多年冻土斜坡路基失稳变形影响因素及特征研究

从力学相似性的角度进行多年冻土斜坡路基失稳变形离心模型试验，分析最大融深状态下冻土斜坡路基土层性质、高度以及地基坡度对其稳定性的影响规律，研究冻土斜坡路基失稳变形特性、失稳机制及模式，将片石路基与普通路基进行对比分析。试验结果表明，冻土斜坡路基土层力学性质、路基高度和地基坡度对其稳定具有显著影响，路基的变形在冻融交界面发生骤变，变形主要集中在冻融交界面之上的土层；在本试验条件下，多年冻土斜坡路基合理高度约为5 m；当斜坡路基高度为5 m时，地基坡度大于1: 6，路基横向变形迅速增大；冻土斜坡路基的沉降和横向变形表现出较大的不均匀性，冻土斜坡路基变形失稳的根本原因是冻融交界附近软弱带的抗剪强度不足，阳坡冻融交界面之上的土层沿软弱带滑移破坏；路基破坏可分为浅层开裂破坏、深层开裂破坏和整体滑移破坏3种；冻土斜坡片石路基的水平位移和沉降明显小于普通路基，片石路基具有较好的整体稳定性。

Deformation failure characteristics and influential factors of subgrade upon slope in permafrost area

Based on the centrifuge model test, models of subgrade upon slope in permafrost area are completed using the mechanical similarity. Impacts of soil mechanical parameters, subgrade height and ground gradient on the deformation characteristics and stability of subgrade are researched. As well as the deformation failure mechanism and failure modes are researched by comparing rubble stone subgrade and ordinary subgrade. The results show that the soil mechanical parameters, the subgrade height and the ground gradient have obvious effects on the stability of subgrade. The deformation mutation point takes place at the freezing-thawing interface; and the deformation mainly concentrates on the soil layer above the freezing-thawing interface. Under the experimental conditions, the reasonable subgrade height is about 5 m. With the subgrade height of 5 m, the critical value of the ground gradient is about 1:6 and the transverse deformation increases. Both vertical and transverse deformations due to permafrost thawing show a positive nonuniform feature. The essential cause of failure is the deficiency of shear resistance strength of the weak belt. The soil layer above the freezing-thawing interface slips along the freezing-thawing interface. Failure modes of the subgrade are divided into cracking failure in shallow layer, cracking failure in deep layer and failure of integral slippage. Besides, the horizontal displacement and settlement of the rubble stone subgrade are smaller than the ordinary subgrade; and the rubble stone subgrade has better whole stability.