Testing of Contact Stress at Ballast Bed-Soil Subgrade Interface under Cyclic Loading Using the Thin-Film Pressure Sensor
Testing of Contact Stress at Ballast Bed-Soil Subgrade Interface under Cyclic Loading Using the Thin-Film Pressure Sensor
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DOI：
10.1520/jte20190171
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发表时间：
2020-05
影响因子：
1.2
通讯作者：
Junhua Xiao;Yanhai Wang;De Zhang;Xiao Zhang;G. Jiaqi
中科院分区：
文献类型：
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作者：
Junhua Xiao;Yanhai Wang;De Zhang;Xiao Zhang;G. Jiaqi
一种新的试压方法，利用薄膜式压力分布测试系统，通过模型试验研究了循环荷载作用下普通铁路道床-土路基界面的接触面积和应力。考虑了循环荷载的幅值、频率以及底碴的存在与否等因素对接触面接触面积和接触面平均应力的影响。并将试验结果与传统的土压力盒试验结果和基于连续介质理论的有限元计算结果进行了比较。研究表明，由于道碴介质的不连续性，道碴层在路基表面的应力分布是不均匀的，但随着道碴层的铺设，应力分布逐渐趋于均匀。由土压力传感器测量的路基表面应力与有限元计算的路基表面应力非常相似，但两者都比由新型薄膜压力传感器测量的接触面积上的平均应力低约50%。由于道床与路基之间的接触应力是路基劣化的关键因素，新的试验方法和数值计算方法可以适当地考虑道床的不连续性，这是研究接触应力的必要条件。
A novel pressure testing method, i.e., a thin-film pressure distribution measurement system, was utilized to investigate the contact area and stress at the ballast bed-soil subgrade interface of conventional railways during cyclic loading in model tests. Factors like the amplitude and frequency of cyclic loading and the existence or nonexistence of the subballast were considered to study their effects on the contact area and average stress over the contact area at the interfaces. In addition, the testing results were compared with those measured by the traditional testing method using earth pressure cells and those calculated by the finite element method (FEM) based on continuum theory. The study shows that, because of the discontinuous characters of the ballast medium, the stress diffused from the ballast bed on the subgrade surface was unevenly distributed but becoming relatively evenly distributed as the subballast was being installed. The subgrade surface stresses measured by the earth pressure cell and calculated by the FEM were very similar, but both were about 50 % lower than the average stress over the contact area measured by the novel thin-film pressure sensor. As the interface stress between the ballast bed and the subgrade is a key factor in subgrade deterioration, new testing methods and numerical calculation methods can consider the discontinuous characters of the ballast appropriately to be necessary for the investigations of the interface contact stress.