重载铁路路基压实粗颗粒土填料动力破坏规律试验研究

Experimental research on dynamic failure rules of compacted coarse-grained soil filling in heavy haul railway subgrade

重载铁路常常通过提高货车轴重来达到增加运量的目的,而大轴重货车运行会对路基粗颗粒土填料产生较大的循环动力作用,这容易导致路基塑性变形过大甚至使路基发生破坏,而这些病害均与粗颗粒土填料的动力破坏规律有关。为研究该类填料在动力作用下的破坏规律进行了一系列大型动三轴试验,分析了围压和含水率对填料塑性变形增长的影响,根据塑性变形增长的特点将试样分为了稳定试样和破坏试样,由此得出了临界动应力的表达公式,并探讨了不同轴重下路基破坏的可能性。此外,还分析了围压和含水率对粗颗粒土填料动强度的影响,结果表明,填料静、动强度之间具有很好的相关性,通过归一化处理提出了利用静强度推求相应动强度的公式。

Heavy haul railway transportation usually enhances freight volume by increasing axle load of the train. However, this change always produces a considerable cyclic loading on coarse-grained soil filling in subgrade. It may result in excessive plastic deformation or even subgrade destruction. These subgrade defects mostly relate to the dynamic failure rules of coarse-grained soil filling. This paper focuses on the dynamic failure rules of subgrade filling. A series of large-scale dynamic triaxial tests is carried out.The influence of confining pressure and water content on plastic strain increase is analyzed. All the specimens are classified as stability type or failure type according to their features of plastic strain increment. An empirical formula of critical dynamic stress is also established by the classification. Moreover, the possibility of subgrade destroy under different axle loads is discussed. Finally,the rules that dynamic strength changes with confining pressure and water content are investigated. The correlation of static strength and dynamic strength is verified. An empirical formula for estimating dynamic strength according to static strength is proposed by the normalizing data.