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针对武广高速铁路无碴轨道红黏土路堑基床长期动力稳定与换填厚度问题,利用改造后的应力控制式动三轴仪,研究了循环荷载作用下原状结构红黏土动应变随振次的变化规律,获得了11种试验条下原状结构红黏土临界动应力。按曲线走势特征,红黏土εd?lg N曲线可分为衰减型、临界型、破坏型3类,具有与其它黏性土相同的曲线型式。基于室内动力试验及现场动响应测试成果,采用临界动应力法初步评价了武广高速铁路无碴轨道红黏土路堑基床的长期动力稳定性,给出了相应的基床换填厚度最小值。探讨了含水比、围压、固结比对红黏土临界动应力及路堑基床换填厚度的影响,通过多元线性回归得到了两个简单实用的经验估算公式。红黏土临界动应力随含水比的增大线性减小,随围压、固结比的增大线性增大。基床换填厚度随含水比的增大线性增大,随围压的增大线性减小,固结比对基床换填厚度的影响就本次试验成果而言还不明显。研究成果为我国高速铁路无碴轨道路堑基床长期动力稳定性评价及换填厚度的确定提出了新的思路和方法,也为红黏土动力特性的深入研究积累了宝贵的第一手资料。
Aiming at the problem of long-term dynamic stability and replacement thickness of red clay cutting bed of ballastless track red clay in Wuhan-Guangzhou high-speed railway, by using the modified stress-controlled triaxial apparatus, the dynamic strain of undisturbed red clay with cyclic vibrations Variations of the original structure of red clay obtained under the 11 kinds of test conditions of the critical dynamic stress. According to the trend of the curve, the red clay εd? Lg N curve can be divided into attenuation type, critical type, destructive type 3, with the same curve with other clay type. Based on the results of indoor dynamic test and field test, the long-term dynamic stability of red clay cut-off bed for ballastless track of Wu-Guang high-speed railway is preliminarily evaluated by the critical dynamic stress method. The corresponding minimum thickness of bed replacement is given. The effects of water cut-off ratio, confining pressure and consolidation ratio on the critical dynamic stress of red clay and the replacement thickness of cutting bed were discussed. Two simple and practical empirical formulas were obtained by multivariate linear regression. The critical dynamic stress of red clay linearly decreases with the increase of water content, and increases linearly with the increase of confining pressure and consolidation ratio. The thickness of the bed replacement liner increases linearly with the increase of the water content ratio and decreases linearly with the increase of the confining pressure. The effect of the consolidation ratio on the bed replacement thickness is not obvious in this test. The research results provide new ideas and methods for evaluating long-term dynamic stability of ballast-bed of cut-off bed for high-speed railway and long-term dynamic stability of fill-bed, and also accumulate valuable first-hand data for in-depth study of dynamic characteristics of red clay.