TY - JOUR
T1 - Role of initial particle arrangement in ballast mechanical behavior
AU - Qian, Yu
AU - Lee, Seung Jae
AU - Tutumluer, Erol
AU - Hashash, Youssef M.A.
AU - Ghaboussi, Jamshid
N1 - Funding Information:
This research project was partially supported by the Federal Railroad Administration (FRA) under Contract FR-RRF-0033-11- 01-00. Mr. Yu Xie, former M.S. student in the Department of Civil and Environmental Engineering (CEE) at the University of Illinois at Urbana-Champaign (UIUC) provided considerable help with the large-scale triaxial tests in the laboratory. Yu Qian has been partially supported by the National Natural Science Foundation of China (Grant 51578469). All the support and help are greatly appreciated. The opinions expressed in this article are solely those of the authors and do not represent the opinions of the funding agency.
Publisher Copyright:
© 2017 American Society of Civil Engineers.
PY - 2018/3/1
Y1 - 2018/3/1
N2 - Ballast containing large aggregate particles with uniformgradation is an essential layer in a railway substructure to facilitate load distribution and drainage. Although it is constructed or maintained in accordance with specifications, ballast is characterized by inherent randomness, not only in particle properties, such as mineralogy, size, and shape, but also in particle arrangement. Because of this randomness, the initial configurations of ballast particle assemblies vary fromplace to place in the field as well as from specimen to specimen in the laboratory. This paper presents a study on the influence of the aggregate scale randomness, which is the initial particle arrangement, on the geomechanical behavior of ballast. A series of large-scale, laboratory, triaxial shear-strength and repeated-load permanent-deformation tests was performed at the University of Illinois at Urbana-Champaign for the study. Numerical simulations using the discrete-elementmethod (DEM) were also performed to understand better the effect of different initial particle arrangement on the basis of the identical particle scale properties of shape and size distribution. The ballast aggregate particles weremodeled as three-dimensional (3D) polyhedral elements according to the properties of particles used in the laboratory tests, and then, the same set of particles was used to simulate laboratory tests with different initial particle arrangements for each specimen. The results from both the laboratory experiments and numerical simulations confirmthat the initial particle arrangementmay significantly affect the strength and deformation behavior of ballast. Hence, multiple tests or simulations with different particle-packing arrangements are needed to study ballast mechanical behavior. However, a stable average response can be obtained with a minimum of three laboratory experiments or numerical simulations.
AB - Ballast containing large aggregate particles with uniformgradation is an essential layer in a railway substructure to facilitate load distribution and drainage. Although it is constructed or maintained in accordance with specifications, ballast is characterized by inherent randomness, not only in particle properties, such as mineralogy, size, and shape, but also in particle arrangement. Because of this randomness, the initial configurations of ballast particle assemblies vary fromplace to place in the field as well as from specimen to specimen in the laboratory. This paper presents a study on the influence of the aggregate scale randomness, which is the initial particle arrangement, on the geomechanical behavior of ballast. A series of large-scale, laboratory, triaxial shear-strength and repeated-load permanent-deformation tests was performed at the University of Illinois at Urbana-Champaign for the study. Numerical simulations using the discrete-elementmethod (DEM) were also performed to understand better the effect of different initial particle arrangement on the basis of the identical particle scale properties of shape and size distribution. The ballast aggregate particles weremodeled as three-dimensional (3D) polyhedral elements according to the properties of particles used in the laboratory tests, and then, the same set of particles was used to simulate laboratory tests with different initial particle arrangements for each specimen. The results from both the laboratory experiments and numerical simulations confirmthat the initial particle arrangementmay significantly affect the strength and deformation behavior of ballast. Hence, multiple tests or simulations with different particle-packing arrangements are needed to study ballast mechanical behavior. However, a stable average response can be obtained with a minimum of three laboratory experiments or numerical simulations.
KW - Ballast
KW - Discrete-element method (DEM)
KW - Particle arrangement
KW - Permanent deformation
KW - Shear strength
KW - Triaxial compression test
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U2 - 10.1061/(ASCE)GM.1943-5622.0001074
DO - 10.1061/(ASCE)GM.1943-5622.0001074
M3 - Article
AN - SCOPUS:85038610817
SN - 1532-3641
VL - 18
JO - International Journal of Geomechanics
JF - International Journal of Geomechanics
IS - 3
M1 - 04017158
ER -