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通过沪宁线提速路基的现场动态试验,在实测轨道不平顺、车速为120~200 km.h-1情况下,采用动力有限元方法计算铁路路基的动力响应。分析路基动应力的分布形式、路基动应力随列车速度的变化规律、路基动应力随深度的衰减规律,以及道床厚度、路堤高度对路基动应力影响规律。研究表明:路基动应力随列车速度的提高而呈线性增加;路基动应力总体上呈双峰的马鞍型分布,且随着路基深度增加,双峰的幅度减小,直至双峰消失,变为路基中心动应力最大的单峰型;随道床厚度的增加,路基竖向动应力显著减小;路堤高度的增加对路基动应力的影响不大,但可有效减小地基表面的动应力。
Through the dynamic test of the embankment on Shanghai-Nanjing line, the dynamic finite element method is used to calculate the dynamic response of the railway subgrade when the measured track is not smooth and the speed is 120 ~ 200 km.h-1. The dynamic stress distribution along the roadbed, the law of subgrade dynamic stress with train speed, the attenuation law of subgrade dynamic stress with depth and the influence of ballast bed thickness and embankment height on the dynamic stress of subgrade are analyzed. The results show that the dynamic stress of subgrade increases linearly with the increase of train speed, and the dynamic stress of subgrade is saddle-shaped with bimodal distribution as a whole. With the increase of subgrade depth, the amplitude of double peak decreases until it disappears, With the increase of the thickness of the track bed, the vertical dynamic stress of the subgrade is significantly reduced. The increase of the embankment height has little effect on the dynamic stress of the subgrade, but it can effectively reduce the dynamic stress on the surface of the subgrade.