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Journal of Zhejiang University SCIENCE A
ISSN 1673-565X(Print), 1862-1775(Online), Monthly
2017 Vol.18 No.8 P.648-659
Longitudinal resistance performance of granular ballast beds under cyclic symmetric displacement loading
Abstract: The longitudinal resistance performance of a granular ballast bed under cyclic symmetric displacement loading was studied based on a full-scale test model of ballast track structures. The change law of the longitudinal resistance characteristics of the ballast bed under variable displacement amplitudes was analyzed. The results show that: the resistance-displacement curves of a granular ballast bed are a set of closed hysteretic curves, indicating obvious energy consumption; a granular ballast bed softens gradually during the cyclic process with constant displacement amplitude, and the residual deformation rate increases nonlinearly with increasing cycle number; the peak value of the longitudinal resistance of lines decreases with increasing cycle number; the cyclic softening of a granular ballast bed is dependent on the displacement amplitude–the higher the displacement, the more severe the cyclic softening will become; after cyclic displacement loading is applied several times, the longitudinal resistance of the bed will degenerate obviously, and the higher the displacement amplitude, the higher the longitudinal resistance attenuation rate of the ballast bed will become.
Key words: Granular ballast bed; Displacement amplitude; Cyclic loading; Longitudinal resistance
创新点:1. 利用有砟轨道结构足尺试验模型及循环加载装置,测试循环荷载下的道床纵向阻力-位移滞回曲线;2. 根据循环加载试验曲线,构建滞回模型,刻划散粒体道床的纵向承载和传力性能。
方法:1. 通过试验分析,得到散粒体道床在周期性荷载作用下的力-位移曲线(图6、8和10); 2. 基于试验数据,分析散粒体道床在周期性荷载下的滞回准则,得到不同位移幅值下滞回曲线的演化规律(图7、9和11);3. 通过图像识别技术,对周期性荷载作用下道砟颗粒的运动规律进行分析,从散粒体道床的细观作用机理分析宏观力学表现(图16~18)。
结论:1. 散粒体道床在循环往复荷载下的纵向阻力-位移曲线为一条封闭的滞回曲线,且存在明显的耗能现象;2. 在位移幅值保持不变的循环过程中,散粒体道床表现出一种循环软化行为;3. 位移幅值不同,道床纵向阻力的衰减率不同,且位移越大,退化效应越明显。
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DOI:
10.1631/jzus.A1700058
CLC number:
U213.71
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On-line Access:
2024-08-27
Received:
2023-10-17
Revision Accepted:
2024-05-08
Crosschecked:
2017-07-07