Investigating the Vertical Stiffness on Railway Track Performance

London Journal of Engineering Research
Volume | Issue | Compilation
Authored by Morteza Esmaeeli , Jabbar Ali Zakeri, Seyed Ali Mosayebi
Classification: For Code: 861304
Keywords: railway sleeper, constant and variable stiffness, desert area.
Language: English

An important factor affecting the behavior of railway tracks is contamination of ballast material. In desert and wilderness areas, elasticity characteristics of railway ballast layer reduce and consequently rigidity of railway track is increased. This phenomenon has destructive effects on the railway lines especially railway sleeper and it could cause break and damage of railway sleeper. In this paper, the process of increased stiffness of track due to ballast fouling on sleeper behavior is investigated. Moreover, in this paper the effect of variable track stiffness on railway sleeper is studied. Also, displacement, velocity and acceleration of railway sleeper due to MD36 train with various speeds are studied.

               

Investigating the Vertical Stiffness on Railway Track Performance

Jabbar Ali Zakeriα, Morteza Esmaeiliσ & Seyed Ali Mosayebiρ

____________________________________________

  1. ABSTRACT

An important factor affecting the behavior of railway tracks is contamination of ballast material. In desert and wilderness areas, elasticity characteristics of ballast layer reduce and consequently rigidity of track increases. This phenomenon has destructive effects on the rail lines especially railway sleeper, and it could be damage to railway sleeper. In this paper, the process of increased stiffness of track due to ballast fouling on sleeper behavior was investigated. Moreover, in this paper, the effect of variable track stiffness on railway sleeper is studied. Also, displacement, velocity, and acceleration of railway sleeper due to MD36 train with various speeds are investigated. Results indicate that the displacement of sleeper reduced by increasing the ballast stiffness. In addition to in this paper, the mathematical relation between rail bed modulus and maximum values of sleeper vibrations due to MD36 train with various speeds were presented.      

Keywords: railway sleeper, Constant and variable stiffness, desert area.

Author α σ ρ: School of Railway Engineering, Iran University of Science and Technology, Tehran, Iran. 

  1. INTRODUCTION

Many factors can be important in the behavior of railway sleeper. For example, the fouling ballast can cause to increase the rigidity of pavement and consequently this phenomenon is considerable effects on the sleeper behavior. In fact, the contamination of granular layer is filling the space between the ballast aggregates with fine particles of soil. Some contamination sources of railway ballast layer are: fine aggregates after ballasting, dust due to wind, materials due to passing traffic (such as coal, ore, and other materials) and penetration of fine soil from bottom layer. So it is stated, fouling and contamination of granular layer are important in sleeper behavior. Selig and Waters [1] presented the effects of fouling ballast and fine aggregates in railway track. Fryba [2] studied the effect of constant and variable stiffness of track on railway bridges. Zakeri and Abbasi [3, 4] investigated rail support modulus and loading pattern of the sleeper in desert areas. Esmaeili et al. [5] and Zakeri et al. [6] studied the environmental train induced vibrations in desert areas. In the mentioned works, the effects of constant and variable track stiffness on the railway sleeper were not studied well. Therefore, in this paper, the effects of the constant and variable stiffness of track on sleeper behavior are investigated.    

  1. CONTAMINATION OF BALLAST LAYER

The increase of railway traffic and environmental conditions (such as water, ice, and other environmental factors) are important factors in crushing the aggregates. Also, surface penetration of materials from a train on the railway ballast is considerable in the behavior of railway track. Ballast layer could be contaminated by displaced particles by wind and rain. Figure 1 shows penetration of windy sands to granular layer in the desert area.

Figure 1: Penetration of windy sands to ballast layer

  1. RAILWAY TRACK IN DESERT AREAS 

In the windy sand areas, ballast loses its elasticity properties, and it is fouling because of penetration of sands to granular layer. Contamination of ballast causes that the track stiffness increases and consequently geometry destructions of longitudinal and horizontal alignment and also twisting of the line is increased. This phenomenon causes to increase noises and vibrations in these areas. From total area of Iran, nearly 34 million hectares is desert areas. In these regions, the movement of the sands is due to periodic storms. This phenomenon could be severe damages to the rail infrastructure. Figure 2 indicates desert areas in railway track in Iran. Also, Figure 3 shows a sample of desert area in railway track in Iran [3-6].  

Figure 2: Desert Areas in railway track in Iran

IMG_1395

Figure 3: A sample of desert area in railway track in Iran

V.   PROCESS OF INCREASED STIFFNESS OF TRACK

Process of increased stiffness of railway track due to fouling the ballast materials is presented in Table 1. As shown in Table 1, with increasing the rail bed modulus, the fouling of ballast layer is increased.

Table 1:  Process of Increased stiffness of track due to fouling the ballast materials

Rail bed modulus (MPa)

Fouling process

20

35

50

65

80

95

110

  1. EFFECT OF THE TRACK STIFFNESS ON THE RAILWAY SLEEPER  

According to values of rail bed modulus and fouling the ballast materials in the previous section, the effects of track stiffness on the railway sleeper due to a harmonic load of the MD36 train are investigated. In this section, displacement, velocity, and acceleration of railway sleeper due to MD36 train with various speeds are studied and finally mathematical relations between rail bed modulus and maximum vibration values of railway sleeper with different speeds of the MD36 train were extracted. In continuation, Figure 4 and Table 2 indicate displacement, velocity, and acceleration of railway sleeper due to MD36 bogie with train speed of 50 Km/hr.

C:\Documents and Settings\ali\Desktop\untitled1.jpg

a) Displacement

C:\Documents and Settings\ali\Desktop\untitled2.jpg

b) Velocity

C:\Documents and Settings\ali\Desktop\untitled3.jpg

c) Acceleration

Figure 4: Displacement, velocity and acceleration of railway sleeper due to MD36 bogie with train speed of 50 Km/hr

Table 2: Maximum railway sleeper vibrations at MD36 train speed of 50 Km/hr

Rail bed modulus (MPa)

Displacement (m)

Velocity (m/s)

Acceleration (m/s2)

20

0.0344

0.1820

0.9626

35

0.0197

0.1041

0.5505

50

0.0138

0.0729

0.3854

65

0.0106

0.0561

0.2965

80

0.0086

0.0455

0.2409

95

0.0073

0.0384

0.2028

110

0.0063

0.0331

0.1752

As observed from Table 2, Displacement, velocity and acceleration of the railway sleeper reduce with increasing the rail bed modulus.  

Table 3:  Relation between rail bed modulus and maximum values of vibration at MD36 train speed of 50 Km/hr

Displacement (m)

Velocity (m/s)

Acceleration (m/s2)

D = -9E-08x3 + 2E-05x2 - 0.001x + 0.063

V = -5E-07x3 + 0.000x2 - 0.01x + 0.336

A = -2E-06x3 + 0.000x2 - 0.052x + 1.777

In this Table, parameter of x is rail bed Modulus in terms of MPa.  Parameters of D, V and A are displacement, velocity and acceleration respectively.

C:\Documents and Settings\ali\Desktop\untitled.jpg

a) Displacement

C:\Documents and Settings\ali\Desktop\untitled2.jpg

b) Velocity

C:\Documents and Settings\ali\Desktop\untitled3.jpg

c) Acceleration

Figure 5: Displacement, velocity, and Acceleration of railway sleeper due to MD36 bogie with train speed of 100 Km/hr

Table 4: Maximum railway sleeper vibrations at MD36 train speed of 100 Km/hr

Rail bed modulus (MPa)

Displacement (m)

Velocity (m/s)

Acceleration (m/s2)

20

0.0343

0.3629

3.8391

35

0.0197

0.2080

2.2005

50

0.0138

0.1457

1.5413

65

0.0106

0.1121

1.1859

80

0.0086

0.0911

0.9636

95

0.0073

0.0767

0.8115

110

0.0063

0.0663

0.7008

Table 5: Relation between rail bed modulus and maximum values of vibration at MD36 train speed of 100 Km/hr

Displacement (m)

Velocity (m/s)

Acceleration (m/s2)

D = -9E-08x3 + 2E-05x2 - 0.001x + 0.063

V = -9E-07x3 + 0.000x2 - 0.019x + 0.669

A = -1E-05x3 + 0.002x2 - 0.209x + 7.080

In this Table, parameter of x is rail bed Modulus in terms of MPa.  Parameters of D, V and A are displacement, velocity and acceleration respectively.

C:\Documents and Settings\ali\Desktop\untitled1.jpg

a) Displacement

C:\Documents and Settings\ali\Desktop\untitled2.jpg

b) Velocity

C:\Documents and Settings\ali\Desktop\untitled3.jpg

c) Acceleration

Figure 6: Displacement, velocity, and Acceleration of railway sleeper due to MD36 bogie with train speed of 150 Km/hr

Table 6: Maximum railway sleeper vibrations at MD36 train speed of 150 Km/hr

Rail bed modulus (MPa)

Displacement (m)

Velocity (m/s)

Acceleration (m/s2)

20

0.0341

0.5418

8.5970

35

0.0196

0.3117

4.9461

50

0.0138

0.2185

3.4672

65

0.0106

0.1682

2.6683

80

0.0086

0.1367

2.1684

95

0.0073

0.1151

1.8261

110

0.0063

0.0994

1.5772

Table 7: Relation between rail bed modulus and maximum values of vibration at MD36 train speed of 150 Km/hr

Displacement (m)

Velocity (m/s)

Acceleration (m/s2)

D = -8E-08x3 + 2E-05x2 - 0.001x + 0.062

V = -1E-06x3 + 0.000x2 - 0.029x + 0.996

A = -2E-05x3 + 0.005x2 - 0.465x + 15.81

In this Table, parameter of x is rail bed Modulus in terms of MPa.  Parameters of D, V and A are displacement, velocity and acceleration respectively.

  1. EFFECT OF THE VARIABLE TRACK STIFFNESS ON THE RAILWAY SLEEPER 

Vehicles passed on the track with the regular wave. The origin of these irregularities was the interaction of bridge and the carbody. Thus, when modeling the effects of trains on the track, elastic springs with variable stiffness along the rail lines were used (Equation 1) [2].

(1)

In order to analyze the effects of variable stiffness, two parameters K1 and K2 can be considered as follow:

a) K2= 100 MPa  & K1= 0, 20, 40, 60, 80, 100 MPa  

C:\Documents and Settings\ali\Desktop\untitled3.jpg

a) Displacement

C:\Documents and Settings\ali\Desktop\untitled2.jpg

b) Velocity

C:\Documents and Settings\ali\Desktop\untitled1.jpg

c) Acceleration

Figure 7: Displacement, velocity, and acceleration of railway sleeper due to MD36 bogie with train speed of 100 Km/hr

Table 8: Maximum railway sleeper vibrations at MD36 train speed of 100 Km/hr (k2=100 MPa)

K1 (MPa)

Displacement (m)

Velocity (m/s)

Acceleration (m/s2)

0

0.5752

188.5306

0.9973  E5

20

0.8128

300.0602

1.5446 E5

40

0.1259

43.7214

0.2223 E5

80

0.0531

18.2133

0.0917 E5

60

0.0304

10.0720

0.0521 E5

100

0.0190

5.9372

0.0310 E5

b) K1= 100 MPa  & K2= 0, 20, 40, 60, 80, 100 MPa  

C:\Documents and Settings\ali\Desktop\untitled1.jpg

a) Displacement

C:\Documents and Settings\ali\Desktop\untitled2.jpg

b) Velocity

C:\Documents and Settings\ali\Desktop\untitled3.jpg

c) Acceleration

Figure 8: Displacement, velocity, and acceleration of railway sleeper due to MD36 bogie with train speed of 100 Km/hr

Table 9: Maximum railway sleeper vibrations at MD36 train speed of 100 Km/hr (k1=100 MPa)

   K2 (MPa)

Displacement (m)

Velocity (m/s)

Acceleration (m/s2)

0

0.0041

0.0437

4.4

20

0.0052

0.3409

116.3

40

0.0069

0.9039

345

80

0.0094

1.8451

767.7

60

0.0132

3.3961

1576.4

100

0.0190

5.9372

3098.4

  1. CONCLUSIONS

Several parameters could be important on the sleeper behavior as one of the superstructure components in railway tracks. One of the significant parameters is fouling the ballast materials. This phenomenon causes to increase the rigidity of track because of small particles of sand that fill the space between the fine and coarse materials of ballast layer. Therefore, fouling and contamination of granular layer are effective in railway sleeper behavior. In this paper, the effects of the constant and variable stiffness of track were investigated. Significant results of this research are as follow:

  1. Maximum vibration velocity of railway sleeper in the case of clean ballast (rail bed modulus is 20 Mpa) and the most fouling ballast (rail bed modulus is 110 Mpa) is 0.1820 m/s and 0.0331 m/s at MD36 train speed of 50 Km/hr respectively.
  2. Maximum vibration velocity of railway sleeper in the case of clean ballast (rail bed modulus is 20 Mpa) and the most fouling ballast (rail bed modulus is 110 Mpa) is 0.3629 m/s and 0.0663 m/s at MD36 train speed of 100 Km/hr respectively.
  3. Maximum vibration velocity of railway sleeper in the case of clean ballast (rail bed modulus is 20 Mpa) and the most fouling ballast (rail bed modulus is 110 Mpa) is 0.5418 m/s and 0.0994 m/s at MD36 train speed of 150 Km/hr respectively.
  4. Obtaining the mathematical relation between rail bed modulus and maximum values of vibration due to MD36 train with various speeds.
  5. With considering the variable stiffness as equation k(x) = k1 + k2 cos (2πx/L), vibration values of railway sleeper were calculated for different values of K1 and K2.

REFERENCES

  1. E.T., Selig, and J.M., Waters, Track Geotechnology and Substructure Management, London: Thomas Telford, (1994).
  2. L., Fryba, Dynamics of Railway bridges, Thomas Telford Publishing, 1996.
  3. J. A., Zakeri, and R., Abbasi, (2012). Field investigation of variation of rail support modulus in ballasted railway track, Latin American Journal of Solids and Structures, 9(6), 643-656.
  4. J. A., Zakeri, and R., Abbasi, (2012). Field investigation of variation of loading pattern of concrete sleeper due to ballast sandy contamination in sandy desert areas, Journal of mechanical science and technology, 26(12), 3885-3892.
  5. M., Esmaeili, J. A., Zakeri, and S. A., Mosayebi, (2014). Effect of sand-fouled ballast on train-induced vibration. International Journal of Pavement Engineering, 15(7), 635-644.
  6. J. A., Zakeri, M., Esmaeili, S. A., Mosayebi, and R., Abbasi, (2012). Effects of vibration in desert area caused by moving trains, Journal of Modern Transportation, 20(1), 16-23.



author

For Authors

Author Membership provide access to scientific innovation, next generation tools, access to conferences/seminars
/symposiums/webinars, networking opportunities, and privileged benefits.
Authors may submit research manuscript or paper without being an existing member of LJP. Once a non-member author submits a research paper he/she becomes a part of "Provisional Author Membership".

Know more

institutes

For Institutions

Society flourish when two institutions come together." Organizations, research institutes, and universities can join LJP Subscription membership or privileged "Fellow Membership" membership facilitating researchers to publish their work with us, become peer reviewers and join us on Advisory Board.

Know more

subsribe

For Subscribers

Subscribe to distinguished STM (scientific, technical, and medical) publisher. Subscription membership is available for individuals universities and institutions (print & online). Subscribers can access journals from our libraries, published in different formats like Printed Hardcopy, Interactive PDFs, EPUBs, eBooks, indexable documents and the author managed dynamic live web page articles, LaTeX, PDFs etc.

Know more