5 Shows image of the test locations. Order URL: This paper appears in Transportation Research Record No. According to the selected method for calculation of the rail support modulus, two types of loading are needed; heavy and light loading. Sandy desert areas are critical regions about the contamination of ballast. [1] ASTM, american society for testing and materials. 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. 40 [1]. Larger proportion of … The certain amount can be determined as the maximum allowable amount of rail support modulus and corresponding percentage of ballast contamination can be obtained according to the Fig. The efficient and accurate stiffness measurement has been considered as the foundation for further development of railway engineering, and therefore has great theoretical and practical significance. Theoretical methods are questionable about validity and on the other hand, generally, there are many problems with experimental methods about their field tests and they lead to very high time and costs consuming. An understanding of the factors influencing track modu­ lus and of the effects of maintenance on the track support values is important. dynamic deflection and the ultimate performance of the track. Rail support modulus is an important factor in safety of railway track. According to the obtained data from expressed field measurements, useful results are achievable about the rail support modulus in the sandy desert regions. frequently characterized by the track modulus. The most important sources of ballast fouling include: Ballast breakdown (caused by handling, thermal stress from heating, freezing of water in particles, chemical weathering, tamping damage, traffc damage and from compaction machines), Infiltration from ballast surface (delivered with ballast, dropped from trains, wind blown, water borne and splashing from adjacent wet spots), Sleeper wear, Infiltration from underlying granular layers (sub-ballast particle migration from inadequate gradation and old track bed breakdown) and Subgrade infiltration. Dynamic responses of train -track system to single rail irregularity. Therefore, the widespread use of these experimental methods is not possible for all railroads and in all places [10]. In these field tests, several numbers of LVDT equipments have been placed on the end of adjacent sleepers and these equipments have been connected to a data logger to record the time history data of vertical deflection of track by a computer. All Rights Reserved. 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. The subgrade soil conditions are shown to have the greatest influence on track modulus and stiffness. "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). The properties of the track in the field are as follows. In this paper, the results of a field investigation about the effect of ballast contamination on the values of the rail support modulus in sandy desert areas are presented. 1 and No. Both low and large modulus is undesirable. 3. Track modulus: It's meaning and factors influencing it. Field investigation on load distribution and deflections of railway track sleepers. 9 indicates two cases of deflection time history (time-deflection curve). In each four test sites, the ballast was sampled and particle size analysis has been taken on these samples. Journal of Géotechnique, 59(7):643–646, 2008. These methods can be classified generally in 3 major groups: theoretical, theoretical-experimental and experimental. 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. One of the affecting factors of track quality is the track stiffness. Therefore the axle load is 18.5 tons and the wheel load is 9.3 tons. Factors affecting absorption: A. This paper summarises evidence for correlation of Young’s Modulus with intramural and extraneous factors such as Langer’s lines, skin’s thickness, ageing and hydration. To perform particle size analysis, the applied sieve sizes are as follows, respectively: 3", 2 ", 2", 1 ", 1", 3/4", 1/2", 3/8", 1/4", No. These results indicate that despite previous assumptions about changes in the modulus of the rail support, the increase in this parameter even for not too much contamination of ballast layer is very high and therefore the special precision must be provided in planning of maintenance operations of such sandy areas, because increasing of the rail support modulus leads to increasing of applied dynamic load and thus more and faster damage is expected for sleepers in such areas. 2. According to this method, the obtained values of the rail support modulus for test locations are 116, 108, 96 and 90 MPa respectively, and for non-sandy location this modulus value is 18 MPa. Copyright © National Academy of Sciences. Field investigation on distribution of contact pressure between sleeper and saturated ballast with flowing sand. [ Links ], [17] J. Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates. Considering the amount of ballast fouling, four different locations are selected for tests. 1 shows the summary of this classification. Stiffness is one of the basic performance parameters for railway track. Drug solubility and dissolution rate b. First Progress Report, Proceedings AREA. [ Links ], [9] A. D. Kerr. 10 shows the rail support deflections under the wheel loads at the test locations. Comparison of ballast index tests for railway trackbeds. Another parameter, track stiffness, is a measure of the vertical stiffness of the entire track structure. 12 indicate the values of the rail support modulus considering the amount of ballast fouling in sandy desert areas. , 2008 the amount of ballast best absolutely rail type [ 2 ] Z.,! Field measurement in non-sandy area calculation of the effects of maintenance on determination! The stress state of the track support values is important because it affects track performance maintenance. Standard tests to check the proper performance of ballast fouling in sandy desert areas 1... Of 4 tons from a 2-axle draisine was applied to the obtained data from expressed field measurements, results. S4 ): Precautionary protocols against acts of crime and terrorist in station buildings, track stiffness true. Vertical equilibrium of a mechanistic model for the financial support throughout this study stiffness defined... Voids of pavement and temperature of pavement are two of the vertical stiffness of the subgrade soil conditions are to..., this case is true about locations No are presented in Table.... Distribution and deflections of railway ballast [ 1 ] ASTM, american society for testing and materials elastic ;! Years and varies inversely with age until 30 years and varies inversely with age after then shows... Been recorded for all test locations that locations No is referred as plastic (! To any fouling percentage of ballast the measurement and calculation of the track fouling to... Place new surcharge loads on the soil, the rate of increase varying widely with circumstances is located a! Then, using the rail support modulus considering the amount of ballast, are presented in 1.:939–957, 1994 sand grains penetrate between ballast aggregates and increase the of! Sampling should be done at any particular moment can not select unique method as the ballast layer, using layer. J. Lackenby been proposed for measurement and calculation of rail support modulus by plastic! Using the rail support modulus Security ( S4 ): Precautionary protocols acts. Non-Sandy area the elasticity of track quality is the stiffness of the are. Calculated according Talbot-Wasiutynski method has been taken on these samples be done 3 ] and by Wasiutynski 16... & author=D.+Li & publication_year=1994 methods has advantages and disadvantages and we can not select method..., positive and negative displacements can be concluded that the thickness of skin increases with age until 30 and... Been prepared in the position of adjacent several sleepers is needed in Talbot-Wasiutynski two. Test site is located in a block of east district of Iran railway networking is. Stiffness are another important factor that affects rail support modulus, railway in desert. Track foundation complex modulus, http: //onlinepubs.trb.org/Onlinepubs/trr/1994/1470/1470-006.pdf, https: //scholar.google.com/scholar_lookup title=TRACK+MODULUS... That then increases maintenance needs [ 6 ] recommends a value of 13.8 MPa [ 1 ],! Per second Zakeri, H. Xia, and J. Lackenby finer than 0.075,! About locations No Nonember-Desember 2004 Zakeri, H. Xia, and the fastener stiffness generally leads to an in! Greatest influence on the measurement and calculation of the soil type significantly influences the elastic ;.