考虑相变作用的冻土路基应力与变形分析模型

基于冻土路基温度场的控制方程,考虑水分转化为冰的相变作用对土体瞬时变形和蠕变变形的影响,建立路基应力和变形的二维数值方程,并通过1月份的路基冻胀力学模型,分析冻胀带内水分相变引起的路基应力和变形的分布规律.研究发现,在冻胀区域一定的情况下,冻胀率的大小决定了路基表面应力和变形的极值大小;竖向位移的最大值在坡脚处产生,并向路基中部和左侧边界逐渐递减;随着冻胀率的增加,路基表面裂缝有从坡脚向路中发展的趋势;路基表面产生最大拉应力的位置与最大竖向位移的位置基本吻合;路中所承受的拉应力主要发生在水分集聚的相变带范围内.结果表明,相变作用是引起路基发生冻胀病害的直接因素,分析路基应力与变形的分布规律是研究多年冻土路基破坏机理的有效方法.

Analysis model of stress and deformation of permafrost subgrade with phase changing

Based on the temperature field control equations of permafrost subgrade, the numerical two-dimension equations of its stress field and deformation field were put forward, the influence of water phase changing from moisture to ice on the instant deformation and creep deformation of soil was synthesized, the frost-heaving model of subgrade was experimented on january, the changing laws of the stress and deformation of permafrost subgrade surface were analyzed. It is pointed that the extreme stress and deformation of permafrost subgrade surface are determined by frost-heaving velocity within frost-heaving region; the maximum value of subgrade vertical displacement is at slope bottom, and deceases to the middle and the left boundary of subgrade little by little; with the increasing of frost-heaving velocity, the crack of subgrade surface tends to the middle of road from the slope bottom; the location of the maximum stress of subgrade surface is consistent with that of the maximum vertical displacement; road stress mainly lies in the phase changing region of moisture convergence. Analysis result shows that the phase changing of subgrade is the direct reason of subgrade frost-heaving damage, the analysis of the stress field and deformation field is an effective method to study the mechanism of permafrost subgrade damage. 1 tab, 5 figs, 15 refs.