UBS) and GGBS. These characterization approaches are used to understand adsorption-associated mechanisms of Pb(II) removal. Batch adsorption tests were performed to evaluate the adsorption capacity of UBS and the GGBS with various proportions (0.5%, 1.0%, 1.5% and 2.0%) of guar gum (GG) towards the removal of Pb(II) ions. Batch adsorption experiments were conducted by varying the pH, dosage of adsorbent, concentration of metal ions and contact time. The experimental results showed that the optimum removal of Pb(II) ions was high at a pH of 3.0 for all blends, and adsorption tests beyond 3.0 pH demonstrated a decline in adsorption performance. The maximum Pb(II) removal efficiency of 95% was obtained using the 2.0% GGBS. The isotherm model assessment for adsorption experimental data of Pb(II) showed the best fit for the Langmuir model on using GG. The present research demonstrated that the guar gum-treated blends exhibited potential Pb(II) ion adsorption properties and therefore can be used as sustainable liner material in sanitary landfills.