冻结层上水的分布及工程影响研究现状与展望

Distribution and engineering effect of supra-permafrost groundwater:review and prospect

作为一种多年冻土区的特殊水文地质现象,冻结层上水(或多年冻土层上水)的分布受局地因素的控制,且随活动层的季节性冻融而变化,影响地表水和地下水循环以及多年冻土环境中的水热平衡。多年冻土将冻结层上水限制在一个狭窄的空间内,在暖季冻结层上水侧向和竖向的渗流传热将加剧多年冻土的退化,也会对上覆工程构筑物的稳定运营造成极大威胁。目前关于冻结层上水的研究主要集中在分布特征、变化规律、流量计算、渗流模拟、水热耦合等方面。研究发现:在全球升温背景下,多年冻土退化速率加剧,随着冻土厚度变薄和融区出现,冻结层上水的流量及其与地下水的交换量均发生变化,除了影响局地水文特征外,还与工程病害密切相关,如坡脚积水、路基沉降以及路面裂缝等。以区域分布特征为出发点,对冻结层上水的研究现状进行了归纳和总结,并对其工程影响有关的渗流传热理论研究成果进行了梳理,对今后需要进行深入研究的方向进行了展望。这有助于全面理解冻结层上水在冻土区水文过程中的功能,为相关研究提供了进一步的理论参考。

Permafrost regions account for one fourth of the lands in the Earth.As a hydrogeological phenomenon in permafrost regions,the distribution of supra-permafrost groundwater is dominated by local factors,which has changed with the seasonal freezing and thawing of the active layer.The supra-permafrost groundwater has affected the cycle of groundwater,ground surface water and hydrothermal balance of the permafrost environment.The supra-permafrost groundwater is limited by the permafrost in a narrow space and aggravates the permafrost degradation by the lateral seepage and heat transfer.Furthermore,the foundation is threatened by the suprapermafrost groundwater by heat convection.The existed research focuses on the distribution,seasonal change,flow,seepage and hydro-thermal coupling.In this paper,the research advances on supra-permafrost groundwater are summarized based on the characteristics of regional distribution.The influence on engineering stability,hydrologic model,water balance calculation and heat transfer effect of supra-permafrost groundwater are reviewed.The supra-permafrost groundwater has interacted and limited with the permafrost,which will cause the profound effects on the ecological environment in permafrost regions.The research prospect in future is proposed.This paper will be helpful to comprehensively understand the role of supra-permafrost groundwater in the hydrologic process and useful to learn the status of supra-permafrost groundwater.