道岔為鐵路系統中重要之軌道構造，其中岔心區因輪重轉移及幾何斷面變化之影響，長期承受較複雜之動態載重作用。當道岔下方道碴因長期營運而產生掏空現象時，將導致支撐條件劣化，使岔心受力狀態改變，進而影響其疲勞壽命。然而目前國內道岔養護作業仍以幾何不整檢測為主，對於支撐劣化對岔心結構之影響尚缺乏量化評估依據。
本研究以臺鐵#12木枕型道岔為研究對象，利用有限元素法建立包含鋼軌、岔心、墊片及木枕之三維模型，並以彈簧元素模擬道碴及路基支撐系統。列車荷載部分採用移動荷載方式模擬莒光號機車頭通過岔心區域之受力過程，並建立不同掏空深度及掏空範圍之支撐劣化工況。進一步結合雨流計數法、S-N曲線及Miner線性累積損傷理論，評估支撐劣化對岔心底部動態應力與疲勞壽命之影響。
研究結果顯示，岔心底部最大應力集中於岔心幾何轉換區附近，為道岔結構中最不利之受力位置。當支撐喪失範圍逐漸擴大時，不僅會提高岔心底部最大應力，亦會增加結構振動反應及高應力循環次數，使疲勞損傷更容易累積。分析結果亦顯示，當岔心區連續四根枕木發生掏空時，局部掏空工況之最大應力皆已超過高錳鋼疲勞極限162.8 MPa，對應破壞前年限分別為2年2個月、2年1個月、2年1個月，全枕失效之二工況則為1年11個月及5個月。而在鼻軌後方連續三個枕木發生掏空時，最大應力範圍非常接近疲勞極限，故可視為發生疲勞損傷之臨界工況。
綜上所述，本研究證實道岔支撐劣化將改變岔心區之受力行為，並對疲勞壽命產生顯著影響，其中掏空範圍為主要控制因子。研究成果可作為未來養護決策及疲勞壽命管理之參考依據，並供國內道岔支撐劣化量化評估之基礎。

Railway turnouts are critical components of railway infrastructure, and the frog region is subjected to complex dynamic loading due to wheel load transfer and geometric discontinuities. Ballast voiding beneath turnouts deteriorates the support conditions, alters the stress distribution, and may reduce the fatigue life of the frog. However, quantitative evaluation of the effects of support deterioration on turnout performance remains limited.This study developed a three-dimensional finite element model of a Taiwan Railway Administration (TRA) No. 12 turnout. Spring elements were used to simulate the ballast and subgrade support system, while a moving load representing a Chu-Kuang Express locomotive was applied. Various ballast voiding depths and extents were investigated. The Rainflow Counting Method, S–N curve, and Miner’s linear cumulative damage rule were employed to evaluate the fatigue life of the frog.
The results show that the maximum stress occurs near the geometric transition region at the bottom of the frog. Increasing the extent of ballast voiding significantly raises the maximum stress and accelerates fatigue damage accumulation. When four consecutive sleepers were voided, the maximum stress exceeded the fatigue limit of high-manganese steel (162.8 MPa), resulting in an estimated fatigue life of approximately 2 years under local ballast voiding, while complete support loss reduced the fatigue life to as short as 5 months. The results also indicate that the extent of ballast voiding has a greater influence on fatigue performance than the voiding depth.The findings provide a quantitative basis for turnout maintenance planning and fatigue life assessment of railway frogs.

[1] M. Loidolt, S. Marschnig, M. Bürgler, A. Berghold, P. Dornig and U. Ossberger, "Quality Behaviour of Turnouts: Comparison, Problem Specification and Recommendation of Measures," Applied Sciences, vol. 13, no. 19, 2023.
[2] G. Evans, F. Shahzad, E. de Vries, M. Cavalletti, S. Iwnicki and Y. Bezin, "An investigation of sleeper voids using a flexible track model integrated with railway multi-body dynamics," Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, vol. 223, no. 6, pp. 597-607, 2009.
[3] M. Sysyn, M. Przybylowicz, O. Nabochenko and J. Liu, "Mechanism of Sleeper–Ballast Dynamic Impact and Residual Settlements Accumulation in Zones with Unsupported Sleepers," Sustainability, vol. 13, no. 14, 2021.
[4] 黃冠瑜, 軌枕間距對軌道承載力之影響分析, 國立成功大學土木工程研究所碩士論文, 2024.
[5] X. Zhu, C. Hao, C. Liang, T. Bai, Y. Qian, J. Xu and P. Wang, "Load characteristics analysis of the high-speed turnout rail bottom under random factors," Engineering Failure Analysis, vol. 173, 2025.
[6] J. S. Siew, O. Mirza and S. Kaewunruen, "Nonlinear Finite Element Modelling of Railway Turnout System considering Bearer/Sleeper-Ballast Interaction," Journal of Structures, 2015.
[7] C. Project, "Operational Failure Modes of Switches and Crossings," 2015.
[8] J. Kang, F. Zhang, X. Long and B. Lv, "Cyclic deformation and fatigue behaviors of Hadfield manganese steel," Materials Science and Engineering: A, vol. 591, pp. 59-68, 2014.
[9] S. Wang, Y. Gao and Q. Yi, "Vibration fatigue failure analysis and life prediction of high-speed," Engineering Failure Analysis, vol. 176, 2025.
[10] J.-Y. Shih, D. Kostovasilis, Y. Bezin and D. Thompson, "Modelling options for ballast track dynamics," in 24th international congress on sound and vibration, London, 2017.
[11] Y.-L. Lee, J. Pan, R. B. Hathaway and M. E. Barkey, Fatigue Testing and Analysis, 2005.
[12] R. G. Budynas 且 N. J. Keith, Shigley's Mechanical Engineering Design, New York: McGraw-Hill Education, 2015.
[13] H. Vilhelmson, B. A. Pålsson and J. C. Nielsen, "Assessment of Structural Requirements for Crossing Panel Design using Dynamic Load Case Scenarios," in Proceedings of the Sixth International Conference on Railway Technology: Research,Development and Maintenance, 2024.
[14] "ASTM E1049-85(2005) Standard Practices for Cycle Counting in Fatigue Analysis," ASTM International, West Conshohocken, PA, USA, 2005.
[15] 中華民國國家標準, “CNS 3830 高錳鋼鑄鋼件,” 經濟部標準檢驗局, 1987.
[16] "JIS G 5131:2008 High Manganese Steel Castings," Japanese Standards Association, Tokyo, 2008.
[17] "NR/L2/TRK/001 Inspection and Maintenance of Permanent Way," Network Rail, London, United Kingdom, 2012.
[18] D. Systèmes, "Abaqus Finite Element Analysis," SIMULIA, [Online]. Available: https://www.3ds.com/products/simulia/abaqus.
[19] 臺灣鐵路規範, “TRAS(E)-011 50kg-N鋼軌,” 交通部臺灣鐵路管理局, 台北市, 2015.
[20] 軌道施工規範, “0650A章-50KG鋼軌橡膠墊片,” 交通部, 2018.
[21] B. A. Pålsson, R. Ambur, S. Michel, P. Wang, . J.-Y. Shih, D. Fan, . J. Xu and J. Chen, "A comparison of track model formulations for simulation of dynamic vehicle–track interaction in switches and crossings," Vehicle System Dynamics, vol. 61, no. 3, pp. 698-724, 2023.
[22] L. Hall, J.-Y. Shih, J. A. Barros, A. Zangeneh, C. Pacoste, J. Johansson and A. M. Kaynia, Design Of Foundations For High-Speed Railway Embarkment-A methodology for setting-up and performing numerical calculations of ground vibrations, SBUF - Svenska Byggbranschens Utvecklingsfond,The Development Fund of the Swedish Construction Industry, 2022.
[23] J.-Y. Shih, Models of vehicle/track/ground interaction in the time domain, UNIVERSITY OF SOUTHAMPTON,Faculty of Engineering and the Environment,Institute of Sound and Vibration Research, Dynamics Group.
[24] 戴耐米系統有限公司, “軌道道岔即時監測系統–地基沉陷監測系統（Ⅰ）期末報告,” 2026.