高温多年冻土区路基纵向裂缝发育的热-力耦合分析

Thermo-mechanical coupled analysis on the embankment longitudinal cracks in warm permafrost regions

通过建立热-力耦合模型就阴阳坡热不对称这一因素来探讨高温不稳定冻土区纵向裂缝形成机理,得到和野外观测结果较为一致的结论:阴阳坡路肩不均匀沉降导致路基本体整体向阳坡一侧倾斜,加上阳坡土体受其下方融化盘的影响,其垂直沉降量大于阴坡一侧土体;纵向裂缝的发育是路基水平位移和竖直位移综合作用的结果,因而纵向裂缝以倾斜的形式贯穿于整个路基.纵向裂缝的发育由多年冻土这种特殊的地基土材料的强度破坏而引起;阳坡路基下方的多年冻土融化为软弱地基土,在其上土压力的作用下使路基填土中出现拉应力.提出0位移线的概念,以路基基底出现最大拉应力(或最小压应力)时路基基底是否出现0位移线作为路基是否出现纵向裂缝的判断标准,以其出现的位置作为纵向裂缝发育的位置.

The thermo-mechanical coupled model was set up to simulate how the sunny-shady slope effects on the embankment longitudinal cracks in warm unstable permafrost regions.The corresponding conclusion had a good agreement with the field results.The uneven settlement between the sunny side and the shady side leads to that the whole embankment slants to the sunny side.And the soil of sunny slope is influenced by the thaw bowl under it,so the settlement of the sunny side is more than that of the shady one.The longitudinal crack was caused by both horizontal and vertical displacement.As a result,the longitudinal crack goes through the embankment in a slantwise direction.The longitudinal cracks development is due to strength failure of permafrost.The permafrost under the sunny slope thaws into soft soil layer,so there will be tensile stress in the embankment under the above earth pressure.The ＂0 displacement line＂ is presented.When the most draw-stress or the minimum compressive stress on the bottom of the embankment takes place,the longitudinal cracks depends on weather there appears ＂0 displacement line＂ on the embankment bottom.Where the ＂0 displacement line＂ locates,and where the longitudinal cracks might be.