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极限状态设计方法是我国铁路工程走向国际的重要步骤,而路基循环累积变形是设计中控制标准之一。基于永久应变经验公式,提出列车荷载作用下路基循环累积变形的预测模型,通过1∶1路基模型试验验证了该预测模型的适用性。在此基础上,引入动应力及路基填料参数的变异性,建立路基循环累积变形的极限状态方程,并根据武广线现场实测数据确定路基面动应力幅值的变异系数。通过可靠度指标对计算参数变异系数的敏感性进行分析,分析动应力及填料参数的变异性等控制因素的影响作用,并确定了变异程度控制范围作为实际工程中的控制标准。可靠度分析的方法考虑了荷载及填料参数的不确定性因素,使得理论预测更加接近工程实际。
The method of limit state design is an important step toward the internationalization of railway engineering in our country. The cumulative deformation of subgrade cycle is one of the control standards in design. Based on the empirical formula of permanent strain, a prediction model of cumulative cyclic deformation of subgrade under train load is proposed. The applicability of this model is verified by a 1: 1 subgrade model test. On this basis, the dynamic stress and the variability of the parameters of subgrade filling are introduced to establish the limit state equation of cumulative deformation of the embankment cycle. The coefficient of variation of the dynamic stress amplitude of subgrade surface is determined according to the measured data of Wu-Guang line. Through the reliability index, the sensitivity of calculating the coefficient of variation is analyzed. The influence of the control factors such as the dynamic stress and the variability of the filler parameters is analyzed. The control range of the variation degree is determined as the control standard in the actual project. The method of reliability analysis takes into account the uncertainties of loading and packing parameters, making the theoretical predictions closer to engineering practice.