重载铁路道床-路基接触层水动力特征与颗粒迁移机理研究

Heavy-haul freight is the development direction of railway transportation in the world. In recent years, railway subgrade problems significantly increase as the increasing operation of great-alxe-load and ten-thousand-ton freight trains in China. Aiming at the key problem of hydrodynamic characteristics and particle migration mechanism of ballast-subgrade contact layer in heavy-haul railway, the following research is planned to conduct: 1) Railway subgrade model tests and soil dynamics tests under dry-wet cycles and moisture variations will be conducted to explore the pore water response patterns and distribution regularities; then the influencing characteristics of local inhomogeneous structures and boundary drainage conditions on the increase pattern of subgrade pore water pressure will be analyzed. 2) Long-term field measurement on the instrumented subgrade will be conducted and the interaction law between ballast-subgrade contact layer and surrounding water and gas environment will be studied. The evolution characteristics of ballast-subgrade contact layer under the change of air relative humidity and rainfall will be analyzed. 3) The seepage erosion control equation of the ballast-subgrade contact layer under dynamic action will be established. The numerical calculation method of fine particle migration will be put forward, and the non-balanced flow characteristics and particle migration law of the ballast-subgrade contact layer will be analyzed. 4) The dynamic response law of heavy-haul railway subgrade will be studied, the solid-liquid-gas coupling analysis model of subgrade under dynamic action is established, and the deterioration mechanism of overall service performance of heavy-haul railway subgrade will be analyzed. It provides a scientific basis for improving the state analysis theory and problem prevention and control of heavy-haul railway subgrade.

货运重载是铁路运输业发展的方向。近年来我国大轴重和万吨级货物列车运行后，路基病害显著增加。针对重载铁路道床-路基接触层水动力特征与颗粒迁移机理这一关键问题，开展如下研究：1)开展干湿循环与水分变化速率条件下路基模型试验与典型填料和道砟相互作用的土动力学试验，探究重载列车荷载作用下道床-路基接触层孔压响应模式与分布规律，分析路基局部非均匀结构与边界排水条件对孔压增减的影响。2)开展现场长期监测，研究重载铁路道床-路基接触层与周边水、气环境相互作用规律，分析空气相对湿度、降雨量变化下道床-路基接触层状态演化特征。3)建立动力作用下道床-路基接触层渗流侵蚀控制方程，提出细颗粒迁移数值计算方法，分析道床-路基接触层非平衡流动特征与颗粒迁移规律。4)研究重载铁路路基动力响应规律，建立动力作用下路基固-液-气耦合分析模型，分析路基服役性能劣化机制。为完善重载铁路路基状态分析理论和病害防控提供科学依据。

货运重载是铁路运输业发展的方向。近年来我国大轴重和万吨级货物列车运行后，路基病害显著增加。针对重载铁路道床-路基接触层水动力特征与颗粒迁移机理这一关键问题，构建了既有重载铁路过渡段路基高精度沉降及不均匀沉降监测系统，揭示了既有重载铁路路桥过渡段的差异沉降量、沉降速率及其沿线路纵向的分布特征和随列车通行吨位的变化规律，提出了既有重载铁路路桥过渡段的沉降组合预测模型；构建了既有重载铁路路基含水率监测系统，揭示了降雨与路基含水率之间的变化规律；开展了重载铁路非饱和路基性能的动力特征研究，分析了动位移幅值沿线路纵向及边坡方向的变化规律，揭示了路基对列车动荷载的周期性响应特征以及振动能量沿路基边坡的衰减规律；开展了非饱和和饱和路基土在列车荷载作用下的变形与强度性状，揭示了考虑重载列车行车间隔时间的路基土变形、强度、孔压响应和时空分布特征，提出了重载铁路路基土的弹性应变、累积塑性应变、骨干曲线和孔压数学模型；开展了典型路基填料和道砟相互作用的土动力学试验，研究了道砟-粉土试样的破坏模式，提出了基于试样整体塑性变形和道砟嵌入深度的道砟-粉土试样破坏标准和道砟嵌入现象的宏观定量表征指标，对道砟嵌入现象的宏观演化规律和影响因素进行分析，并阐明了道砟嵌入对道砟-粉土试样整体变形特性的影响特征。开展了轨道-路基1:1室内足尺翻浆冒泥模型试验，系统再现了路基翻浆现象，揭示了超孔压演变规律和时空分布特征，研究表明路基接近或处于饱和状态是翻浆发生的必备条件，超孔压显著增大标志着路基翻浆的发生。构建了车辆-轨道-路基三维动力有限元模型，得到了不同轴重列车作用下路基面动应力峰值的正态分布特征参数。建立了重载铁路道床-路基相互作用单元体离散元数值模型，揭示了重载铁路道砟嵌入和路基土细颗粒迁移的细观机理。所得研究成果直接应用于朔黄铁路，可为重载铁路、既有普通铁路的扩能改造、提质增效和安全运营提供重要的理论基础。