A study on the stress-strain behavior of railroad ballast materials by use of parallel gradation technique

Download
2004
Kaya, Mustafa
The shear strength, elastic moduli and plastic strain characteristics of scaled-down ballast materials are investigated by use of the parallel gradation technique. Uniformly graded ballast materials chosen for the investigation are limestone, basalt and steel-slag. Steel-slag is a byproduct material of Eregli Iron and Steel Works, which is suitable to meet the durability test requirements as well as the electrical resistivity and the waste contaminants regulatory level. Conventional triaxial testing at a strain rate of 0.4 mm/min is used to obtain these characteristics for the scaled-down materials with a diameter of 100 mm specimen under a confining stress of 35 kPa, 70 kPa and 105 kPa; whereas that of only 35 kPa is used to characterize the accumulated plastic strain. The angle of internal friction, f, and the apparent cohesion, c, may be conservatively taken to be 42o and 35 kPa for all materials. The elastic moduli values for all materials may be predicted within an adequate estimate for the engineering purposes by using the power law parameters, K and n, determined for L-9.5 (D50 = 12.7 mm), the coarsest gradation tested for limestone. K with a reference pressure, pr = 1 kPa and n values for L-9.5, respectively, are 4365 and 0.636 for initial; 8511 and 0.419 for secant; 25704 and 0.430 for unloading-reloading elastic moduli. The unloading-reloading moduli increased, as the number of cycles increased. An increase in unloading-reloading modulus at N = 20 obtained was roughly 15% for scaled-down limestone; 10% for the basalt; and 5% for the steel-slag. The plastic strain after first cycle, e1, and the plastic strain coefficient, C can be represented as a function of mean particle size for each material type. For the limestone, basalt and steel-slag prototype size, D50 = 45 mm, e1 values of 0.59, 0.43 and 0.75 and C values of 0.54, 1.42 and 0.74 are predicted,

Suggestions

A Study on Tensile Strength of Compacted Fine-Grained Soils
Dagar, Volkan; Çokça, Erdal (Springer Science and Business Media LLC, 2020-08-01)
The tensile strength of clay is a major mechanical parameter and the main controlling parameter of tensile crack development which is generally encountered in geostructures. In this experimental study, 8-shaped direct tensile test and split tensile test were used to measure the tensile strength of compacted clay soil. Unconfined compression tests on the same clay samples were also carried out. Tensile strength and unconfined compression test results were compared. Laboratory tests were performed on Ankara c...
A non-linear mathematical model for dynamic analysis of spur gears including shaft and bearing dynamics
Özgüven, Hasan Nevzat (Elsevier BV, 1991-3)
A six-degree-of-freedom non-linear semi-definite model with time varying mesh stiffness has been developed for the dynamic analysis of spur gears. The model includes a spur gear pair, two shafts, two inertias representing load and prime mover, and bearings. As the shaft and bearing dynamics have also been considered in the model, the effect of lateral-torsional vibration coupling on the dynamics of gears can be studied. In the non-linear model developed several factors such as time varying mesh stiffness an...
A NUMERICAL AND EXPERIMENTAL STUDY ON THE CHARACTERISTICS OF HYDRAULIC JUMPS ON ROUGH BEDS
Velioglu, Deniz; Tokyay, Nuray; Dincer, Ali Ersin (2015-07-03)
Baffle blocks and sills are common accessory devices which are used in order to stabilize the location of a hydraulic jump and shorten the length of a stilling basin. On the other hand, strip roughness elements which cover the entire length of a basin may be an alternative. The objective of this study is to determine the effects of this type of roughness elements on the characteristics of hydraulic jumps such as conjugate depth ratio, jump length and energy dissipation. The study is carried out using experi...
Characterization of Homogeneity of Asphalt Concrete Using 2D Cross Sectional Images
Yücel, Ayhan Öner; Güler, Murat (2017-07-28)
Asphalt concrete is fabricated from a three-phase mixture consisting of aggregate, asphalt binder, and air voids. Homogeneity of asphalt mixtures affects performance characteristics of asphalt concrete pavements. In this study, homogeneity is determined from 2D vertical section images of gyratory compacted specimens. Because the aggregate structure dominates the performance of asphalt concrete, the mixture homogeneity is determined via statistical distribution of aggregate particles. The cross-sectional ima...
Determination of the Tensile Strength of Different Fiber Reinforced Concrete Mixtures
Ardoğa, Mehmet Kemal; Alam, Burhan; Yaman, İsmail Özgür (null; 2016-09-21)
Enhancing the tensile performance of concrete is the main advantage when fibers are added to this type of building materials. This improvement is usually measured through indirect methods like bending or split-tensile tests, in a way similar to normal concrete due to the absence of a standard tensile test for such purpose. Naturally, this type of tests does not determine the real tensile strength of the fiber reinforced concrete. Hence an important parameter, that is needed in modelling and designing proces...
Citation Formats
M. Kaya, “A study on the stress-strain behavior of railroad ballast materials by use of parallel gradation technique,” Ph.D. - Doctoral Program, Middle East Technical University, 2004.