Engineering Commons^™

Static Liquefaction And Critical State Mechanics Of Gold Mine Tailings Subjected To Different Stress Paths, Amir Reza Fotovvat

Electronic Thesis and Dissertation Repository

The mechanisms through which mine tailings fail have been the interests of many studies recently. In this series of studies, the flow liquefaction and instability behavior of gold mine tailings were examined within the framework of critical state soil mechanics. In the first study, the behavior of a gold mine tailings in stress paths involving extensional consolidation or shearing in extension was evaluated. Monotonic tests were carried out on isotropically and K_o-consolidated samples to assess the effect of stress-induced anisotropy and mode of shearing on the static liquefaction characteristics tailings. In the second study, the drained instability of …

Static Liquefaction Of Oil Sand Tailings: An Experimental Investigation Into The Effect Of Saturation And Fines Content, Farshad Zehforoosh

Electronic Thesis and Dissertation Repository

The main goals of this research are to explore the influence of partial saturation and fine content on the shear response of oil sand tailings, to identify the liquefaction susceptibility under different initial states. Monotonic triaxial compression tests were carried out to understand the mechanical behavior of the saturated oil sand tailings with varying void ratios. Then the effect of fine content on the yield and critical shear strength, critical state line, and instability line was evaluated by increasing the fine content up to 50%. The experimental results revealed that the shear strength of the oil sand increases with fine …

Towards Realistic Simulation Of Penetration Tests And Instability Analysis Of Sand: A Micromechanical Perspective, Seyedshayan Hashemi

Electronic Thesis and Dissertation Repository

In this series of studies, the capability of Discrete Element Method (DEM) to simulate the behavior of granular materials has been examined. In the first study, various boundary conditions are simulated through a series of DEM-based miniature calibration chamber tests to investigate the influence of boundary conditions on cone tip (q_c) and sleeve frictional (f_s) resistances. The second study focuses on the influence of microparameters such as state, modulus, rolling resistance, inter-particle friction, and probe properties on CPT measurements in a centrifuge setting. DEM has been used in the last study to investigate the instability of …

Studies On The Liquefaction Behaviour Of Tailings And Natural Sand, Guillermo Riveros

Electronic Thesis and Dissertation Repository

This series of studies explores the liquefaction behaviour of cohesionless mine tailings and a natural sand and examines the effectiveness of a bio-mediated treatment for the mitigation of liquefaction. The first study investigates the flow liquefaction failure of the Fundão tailings dam (2015) by analytically assessing the stability of the breached abutment, accounting for the specific triggering mechanism and subsequent strength loss that led to its collapse. The second study evaluates the static liquefaction behaviour of gold mine tailings and its correlations with shear-wave velocity through an experimental program comprised of direct simple-shear and bender element tests. The last study …

Cyclic And Post-Cyclic Response Of Silt And Sandy Silt Soils, Ali El Takch

Electronic Thesis and Dissertation Repository

A series of cyclic and monotonic constant-volume ring shear tests were carried out to determine the cyclic and post-cyclic response of silts and sandy silts with 25% and 50% sand. The elastic soil behavior at very small shear strain (γ < 10^-4%) was investigated through shear wave velocity (Vs) measurements using bender elements at vertical stresses ranging from 50 to 300 kPa, while strain-controlled constant volume cyclic ring shear tests were conducted to establish shear modulus (G) and damping ratio (D) at larger shear strain amplitudes (γ > 0.01%). Liquefaction and strain-softening occurred at excess pore water pressure ratios (r_{u …}

The Behaviour Of Cement Stabilized Clay At High Water Contents, Saeed Sasanian

Electronic Thesis and Dissertation Repository

Artificial cementation of soft clays has been used for several years for different ground improvement projects. Although considerable work has been done to develop advanced machinery and techniques for the implementation of artificial cementation, less knowledge is available on the mechanisms involving the formation of the artificial structure and the resulting mechanical behaviour. The primary objectives of the present work were to investigate the formation of microstructure in artificially cemented material with Portland cement, find the relationships between cementitious bonding and clay mineralogy, and create constitutive frameworks for predicting the mechanical behaviour of cement-treated clays.

Qualitative and quantitative microstructural characterisation …