Degree Type

Thesis

Date of Award

2019

Degree Name

Master of Science

Department

Civil, Construction, and Environmental Engineering

Major

Civil Engineering

First Advisor

Cassandra Rutherford

Abstract

Numerous ground improvement technologies have been developed over the last few decades to address problematic soils, marginal sites, and geohazards. Soil erosion is a leading geohazard causing infrastructure damage during storm and flooding events. Researchers have studied various bio-treatment methods to decrease erosion susceptibility of coarse-grained soils. Bacterial Enzyme Induced Calcite Precipitation (BEICP) was explored in this study to increase undrained shear strength and decrease soil erosion from moving water. This research investigates the surface erosion control for the mixture of 20-30 standard Ottawa sand and Iowa Western loess silt stabilized by BEICP applied by a spray method. The results obtained in this study indicate that the higher enzyme concentrations increase the surface shear strength and that the formation of the calcite precipitation provides increased resistance to erosion. The depth of the calcite precipitation into the soil specimen was also investigated.

Soft soils are also considered problematic soil due to their low undrained shear strength and compressibility. Various methods have been used to increase the shear strength such as addition of fibers, shredded rubber tires and geosynthetics. This research investigates adding magnetic particles and using a magnetic field to rotate the particle orientation to increase the shear strength of soft soils. A soft soil surrogate (laponite) which is also a transparent material, was used to visualize the rotation of the magnetic particles. The addition of the magnetic particles was shown to significantly increase the undrained shear strength. Preliminary work using a controllable electro-magnet to create a magnetic field to rotate the orientation of the magnetic particles at small scale is also presented.

Copyright Owner

Xinyi Jiang

Language

en

File Format

application/pdf

File Size

75 pages

Available for download on Tuesday, July 14, 2020

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