Since most of the current researches on the crushed-rock interlayer for highway embankment in permafrost region are based on thermal properties, there are few studies on their mechanical deformation characteristics. In order to study the deformation and failure process of crushed-rock interlayer under the long-term settlement deformation of permafrost foundation and to fully consider the discrete characteristics of the crushed-rock interlayer, the finite element model and discrete element model were coupled in this study to accomplish the numerical calculation of long-term settlement deformation of crushed-rock interlayer highway embankment as well as permafrost foundation. The results show that as for the granite blocks adopted in the Gonghe–Yushu expressway, the blocks in the interlayer would be rarely broken, and the deformation of crushed-rock interlayer is mainly caused by the relative movement and rearrangement of the blocks. Based on the calculation results, it is suggested to adopt the uncompacted randomly piled crushed-rock interlayer, which is composed of crushed blocks with more sharp corners. When the size of block varies from 20 to 40 cm, the block size has no obvious effect on the deformation of crushed-rock interlayer, and therefore, the block size could be determined only by the cooling effect of crushed-rock interlayer. At the meantime, the structure layer above the crushed-rock interlayer should also be rigid enough to ensure a smaller uneven settlement value for the superstructure.

由于目前对多年冻土区公路碎石夹层的研究大多基于热性能，对其力学变形特性的研究较少。为了研究多年冻土地基长期沉降变形作用下碎石夹层的变形破坏过程，并充分考虑碎石夹层的离散特性，将有限元模型与离散元模型耦合起来。研究完成碎石夹层公路路堤及多年冻土地基长期沉降变形数值计算。结果表明，共和至玉树高速公路采用的花岗岩块体，夹层块体很少发生破碎，碎石夹层变形主要是由块体的相对移动和重新排列引起的。根据计算结果，建议采用未压实散堆碎石夹层，夹层由尖角较多的碎块组成。当块体尺寸在20～40cm范围内时，块体尺寸对碎石夹层的变形影响不明显，因此只能根据碎石夹层的冷却效果来确定块体尺寸。同时，碎石夹层之上的结构层也应具有足够的刚性，以保证上部结构较小的不均匀沉降值。