Electronic Theses and Dissertations

Identifier

6138

Date

2018

Document Type

Thesis

Degree Name

Master of Science

Major

Civil Engineering

Concentration

Geotechnical Engineering

Committee Chair

David Arellano

Committee Member

Roger W Meier

Committee Member

Shahram Pezeshk

Abstract

This study was motivated by the fact that the current practice for performing seismic site response analysis in the Memphis area uses shear modulus degradation and damping that are based on test results of soils obtained outside of the Memphis area. Memphis is located in the New Madrid seismic zone and is covered predominantly by loess soil. Loess has unique behavior from other soils. The purpose of the research is to determine the dynamic properties of Memphis area loess. Inorder to investigate the dynamic properties, remolded specimens with varying saturation levels and densities were prepared and tested using a resonant column and torsional shear, RCTS, device. Each specimen was tested at increasing confining stress and strain amplitudes.Shear modulus degradation and material damping curves were developed to evaluate the parameters that affect the dynamic properties of loess. The influence of void ratio, confining pressure, coefficient of lateral earth pressure, and saturation on shear modulus and damping ratio were evaluated. The dynamic properties of loess soil was found to vary at low saturation, 23%, and remains the same from medium to high saturation levels, 36% to 74%. The effect of confinig stress is found to be more pronounced at low saturation than at high saturation and the influence of void ration is found to insignificant. Shear modulus degradation of loess soil increases slightly and damping reamins constant with decrease of coefficient of lateral earth pressure. The test resuults were also compared with current shear modulus degradation and damping models. Seismic site response analysis was also performed to further compare the impact of using current models and this study test results on ground response.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to the local University of Memphis Electronic Theses & dissertation (ETD) Repository.

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