Demiryolu Taban Zemini Su İçeriğinin TDR Yöntemi ile Ölçümü için Dielektrik Karışım Modeli Yardımıyla Kalibrasyon Geliştirilmesi

Öz

Demiryollarında hat performansını değerlendirmek için en sık başvurulan parametrelerden birisi hat modülüdür. Altyapı ve üstyapı elemanlarından etkilenmekle birlikte hat modülü büyük oranda taban zemini esneklik modülüne bağlıdır. Esneklik modülü ise tüm zeminlerde su içeriğinin bir fonksiyonudur. Bu sebeple hat modülü yağış rejimine bağlı olarak mevsimsel farklılıklar gösterebilir. Bu durumun hat performansı değerlendirilirken göz önünde bulundurulabilmesi için taban zemini su içeriğinin periyodik ölçümleri yapılmalıdır. Zemin su içeriğinin ölçülmesi için kullanılan yöntemlerin başında etüvde kurutma gelmektedir. Taban zemininden örnek almanın zor olmasının yanı sıra deney prosedürünün 24 saat kurutmaya dayalı olması nedeniyle etüvde kurutma yavaş bir yöntem olarak değerlendirilebilir. Alternatif olarak Zaman Tanım Alanında Yansıma Yöntemi (Time Domain Reflectometry, TDR), gerçek zamanlı ve uzaktan ölçüm alabilmeyi sağlayan bir elektromanyetik ölçüm yöntemidir. TDR ile ölçülen zeminin dielektrik iletkenliği ile kurulan kalibrasyon denklemi yardımıyla su içeriği belirlenir. Bu çalışmada taban zemini malzemesi olabilecek ve ince dane içeriği en fazla %15 olan 7 farklı zemin sınıfında yapılmış olan TDR ölçümleri literatürden elde edilmiştir. Kalibrasyon denklemi için diğer çalışmalardan farklı olarak regresyon yöntemleri yerine dielektrik karışım modeli kullanılmıştır. Önerilen kalibrasyon, sınama setinde seçilen performans göstergeleri ile değerlendirilmiştir. Yine diğer çalışmalardan farklı olarak bir zemin sınıfı yerine zemin grubuna özgü olan kalibrasyon, geniş bir su içeriği aralığında %2,0 hata bandında kalmak koşuluyla %93 tahmin başarısı sağlamıştır. Ayrıca tahmin hatası dağılımının yeterince dar ve sıfıra yakın merkezlenmiş olduğu görülmüştür. Bu bağlamda demiryolu hatlarında taban zemini su içeriğinin periyodik ölçümleri için Türkiye’de kullanımı son derece sınırlı olan TDR, yüksek doğruluk sağlayan hızlı bir ölçüm yöntemi olarak önerilmektedir.

Anahtar Kelimeler

• Hat modülü
• Taban zemini
• Su içeriği
• TDR
• Kalibrasyon

Calibration Development Based on Dielectric Mixture Model for Measurement of Subgrade Water Content with TDR Method

Öz

One of the most frequently used parameters to evaluate track performance in railways is the track modulus. Although it is affected by substructure and superstructure elements, the track modulus mainly depends on the subgrade resilient modulus. The resilient modulus is a function of water content in all soils. Consequently, the track modulus may show seasonal variations depending on the rainfall regime. Periodic measurements of the subgrade water content should be made in order to consider this situation when evaluating track performance. Oven drying is one of the primary methods used to measure soil water content. In addition to the difficulty of taking samples from the subgrade, oven drying can be considered as time consuming since the procedure is based on 24-hour drying. Alternatively, Time Domain Reflectometry (TDR) is an electromagnetic measurement method that enables real-time and remote measurement. Water content is determined with the help of the calibration equation established with the dielectric permittivity of the soil measured by TDR. In this study, TDR measurements made on 7 different soil classes, which can be considered as subgrade material and whose fine content is maximum 15%, were obtained from the literature. For the calibration equation, unlike other studies, dielectric mixture model was used instead of regression methods. The proposed calibration was evaluated with the performance metrics selected in the test set. Again, unlike other studies, the calibration, which is specific to a soil group rather than a soil class, provided 93% prediction success within a wide water content range, provided that it remains within the 2.0% error band. Additionally, it was observed that the prediction error distribution was adequately narrow and centered close to zero. In this context, TDR, whose use is extremely limited in Türkiye is recommended as a rapid method for periodic measurements of subgrade water content on railway tracks that provides high accuracy.

Anahtar Kelimeler

• Track modulus
• Subgrade
• Water content
• TDR
• Calibration

Kaynakça

1. [1] Intergovernmental Panel on Climate Change (IPCC), Climate Change 2022: Mitigation of Climate Change, Cambridge, UK and New York, USA: Cambridge University Press, 2022
2. [2] Community of European Railway and Infrastructure Companies (CER), “Activity Report 2021,” 2022. [Online]. Available: https://www.cer.be/images/publications/positions/CER_Activity_Report_ 2021.pdf [Accessed August 12, 2023]
3. [3] M. J. Roshan, A. S. A. Rashid, N. A. Wahab, S. Tamassoki, S. N. Jusoh, M. A. Hezmi, N. N. N. Daud, N. M. Apandi, M. Azmi, “Improved methods to prevent railway embankment failure and subgrade degradation: A review,” Transportation Geotechnics, vol. 37, no. 100834, 2022, doi: 10.1016/j.trgeo.2022.100834
4. [4] J. Campos, G. Rus, “Some stylized facts about high-speed rail: a review of HSR experiences around the World,” Transport Policy, vol. 16, no. 1, pp. 19–28, 2009, doi: 10.1016/j.tranpol.2009.02.008
5. [5] B. Indraratna, S. Nimbalkar, “Stress-strain degradation response of railway ballast stabilized with geosynthetics,” Journal of Geotechnical and Geoenvironmental Engineering, vol. 139, no. 5, pp. 684–700, 2013, doi: 10.1061/(ASCE)GT.1943-5606.0000758.
6. [6] Community of European Railway and Infrastructure Companies (CER), “Track Maintenance and Renewal,” 2012. [Online]. Available: https://www.cer.be/images/publications/positions/ CER_Activity_Report_2021.pdf [Accessed August 14, 2023]
7. [7] S. S. Artagan, L. B. Ciampoli, F. D’Amico, A. Calvi, F. Tosti, “Non-destructive assessment and health monitoring of railway infrastructures,” Surveys in Geophysics, vol. 41, pp. 447–483, 2020, doi:10.1007/s10712-019-09544-w
8. [8] S. Arsoy, M. Ozgur, E. Keskin, C. Yilmaz, “Usability of calcium carbide gas pressure method in hydrological sciences,” Journal of Hydrology, vol. 503, pp. 67–76, 2013, doi: 10.1016/j.jhydrol.2013.08.044

9. [9] K. Noborio, “Measurement of soil water content and electrical conductivity by time domain reflectometry: a review,” Computers and Electronics in Agriculture, vol. 31, no. 3, pp. 213–237, 2001, doi: 10.1016/S0168-1699(00)00184-8
10. [10] M. Ozgur, “Development and validation of a degree of saturation prediction model using time domain reflectometry for compaction control,” Transportation Geotechnics, vol. 42, no. 101062, 2023, doi: 10.1016/j.trgeo.2023.101062
11. [11] G. Curioni, D. N. Chapman, A. C. Royal, N. Metje, B. Dashwood, D. A. Gunn, C. M. Inauen, J. E. Chambers, P. I. Meldrum, P. B. Wilkinson, R. T. Swift, H. J. Reeves, “Time domain reflectometry (TDR) potential for soil condition monitoring of geotechnical assets,” Canadian Geotechnical Journal, vol. 56, no. 7, pp. 942–955, 2019, doi: 10.1139/cgj-2017-0618
12. [12] J. Pies, L. Mocova, “Application of TDR test probe for determination of moisture changes of railway substructure materials,” Transportation Research Procedia, vol. 40, pp. 74–81, 2019, doi: 10.1016/j.trpro.2019.07.013
13. [13] L. Izvolt, P. Dobes, M. Mecar, “Calibration of TDR test probes for measuring moisture changes in the construction layers of the railway line,” Procedia Engineering, vol. 161, pp. 1057–1063, 2016, doi: 10.1016/j.proeng.2016.08.848
14. [14] L. Izvolt, P. Dobes, “Monitoring of moisture changes in the construction layers of the railway substructure body and its subgrade,” Procedia Engineering, vol.161, pp. 1049–1056, 2016, doi: 10.1016/j.proeng.2016.08.847
15. [15] A. Alsabhan, D. Fratta, B. J. Warren, J. M. Tinjum, T. B. Edil, “Using Time Domain Reflectometry to determine depth of fouling and fouling type in railway track substructure,” Geotechnical Testing Journal, vol. 42, no. 1, pp. 156–179, 2019, doi:10.1520/GTJ20170305
16. [16] J. Liu, J. Xiao, “Experimental study on the stability of railroad silt subgrade with increasing train speed,” Journal of Geotechnical and Geoenvironmental Engineering, vol.136, no. 6, pp. 833–841, 2009, doi: 10.1061/(ASCE)GT.1943-5606.00002
17. [17] E. T. Selig, D. Li, “Track modulus: Its meaning and factors influencing it,” Transportation Research Record, vol. 1470, pp. 47–54, 1994.
18. [18] E. Balcı, N. Bezgin, “Hat esneme direncinin hat performansı üzerindeki etkileri,” Demiryolu Mühendisliği, vol. 11, pp. 75–85, 2020.
19. [19] Y. Tong, G. Liu, K. Yousefian, G. Jing, “Track vertical stiffness–value, measurement methods, effective parameters and challenges: A review,” Transportation Geotechnics, vol. 37, no. 100833, 2022, doi: 10.1016/j.trgeo.2022.100833
20. [20] C. Shi, Y. Zhou, L. Xu, X. Zhang, Y. Guo, “A critical review on the vertical stiffness irregularity of railway ballasted track,” Construction and Building Materials, vol. 400, no. 132715, 2023, doi: 10.1016/j.conbuildmat.2023.132715
21. [21] E. T. Selig, J. M. Waters. Track Geotechnology and Substructure Management. London, UK: Thomas Telford, 1994.
22. [22] B. Indraratna, D. J. Armaghani, A. G. Correia, H. Hunt, T. Ngo, “Prediction of resilient modulus of ballast under cyclic loading using machine learning techniques,” Transportation Geotechnics, vol. 38, no. 100895, 2023, doi: 10.1016/j.trgeo.2022.100895
23. [23] D. Li, J. Hyslip, T. Sussmann, S. Chrismer. Substructure from: Railway Geotechnics. Florida, USA: CRC Press, 2016.
24. [24] L. Zhang, X. Jiang, Z. Li, Z. Yang, G. Liu, Z. Dong, Y. Qiu, “Influence of the attenuation of subgrade elastic modulus caused by precipitation on ballasted track structure,” Construction and Building Materials, vol. 352, no. 128971, 2022, doi: 10.1016/j.conbuildmat.2022.128971
25. [25] K. Gaspard, Z. Zhang, G. Gautreau, K. Hanifa, C. E. Zapata, M. Abufarsakh, “Modeling the resilient modulus variation of in situ soils due to seasonal moisture content variations,” Advances in Civil Engineering, vol. 2019, no. 1793601, 2019, doi: 10.1155/2019/1793601
26. [26] M. Ozgur, S. Arsoy, “A practical modification to coaxial cables as damage sensor with TDR in obscured structural members and RC piles,” Structural Monitoring and Maintenance, vol. 10, no. 2, pp. 133–154, 2023, doi: 10.12989/smm.2023.10.2.133
27. [27] M. W. Lin, J. Thaduri, “Structural deflection monitoring using an embedded ETDR distributed strain sensor,” Journal of Intelligent Materials Systems and Structures, vol. 17, no. 5, pp. 423–430, 2006, doi: 10.1177/1045389X06058631
28. [28] G. C. Topp, J. L. Davis, A. P. Annan, “Electromagnetic determination of soil water content: measurements in coaxial transmission lines,” Water Resources Research, vol. 16, no. 3, pp. 574–582, 1980, doi: 10.1029/WR016i003p00574
29. [29] J. Ledieu, P. D. Ridder, P. D. Clerck, S. Dautrebande, “A method of measuring soil moisture by time-domain reflectometry,” Journal of Hydrology, vol. 88, no. 3–4, pp.319–328, 1986, doi: 10.1016/0022-1694(86)90097-1
30. [30] M. Ansoult, L. W. D. Backer, M. Declercq, “Statistical relationship between apparent dielectric constant and water content in porous media,” Soil Science Society of America Journal, vol. 49, no. 1, pp. 47–50, 1985, doi: 10.2136/SSSAJ1985.03615995004900010009X
31. [31] S. S. Artagan, V. Borecky, “Advances in the nondestructive condition assessment of railway ballast: A focus on GPR,” NDT & E International, vol. 115, no. 102290, 2020, doi: 10.1016/j.ndteint.2020.102290
32. [32] S. Arsoy, M. Ozgur, E. Keskin, C. Yilmaz, “Enhancing TDR based water content measurements by ANN in sandy soils,” Geoderma, vol. 195–196, pp. 133–144, 2013, doi: 10.1016/j.geoderma.2012.11.019
33. [33] Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System), ASTM D2487, 2017