关键词: 多年冻土, 地基承载力, 温度状况, 气候变暖, 敏感性

Abstract:

Significant climatic warming is in progress in Northeast China permafrost regions and causes degradation of permafrost and influences the stability of structure. A finite-element heat conduction model with phase change was used to predict thermal regimes of foundations with various ice contents. MAAT (mean annual air temperature) of -2, -3, -4, -5 and -6℃ and medium climatic warming scenarios of 0.05℃/year were used as inputs to estimate the thermal response of frozen ground for the next fifty years. Based on results of ground thermal field FEM and experimental data of ground bearing capacity, the sensitivity of frozen ground bearing capacity to air temperature changes was analyzed and evaluated. The impact of climate change on the bearing capacity of frozen ground and stability of structure depends on the thermal response of the frozen ground thermal regimes to climatic warming and the sensitivity of frozen ground mechanical behavior to ground temperature changes. The results show that the sensitivity of frozen ground mechanical behavior to air temperature changes strongly depends on the ice content and the initial thermal regimes of frozen ground. The bearing capacity of frozen ground with ice layers is more sensitive to air temperature changes. The climate warming has significant influences on the bearing capacity of shallow foundation in high temperature permafrost and the adfreezing bond strengths between piles and permafrost with high temperature; while the temperature increase have less effect on the bearing capacity of deep foundation in permafrost regions.

Key words: permafrost, ground bearing capacity, thermal regimes, climate warming, sensitivity