Abstract
Dynamic penetrometer tests are widely used in geotechnical studies for soils characterization but their implementation tends to be difficult. The light penetrometer test is able to give information about a cone resistance useful in the field of geotechnics and recently validated as a parameter for the case of coarse granular materials. In order to characterize directly the railway ballast on track and sublayers of ballast, a huge test campaign has been carried out for more than 5 years in order to build up a database composed of 19,000 penetration tests including endoscopic video record on the French railway network. The main objective of this work is to give a first statistical analysis of cone resistance in the coarse granular layer which represents a major component of railway track: the ballast. The results show that the cone resistance (qd ) increases with depth and presents strong variations corresponding to layers of different natures identified using the endoscopic records. In the first zone corresponding to the top 30cm, (qd ) increases linearly with a slope of around 1MPa/cm for fresh ballast and fouled ballast. In the second zone below 30cm deep, (qd ) increases more slowly with a slope of around 0,3MPa/cm and decreases below 50cm. These results show that there is no clear difference between fresh and fouled ballast. Hence, the (qd ) sensitivity is important and increases with depth. The (qd ) distribution for a set of tests does not follow a normal distribution. In the upper 30cm layer of ballast of track, data statistical treatment shows that train load and speed do not have any significant impact on the (qd ) distribution for clean ballast; they increase by 50% the average value of (qd ) for fouled ballast and increase the thickness as well. Below the 30cm upper layer, train load and speed have a clear impact on the (qd ) distribution.
Highlights
The ballast layer is composed of coarse granular material and supports the loading of railway traffic
To this mechanical information is added visual information given by an endoscope camera
The database consists in several columns table where each line contains: cone resistance value at a given depth and several parameters related to this measure
Summary
The ballast layer is composed of coarse granular material and supports the loading of railway traffic. The dynamic penetrometer test, known as Panda’s test [2,3,11], offers the opportunity to study changes in the stiffness by measuring the dynamic cone resistance (qd) at a given depth. For more than 5 years, a huge campaign test has been realized on the French railway network using this technique. On the basis of strain energy measured at each hammer hit and the driving depth, the dynamic cone resistance is calculated. To this mechanical information is added visual information given by an endoscope camera. This paper addresses some statistical analyses carried out on the database built from more than 19,000 penetration tests
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
