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目的:研究散粒体道床在纵向反复荷载下的阻力性能及变化规律是深入理解有砟轨道无缝线路动态服役性能和辨识无缝线路在循环荷载作用下的受力变形机理的基础。本文旨在利用室内足尺试验模型及专用加载系统,分析散粒体道床受循环位移荷载时的纵向阻力性能,探索不同位移加载幅值对有砟道床纵向阻力的影响。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。
OBJECTIVE: To study the resistance performance and variation of loose track bed under longitudinal cyclic loading is the basis of deep understanding of the dynamic service performance of ballasted track seamless track and the identification of the stress-strain mechanism of the continuous track under cyclic loading. The purpose of this paper is to analyze the longitudinal resistance performance of bulkhead ballast with cyclic displacement load and to explore the influence of different displacement loading amplitude on the longitudinal resistance of ballast bed with indoor full-scale test model and special loading system. Innovative points: 1. Using the full-scale test model with 砟 orbital structure and cyclic loading device to test the longitudinal resistance of the bed under cyclic load - displacement hysteresis curve; 2. According to the cyclic loading test curve, build hysteresis model, Longitudinal bearing and force transmission of bed. Through the experimental analysis, the force-displacement curves of the bulkhead bed under cyclic loading are obtained (Figures 6, 8 and 10). Based on the experimental data, Hysteresis curve, the evolution law of the hysteresis curve under different displacement amplitudes is obtained (Figures 7, 9 and 11); 3. By the image recognition technology, Macroscopical mechanistic analysis of the meso-mechanism of the channel bed (Figures 16-18). The conclusion is as follows: 1. The longitudinal resistance-displacement curve of granular bed under cyclic cyclic load is a closed hysteresis curve, and there is a significant energy dissipation phenomenon. (2) In the cyclic process where the displacement amplitude remains constant, The behavior of cyclical softening is shown in the bed of the granite. (3) The attenuation rates of the vertical resistance of the bed are different with different displacement amplitudes, and the greater the displacement, the more obvious the degenerative effect.