Experimental Study on the Behaviour of Expansive Soils

In this research, laboratory-based experiments were conducted to investigate the volumetric and mechanical behaviour of expansive soils. The effects of clay mineralogy, initial water content and preconsolidation stress on the compressibility and shear strength of expansive clays were investigated. Predictive models based on regression analysis and artificial neural networks are proposed to estimate the compression and shear behaviour of expansive soils. Additionally, a green stabiliser was introduced to reduce the swell potential of expansive clays

A decision support system for ground improvement method selection

Abstract unavailable please refer to PD

Characterisation of Static Liquefaction of Sand with Different Mixtures of Fines

Liquefaction is a phenomenon of a sudden reduction in shear strength of saturated soils when subjected to undrained static or cyclic loading. Static liquefaction susceptibility of sand with various amounts of fines was investigated using experimental and artificial intelligence approaches. Liquefaction behaviour of sandy soils was considerably dependent on the fines content and fines types. The artificial intelligence results showed that both of ANN and GP could well predict the liquefaction susceptibility of mixtures

EXPLORATION OF LIGNIN-BASED SUPERABSORBENT POLYMERS (HYDROGELS) FOR SOIL WATER MANAGEMENT AND AS A CARRIER FOR DELIVERING RHIZOBIUM SPP.

Superabsorbent polymers (hydrogels) as soil amendments may improve soil hydraulic properties and act as carrier materials beneficial to soil microorganisms. Researchers have mostly explored synthetic hydrogels which may not be environmentally sustainable. This dissertation focused on the development and application of lignin-based hydrogels as sustainable soil amendments. This dissertation also explores the development of pedotransfer transfer functions (PTFs) for predicting saturated hydraulic conductivity using statistical and machine learning methods with a publicly available large data set. A lignin-based hydrogel was synthesized, and its impact on soil water retention was determined in silt loam and loamy fine sand soils. Hydrogel treatment significantly increased water retention at saturation/near saturation by 0.12 cm3 cm-3 and at field capacity by 0.08 cm3 cm-3 for silt loam soil compared to a control treatment with no added lignin hydrogel. Hydrogel application significantly increased water retention at -3 cm to -15,000 cm soil water pressure head by 0.01 - 0.03 cm3 cm-3 for the loamy fine sand soil. Calculations demonstrated that at a 1% (w/w) concentration or lower, lignin-based hydrogels in silt loam and loamy fine sand soils would not increase plant available soil water storage. The incorporation of lignin-hydrogels significantly decreased saturated hydraulic conductivity. In unsaturated conditions, application of the lignin-based hydrogel at 0.1 and 0.3% (w/w) increased hydraulic conductivity. New pedotransfer functions (PTFs) for predicting saturated hydraulic conductivity were developed using machine learning (ML) and a large public database. Random forest regression and gradient boosted regression both gave the best performances with R2 =0.71 and RMSE = 0.47 cm h-1 on the validation data set. The concentration of lignin-alginate hydrogel added to Rhizobial cell culture did not affect cell survival. All treatments of wet bioencapsulated beads achieved a similar yield of 97%, however, the presence of starch in the lignin-alginate beads increased the survival of Rhizobium cells

Master of Science in Geological Engineering

thesisDynamic testing of expanded polystyrene (EPS) results in behavior alterations when certain testing criteria are modified. Triaxial testing affirms the behavior of EPS geofoam under axial compression tests related to a seismic compressible inclusion application. An evaluation of initial static deviator stress, load frequency of deviator stress amplitudes, and the effect of static confining stress of EPS geofoam dynamic response are performed. The behavior of viscoelastic and visco-elasto-plastic are compared through the use of cyclic compression tests. Comparative measurements used in supporting behavior change were: Young's modulus, damping ratio, cyclic deviator stress, and plastic axial strains. The resulting data is interpreted through data charts and data trends. Comparative conclusions show significant behavior changes to EPS geofoam when frequency and confining stress influential effects are observed