重载铁路桥梁-有砟轨道层间阻力时变模型与梁轨相互作用研究

The evolution of the resistance between bridge and ballast track, as well as the time-dependent characteristics of track-bridge interaction on heavy haul railway are the basic scientific problems to evaluate the safety of the heavy haul railway engineering. Due to the repeated effect of the heavy haul train loads, the performance of ballast gradually degrades during the service period, and the constitutive relationship of the railway resistance evolves along with it. An exact and reasonable calculation model of the railway resistance is the basis and premise of studying track-bridge interaction. However, the railway resistance models in the existing domestic and international codes are short-term static models without considering the dynamic characteristics, which can't be used to carry out the regular analysis and safety evaluation of the track-bridge time-dependent system..In this project, the following studies are planned to be carried out via theoretical analysis, full-scale model test, DEM-FEM coupling simulation and field measurement..(1) The track resistance experiments and DEM-FEM coupling simulation will be utilized to explore the evolution law of the resistance of track-bridge system during the whole service period caused by ballast degradation. Furthermore, the evolutionary models of the resistance will be established..(2) Based on the time-dependent resistance models, the evolution characteristics of the track-bridge interaction in the heavy haul railway will be identified, and the adaptability of bridge and track will be investigated..(3) A comprehensive evaluation index system of time-dependent track-bridge system on heavy haul railway will be explored and proposed. In addition, the threshold index values of the resistance and crashed ballast rate in track-bridge system under different axle loads and typical spans will be obtained..The research results can provide references for the construction, operation and maintenance of the track-bridge system in heavy haul railways.

重载铁路桥梁-有砟轨道层间阻力的演化与梁轨相互作用时变特征是评价重载铁路运营安全的基础科学问题。在列车荷载长期反复作用下，道砟性能不断劣化，有砟轨道线路阻力也随之演化，进而影响梁轨间相互作用。目前，国内外相关规范中线路阻力模型均为短期静态模型，未考虑其时变特性，无法对梁-轨时变系统进行分析评价。本项目拟采用理论分析、足尺模型试验、离散元-有限元联合仿真与现场实测相结合的方法，开展以下研究：探明不同服役阶段重载列车循环作用下桥梁与有砟轨道间的真实阻力关系，构建可反映服役状态的梁-轨层间阻力的时变模型；基于层间阻力时变模型，研究重载铁路梁-轨系统相互作用的时变特征与演化规律，开展桥梁与有砟轨道的适应性研究；建立重载铁路梁-轨时变系统安全度的综合评价指标体系，提出不同轴重、典型跨径下梁-轨系统的线路阻力安全阈值与道砟破碎率阈值。研究成果可为重载铁路桥梁-轨道结构的建造、运营及维护提供科学依据。

重载铁路桥梁-有砟轨道层间阻力的演化与梁轨相互作用时变特征是评价重载铁路运营安全的基础科学问题。在列车荷载长期反复作用下，道砟性能不断劣化，有砟轨道线路阻力也随之演化，进而影响梁轨间相互作用。本项目基于桥梁与无缝线路的相互作用机理，采用理论分析、足尺模型试验、离散元仿真与有限元模拟相结合，针对重载铁路桥梁-有砟轨道层间阻力时变模型与梁轨相互作用开展研究：（1）基于三维激光扫描技术，开展了典型道砟颗粒形状扫描与识别；（2）采用Clump法建立可反应真实道砟外形的仿真颗粒，建立了有砟轨道轨枕-道砟的离散元节段模型，开展精细化仿真分析；（3）开展了重载铁路有砟轨道线路阻力室内足尺模型试验，验证了离散元仿真模型的准确性，构建了反映服役状态的梁-轨层间阻力的时变模型；（4）建立了温度、列车过桥、列车制动及耦合作用下桥上无缝线路钢轨位移及附加应力的解析算法，编制了可视化计算分析软件；（5）基于层间阻力时变模型，研究重载铁路梁-轨系统相互作用的时变特征与演化规律，开展桥梁与有砟轨道的适应性研究；（6）建立重载铁路梁-轨时变系统安全度的综合评价指标体系，提出典型跨径下梁-轨系统的线路阻力安全阈值。项目执行期间培养研究生5名；发表科技论文6篇，其中SCI检索2篇，EI检索4篇；授权专利3项、软件著作权1项。研究成果可为重载铁路桥梁-轨道结构的建造、运营及维护提供科学依据。