Doctoral Dissertations

Zhaochao Li

Keywords and Phrases

Buckling; External pressure; Polyhedral; Rigid confinement; Stability; Thin-walled liner

Abstract

"This study aims to investigate the structural stability of thin-walled liners encased in functionally-obsolete underground pipelines in saturated soil under external hydrostatic pressure, a concentrated load, temperature change or their combination, and develop a simplified circular arch model of thin-walled liners when not constrained by the pipelines. The friction and adhesion on the interface between a liner and its constraining surface (pipeline or grouting), and the pressure gradient on deeply-buried pipelines are neglected. The critical buckling load of elastic liners is analytically derived under a plane strain condition using the principle of minimum potential energy. The analytical solution is either validated experimentally by test data available in the literature or verified numerically by 2D or 3D finite element modeling. This study starts with a circular liner that is constrained by grouting except at the grouting void area. Under uniform pressure, the critical buckling pressure that the liner can sustain is reduced substantially with the presence of grouting voids and slightly with potential slippage between the liner and grouting. The confined liner is then subjected to combined pressure and thermal loading, resulting in a significantly reduced critical buckling load. The pressure-displacement equilibrium paths of various elastoplastic liners at their crown point are traced in numerical simulations. The maximum pressures are in good agreement with the analytical solutions. Next, a thin-walled circular arch with semi-rigid support conditions is symmetrically loaded at crown, giving satisfactory analytical solutions. Finally, a novel polyhedral liner is proposed and analyzed with an admissible displacement function. Its load capacity is increased up to 10 times compared with that of circular liners, depending on the number of sides in polyhedral liner"--Abstract, page iv.

Advisor(s)

Chen, Genda

Committee Member(s)

Chandrashekhara, K.
ElGawady, Mohamed
Yan, Guirong Grace
Wu, Chenglin

Department(s)

Civil, Architectural and Environmental Engineering

Degree Name

Ph. D. in Civil Engineering

Sponsor(s)

Missouri University of Science and Technology. Department of Civil, Architectural and Environmental Engineering

Comments

Financial support for this study was provided in part by the Department of Civil, Architectural, and Environmental Engineering through Robert W. Abbett endowment funds.

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2018

Journal article titles appearing in thesis/dissertation

  • Buckling of thin-walled liners encased in underground pipelines with grouting voids under external pressure
  • Elastic and inelastic buckling behavior of thin-walled rings encased in circular cavities with non-uniform spacing under mechanical and thermal loadings
  • Elastic buckling of thin-walled polyhedral pipe liners encased in a circular pipe under uniform external pressure
  • Stability of arches with rotational spring supports under a crown point load

Pagination

xiii, 119 pages

Note about bibliography

Includes bibliographic references.

Rights

© 2018 Zhaochao Li, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Thesis Number

T 11716

Electronic OCLC #

1164805556

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