ASU Electronic Theses and Dissertations
This collection includes most of the ASU Theses and Dissertations from 2011 to present. ASU Theses and Dissertations are available in downloadable PDF format; however, a small percentage of items are under embargo. Information about the dissertations/theses includes degree information, committee members, an abstract, supporting data or media.
In addition to the electronic theses found in the ASU Digital Repository, ASU Theses and Dissertations can be found in the ASU Library Catalog.
Dissertations and Theses granted by Arizona State University are archived and made available through a joint effort of the ASU Graduate College and the ASU Libraries. For more information or questions about this collection contact or visit the Digital Repository ETD Library Guide or contact the ASU Graduate College at gradformat@asu.edu.
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- Creators: Kavazanjian, Edward
Description
The Atlantic razor clam burrows underground with effectiveness and efficiency by coordinating shape changings of its shell and foot. Inspired by the burrowing strategy of razor clams, this research is dedicated to developing a self-burrowing technology for active underground explorations by investigating the burrowing mechanism of razor clams from the perspective of soil mechanics. In this study, the razor clam was observed to burrow out of sands simply by extending and contracting its foot periodically. This upward burrowing gait is much simpler than its downward burrowing gait, which also involves opening/closing of the shell and dilation of the foot. The upward burrowing gait inspired the design of a self-burrowing-out soft robot, which drives itself out of sands naturally by extension and contraction through pneumatic inflation and deflation. A simplified analytical model was then proposed and explained the upward burrowing behavior of the robot and razor clams as the asymmetric nature of soil resistances applied on both ends due to the intrinsic stress gradient of sand deposits. To burrow downward, additional symmetry-breaking features are needed for the robot to increase the resistance in the upward burrowing direction and to decrease the resistance in the downward burrowing direction. A potential approach is by incorporating friction anisotropy, which was then experimentally demonstrated to affect the upward burrowing of the soft robot. The downward burrowing gait of razor clams provides another inspiration. By exploring the analogies between the downward burrowing gait and in-situ soil characterization methods, a clam-inspired shape-changing penetrator was designed and penetrated dry granular materials both numerically and experimentally. Results demonstrated that the shell opening not only contributes to forming a penetration anchor by compressing the surrounding particles, but also reduces the foot penetration resistance temporally by creating a stress arch above the foot; the shell closing facilitates the downward burrowing by reducing the friction resistance to the subsequent shell retraction. Findings from this research shed lights on the future design of a clam-inspired self-burrowing robot.
ContributorsHuang, Sichuan (Author) / Tao, Junliang (Thesis advisor) / Kavazanjian, Edward (Committee member) / Marvi, Hamidreza (Committee member) / Zapata, Claudia (Committee member) / van Paassen, Leon (Committee member) / Arizona State University (Publisher)
Created2020
Description
Expansive soils pose considerable geotechnical and structural challenges all over the world. Many cities, towns, transport systems, and structures are built on expansive soils. This study evaluates stabilization of expansive soils using silicate solution extracted from rice husk taking advantage of an agricultural material waste. Rice husk ash production was optimized considering several factors including rinsing solution, rinsing temperature, burning time, and burning temperature. Results indicated that washing the rice husk with HCl (1M) produced an ash with surface area of 320 m2/g and 97% of silicon oxide. Two local soils were treated with sodium silicate solution, silica gel at pH 1.5, and silica gel at pH 4 to evaluate its mechanical properties at curing times of 1 day, 7 days, and 14 days. Results indicated that sodium silicate solution reduced the one-dimensional swell by 48% for Soil A, however, swell for soil B remained about the same. Silica gel at pH 1.5 reduced the one-dimensional swell by 67% for soil A and by 35% for soil B. Silica gel at pH 4 did also reduce the free swell by 40% for soil A and by 35% for soil B. Results also indicated that the swell pressures for all treated soils increased significantly compared to untreated soils. Soils treated with sodium silicate solution showed irregular compaction curves. Silica gel-treated soils showed a reduction in the maximum dry unit weight for both soils but optimum water content decreased for soil A and increased for soil B. Atterberg limits were also reduced for sodium silicate and silica gels-treated soils. Swelling index for bentonite showed a reduction by 53% for all treated bentonites. Soil-water characteristics curves (SWCC) for sodium silicate-treated soils remined almost the same as untreated soils. However, silica gels-treated soils retain more water. Surface area (SSA) decreased for sodium silicate-treated soil but increased for all silica gels-treated soils. It was concluded that curing times did not show additional improvement in most of the experiments, but the results remained about the same as 1-day treatment. The study demonstrated that silicate solution is promising and sustainable technique for stabilization of expansive soils.
Contributorsalharbi, hani (Author) / Zapata, Claudia (Thesis advisor) / Kavazanjian, Edward (Committee member) / van Paassen, Leon (Committee member) / Khodadaditirkolaei, Hamed (Committee member) / Arizona State University (Publisher)
Created2020
Description
Microbially- and enzyme-induced carbonate precipitation (EICP and MICP) offer potentially sustainable and cost-effective mitigation methods for fugitive dust by forming an erosion-resistant crust on the soil through precipitation of a natural calcium carbonate (CaCO3) cement. While there have been isolated studies on the efficacy of the carbonate precipitation process, there are few systematic studies of the influence of the properties of the soil being treated (e.g., gradation, salt content) on the precipitation and the resulting wind erosion resistance. Moreover, the influence of environmental conditions on the durability of the crust formed by the induced carbonate precipitation has not been systematically investigated. In this research program, the efficacy and durability of EICP and MICP for dust mitigation were investigated for a variety of soil types and in different environmental conditions. Soil samples from seven sites with fugitive dust problems were treated with MICP or EICP and subjected to lab or field testing. The results of these tests showed that the effectiveness of biocementation treatment varies depending on the grain size distribution of soil and mineralogical composition. Testing on iron ore tailings materials demonstrated that treating by application of EICP solutions at lower concentrations (i.e., 0.5M and 0.75M of urea and calcium chloride) yielded effective results for poorly graded fine sand-sized tailings but the same solutions were ineffective for the well graded sand-sized tailings that contained large gravel-sized particles. Additionally, the application of MICP and EICP on sediments adjacent to a shrinking lake (the Salton Sea) with different salt contents exhibited enhanced performance in soils with lower salt content. The effect of temperature during deployment and precipitation cycles are shown to be significant environmental factors by simulating wetting-drying and freeze-thaw cycles in the laboratory. A dust-resistance crust formed through biocementation remained mostly intact after undergoing multiple cycles of wetting-drying. However, the durability of a dust-resistance crust formed through biocementation to multiple cycles of freeze-thaw depended on treatment solution concentration and soil grain size. Additionally, high temperature during field deployment of MICP adversely effected crust formation due to rapid evaporation that inhibited the complete hydrolysis of urea and the precipitation of carbonate.
ContributorsEhsasi, Farideh (Author) / Kavazanjian, Edward (Thesis advisor) / van Paassen, Leon (Committee member) / Khodadaditirkolaei, Hamed (Committee member) / Arizona State University (Publisher)
Created2023