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Title:Three-dimensional numerical analysis of reflective cracks in airfield pavements
Author(s):Garzon Torres, Jorge
Director of Research:Duarte, C. Armando; Buttlar, William G.
Doctoral Committee Chair(s):Duarte, C. Armando; Buttlar, William G.
Doctoral Committee Member(s):Hilton, Harry H.; Brill, David; O'Hara, Patrick
Department / Program:Civil & Environmental Eng
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Generalized Finite Element Method (GFEM)
crack propagation
reflective cracking
energy release rate
Abstract:Hot mix asphalt (HMA) is used as the primary overlying material of concrete pavements during rehabilitation because of its inexpensive nature when compared to most Portland cement concrete (PCC) rehabilitation/reconstruction alternatives. In airfield pavements for example, a common technique is to place a HMA concrete overlay on top of an existing deteriorated PCC, since the initial cost is low and the placement process is fast. This restores smoothness, structure and water-proofing benefits to existing pavement. However, due to the majority of the PCC pavements being in average to poor condition, many HMA overlays are exposed to extreme movements (both vertical and horizontal). The combination of associated load and environmentally induced movements creates complex stresses and strains in the vicinity of expansion joints and cracks in the PCC, thus dramatically reducing the life of the HMA overlay, typically in the form of reflective cracking. Reflective cracking is a fatigue cracking distress, which is initiated at the bottom of the HMA overlay and propagates through its thickness and the surface. It can reduce the life expectancy of the overlay because it leads to roughness, raveling, and moisture infiltration. The analysis of reflective cracking involves all modes of fracturing i.e., Mode I (opening), Mode II (shearing), and Mode III (tearing) [61] and thus 3-D models are required. The need for true 3-D modeling of reflective cracking complicates the development of computational models using standard finite element methods. Furthermore, the nature of the linear viscoelastic material (asphalt) makes the crack analysis time dependent. The Generalized or eXtended Finite Element Method (G/XFEM) [10, 12, 41, 108, 109, 119, 163] adds flexibility to the FEM while retaining its attractive features. In this study, the computation of the time-dependent energy release rate G (t) along 3-D crack fronts is done by applying the elastic-viscoelastic correspondence principle to the associated GFEM elastic solution. The inversion from the Laplace domain to the physical domain is done numerically using the Fourier series method. In this proposed linear viscoelastic GFEM, adaptive surface triangulations are utilized to ex- plicitly represent complex 3-D crack surfaces. Computational geometry algorithms are used to track the evolution of the crack front and the crack surface representation based on GFEM solutions. This methodology allows us to investigate the behavior of complex 3-D reflective crack surfaces accounting for the viscoelastic behavior of the material while keeping the computational cost and implementation complexity comparable to the case of linear elastic materials. Numerical experiments of long crack growth (crack surface significantly increases from its initial size) and coalescence of multiple crack surfaces demonstrate that the method is robust and is able to perform complex 3-D crack growth simulations. As such, it provides support for the development of mechanistic based design procedures for airfield overlays that are tolerant to reflective cracking.
Issue Date:2013-05-24
Rights Information:Copyright 2013 by Jorge Luis Garzon Torres. All rights reserved.
Date Available in IDEALS:2013-05-24
Date Deposited:2013-05

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