Principal stress rotation induced by moving loads from trains significantly influences railway track settlement accumulation. The stationary cyclic loading commonly adopted to study railway ballast behaviour under repeated train loading cannot fully represent the effects of principal stress rotation, which needs to be properly considered in both laboratory tests and numerical simulations for a better understanding of ballast deformation behaviour. This paper focuses on studying railway ballast deformation behaviour with an emphasis on particle scale interactions under two different loading scenarios – namely, stationary cyclic and moving wheel loading. A ballasted track model consisting of five sleepers was established based on the discrete-element method (DEM) with realistic polyhedron-shaped elements. The numerical model was validated first based on the testing results from a full-scale high-speed railway testing facility at Zhejiang University. Numerical results clearly indicated that moving wheel loading induced larger principal stress rotation than stationed cyclic loading did. Larger principal stress rotation mobilised higher particle rotation and displacement, which further increased particle rearrangements through individual particle rolling and sliding, and potentially could cause accelerated ballast degradation. It is recommended to consider principal stress rotation in ballast settlement predictions to prevent possible underestimation by stationary cyclic loading and its limitations.

中文翻译：

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用离散元法分析主应力旋转对铁路轨道沉降的影响

火车移动载荷引起的主应力旋转会显着影响铁路轨道沉降的累积。通常用于研究反复列车荷载下铁路道ast行为的静态循环荷载不能完全代表主应力旋转的影响，在实验室测试和数值模拟中都需要适当考虑这一点，以更好地理解道ast变形行为。本文着重研究铁路道ast的变形行为，重点是在两种不同的载荷情况下，即静态循环载荷和动轮载荷下的颗粒尺度相互作用。基于具有实际多面体形状元素的离散元素方法（DEM），建立了由五个轨枕组成的道track轨道模型。首先根据浙江大学全面的高速铁路测试设施的测试结果对数值模型进行了验证。数值结果清楚地表明，与固定式周期性载荷相比，动轮载荷引起更大的主应力旋转。较大的主应力旋转动员了较高的粒子旋转和位移，这通过单个粒子的滚动和滑动进一步增加了粒子重排，并可能导致加速的压载物降解。建议在压载沉降预测中考虑主应力旋转，以防止由于静态循环载荷及其局限性而导致的低估。数值结果清楚地表明，与固定式周期性载荷相比，动轮载荷引起更大的主应力旋转。较大的主应力旋转动员了较高的粒子旋转和位移，这通过单个粒子的滚动和滑动进一步增加了粒子重排，并可能导致加速的压载物降解。建议在压载沉降预测中考虑主应力旋转，以防止由于静态循环载荷及其局限性而导致的低估。数值结果清楚地表明，与固定式周期性载荷相比，动轮载荷引起更大的主应力旋转。较大的主应力旋转动员了较高的粒子旋转和位移，这通过单个粒子的滚动和滑动进一步增加了粒子重排，并可能导致加速的压载物降解。建议在压载沉降预测中考虑主应力旋转，以防止固定循环载荷及其局限性引起的低估。并可能导致镇流器加速退化。建议在压载沉降预测中考虑主应力旋转，以防止因静态循环载荷及其局限性而造成的低估。并可能导致镇流器加速老化。建议在压载沉降预测中考虑主应力旋转，以防止因静态循环载荷及其局限性而造成的低估。