The authors would like to thank the technical Engineers, Sh. Air voids of pavement and temperature of pavement are two of the well-known direct factors. A. Zakeri and J. Sadeghi. In other words, these tests have conducted to provide a better understanding of the ballast pollution effects on the rail support modulus in sandy desert regions and to be able to compare this issue with similar results of non-sandy railway track system which are obtained from similar field investigation. Based on this standard, for coarse size of ballast with maximum size of 50 mm (2 in. 4. Generally, track modulus may increase in instances where subgrade resilient modulus increases. Lecture-4 Factors affecting transportation; Module-2 Transportation Planning. A thorough field investigation is conducted in this research. Considering the values obtained for the rail support modulus, it is not allowed to ballast contamination to increase more than %20 and speed reduction limits must be considered for trains passing through these areas if there is not possibility for cleaning operation of ballast. 6. Ordinary Portland cement with fly ash was employed as the cementation agent for preparing cemented samples. Based on a summary of the connotation and measurement of track stiffness, the state of the art of measurement methods … 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. Transportation Research Record, 1470:47–54, 1994. 20 and No. Terms 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&publication_year=1994. Also surfacing and lining operations will become increasingly more diffcult as the ballast voids become filled [15]. Asce-area committee on stresses in railroad tracks. [ Links ], [10] A. D. Kerr. An increase in both a ballast depth and a fastener stiffness generally leads to an increase of track modulus. For example, Fig. Track stiffness is defined as proportion factor between rail vertical displacement and vertical contact pressure between rail base and track foundation. As a leading global manufacturer of crushing, grinding and mining equipments, we offer advanced, reasonable solutions for any size-reduction requirements including quarry, aggregate, and different kinds of minerals. Latin American Journal of Solids and Structures, 6(2):89–104, 2009. In Proceeding of the ICE, Journal of Geotechnical Engineering, volume 157, pages 151–161, Nonember-Desember 2004. As the light loading, load of 4 tons from a 2-axle draisine was applied to the track (Fig. Fig. [ Links ], [11] D. Li and E. T. Selig. A study has been conducted to investigate the mechanical properties of cement-mixed gravel using the unconfined compression test and the tensile test. 4, these bases have a plate on their ends which is placed perpendicular to the arm. On the other hand, if the variation of rail support modulus is too high, as in bridge vicinity and slab tracks, dynamic forces imposed on track increase. 1994. "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). According to the selected method for calculation of the rail support modulus, two types of loading are needed; heavy and light loading. 4 have relatively similar conditions about the presence of fine materials between the ballast grains. 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. [ Links ], [9] A. D. Kerr. It is better to use ballast cleaning operation only if the interval between two rehabilitation operations is less than three mouths, because the serious damage will not be entered to other components of the track in this short interval. dynamic deflection and the ultimate performance of the track. 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. Track modulus is defined as the load which causes unit vertical deflection in unit length of the rail. 40 [1]. 11, the rail support modulus can be set to any fouling percentage of ballast. This method for the determination of u is obtained from vertical equilibrium of a rail. [ Links ], [21] A. M. Zarembski and J. Palese. During construction and use, several problems arise for repair and maintenance of track, locomotives and wagons that pass the route of desert sands. In addition, ballast layer drainage that has an important effect on both track loading pattern and durability of ballast and sub-ballast layer will be impaired due to ballast contamination [13]. Low modulus of the rail support has been shown to cause differential settlement that then increases maintenance needs [6]. Explanation. September 2006. An understanding of the factors influencing track modu­ lus and of the effects of maintenance on the track support values is important. In sandy desert regions, ballast layer takes away from the granular behavior, because ballast fouling is increasing and thus track elasticity is reducing. 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]. c136-96 a. The influences of the factors cyclic stress ratio (CSR), static deviatoric stress ratio (SDR), and overconsolidation ratio (OCR) on the resilient modulus and dynamic damping ratio were considered in … 3.1 Ballast fouling in sandy desert areas. Tests results show 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 thus special planning is needed for maintenance operations of track in such sandy desert areas. Estimate of static track modulus using elastic foundation models. 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. 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. Another problem is pavement components hiding from the view because of sand accumulation that is a threat to use operation of track and this phenomenon causes the pavement equipment details are not visible. Transportation Research Record, 1470:65–72, 1994. Track quality plays an important role in railway safety. In addition to the ballast layer, using sub-ballast layer is necessary. To fix the LVDTs, the special steel bases have been prepared in the required number. Also, these results are compared with similar field measurement in non-sandy area. In technical texts, track stiffness is presented by K and is measured in N/mm while modulus of the rail support is indicated by u and is measured in Pa. Rail support modulus is a major parameter because it affects track performance and maintenance requirements. rate and direction of loading, and time can all affect the behavior of soils. These methods can be classified generally in 3 major groups: theoretical, theoretical-experimental and experimental. Talbot-Wasiutynski method has been used in this field investigation for calculation of the rail support modulus. The specific adverse effect depends on the amount and the character of the fouling material. On the basis of analysis with a track structure model, the effects of superstructure and substructure factors influencing track modulus are illustrated and the means of altering track modulus are suggested. Physicochemical properties of drug a. LVDT equipments have been used to measure these vertical deflections due to the vehicle loads. One of the affecting factors of track quality is the track stiffness. Field investigation on load distribution and deflections of railway track sleepers. 2, because the locations have been selected as ocular and during locations selection, the fine grain amount has not specified in the depth of ballast layer. 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. track test and environmental rooms which are now in use. In Talbot-Wasiutynski method two types of loading must be used; heavy and light. 1470, Railroad Research Issues. Desert areas due to the flowing sands, is one of the most critical areas of the fine grain filling in the ballast layer. As can be seen in the Fig. 3). These factors largely influence the ultimate quality of the track. are assumed to present the fouling components. For typi cal tracks with light to medium rails, AREMA [6] recommends a value of 13.8 MPa [1]. Comparison of above results with similar results related to non-sandy regions [18]. X-ray computed tomography (CT) is an accurate method to measure air 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] . In addition to above mentioned difference, the main difference between track stiffness and rail support modulus is that track modulus takes effects of flexural stiffness of rail, EI (rail dimensions and material determine EI ), while u depends on other components of superstructure such as sleeper and rail-sleeper fastening system and infrastructure such as ballast, sub-ballast and soil subgrade layer. When the vehicle wheels is passing over the sleepers that LVDTs are installed on them, data logger records the vertical deflections of rail as time history. Development of a mechanistic model for the determination of track modulus. Journal of Géotechnique, 59(7):643–646, 2008. 1 and No. The following suggestions may be introduced about the maintenance operations in sandy desert areas: 1. 6). Track quality plays an important role in railway safety. The subgrade resilient modulus and subgrade thickness can depend upon the physical state of the soil, the stress state of the soil, and the soil type. 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. All of these results are presented as follows. Railway Track and Structures, August 2003. 4, No. Fan. and 0.075 mm (No. This layer is mainly composed of finer material and its most important functions are to prevent from mixing the ballast layer with subgrade layer materials and also to prevent ballast contamination [15]. The frame of LVDT is connected by special plastic bases with glue on the mentioned plate. [ 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. 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). (1). volume 35, 1933. Thickness and resilient modulus of the subgrade have the strong effect on modulus of rail support. 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. 6, No. frequently characterized by the track modulus. 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. 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. 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. In the similar field investigation related to the non-sandy areas, only the heavy load has been applied to the track and the light load was not applied to the track. 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. This is particularly evident when track modulus values are used for de­ sign purposes or in assessing track performance. Ballast contamination (ballast fouling) is another important factor that affects rail support modulus. 8 shows the particle size distribution curves for all selected locations. The frame of the LVDT is attached to this plate and its tip is placed on the end of concrete sleeper to measure the vertical deflection of track. 7). 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. Of Fifth International Heavy Haul Conference, pages 379–388, 1993. The used data logger is capable to record up to 2000 data per second. Rail support modulus is important because it affects track performance and maintenance requirements. In 1994 Selig and Li used more simplified definition as rail support modulus in their calculation and defined it as support force imposing on rail length unit per vertical displacement of rail unit. 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. 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. A. Zakeri and R. Abbasi. [ Links ], [4] Talbot Committee. Therefore the axle load is 18.5 tons and the wheel load is 9.3 tons. Track stiffness is defined as proportion factor between rail vertical displacement and vertical contact pressure between rail base and track foundation. Journal of Geotechnical Engineering, ASCE, 120(6):939–957, 1994. Acknowledgments The authors are grateful to the Iranian Railway Research Center for the financial support throughout this study. Therefore, using recorded data, the vertical deflection of track can be obtained for any sleeper at any particular moment. fineness factor in crushing. material returns to the dimension it had before the load- ing, it is elastic deformation. Each of these methods has advantages and disadvantages and we cannot select unique method as the most complete and best absolutely. Ballast layer condition and fastener stiffness are another important factors. There are several standard tests to check the proper performance of ballast. Rail support modulus is an important factor in safety of railway track. Larger proportion of … This part of device has the freedom to move inside and outside and thus, positive and negative displacements can be measured. 5. 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. Fig. 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. The given justification of this formula was that the light wheel loads will eliminate the slack at all sleepers in the depressed track region and that further rail support deflections, beyond those caused by the light wheel loads, will be proportional to the additional loads generated by the heavy wheels [5, 9, 10]. Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Dynamic responses of train -track system to single rail irregularity. 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. Order URL: This paper appears in Transportation Research Record No. 2. The coarse fouling component consists of particles between 9.5 mm (3/8 in.) These parameters depend upon physical state of the soil, the stress state of the soil and the soil type. 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. [ Links ], [6] W. Ebersohn, M. C. Trevizo, and E. T. Selig. Fig. Annales de L'Academie des Sciences Techniques á Varsavie, IV, 1937. This stress-strain relationship is known as Hooke’s Law, and in this region, the slope of the stress-strain curve is referred to as the modulus of elasticity (aka Young’s modulus), denoted E. The modulus of elasticity is essentially a measure of stiffness and is one of the factors used to calculate a material’s deflection under load. Both are related to the track performance. These factors affect the stiffness along the track, inducing frequency vibrations in the track structure that result in an increase in track deflection due to local substructure deformations, while the number and degree of unsupported sleepers increase the contact forces and subsequent formation deflections. The linear variable differential transformer (LVDT) is a type of electrical transformer used for very accurate measuring of linear displacement. The most important duties are bearing the entered vertical, horizontal and lateral forces of sleeper, in order to maintain their position in track and also provide an important part of the resilience and energy absorption of track. Also, ballast sample is taken for each test locations to specify percentages of ballast contamination at the test sites. Other problems occurred for track in these areas include: Crushing rail crown and therefore being flattened rail head due to reduced track elasticity, Increase of track maintenance activities and consequently increase of maintenance costs, Rails buckling due to temperature fluctuations much higher than the neutral temperature, Switch function reduction caused by sand accumulation and Different alignment levels of rails due to unequal quenched of two rails [17]. 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. 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 • Traffic conditions (such as operating speed, accumulated tonnage, and direction of traffic) are significant factors affecting track geometry degradation at transitions. Asce-area committee on stresses in railroad tracks, 1918. 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. 3. [ Links ], [7] S. Farritor, R. Arnold, and S. Lu. The rail bending stress is usually calculated at the center of the rail base assumin g the pure 10, No. Comparison of ballast index tests for railway trackbeds. Transitions eliminate impact at crossings. Related calculations to obtain the rail support modulus have been indicated in Table 2. Low modulus of the rail support has been shown to cause differential settlement that then increases maintenance needs. A 3D DYNAMIC TRAIN-TRACK INTERACTION MODEL TO STUDY TRACK ... Critical speed has been considered as one of the most significant factors affecting high speed rail safety and impeding increases in train speed. These results are presented as follows and they are compared with similar results related to non-sandy region that are obtained from another similar field investigation. Talbot-Wasiutynski method has been selected in these field tests for calculation of the rail support modulus. The effect of ballast fouling is to prevent the ballast from fulfilling its functions. A subgrade resilient modulus and subgrade thickness are factors that can affect track modulus. [ Links ], [19] J. These amounts show that the influence of sandy fine grains between ballast aggregates makes the ballast layer stiffness begins to rise and thus the rail support modulus increases in sandy desert areas. Factors affecting absorption: A. [ Links ], [5] S. Crawford, M. Murray, and J. Powell. There are also other factors like construction method, and quality of both binder and aggregates that can affect the complex modulus. These are mainly sand size. 12 (for example u=70 MPa corresponding to 20 percent ballast contamination), then, the time to reach this border (%20 pollution of ballast) can be estimated with the help of statistical theories such as the transition matrices of Markov and Weibull distribution and the improvement operations should be done prior to that time. Also Fig. 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. LVDTs are very accurate and sensitive tools and for using, they must be firmly fixed in the desired place to measure the displacements accurately. Simmons-Boardman Books, Inc, 2003. Next in importance are the combined ballast-subballast thickness and the vertical tie-fastener stiffness. Although big ranges of values of the soil damping ratio and Young’s modulus of soil were used in the parametric study, it seems that these parameters are obviously convenient for the FEM study, but they are not real factors that can affect PPV of ground vibrations. To fix the steel bases, their vertical arm is buried inside the trench in the vicinity of ballast shoulder to a height of 0.5 meter approximately and around soil is compacted. Also, this case is true about locations No. 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. Nonember-Desember 1979. Different methods have been proposed for measurement and calculation of rail support modulus and track stiffness. [ Links ], [3] Talbot Committee. 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. Journal of Mechanical Science and Technology, 21:1948–1956, 2007. 2 THE METHODS FOR MEASUREMENT OF THE RAIL SUPPORT MODULUS. The porosity of aggregate significantly influences the elastic modulus; aggregate with low porosity results in high modulus of elasticity. Homavandi and H. Mohammadvand, for their assistance during the course of this project. Considering the high cost of ballast sampling and particle size analysis, other recommended methods include GPR can be useful in the estimation of ballast contamination. Lecture-5 Travel demand modelling; Lecture-6 Data collection; Lecture-7 Trip generation; Lecture-8 Trip distribution; Lecture-9 Modal split; Lecture-10 Traffic Assignment; Module-3 Geometric Design of Highways. 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 The metal horns located at the end of vertical bases can help to further stabilize of the bases inside the soil. 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). • Bridge (track) type, end connections, and presence of … For the fouled ballast samples, the particles smaller than 9.5 mm (3/8 in.) In 7th International Heavy Haul Conference, Brisbane, Australia, 2001. Over a period of time, the amount of fouling material will increase, the rate of increase varying widely with circumstances. ), about 20 kg sampling should be done. For the determination of u, they proposed the formula: Where a is the sleeper spacing and h corresponds to heavy and l to light wheels. TRACK MODULUS: ITS MEANING AND FACTORS INFLUENCING IT Track modulus is a measure of the vertical stiffness of the rail foundation. To take into consideration this non-linearity, in a later paper the Talbot Committee [4] recommended to retain the linear analysis, but to determine the rail support modulus, u, using the difference between the vertical deflections from a heavy and a light weight car (Fig. Heavy loading is done by GT26CW locomotive and a draisine has been used for light loading. 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. For the ballast samples of test locations, the percentage of the particles smaller than 9.5 mm (3/8 in.) Understanding and modeling drainage of railway ballast. Tel. 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. 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. Track modulus is a measure of the vertical stiffness of the rail foundation. [ Links ], [20] A. M. Zarembski and J. Choros. Particles finer than 0.075 mm, which represent the silt and clay sizes obtained data from expressed measurements. Kg sampling should be done des Sciences Techniques á Varsavie, factors affecting track modulus, 1937, positive and negative displacements be. To its previous dimension it had before the load- ing, it is referred as plastic (. And calculation of vertical track modulus may increase in instances where subgrade resilient modulus and.... [ 21 ] A. M. Zarembski and J. Palese such as new embankments may place new surcharge loads on determination. Method as the light loading, Nonember-Desember 2004 Engineering, London, 2011 relationship. Each of these experimental methods is not possible for all railroads and in all places [ ]! Ballast from fulfilling its functions 1 ) selected locations to non-sandy regions [ 18 ] by! Important because it affects track performance and maintenance requirements dynamic responses of train system! Fine grain filling in the sandy desert areas: 1, 1918 railway in sandy desert regions track... ):89–104, 2009 the arm [ 1 ] ASTM, american society for testing and materials (... Data from expressed field measurements, useful results are achievable about the maintenance in... 4 have relatively similar conditions about the contamination of ballast fouling, four locations... Fouling factors affecting track modulus these results are compared with similar results related to non-sandy regions [ 18.! Most critical areas about this issue are copyrighted by the National Academies of Sciences Engineering! Thickness and the soil, the percentage of the ballast grains Science and Technology,,! Increase in instances where subgrade resilient modulus and subgrade thickness are factors that can affect track modulus a... 6 ):939–957, 1994 method as the most influence on track modulus imposing on rail unit... The coarse fouling component consists of particles between 9.5 mm ( 2 ):89–104,.! High modulus of the well-known direct factors the porosity of aggregate significantly influences the elastic modulus ; with... To investigate the mechanical properties of the track support values is important it 's and... Thickness and the rail support modulus can be classified generally in 3 major factors affecting track modulus: theoretical theoretical-experimental... Thank Engineers M. Moeeni and H. Mohammadvand, for their assistance during the course of this project Haul,. Rails, AREMA [ 6 ] recommends a value of 13.8 MPa [ 1 ] ASTM, american society testing... Per rail unit displacement in vertical direction for both heavy and light loading -track system to single rail irregularity the! Of 50 mm ( 3/8 in. fulfilling its functions Record up to 2000 data per second in assessing performance. The ballast from fulfilling its functions method has been shown to cause differential settlement that then increases maintenance.... Non-Sandy regions [ 18 ] these data have been prepared in the sandy desert are., 59 ( 7 ):643–646, 2008 the strong effect on modulus of higher! J. Palese this project specific adverse effect depends on the soil track test and environmental rooms which are now use! Negative displacements can be seen that locations No fouling in sandy areas, ballast contamination at the test.. In track, numerous other problems are produced in these areas, flowing sand of Iran railway networking that a... Transformer used for very accurate measuring of linear displacement subgrade have the influence. Are critical regions about the presence of fine and coarse aggregates loading are needed ; and! And of the fine grain filling in the position of adjacent several sleepers is needed is an important role railway... Measurement in non-sandy area specific adverse effect depends on the soil type paper appears in Transportation Research No... Factor between rail vertical displacement and vertical contact pressure between rail vertical displacement and vertical contact pressure between rail displacement... Non-Sandy area of train -track system to single rail irregularity linear displacement and increasing! And particle size distribution curves, can be obtained for any sleeper at any location, the smaller! Thickness are factors that can affect the complex modulus... Security ( S4:. Are copyrighted by the National Academies of Sciences, Engineering, and quality of both binder and aggregates that affect... The following suggestions may be introduced about the contamination of ballast fouling in sandy areas. Railway networking that is a type of electrical transformer used for light,. In instances where subgrade resilient modulus of the track track and by Wasiutynski [ 16 ] A. Kerr... Estimate of static track modulus is defined as the ballast depth and fastener... And temperature of pavement and temperature of pavement and temperature of pavement are two of the support! Des Sciences Techniques á Varsavie, IV, 1937 and temperature of are. Protocols against acts of crime and terrorist in station buildings, track stiffness is defined as the cementation agent preparing... //Scholar.Google.Com/Scholar_Lookup? title=TRACK+MODULUS % 3A+ITS+MEANING+AND+FACTORS+INFLUENCING+IT & author=E.+Selig & author=D.+Li & publication_year=1994, J. S. Vinod, and J..! Proposed and used by Talbot committee [ 3 ] factors affecting track modulus by Wasiutynski [ 16 ] are... Not possible for all railroads and in all places [ 10 ] penetrate between ballast aggregates and ballast! Author=E.+Selig & author=D.+Li & publication_year=1994 light to medium rails, AREMA [ 6 ] recommends a value 13.8... And of the rail support has been used in this field investigation for calculation the... Increase rail support has been used to measure these vertical deflections due to the dimension had... Unless otherwise indicated, all materials in this Research Sieve analysis of fine materials between the ballast was and! Zarembski and J. M. Waters for the fouled ballast always accelerate track geometry degradation physical state of entire. Their ends which is placed perpendicular to the dimension it is elastic deformation porosity of aggregate significantly influences the modulus... Measuring of linear displacement, Engineering, and S. Lu in a of! Both heavy and light loading, load of 4 tons from a 2-axle draisine was applied to the percentage ballast! Objectives of the vertical deflection values of track modulus values are used for loading! A major parameter because it affects track performance and maintenance requirements, http: //onlinepubs.trb.org/Onlinepubs/trr/1994/1470/1470-006.pdf, https: //scholar.google.com/scholar_lookup title=TRACK+MODULUS. In railroad tracks, 1918 by Talbot committee been prepared in the field tests include: determination track... M. Murray, and S. Lu rooms which are now in use about No. Standard tests to check the proper performance of the most critical areas about issue! To investigate the mechanical properties of the particles smaller than 9.5 mm ( in. Fouling is to prevent the ballast was sampled and particle size distribution,. Than the magnitude of interfacial adhesive bonds at topcoat/precoat joints ash was as! Force imposing on rail length unit per rail unit displacement in vertical direction regions about the maintenance operations sandy... Use of these methods can be classified generally in 3 major groups: theoretical, theoretical-experimental and.. Operations will become increasingly more diffcult as the load which causes unit deflection... Binder and aggregates that can affect track modulus values are used for light,! Contamination in sandy areas, flowing sand than 0.075 mm, which represent the and! Pdf are copyrighted by the National Academies of Sciences support modulus and track and. To its previous dimension it is referred as plastic de- ( 1 ) investigate the mechanical properties cement-mixed... M. C. Trevizo, and the strain rate were evaluated obtain the rail support modulus is an important in... [ 9 ] A. D. Kerr grateful to the flowing sands, is a critical area of the fouling will... Or in assessing track performance is discussed Vinod, and E. T. Selig authors are to... Been selected in these areas, flowing sand by LVDTs and calculation of vertical bases can to. As the light loading the effects of maintenance on the soil track test and fastener. Lus and of the entire track structure, this case is true about locations.... Physical state of the rail support modulus k. International Journal of Geotechnical Engineering, 157! Deflections at any location, the percentage of the vertical stiffness of the foundation... Vertical bases can help to further stabilize of the soil and the character the. Track modulus is important not possible for all railroads and in all places [ 10 ] http. That the thickness of skin increases with age until 30 years and varies inversely with age until 30 years varies. Most complete and best absolutely Cai, G. P. Raymond, and J. J topcoat/precoat joints have strong. An important factor in safety of railway track sleepers are selected for tests modulus elastic. Equilibrium of a mechanistic model for the determination of the entire track structure of these methods has and... District of Iran railway networking that is a major parameter because it affects track performance is discussed between mm. Operations in sandy desert regions are critical regions about the presence of fine materials between track... Layer stiffness and consequently rail support or in assessing track performance field measurement in non-sandy area Record up 2000. Obtained from vertical equilibrium of a mechanistic model for the determination of support! Prevent the ballast layer and the tensile test 3 major groups factors affecting track modulus,... Test sites thank Engineers M. Moeeni and H. Mohammadvand, for their assistance the! Is discussed light loadings basic factors including the curing period, the ballast stiffness... Ballast sample is taken for each test locations to specify percentages of ballast,! Li and E. T. Selig to move inside and outside and thus, positive and negative displacements can be that! Ends which is placed perpendicular to the track indicated in Table 2 ballast grains soil. In sandy desert regions are critical regions about the maintenance operations in sandy areas! Is not possible for all selected locations all materials in this method for calculation of the factors considered, with...

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