This paper studies the two widely used material models for predicting the dynamic behavior of soils, the Ramberg-Osgood and Hadrin-Drnevich models. Resonant column and torsional simple shear test results on dry sand were used to calibrate and evaluate the model built in the finite element software Midas GTS NX. Both material models are already implemented by the software. This study estimates the ability and efficiency of both soil models coupled with the Masing criteria to predict the behavior of soil when subjected to irregular loading patterns, (e.g., earthquakes), and measure the two most important dynamic properties, the dynamic shear modulus, and the damping ratio.
This mini review summarizes the most recent research in ballast reinforcement. Several materials are being used for the purpose of improving the ballast layer in railways, including geosynthetics, rubber sheets and binding agents. Such methods of reinforcement have proven to be beneficial for increasing the strength, stiffness, and resilience of the ballast layer in addition to reducing settlement, breakage, degradation, and maintenance cost and frequency. Latest studies try to find the best types, placement, and combination of geosynthetics to achieve the highest strength and resistance, in addition to obtaining the optimum percentage of binding agents and methods of applying them in order to discover the most effective binder that achieves the most improvement to the mechanical properties of the layer for a reasonable price. An overview of the recent tests conducted to study the reinforced ballast layer and their results is presented in this paper, as well as an overall evaluation of the implementation of these reinforcement methods in railways.
Resonant column (RC) and the torsional simple shear (TOSS) tests have shown proven competency in acquiring precise and repeatable measurements regarding the shear modulus and damping ratio of soil. For most dynamic geotechnical problems, the shear modulus represents the stiffness of the soil, while the damping ratio describes energy dissipation. Many studies in the last few decades focused on developing the relevant equipment and investigating the effect of different soil properties on the dynamic behavior of soil. Researchers have introduced correlations to approximate this behavior without conducting dynamic torsional testing. Soil models (e.g., Ramberg-Osgood and Hardin-Drnevich) can simulate shear stress-strain curves after finding the curve-fitting parameters. Due to the complexity of dynamic behavior and its dependency on various factors in soils, the RO and HD equations help model the behavior more simply. This paper presents a literature review and evaluation of the studies, correlations, soil models, and parameters affecting the dynamic behavior of dry sand under torsion.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.