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中南大学学报(自然科学版)

Journal of Central South University

第51卷    第12期    总第316期    2020年12月

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文章编号:1672-7207(2020)12-3554-12
基于数值试验的风沙区散体道床内尺度比研究
张智海1, 2,肖宏1, 2,令行1, 2

(1. 北京交通大学 土木建筑工程学院,北京,100044;
2. 北京交通大学 轨道工程北京市重点实验室,北京,100044
)

摘 要: 为研究沙粒粒径对道床宏细观力学特性的影响,引入量纲一参数内尺度比表征道床内部颗粒的粒径,设计8种不同沙粒粒径的风沙区铁路钢轨-轨枕-道床的一体化数值试验,借助Logistic相关性分析模型建立内尺度比与道床力学特性之间的联系;开展现场轮轨力及位移试验,标定离散元模型的微观参数,验证模型的正确性。在此基础上,系统分析沙粒粒径对离散元模型计算效率、道床内部细观接触特性及轨道结构宏观动位移的影响。研究结果表明:当道床中颗粒内尺度比大于57.52时,计算时间急剧增加,计算效率低;随着内尺度比不断增大,道床内部颗粒法向接触力和切向接触力的强力键分布面积逐渐减小,且沙粒粒径对法向接触力的影响更明显;随着沙粒粒径减小,颗粒水平位移概率密度峰值逐渐减小,垂向位移概率密度峰值向正位移方向移动;道砟颗粒平均配位数与内尺度比呈正相关,随着内尺度比增大,道砟颗粒的平均配位数逐渐增大,但配位数曲线斜率逐渐减小;轨枕平均动位移与内尺度比呈负相关,随着内尺度比增大,轨枕平均动位移过渡到收敛区,沙粒粒径影响减弱,根据Logistic模型预测结果可知真实沙粒作用下轨枕动位移平均值不超过0.302 mm。综合研究表明,风沙道床存在内尺度比,多尺度效应显著,需在风沙铁路道床建模过程中重点关注。

 

关键词: 风沙铁路;内尺度比;离散单元法;细观接触;位移场

Intrinsic scale ratio of scattered ballast bed in sandy desert areas based on numerical experiment
ZHANG Zhihai1, 2, XIAO Hong1, 2, LING Xing1, 2

1. School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China;
2. Beijing Key Lab of Track Engineering, Beijing Jiaotong University, Beijing 100044, China

Abstract:In order to study the influence of sand size on the macro and micro mechanical properties of ballast bed, the dimensionless parameter internal scale ratio was introduced to characterize the particle size scale in ballast bed. A test of rail-sleeper-ballast bed in sandy desert areas with 8 kinds of sand particle size was completed. With the logistic correlation analysis model, the relationship between the internal scale ratio and the mechanical properties of ballast bed was established. Field wheel-rail force and displacement tests were carried out, and the micro parameters of the discrete element model were calibrated to verify the correctness of the model. On this basis, the influence of sand size on the calculation efficiency of discrete element model, the micro contact characteristics inside the ballast bed and the macro dynamic displacement of track structure were analyzed systematically. The results show that when the intrinsic scale ratio is greater than 57.52, the calculation time increases sharply and the calculation efficiency is lower. With the increase of internal scale ratio, the distribution areas of strong bond of normal contact force and tangential contact force of particles in ballast bed gradually decrease, and the influence of sand particle size on normal contact force is more intuitive. As the particle size of sand decreases, the peak of probability density of particles horizontal displacement gradually decreases, and the peak value of the vertical displacement probability density moves in the direction of positive displacement. With the increase of internal scale ratio, the average coordination number of ballast increases gradually, but the slope of coordination number curve decreases gradually. The average dynamic displacement of sleepers is negatively correlated with the internal scale ratio. With the increase of the internal scale ratio, the average dynamic displacement of sleepers transits to the convergence zone, and the influence of sand size is weakened. According to the results predicted by the logistic model, the average value of sleeper dynamic displacement under the action of real sand will not exceed 0.302 mm. Comprehensively, there is an intrinsic scale ratio in the ballast bed with sand, and the multi-scale effect is significant, which should be paid more attention in the process of ballast bed modeling.

 

Key words: windblown sand railway; intrinsic scale ratio; discrete element method; mesoscopic contact; displacement field

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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