多年冻土地区路基稳定性计算方法及适应性研究

Study on Calculation Method and Adaptability of Subgrade Stability in Permafrost Region

针对冻土路基稳定性受冻融交界面抗剪强度参数控制的特点,基于扩展的简化BISHOP法,对冻土路基分别采用圆弧法和折线法计算了其稳定性。结果表明:折线法与冻融交界面契合度较高,更适合评价冻土路基的稳定性。冻土路基稳定性受冰水相变过程的影响,在暖季中期(6~7月)达到最不利状况。冻土区半填半挖路基和拓宽路基的稳定性除了要考虑软弱接触面的稳定性系数外,还必须结合冻融交界面的稳定性和两者的空间状态综合确定。

In response to the characteristic that the stability of permafrost subgrade is dominated by the shear strength parameters at freeze-thaw interface, the stability of permafrost subgrade was calculated through circular arc method and polygon method based on extensive simplified BISHOP method. The results showed that, the polygon method had a better coincidence with the freeze-thaw interface, consequently, it was more suitable for evaluating the stability of permafrost subgrade. The stability of permafrost subgrade was influenced by water-ice phase change, which has reached a weakest situation in mid warm seasons (June to July). For the stabilities of half filling and half digging subgrade and widened subgrade, in addition to considering the stability coefficient of weak contact face, the stability at freeze-thaw interface and their spatial conditions must be taken into account.