Engineering Commons^™

Lunar Regolith Simulant Behaviours Affected By Shock Metamorphism And Mineralogy, Xiao Chen Zhang

Electronic Thesis and Dissertation Repository

There are still many gaps in improving the fidelity of lunar regolith simulants to simulate more properties. This study compares some fundamental physical and mineralogical properties of three types of lunar highland regolith simulants: LHS-1, a commercial product with high mineralogical fidelity; UWO-1G, an original simulant that is the main component of LHS-1; and UWO-1S, another original product that is attempted to produce shocked grains in lunar simulants from pulverizing and mixing impact rocks sourced from the Mistastin Crater.

Preliminary results indicated that even though all simulants are composed of mostly plagioclase minerals and have similar particle size distribution patterns, …

Seismic Response Of Driven And Helical Piles In Non-Liquefiable And Liquefiable Soils, Ahmed Fouad Hussein

Electronic Thesis and Dissertation Repository

The thesis investigates the nonlinear soil-pile-structure interaction through three-dimensional nonlinear finite element models (FEM) employing the OpenSees platform. The FEMs were validated with the results of large-scale shaking table tests of model pile groups-superstructure systems in dry and saturated sand and large-scale field tests on single piles installed in cohesive soil. The numerical models correctly predicted the different pile deformation modes that were exhibited in the experiments. The results illustrated that the inertial interaction contributed to the bending moments at the pile top, while the kinematic interaction contributed to the bending moment at the layers interface. In addition, the excess …

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 …

Guidelines For Designing The Overhead Transmission Tower Foundations Adjacent To Cohesionless Slopes, Meshel Q. Alkahtani

Electronic Thesis and Dissertation Repository

Foundations supporting electrical transmission line towers are subjected to oblique loading due to tower own weight along with wind loading. Due to land limitation and linear alignment of transmission lines, many power transmission towers are situated in sand near sloping grounds and proper evaluation of their foundation performance is essential for the safety and reliability of the critical power transmission lines. There is currently no guidance available on the behaviour of transmission towers foundations constructed near slopes. Thus, the primary objectives of this study are to evaluate the response of transmission tower foundations in cohesionless sloping grounds and investigate the …

Scaled Physical Modeling Of The Dynamics Of Granular Flow In Hopper Silos, Hagos Eman

Electronic Thesis and Dissertation Repository

To understand the challenges on grain flow during handling in hoppers and silos require better understanding of the granular physical flow characteristics through experiments done at large scale. However, due to the complexity of the large, controlled tests, scaled models are often used to study the behaviour. Very few of these model scale studies had been done appropriately taking the effects of gravity on silo discharge into account. This subject has also been widely investigated in different areas of geotechnical engineering related to soil erosion, land slides, and dynamic liquefaction. Granular flow rate and the dynamics of the flow are …

Performance Of Single And Grouped Helical Piles Under Strong Earthquake Shaking, Abdelrahman F.F. Aly

Electronic Thesis and Dissertation Repository

Full-scale shaking table testing was conducted to evaluate the seismic performance of single and grouped helical piles. Eight circular and one square helical piles with different properties as well as one driven circular pile were installed in dry sand enclosed in a laminar soil shear box that was situated on the shaking table. Dynamic properties of sand bed and its natural frequency, as well as the natural frequencies of single and grouped helical pile-soil systems were evaluated from the collected data during different shaking events. The effects of different pile configurations as well as successive shakings on the characteristics of …

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 …

Full-Scale Field Study Of A Geogrid-Reinforced Unpaved Road System, Abdalla El Tawati

Electronic Thesis and Dissertation Repository

Geogrids are widely used to improve the performance of unpaved roads constructed over weak subgrade. However, the behavior of geogrids under traffic loads and their reinforcing mechanisms, as well as the resulting benefits to the roadway performance are not well understood. A full-scale field study was conducted to quantify the effectiveness of geogrids in unpaved roads, evaluate their reinforcing mechanism, and identify which geogrid properties are most directly related to performance improvement. Ten full-scale unpaved road test sections were constructed with varying relevant parameters including geogrid aperture shape, geogrid tensile modulus, and thickness of the base course layer. Five of …