多年冻土区冻融灾害风险性评价

Risk assessment of freeze thawing disaster in permafrost zone

青藏高原多年冻土区由于自然环境变化和人为活动的影响,不少区域存在如热融滑塌、冻胀丘、融沉、冻胀等与冻土变化相关的冻融灾害。冻融灾害的存在与发展给冻土区环境与开发带来极大影响。在广泛现场调查和查阅相关资料的基础上,分析了各种灾害的形成机制以及冻融灾害的主要影响因素。结合地质灾害形成机理和多年冻土区工程建设的实际情况,确定了以岩土性质、活动层厚度、植被覆盖度、坡度、海拔、纬度为内因,年平均气温变化、人为活动为外因的评价模式。评价结果表明,整个青藏高原在现状条件下以中低风险性为主。中高风险区主要分布在年平均地温较高、人类活动强度较大的区域。

Because of the impact of environment change and human activities,some part of the Qinghai-Tibet permafrost areas exist freeze-thawing disasters related to the permafrost change,such as the thaw slumping,frost hearing,thaw subsidence,frost boil and so on.The existence and development of freezing and thawing hazards have a significant effect on the permafrost environment and economic development.This study identified the main types of geological hazards of permafrost zone and analyzed the formation mechanism of various disasters and their main factors based on field investigation and consulting relevant information.Combining geological hazards mechanism with the actual situation of engineering construction in permafrost regions,an evaluation model that takes geotechnical properties,active layer depth,vegetation coverage,slope,elevation,and latitude as internal factors,and annual mean temperature changes,human activities as external factors,was determined.Evaluation＇s results show that Qinghai-Tibet Plateau is mainly in medium-to-low risk in the current conditions.Medium-to-high risk areas are mainly distributed in areas where the average ground temperature is relatively higher,and intensity of human activity is relatively stronger.