微冻胀填料中填充料冻胀与骨架颗粒的相互作用机制

Interaction Mechanism of Filling Material and Skeleton Particle in Micro Frost Heaving Filler

针对季节性冻土地区路基冻胀对高速铁路平顺性影响的问题,运用室内试验与理论分析相结合的方法,研究填充料、含水率及外荷载等因素对微冻胀填料冻胀的影响,并分析冻胀过程中填充料与骨架颗粒之间的相互作用机制。结果表明:微冻胀填料由粗粒骨架、骨架颗粒之间的填充料及未填充的剩余孔隙组成;当填充料填充率为0.25时,填料发生初始宏观冻胀;上覆荷载具有抑制填料冻胀的作用;冻结过程中刚度较大骨架粗颗粒的体积基本不发生变化,而填充料体积发生膨胀起到填充骨架颗粒间剩余孔隙和抬升骨架颗粒的作用,引起宏观冻胀;当骨架颗粒间的剩余孔隙率较大时消纳作用强,同时削减了抬升作用,而抬升作用使骨架颗粒间的间隙增大,从而又促进了填充料填充作用的发展;当骨架结构稳定时,填充料的填充作用明显;微冻胀填料的冻胀过程实际上是填充料的填充作用与抬升作用的动态平衡过程。

To solve the problem about the influence of subgrade frost heaving on the riding comfort of high speed railway in seasonal frozen soil area,the influence of various factors such as the filling material,water content and external load on micro frost heaving filling material has been studied using the combined method of laboratory test and theoretical analysis,and the interaction mechanism between the filling material and skeleton particle in the process of frost heaving has been analyzed.Research shows that the micro frost heaving filler consists of coarse skeleton,filling material between skeleton particles and residual pore without filling.When the filler filling rate is 0.25,the initial macro frost heaving occurs in filling material.The frost heaving can be inhibited by the overlying load.The volume of coarse particle skeleton with large rigidity does not change in the process of frost heaving,but the volume expansion of filling material has the function of filling the residual pore between skeleton particles and uplifting the skeleton particle,and macro frost heaving occurs.The absorptive function is strong and the uplift function is cut down when the skeleton particles remain large porosity,and the uplift function makes the gap between the skeleton particles increase,thus promotes the development of filling function for filling material.The filling function of filling material is obvious when the skeleton structure is stable.The process of frost heaving of micro frost heaving filling material is actually a dynamic balance process between the filling function and uplift function of filling material.