ABSTRACT Heavy haul railway, recognized for high capacity and efficiency, is gaining traction worldwide. However, heavier axle loads can accelerate track and foundation deterioration without robust structural design. This study proposes a practical design methodology for heavy-haul track foundations under 40-tonne axle loads. Short axle spacing was considered in analyzing train load distribution, revealing significant stress superposition on the subgrade. Based on general strength, deformation, and long-term stability, a standardized multi-axle load pattern (4Z1800/2400) is introduced to capture these effects. The recommended design ensures cumulative deformation remains within the subgrade “working zone” by integrating induced stress levels and fill materials, surpassing single-factor approaches. Long-term stability, indicated by cumulative deformation approaching slow convergence, serves as the control requirement. Proposed design solutions include: 1) roadbed thickness of 3.5 m, with subgrade reaction modulus (K30) ≥110 MPa/m below the roadbed; 2) lower roadbed of 2.3 m, K30 ≥130 MPa/m, with thickness adjustments as needed; 3) upper roadbed of 0.7 m using high-quality graded gravel. These measures effectively control deformation, thus ensuring the performance and longevity of heavy-haul track foundations under extreme axle loads. The outcomes support global heavy-haul development.
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