不同含水状态火山渣掺配土质砾砂改良填料动力特性及累积变形规律研究

具有多孔轻质特征的火山渣在水和列车动载耦合作用下的颗粒抗破碎能力及填料的变形和强度特性是影响其作为基床填料的关键问题。通过开展体积比3∶1火山渣掺配土质砾砂改良填料的室内动三轴试验,讨论了试样制备、动载及水和动载耦合作用下火山渣颗粒的破碎程度,分析了含水率及围压对改良填料临界动应力和累积塑性变形的影响规律。试验结果表明:处于压实状态的体积比3∶1火山渣掺配土质砾砂改良填料在动载及水和动载耦合作用下的相对破碎率低于3%,颗粒破碎不显著;临界动应力随含水率的增大而减小,随围压的增大而增大,饱和含水状态对应的临界动应力较最优含水状态小42%,但仍能满足普通铁路对基床底层填料动力特性的要求。

Dynamic Characteristics and Deformation Law of Volcanic cinder filling improved by gravely sand Under Different Moisture Content

Volcanic cinders are generally viewed as special material for their porou and low quality characteristics. The particle breakage strength and deformation characteristics of filling under water and train dynamic coupling is key issue for it can be working as subgrade filling. In order to verify the applicability of volcanic cinder as subgrade filling, a series of dynamic triaxial tests about volcanic cinder improved by gravely sand at the volume mixing ratio of 3∶1 were carried out, the content of particle breakage during sample preparation dynamic stress and water and train dynamic coupling were discussed, and also the characteristics of dynamic behavior with different confining pressure levels and content of moisture were analyzed. The test shows that: under the long-term dynamic loading, the particle breakage index of volcanic cinder Improved by gravely sand in the compacted state is less than 3%, the particle breakage is not significant. The Critical Dynamic Stress of volcanic cinder improved by gravely sand at the volume mixing ratio of 3∶1 decreased with the increase of Moisture content while increased with the increase of confining pressure. The Critical Dynamic Stress at the state of saturated water content was reduced on average by 42% compared with that at the state of optimum moisture content, which still can meet the bottom layer of subgrade' requirement of railways grades Ⅱ.