多年冻土区斜坡稳定性研究综述

Stability of permafrost slopes:a review

全球变暖、极端天气频发,引发的地质灾害对自然生态环境和人类生产生活造成了很大的影响。尤其对气候变化较为敏感的高温(年平均地温>-1°C)和高含冰量多年冻土区,气候变暖以及人类活动导致的冻融地质灾害日益频繁。冻土退化条件下,土体结构和物理力学性质发生改变,黏聚力和抗剪强度降低,造成多年冻土区斜坡发生滑坡、崩塌、泥流等灾害。斜坡失稳加剧了多年冻土区脆弱生态环境的恶化,同时对建(构)筑物安全运营产生威胁。与非冻土区相比,多年冻土区斜坡稳定性研究主要针对高含冰量斜坡段,斜坡失稳模式主要以热融滑塌和活动层滑脱为主。热融滑塌由斜坡段地下冰暴露融化引起,而活动层滑脱产生的原因是冻土融化导致土体孔隙水压力过大,形成的超孔隙水压力降低了土体强度,造成斜坡失稳。此外,多年冻土区斜坡失稳模式还包括融冻泥流、崩塌以及蠕变滑坡等。通过综述近期多年冻土区斜坡稳定性研究进展,概括了多年冻土区斜坡失稳的模式、特征、影响因素、失稳机理、分析方法及防治措施等,并对未来多年冻土区斜坡失稳的研究重点提出建议。

Geohazards induced by climate warming and extreme weather events have great impacts on the eco⁃logical environment and human community.In particular,in regions with more thaw-unstable,ice-rich,and warm(mean annual ground temperature>-1°C)permafrost,climate warming and human activities have led to more frequent freeze-thaw geohazards.With the degradation of permafrost,the cohesion and shear strength of soil would be reduced,resulting in active layer detachment failures,rockfalls,mudflows,and frozen debris flows/lobes,and other frost-related geohazards in permafrost slopes.Slope instability may further aggravate the deterioration of the fragile ecological environment in permafrost regions,threatening the safe operation of engi⁃neered infrastructures.Compared with the unfrozen soil zone,the research on the stability of permafrost slopes mainly aims at ice-richer slopes.The main types of slope instability in permafrost regions include retrogressive thaw slump and active layer detachment.The former is caused by exposure and the melting of ground ice in the slope cut.The latter is by the excess pore water pressure in slope soils due to the thawing of frozen soil and the resultant excess pore water pressure reduces the soil strength,destabilizing permafrost slopes.In addition,slope instability modes in permafrost regions include gelifluction,frozen debris flows/lobes,rockfalls and creep land⁃slides,among others.This paper reviews the latest progress on the studies on basic characteristics,influencing factors,instability mechanisms,stability evaluation methods,and mitigative measures of permafrost slope insta⁃bility,identifies inadequacies,and prospects for future research.