China’s railway covers a broad area, the geological environment and climate along the line are complex and variable, the operation and maintenance of railway are facing tremendous challenges. As an integral part of railway, the maintenance of ballast bed has always attracted considerable attention, nevertheless, the variety and uneven distribution of rock materials, as well as the single ballast material standard and selection in China, which don’t take into consideration factors such as geological conditions and climatic environment, bring a host of issues to railway construction and operation and maintenance. To deal with this problem, this paper summarizes railway ballast selection methods and methodology around the world, compares the ballast material selection criteria for complex environments, summarizes novel ballast materials, and explains the indicators and test approaches used to quantify ballast performance in the standards. Comparing the ballast materials and their matching selection standards in various countries, the main conclusions of this paper are as follows: (1) For the existing ballast specification problems in China, the ballast materials can be considered to be selected according to the geological and climatic factors along the railway line; (2) There is still no method to accurately and rapidly measure the density of ballast bed without damaging it. (3) To achieve the goal of double carbon, novel ballast materials such as construction solid waste and industrial solid waste can be considered on new or modified lines where conditions are favorable.

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The properties of railway ballast material are affected by the local geologies and climatic environments from which the parent rock is sourced. These factors can make it challenging to select the most appropriate material for railway applications. To address this issue, this paper first reviews the means of ballast selection in complex environments across the world. The selection criteria for ballast materials are compared and test methods for ballast quality quantification are summarised. Next, ballast parent rock types and the implications of mining approaches are discussed, before analysing ballast morphology with respect to ballast size and shape. Then ballast petrography is reviewed with a focus on the effect of mineral composition on performance. Finally, some promising future ballast technologies are discussed with a focus on environmental performance. These include recycled ballast, asphaltic materials, steel slag and ballast gluing. The review shows that regarding ballast selection means and criteria, the number and type of quantitative indicators varies greatly between countries. In particular there are divergences in test methods and quantitative indicators for ballast quality considering material types and local geologies. Suggested future research directions are proposed, such as the effect of tamping and dynamic track stabilisation on ballast properties.@en

Research purposes: The longitudinal resistance of track bed reflects the ability of track bed to limit the longitudinal displacement of track and directly affects the stability of track. In order to further study the longitudinal resistance characteristics of ballast track panel, this paper established a full-scale model, carried out a series of tests to get the longitudinal resistance and displacement curve of the track, to explore the influence of the number of sleepers, sleeper crib fullness and sleeper spacing on the longitudinal resistance, and summarized and proposed measures to enhance the longitudinal resistance.

Research conclusions:(1) With the increase of the number of sleepers, the longitudinal resistance increases, but the average longitudinal resistance to each sleeper decreases. (2) The ballast crib fullness has a great influence on the longitudinal resistance of the track panel. When the crib ballast change from zero to full, the longitudinal resistance increases by 83.2%. (3) The sleeper spacing has a significant effect on the longitudinal resistance. When the sleeper spacing decreases from 600 mm to 500 mm, the longitudinal resistance increases by 12.27%. (4) The research results can be applied to the design, construction and maintenance of ballasted tracks, which can be used as a reference for improving the stability of ballast bed.@en