Iris Publishers - Global Journal of Engineering Sciences (GJES)

State of the Art: Deterioration Models of Railway Ballasts and Subgrades. Recommendations and Applications


Authored by Santos Sánchez Cambronero



The need to build efficiently and sustainably in recent years has changed the trends in the design and exploitation of infrastructure, which is essential for the social and economic development of each country. This change is being seen more frequently in the field of transportation infrastructure and other types of construction of special interest, since it is important to know the long-term behavior and deterioration of certain materials to verify their functionality and security. The study of behavior and deterioration over time is motivating the development of new and innovative design methodologies that evolve from purely numerical methods that allow us to predict the long-term response to new experimental work that serves as a guide and reference in this engineering field. This review of the state of the art shows a set of deterioration models, collected in the literature, that quantify the deterioration of materials, with special interest in the railway field. These models have been classified and analyzed according to criteria that may be useful for railway infrastructure designers.

In recent years, rail transport has experienced a great expansion throughout the world, becoming an efficient and competitive transportation system for countries that have thousands of kilometers of tracks. In the coming decades, we contemplate that new and ambitious railway projects will be developed, and the technical difficulties in the interaction with the environment, through which the track aims to circulate and reach greater speeds, make these projects a real challenge for civil engineering. Such are the cases of the expansion of the High-Speed network in China [1] and the expected development of high-speed lines in the United States [2].

With respect to high-speed networks, the demographic and economic growth of many of the countries that have a rail network with these characteristics with optimal exploitation conditions and study experience has forced the networks to reach higher speeds to meet the demand and/or economic objectives that are required of this transportation system. The increase in speed could generate an increase in the values of the loads that are transmitted to the railway platform, since the speed is proportional to the value of the loads. This proportion is related to the effect of the weight of the nonsuspense masses of the train, since if this weight does not change but the value of the speed increases, the dynamic effects that occur in the vehicle-track interaction cause this interaction to generate a dynamic overload that increases the value of the loads to be supported by the track. In terms of railway freight transport, the future commercial expansion of several countries can lead to trains having to increase their load and/or transport capacity, either by increasing the number of cars or the axle load that is transmitted to the railway platform [3], thus considering the adaptation of this With respect to high-speed networks, the demographic and economic growth of many of the countries that have a rail network with these characteristics with optimal exploitation conditions and study experience has forced the networks to reach higher speeds to meet the demand and/or economic objectives that are required of this transportation system. The increase in speed could generate an increase in the values of the loads that are transmitted to the railway platform, since the speed is proportional to the value of the loads. This proportion is related to the effect of the weight of the nonsuspense masses of the train, since if this weight does not change but the value of the speed increases, the dynamic effects that occur in the vehicle-track interaction cause this interaction to generate a dynamic overload that increases the value of the loads to be supported by the track. In terms of railway freight transport, the future commercial expansion of several countries can lead to trains having to increase their load and/or transport capacity, either by increasing the number of cars or the axle load that is transmitted to the railway platform [3], thus considering the adaptation of this

 

Awareness of the economic and landscape impact generated by the design and construction of a track with these characteristics has led to an awareness of the need to assess and treat local trace materials by avoiding the massive waste of these materials, as this waste may raise consideration of the possibility of subjecting them to a treatment that improves their geomechanically behavior and makes these wastes suitable to be used in the construction of the railway platform.

The design of railway platforms has been performed, from the point of view of experience in the case of high speed, from a very conservative approach for subgrades that form the track. In the current context of economic crisis, it is necessary, both in the fields of exploitation and design, to introduce certain design criteria that ensure the cross section of the railway platform, for any type of traffic, is defined according to efficiency criteria, rationalization of these criteria and long-term sustainability

These three aspects-increased loads on the railway platform, geotechnical characterization of the materials available in the trace materials, and the efficient and sustainable design of the infrastructure- make it necessary to elaborate a new paradigm of design methodology that can include these aspects when designing a railway network with different traffic configurations, typologies of structural sections and exploitation criteria. In recent years, the continuous development of new numerical tools and more sophisticated designs has allowed integrating, in a comprehensive manner, some of these criteria that intervene in certain infrastructure projects. However, one of the least-considered criteria in this whole process is evaluating the deterioration over time of the infrastructure as a whole or of some of the materials that compose the infrastructure, since these materials can condition the overall long-term behavior throughout the useful life.

 

To read more about this article: https://irispublishers.com/gjes/fulltext/state-of-the-art-deterioration-models.ID.000597.php

 

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