重载铁路路基荷载特征和路基动力响应分析

Loading Characteristics and Dynamic Response Analysis of Subgrade for Heavy Haul Railway

研究目的:近年来,重载铁路因其经济性较好在我国广泛建设,重载铁路路基基床承受重载列车动荷载作用较大,为了更好地分析重载铁路动荷载对路基病害诱发的影响,进一步优化重载铁路路基基床厚度结构设计,本文利用三维有限元对道砟厚度、基床表层厚度、基床表层模量、轴重等因素对重载铁路路基动应力特征和基床范围内动应力的传递分布影响进行仔细的研究。研究结论:通过数值计算和与既有重载铁路实测动应力比较分析得出以下结论:(1)路基中竖向动应力随着轴重、道床厚度、表层厚度和表层模量的变化规律为:路基基床中的竖向动应力随着轴重的增大而增大,随着道床厚度增大而减小,而基床表层模量和基床表层厚度对竖向动应力影响较小;(2)重载铁路30 t轴重相对于普通铁路23 t轴重增加约30%,而增加道床厚度可显著减小其动应力,50 cm较35 cm道床厚度各部位动应力减小约20%;(3)计算得出重载铁路路基动应力的合理数值模型和相关参数,为重载铁路路基基床厚度结构设计提供了合理的计算方法。

Research purposes： In recent years, because of its good economic heavy haul railway has an extensive constructions. Subgrade of heavy haul railway bears more large dynamic load of heavy haul train. In order to analyze the heavy haul railway dynamic load＇ s influence to roadbed diseases better, and further optimize the thickness of subgrade bed of heavy haul railway, this article uses the three - dimensional finite element software analyzing the dynamic stress changes of heavy rail subgrade bed from the following factors ： ballast thickness, surface of subgrade bed＇ s thickness and modulus, axle load, etc. Research conclusions：Through numerical analysis and comparison with the existing heavy haul railway embankment measured dynamic stress, the follow conclusions are obtained： （1） The dynamic stress in the vertical variation as the axle load, ballast bed thickness, surface layer of subgrade bed＇ s thickness and modulus＇ s changes is obtained. The vertical dynamic stress in the subgrade bed increases with the axle load increasing, and decreases with the thickness of ballast bed increasing, and the surface layer of subgrade bed＇ s modulus and thickness have little effect on the vertical dynamic stress. （2） 30 t axle load of heavy haul railway compared with 23 t axle load of ordinary railway increases by about 30% , while increasing the thickness of ballast bed can significantly reduce the dynamic stress . Compared with 35 cm thickness of ballast bed, the dynamic stress by using 50 cm thickness of ballast bed can decrease by about 20%.（3） The reasonable numerical model and parameter for calculating dynamic stress of heavy railway subgrade are obtained. Meanwhile, these provide a reasonable calculation for structure design of heavy rail subgrade bed thickness.