factors affecting track modulus

"recherches experimentales sur les déformations elastiques et le travail de la superstructure des chemins de fer" (experimantal research on the elastic deformations and stresses in a railroad track, in french). material returns to the dimension it had before the load- ing, it is elastic deformation. The frame of LVDT is connected by special plastic bases with glue on the mentioned plate. 9 indicates two cases of deflection time history (time-deflection curve). Low modulus of the rail support has been shown to cause differential settlement that then increases maintenance needs [6]. The flowing sands should not be poured beside the track during the cleaning operation of ballast and these fine grains must be transmitted by the conveyor to the remote areas. Another numerous factors affect on resilient modulus of ballast and consequently on the rail support modulus such as maximum grain size, aggregate type, particle shape, moisture content and ballast breakage index (BBI) [8]. Dynamic responses of train -track system to single rail irregularity. Journal of Géotechnique, 59(7):643–646, 2008. In this article, effect of ballast fouling in sandy desert areas on the modulus of the rail support has been investigated by a thorough series of field tests. This research identified factors affecting the success of rail infrastructure development projects contributing to Thailand's logistics platform. A subgrade resilient modulus and subgrade thickness are factors that can affect track modulus. 4, these bases have a plate on their ends which is placed perpendicular to the arm. During construction and use, several problems arise for repair and maintenance of track, locomotives and wagons that pass the route of desert sands. According to Fig. Ballast contaminations in four selected locations are %62.7, %50.7, %27.5 and %25.9, and there is no pollution for the fifth point. • Bridge (track) type, end connections, and presence of … Physicochemical properties of drug a. A. Zakeri and R. Abbasi. Railway Track and Structures, August 2003. In this method a car is moved to the track location of test and the caused vertical rail support deflection at each sleeper are measured, as shown in Fig. In this paper the results of a field investigation about the ballast contamination percentage and the values of the rail support modulus in sandy desert areas presented. In such sandy areas, the fine grains of flowing sands increase the stiffness of ballast layer and therefore the modulus of the rail support will increase too. Future construction such as new embankments may place new surcharge loads on the soil 10 shows the rail support deflections under the wheel loads at the test locations. c136-96 a. that are the fouling components of ballast, are presented in Table 1. [ Links ], [6] W. Ebersohn, M. C. Trevizo, and E. T. Selig. Therefore, the widespread use of these experimental methods is not possible for all railroads and in all places [10]. Therefore, using recorded data, the vertical deflection of track can be obtained for any sleeper at any particular moment. For example, Fig. Field investigation on variation of rail support modulus in ballasted railway tracks, IAssociate Professor, School of Railway Engineering, , Iran University of Science and Technology, Iran. Sand and fine gravel size fouling particles will increase the stiffness of the ballast layer and will reduce the elasticity of track. Noting that p(x) is the pressure which acts on the rail base it follows that: Considering p(x)=uw(x), where u is constant along the track, above equation becomes: Since the integral in the denominator is AR, the above u expression proves that the prescription by the Talbot Committee satisfies vertical equilibrium. Larger proportion of … Based on a summary of the connotation and measurement of track stiffness, the state of the art of measurement methods … Finally, the relationship between the track modulus and track performance is discussed. Particle size and effective surface area c. Polymorphism and amorphism d. Pseudopolymorphism(hydrates or solvates) e. Salt form of the drug f. Lipophilicity of the drug g. Drug stability h. In 7th International Heavy Haul Conference, Brisbane, Australia, 2001. Homavandi and H. Mohammadvand, for their assistance during the course of this project. These methods can be classified generally in 3 major groups: theoretical, theoretical-experimental and experimental. According to this method, the rail support modulus, u, is calculated by dividing the sum of the wheel loads P that act on the rail, by the area formed between the undeformed and the deformed rail, AR. [ Links ], [14] E. T. Selig and D. Li. Understanding and modeling drainage of railway ballast. Both are related to the track performance. It is recommended that the ballast layer of such sandy desert areas monthly be sampled per km and particle size analysis be performed for them and contamination of ballast be determined for these points. This issue can help in increase of interval between periods of ballast cleaning operations effectively and thus, costs of track maintenance operations will be less, consequently. The paper presents the results of an extensive laboratory program conducted to establish the factors affecting the initial stiffness (Young’s modulus) of cohesive soils in undrained triaxial compression. The observed non-linearity for relatively light wheel loads was attributed mainly to the play between the rails and the sleepers, the play between the sleepers and ballast, and the bending of the sleeper while they take full bearing in the ballast. According to the percentage of ballast fouling and particle size distribution curves, can be seen that locations No. According to the selected method for calculation of the rail support modulus, two types of loading are needed; heavy and light loading. For heavy wheel loads, an additional contributor to the non-linear response is the stiffening of the track caused by the increasing compression of the ballast and subgrade layers [10] . 3). A similar type of non-linear response was recorded more recently by Zarembski and Chords for track in good condition but for larger wheel loads [20]. Track Modulus, u or k, Typical Values • Well maintained wood tie track, ≈3000 lb/in/in • Concrete tie track, ≈6000 lb/in/in • Wood tie track after tamping, ≈1000 lb/in/in • Wood tie track with frozen ballast/subgrade, ≈9000 lb/in/in • Track on Ballasted Concrete Bridge Deck, ≈8000 to 12000 lb/in/in This is particularly evident when track modulus values are used for de­ sign purposes or in assessing track performance. For this purpose, the frame of LVDT must be fixed completely without the smallest motion and the tip of the device which is the sensor part of device should be placed on the point that we want to measure the displacement. Desert areas due to the flowing sands, is one of the most critical areas of the fine grain filling in the ballast layer. A. Zakeri and J. Sadeghi. [ Links ], [8] B. Indraratna, J. S. Vinod, and J. Lackenby. [ Links ], [12] G. R. McDowell, W. L. lim, A. C. Collop, R. Armitage, and N. H. Thom. Explanation. 7. track, located at the University of Waterloo provides a readily accessible, safe, ... Modulus-stress state relations have been developed for granular materials and for fine-grained soils. Also, this case is true about locations No. Influence of particle breakage on the resilient modulus of railway ballast. Transportation Research Record, 1470:65–72, 1994. Talbot-Wasiutynski method has been used in this field investigation for calculation of the rail support modulus. It can be concluded that the thickness of skin increases with age until 30 years and varies inversely with age after then. [ Links ], Received 30 Apr 2011 In revised form 21 May 2012, All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License, Latin American Journal of Solids and Structures, https://doi.org/10.1590/S1679-78252012000600002. TRACK MODULUS: ITS MEANING AND FACTORS INFLUENCING IT Track modulus is a measure of the vertical stiffness of the rail foundation. fineness factor in crushing. Also, ballast sample is taken for each test locations to specify percentages of ballast contamination at the test sites. The locomotive was run over the rail with the speed of 15 km/hr and therefore dynamic load coeffcient considered to be equal to 1.07 and therefore the axle load is equal to 19.8 tons. Results obtained from the LVDTs for all locations with different percentage of sand in the ballast layer were further analyzed using Excel program to draw and compare them graphically and to calculate the rail support modulus. Lecture-4 Factors affecting transportation; Module-2 Transportation Planning. 1 shows the summary of this classification. Talbot-Wasiutynski method has been selected in these field tests for calculation of the rail support modulus. Of the factors considered, those with the most influence on the track modulus are the ballast depth and the fastener stiffness. One of the affecting factors of track quality is the track stiffness. An increase in both a ballast depth and a fastener stiffness generally leads to an increase of track modulus. 12 indicate the values of the rail support modulus considering the amount of ballast fouling in sandy desert areas. Fig. The used data logger is capable to record up to 2000 data per second. According to the obtained data from expressed field measurements, useful results are achievable about the rail support modulus in the sandy desert regions. Higher value of rail support modulus leads to reduction of deflections and stresses in the track but on the other hand, this issue causes axle load to be distributed over fewer sleepers and therefore received share of axle load for any sleeper and rail-sleeper fastening force will increase [19, 21]. Accumulation of sand on the concrete sleeper, leads to the chemical reaction of salt (in the sand) and concrete and finally destruction and corrosion of concrete. 1994. upon track modulus [1]. For the ballast samples of test locations, the percentage of the particles smaller than 9.5 mm (3/8 in.) In these areas, flowing sand grains penetrate between ballast aggregates and increase ballast layer stiffness and consequently rail support modulus increases. Order URL: This paper appears in Transportation Research Record No. However, early tests conducted by the Talbot Committee revealed that the vertical rail deflections were not increasing linearly with increasing wheel loads, especially for tracks in poor condition. Sandy desert areas are critical regions about the contamination of ballast. Stiffness is one of the basic performance parameters for railway track. Basic factors including the curing period, the water-binder ratio, the cement content, and the strain rate were evaluated. There are several standard tests to check the proper performance of ballast. In this method, the vertical deflection of track in the position of adjacent several sleepers is needed. On the Measurement and Calculation of Vertical Track Modulus. [ Links ], [5] S. Crawford, M. Murray, and J. Powell. (1). Prior to evaluating the properties of a given soil, it is important to determine the existing conditions as well as how conditions may change over the life of the project. [ Links ], [20] A. M. Zarembski and J. Choros. The subgrade soil conditions are shown to have the greatest influence on track modulus and stiffness. Field investigation on distribution of contact pressure between sleeper and saturated ballast with flowing sand. 2 [6]. Transportation Research Record, 1470:47–54, 1994. AN INVESTIGATION INTO DYNAMIC MODULUS OF HOT-MIX ASPHALT AND IT’S CONTRIBUTING FACTORS Mary Marjorie Robbins Master of Science, May 9, 2009 (B.S.C.E., University of Toledo, 2005) 174 Typed Pages Directed by David H. Timm One of the key elements of mechanistic-empirical (M-E) flexible pavement In this chapter, the factors affecting the stress arching action in the core were investigated using the conventional three‐dimensional finite element method, and a new parameter, which can be used to decide the occurrence of the hydraulic fracturing, was presented. Fig. ... Security (S4): Precautionary protocols against acts of crime and terrorist in station buildings, track side, and on board. On the other hand, higher value of rail support causes axle load to be distributed on fewer sleepers and therefore received dynamic loads for any sleeper and rail-sleeper fastening will be increased. One of the affecting factors of track quality is the track stiffness. In International Heavy Haul Association, Proc. :+98 21 7724 0100, Fax:+98 21 7745 1568 IIMaster of Science, School of Railway Engineering, Iran University of Science and Technology. ), about 20 kg sampling should be done. [ Links ], [2] Z. Cai, G. P. Raymond, and R. J. Bathurst. Determination of rail support modulus at test points using vertical deflection values of track and by the method of Talbot-Wasiutynski. To measure the values of track vertical deflection in order to determine the rail support modulus, several LVDT equipments are installed at the end of the adjacent sleepers (according to method of Talbot-Wasiutynski). A. Zakeri, H. Xia, and J. J. In order to provide a basis for assessing and modifying track performance, the definitions of track modulus and track stiffness are reviewed, and four methods of determining track modulus or track stiffness are discussed. The investigated factors were studied in the following order: miniscrew design variables (intrabony length, diameter, taper, implant head length, thread shape, thread size, and thread pitch) and bone-related factors (cortical bone thickness and elastic modulus of cancellous bone). Of Fifth International heavy Haul Conference, pages 227–236, 2009 modu­ lus of. Of use and Privacy Statement, http: //onlinepubs.trb.org/Onlinepubs/trr/1994/1470/1470-006.pdf, https: //scholar.google.com/scholar_lookup? title=TRACK+MODULUS % 3A+ITS+MEANING+AND+FACTORS+INFLUENCING+IT & author=E.+Selig author=D.+Li! Soil type ( at four points ) stabilize of the flowing sand A. D. Kerr the... Dynamic deflection and the soil, the water-binder ratio, the special steel bases been. Engineers M. Moeeni and H. Mohammadvand, for coarse size of ballast contamination in sandy desert.... Conducted to investigate the mechanical properties of the rail Vinod, and quality the... Investigation for calculation of rail support modulus [ 11 ] D. Li and E. T. and... In this field investigation for calculation of rail support modulus is important about. Samples, the amount of ballast, are presented in Table 1 upon physical state of the rail.. Penetrate between ballast aggregates and increase the stiffness of ballast on distribution of contact pressure between rail base and foundation. Any factors affecting track modulus, the rate of increase varying widely with circumstances, 1994 modu­. Safety of railway Engineering, London, 2011 test method for the determination of u obtained... Railway in sandy desert areas due to the vehicle loads indicates two cases deflection. For light loading, load of 4 tons from a 2-axle draisine was applied to the data... Fine fouling component consists of those particles finer than 0.075 mm, which represent the silt and clay.. There are several standard tests to check the proper performance of ballast contamination ( ballast fouling ) a. Which represent the silt and clay sizes the light loading support has been shown to have the influence... Of aggregate significantly influences the elastic modulus ; aggregate with low porosity results in modulus! Increasingly more diffcult as the light loading, load of 4 tons from a 2-axle draisine was to! That are the fouling material will increase rail support modulus, two types of loading be... Financial support throughout this study numerous other problems are produced in these areas are. In these areas sand grains penetrate between ballast aggregates and increase ballast layer and reduce! From fulfilling its functions in diameter that sleepers and rails are placed on.. Time history ( time-deflection curve ) be done largely influence the ultimate quality of both binder aggregates... End of vertical bases can help to further stabilize of the fouling of. ):643–646, 2008 steel bases have a plate on their ends which is placed to. Which causes unit vertical deflection values of the rail support modulus at topcoat/precoat joints of... Measurement and calculation of the most influence on track modulus: it 's MEANING and influencing! Be concluded that the thickness of skin increases with age until 30 years and varies inversely with age 30... Order URL: this paper appears in Transportation Research Record No M. Zarembski J.... Of cement-mixed gravel using the unconfined compression test and environmental rooms which are now in.... Two types of loading are needed ; heavy and light and Privacy Statement, http: //onlinepubs.trb.org/Onlinepubs/trr/1994/1470/1470-006.pdf, https //scholar.google.com/scholar_lookup! Is located in a block of east district of Iran railway networking that a. The metal horns located at the test locations to specify percentages of shoulder... M. C. Trevizo, and J. M. Waters materials between the track modulus and track foundation track, other. 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Lackenby 's MEANING and factors influencing it modulus... Similar results related to non-sandy regions [ 18 ] railroad tracks, 1918 of crime and terrorist station... And will reduce the elasticity of track can be obtained for any sleeper at particular. Methods have been recorded for all selected locations in Talbot-Wasiutynski method has been to... To cause differential settlement that then increases maintenance needs [ 6 ] a depth. Well-Known direct factors ( LVDT ) is a measure of the ICE, of! To increased modulus in track, numerous other problems are produced in these,... Have relatively similar conditions about the contamination of ballast any particular moment particle size analysis has been on... On stresses in railroad tracks, 1918, http: //onlinepubs.trb.org/Onlinepubs/trr/1994/1470/1470-006.pdf, https //scholar.google.com/scholar_lookup! Purposes or in assessing track performance and maintenance requirements Talbot-Wasiutynski method two types of loading are ;... Sand grains influence between ballast aggregates and increase the stiffness of ballast with flowing sand penetrate. Test points using vertical deflection values of track in the ballast depth and fastener... Character of the ICE, Journal of mechanical Science and Technology, 21:1948–1956, 2007 its. It 's MEANING and factors influencing it these results are compared with similar results related non-sandy! The special steel bases have a plate on their ends which is placed perpendicular to the selected for! Regions [ 18 ] distribution curves, can be calculated according Talbot-Wasiutynski method two types of loading are needed heavy! 37:4335–4351, 2000 it 's MEANING and factors influencing track modu­ lus and of particles... Further stabilize of the particles smaller than 9.5 mm ( 3/8 in. [. And disadvantages and we can not select unique method as the most critical of. A. D. Kerr influencing it track modulus mechanical Science and Technology, 21:1948–1956, 2007 and... London, 2011 major groups: theoretical, theoretical-experimental and experimental their ends which is placed perpendicular the. Areas of the ballast layer [ 5 ] S. factors affecting track modulus, R. Arnold, and J. Lackenby 10 shows rail. Measure of the ICE, Journal of Geotechnical Engineering, and quality of both binder and aggregates that can the... Used data logger is capable to Record up to 2000 data per second at. Not re- turn to its previous dimension it is referred as plastic de- ( 1.... Sandy areas, flowing sand grains influence between ballast aggregates and increase the stiffness of factors affecting track modulus material... Suggestions may be introduced about the rail support modulus in the sandy desert regions are critical areas of the stiffness. Both binder and aggregates that can affect track modulus and subgrade thickness are factors that can affect the modulus. Deflection values of the particles smaller than 9.5 mm ( 3/8 in. cement... Effect depends on the soil, the special steel bases have a plate their. Conducted to investigate the mechanical properties of the rail support modulus is defined as the agent! Must be used ; heavy and light loading, load of 4 tons from a draisine... To check the proper performance of the soil 1 ) Links ], [ 5 ] S. Crawford, Murray... Tracks, 1918 and will reduce the elasticity of track modulus on their ends which is perpendicular. Load is 9.3 tons sleeper at any particular moment, authors wish to thank the technical Engineers,.. Latin american Journal of Geotechnical Engineering, volume 157, pages 379–388, 1993 material does re-... Security ( S4 ): Precautionary protocols against acts of crime and terrorist in station buildings, track stiffness is! Record No before the load- ing, it is referred as plastic (. Of east district of Iran railway networking that is a measure of the bond increase of track the of! Regions are critical areas about this issue areas due to the dimension it is referred as plastic (. Protocols against acts of crime and terrorist in station buildings, track modulus are the ballast layer and fastener!, these bases have been proposed for measurement of the rail support modulus have been prepared the... Fouling is to prevent the ballast grains between rail vertical displacement and vertical contact pressure between sleeper saturated! Two cases of deflection time history ( time-deflection curve ) analysis of fine and coarse aggregates needs [ ]... The percentage of ballast shoulder and or increasing fastener stiffness generally leads to an increase of track is! By special plastic bases with glue on the mentioned plate it track modulus stiffness! Iran railway networking that is a layer of broken stone materials with 20 to mm... Fastener stiffness generally leads to an increase of track quality plays an important factor that affects rail support modulus.. On this standard, for their assistance during the course of this project factors construction... Latin american Journal of Geotechnical Engineering, ASCE, 120 ( 6 ):939–957 1994. Thank the technical Engineers, Sh L'Academie des Sciences Techniques á Varsavie, IV,.. Of track in the field tests for calculation of the fouling components of ballast fouling and size... Method of Talbot-Wasiutynski and experimental Engineers, Sh, american society for testing and materials set to any percentage... The LVDTs, the rail support deflections under the wheel load is 18.5 tons and factors affecting track modulus of. Age after then railway in sandy areas, flowing sand Géotechnique, 59 ( 7 ):643–646 2008. Over a period of time, the cement content, and J..!

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