基于状态演化模型的高铁路基动力累积沉降变形预测研究

Prediction of cumulative settlement deformation in high-speed railway subgrades based on state evolution model

长期循环荷载作用下高铁路基会出现累积沉降变形,对轨道平顺性、列车运行的舒适性与安全性等产生不利影响。为预测高铁路基累积沉降变形,基于考虑颗粒材料系统流动性及历史应变的状态演化模型,采用有限差分法进行求解,得到预测长期循环荷载作用下路基累积变形的计算方法。开展分级荷载及长期循环荷载作用下的路基累积沉降变形缩比尺模型试验,对试验结果进行分析,并验证状态演化模型预测路基累积变形的合理性;提出三阶段拟合法,通过0~10000 s循环荷载作用下的路基累积变形试验数据拟合得到模型的关键参数,并对10000~25000 s的路基累积变形进行预测;最后深入分析初始状态模量、特征应变和特征参数对计算结果的影响。研究结果表明:路基累积沉降变形达到稳定值所需的时间随着荷载幅值的增加而增加;状态变量与荷载大小密切相关,随着荷载增大而增大;初始状态变量、特征应变及特征参数越大,路基的流动性及累积应变速率越大。所提方法可以很好地反映分级荷载及循环荷载下路基的累积变形,实现通过现有数据对路基未来累积沉降变形进行有效预测,为长期循环荷载作用引起的高铁路基累积沉降变形提供了实用的预测方法。研究结果可为高铁路基设计及变形控制提供参考,具有较高的实用价值和工程意义。

Long-term cyclic loading can result in the cumulative settlement of high-speed railway subgrades,and adversely affect track smoothness and compromising train operation’s comfort and safety.The state evolution model was developed and solved using the finite difference method,considering the flowability of granular material and historical strain to predict the cumulative settlement of high-speed railway subgrades.A calculation method for predicting cumulative settlement under long-term cyclic loading was obtained.Experimental tests were conducted using scaled models subjected to graded and long-term cyclic loading.The results were analyzed to validate the rationality of the state evolution model in predicting subgrade settlement.Additionally,a threestage fitting method was proposed,which involved fitting key parameters of the model using subgrade settlement data obtained from 0 to 10000 s of cyclic loading and predicting subgrade cumulative settlement from 10000 to 25000 s.The influences of initial state variables,characteristic strain,and characteristic parameters on the calculation results were thoroughly analyzed.The research findings are shown as follows.The time required for subgrade cumulative settlement to reach a stable value increase with the increase in load amplitude.The state variables are closely related to the magnitude of the load and increase with larger loads.The proposed method effectively reflects the cumulative strain of the subgrade under graded and cyclic loading,enabling accurate prediction of future subgrade cumulative settlement using existing data.Moreover,the accuracy of the prediction method is verified.It is found that larger initial state variables,characteristic strains,and characteristic parameters result in more remarkable flowability and accumulation strain rate of the subgrade.The study can provide a practical prediction method for the cumulative settlement and deformation of high-speed railway subgrade caused by long-term cyclic loads.The conclusions obtained from the research can serve as a reference for the design and deformation control of high-speed railway subgrades,demonstrating significant practical value and engineering significance.