多年冻土区路基路面变形及应力的数值分析

Numerical Analyses of Pavement Deformation and Stress in Permafrost Regions

针对青藏公路路基下发育多年冻土融化盘的实际情况,选择两种模型,应用ABAQUS有限元分析软件,对冻土路基从修筑到开放交通过程中的路基路面位移及应力进行了分析.结果表明:冻土路基以融沉为主的变形,一般情况下以路中心下最大,变形呈凹形;当路基下融化盘偏移时,最大变形位置随之偏移;路面层底拉应力最大,对融沉变形反映敏感;路面顶部压应力最大值出现在轴载作用位置,面层应力对轴载反映敏感.计算模型断面尺寸、路基填料、路面结构等对青藏公路具有代表性,在3.6 m路基总高度条件下,无论路基下融化盘偏移与否,融化盘厚达0.5 m时路基顶部(路面层底)拉应力即达基层抗拉强度,显示路基融沉变形可能导致路基失稳及路面破坏,此时路基高度即达最大值.

Aimed at the thawing plates developed under the highway constructed in permafrost regions, two calculation models are chosen to analyze the displacement and stress of pavement from construction to operation, using ABAQUS software. Calculated results indicate that thawing settlement is the main deformation of subgrade and the maximum deformation appears in the middle of a road in permafrost regions, with a dished deformation profile. The maximum displacement point will offset with the offsetting of thawing plate. The maximum tension stress appears at the base bottom, which is sensitive to thawing settlement. At pavement top, the maximum compressive stress would appear at the place of axis load. The section size, embankment fill and pavement structure in the models are of representative in the Qinghai-Tibet highway. When the embankment height is 3.6 m, in despite of the thawing plate offsetting or not, the tension stress of base bottom will reach the tensile strength as the thawing plate depth reach 0. 5 m, indicating that the thawing settlement is likely to cause pavement failure, therefore, the embankment height （3.6 m） is so called maximum height.