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Author: Hai Huang Publisher: ISBN: Category : Languages : en Pages :
Book Description
Ballast is an essential layer of the railroad track structure, and provides primarily drainage and load distribution. In general, ballast aggregates are considered as uniformly graded, angular shaped with crushed faces. However, various ballast aggregate gradations and particle shapes are in use yet their effects on ballast performances remain unknown. In previous designs and modeling practices, railroad ballast has usually been treated as a homogeneous and continuous layer. This approach is not suitable to model the deformation behavior of the particulate nature railroad ballast aggregates under dynamic moving loads. Further, continuum solutions do not take into account realistically the morphological characteristics of aggregates such as particle size distribution and shapes. A combined digital image and Discrete Element Modeling (DEM) methodology has been developed in this PhD thesis to study effects of aggregate particle size and morphological characteristics on ballast performances. The approach has been calibrated using actual ballast aggregates through laboratory shear box texts and validated by further laboratory as well as field experiments. Using the DEM ballast model, individual effects of aggregate particle size distributions and shape properties on railroad ballast strength, lateral stability, and settlement potential were studied. From the DEM simulation results, it was found that aggregate particle size distribution and shape have significant impact on ballast performances. Ballast with broader size distribution was shown to yield less settlement potential than ballast with more uniformly graded aggregates. Also, ballast with angular aggregate particles were found from the DEM simulations to have higher strength as well as better lateral stability than ballast with rounded aggregate particles due to better stone on stone contact and aggregate interlock. In summary, the developed DEM ballast model has been proven in this PhD research to be a promising tool for studying railroad ballast load and deformation characteristics and could lead to the ultimate goal of designing better 0́−engineered ballast.0́+
Author: Hai Huang Publisher: ISBN: Category : Languages : en Pages :
Book Description
Ballast is an essential layer of the railroad track structure, and provides primarily drainage and load distribution. In general, ballast aggregates are considered as uniformly graded, angular shaped with crushed faces. However, various ballast aggregate gradations and particle shapes are in use yet their effects on ballast performances remain unknown. In previous designs and modeling practices, railroad ballast has usually been treated as a homogeneous and continuous layer. This approach is not suitable to model the deformation behavior of the particulate nature railroad ballast aggregates under dynamic moving loads. Further, continuum solutions do not take into account realistically the morphological characteristics of aggregates such as particle size distribution and shapes. A combined digital image and Discrete Element Modeling (DEM) methodology has been developed in this PhD thesis to study effects of aggregate particle size and morphological characteristics on ballast performances. The approach has been calibrated using actual ballast aggregates through laboratory shear box texts and validated by further laboratory as well as field experiments. Using the DEM ballast model, individual effects of aggregate particle size distributions and shape properties on railroad ballast strength, lateral stability, and settlement potential were studied. From the DEM simulation results, it was found that aggregate particle size distribution and shape have significant impact on ballast performances. Ballast with broader size distribution was shown to yield less settlement potential than ballast with more uniformly graded aggregates. Also, ballast with angular aggregate particles were found from the DEM simulations to have higher strength as well as better lateral stability than ballast with rounded aggregate particles due to better stone on stone contact and aggregate interlock. In summary, the developed DEM ballast model has been proven in this PhD research to be a promising tool for studying railroad ballast load and deformation characteristics and could lead to the ultimate goal of designing better 0́−engineered ballast.0́+
Author: Bo Wang Publisher: BoD – Books on Demand ISBN: 3734746663 Category : Technology & Engineering Languages : en Pages : 146
Book Description
As an essential component of the ballast track, the ballast layer provides functionali-ties such as drainage, load distribution, as well as strength and stability for the rail-way track. The mechanical behaviors of ballast track such as its permanent settle-ment, breakage, force propagation and void ratio are in a great extent influenced by the form distribution of ballast stones. Its reasonable design will greatly improve the mechanical behaviors, and thus prolong the maintenance cycle of ballast track, or reduce the number of ballast stones needed for construction. This dissertation focuses on proposing optimized ballast stones in the ballast aggre-gate in regard to their geometrical forms. As the first step, a ballast random form gen-erator, which is designed to generate ballast form databases with different form dis-tributions, is proposed. 15 databases are created for further usage. Afterwards, Dis-crete Element Method (DEM) based simulations are performed to investigate the mechanical behaviors of ballast aggregates. The simulation model is established based on a box test, whose result is presented firstly. Establishment and calibration process of the model are expatiated afterwards. A parameter study regarding to cru-cial modeling parameters is also performed. Using the validated parameters and the 15 generated form databases, DEM simulation models with different form distribu-tions of ballast stones in the ballast aggregate are proposed. Simulative methods to quantify the mechanical behaviors are elaborated. Based on the obtained results, the interrelation between mechanical behaviors of ballast aggregate and the form effect on mechanical behavior of the ballast aggregates are studied. The optimized ballast aggregate is proposed based on the findings stated above. The proposed optimized ballast aggregate is expected to be a reference for construc-tion of ballast track in real world. The modeling technic and the calibrated modeling parameters can be used for optimization for different railway operating programs.
Author: João Pombo Publisher: Springer ISBN: 3319616277 Category : Science Languages : en Pages : 177
Book Description
This volume brings together scientific experts in different areas that contribute to the Railway Track & Transportation Engineering challenges, evaluate the State-of-the-Art, identify the shortcomings and opportunities for research and promote the interaction with the industry. In particular, scientific topics that are addressed in this volume include railway ballasted track degradation/settlement problems and stabilization/reinforcement technologies, switches and crossings and related derailments causes, train-induced vibrations and mitigation measures, operations, management and performance of ground transportation, and traffic congestion and safety procedures. This volume is part of the proceedings of the 1st GeoMEast International Congress and Exhibition on Sustainable Civil Infrastructures, Egypt 2017.
Author: Erol Tutumluer Publisher: Springer Nature ISBN: 3030772349 Category : Science Languages : en Pages : 976
Book Description
This volume presents selected papers presented during the 4th International Conference on Transportation Geotechnics. The papers address the geotechnical challenges in design, construction, maintenance, monitoring, and upgrading of roads, railways, airfields, and harbor facilities and other ground transportation infrastructure with the goal of providing safe, economic, environmental, reliable and sustainable infrastructures. This volume will be of interest to postgraduate students, academics, researchers, and consultants working in the field of civil and transport infrastructure.
Author: Andreas Loizos Publisher: CRC Press ISBN: 1351585797 Category : Technology & Engineering Languages : en Pages : 364
Book Description
Bearing Capacity of Roads, Railways and Airfields includes the contributions to the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields (BCRRA 2017, 28-30 June 2017, Athens, Greece). The papers cover aspects related to materials, laboratory testing, design, construction, maintenance and management systems of transport infrastructure, and focus on roads, railways and airfields. Additional aspects that concern new materials and characterization, alternative rehabilitation techniques, technological advances as well as pavement and railway track substructure sustainability are included. The contributions discuss new concepts and innovative solutions, and are concentrated but not limited on the following topics: · Unbound aggregate materials and soil properties · Bound materials characteritics, mechanical properties and testing · Effect of traffic loading · In-situ measurements techniques and monitoring · Structural evaluation · Pavement serviceability condition · Rehabilitation and maintenance issues · Geophysical assessment · Stabilization and reinforcement · Performance modeling · Environmental challenges · Life cycle assessment and sustainability Bearing Capacity of Roads, Railways and Airfields is essential reading for academics and professionals involved or interested in transport infrastructure systems, in particular roads, railways and airfields.
Author: D. Manzanal Publisher: IOS Press ISBN: 1614996032 Category : Technology & Engineering Languages : en Pages : 3344
Book Description
The work of geotechnical engineers contributes to the creation of safe, economic and pleasant spaces to live, work and relax all over the world. Advances are constantly being made, and the expertise of the profession becomes ever more important with the increased pressure on space and resources. This book presents the proceedings of the 15th Pan-American Conference on Soil Mechanics and Geotechnical Engineering (XV PCSMGE), held in Buenos Aires, Argentina, in November 2015. This conference, held every four years, is an important opportunity for international experts, researchers, academics, professionals and geo-engineering companies to meet and exchange ideas and research findings in the areas of soil mechanics, rock mechanics, and their applications in civil, mining and environmental engineering. The articles are divided into nine sections: transportation geotechnics; in-situ testing; geo-engineering for energy and sustainability; numerical modeling in geotechnics; foundations and ground improvement; unsaturated soil behavior; embankments, dams and tailings; excavations and tunnels; and geo-risks, and cover a wide spectrum of issues from fundamentals to applications in geotechnics. This book will undoubtedly represent an essential reference for academics, researchers and practitioners in the field of soil mechanics and geotechnical engineering. In this proceedings, approximately 65% of the contributions are in English, and 35% of the contributions are in Spanish or Portuguese.
Author: Buddhima Indraratna Publisher: CRC Press ISBN: 0203815777 Category : Science Languages : en Pages : 429
Book Description
Ballast plays a vital role in transmitting and distributing train wheel loads to the underlying sub-ballast and subgrade. Bearing capacity of track, train speed, riding quality and passenger comfort all depend on the stability of ballast through mechanical interlocking of particles. Ballast attrition and breakage occur progressively under heavy cyc
Author: Ed Ellis Publisher: CRC Press ISBN: 0203885945 Category : Technology & Engineering Languages : en Pages : 786
Book Description
Highways provide the arteries of modern society. The interaction of road, rail and other transport infrastructure with the ground is unusually intimate, and thus needs to be well-understood to provide economic and reliable infrastructure for society. Challenges include not only the design of new infrastructure (often on problematic ground), but inc
Author: Carlos Chastre Publisher: Springer Nature ISBN: 3031058755 Category : Technology & Engineering Languages : en Pages : 382
Book Description
The book presents the recent advances on testing and experimentation in civil engineering, especially in the branches of geotechnics, transportation, hydraulics, and natural resources. It includes advances in physical modelling, monitoring techniques, data acquisition and analysis, and provides an invaluable contribution for the installation of new civil engineering experimental facilities. The first part of the book covers the latest advances in testing and experimentation in key domains of geotechnics: soil mechanics and geotechnical engineering, rock mechanics and rock engineering, and engineering geology. Some of the topics covered include new developments in topographic survey acquisition for applied mapping and in situ geotechnical investigations; laboratory and in situ tests to estimate the relevant parameters needed to model the behaviour of rock masses and land structures; monitoring and inspection techniques designed for offshore wind foundations. The second part of the book highlights the relevance of testing and monitoring in transportation. Full-scale accelerated pavement testing, and instrumentation becomes even more important nowadays when, for sustainability purposes, non-traditional materials are used in road and airfield pavements. Innovation in testing and monitoring pavements and railway tracks is also developed in this part of the book. Intelligent traffic systems are the new traffic management paradigm, and an overview of new solutions is addressed here. Finally, in the third part of the book, trends in the field and laboratory measurements and corresponding data analysis are presented according to the different hydraulic domains addressed in this publication, namely maritime hydraulics, surface water and river hydraulics and urban water.
Author: Ernest Theodore Selig Publisher: Thomas Telford ISBN: 9780727720139 Category : Business & Economics Languages : en Pages : 468
Book Description
This comprehensive study provides practical advice and guidance on the important topics of rail transport and ground engineering, the use of which will result in optimum quality with the minimum maintenance effort and the most economical use of resources. The authors have synthesized all of their international knowledge and experience in this field, and produced, for the first time, a definitive guide for the design, construction, maintenance and renewal of railway track as they relate to geotechnology.
Author: Hai Huang
Author: Hai Huang
Author: Bo Wang
Author: João Pombo
Author: Erol Tutumluer
Author: Andreas Loizos
Author: D. Manzanal
Author: Buddhima Indraratna
Author: Ed Ellis
Author: Carlos Chastre
Author: Ernest Theodore Selig