【摘要】 近年来,中国东北多年冻土地区正处于显著的增温过程中。由此导致多年冻土逐渐退化,并严重影响到构筑物的稳定性。以0.05℃的年平均气温上升率为背景,采用带有相变的传热学有限元方法,对中国东北多年冻土地区不同初始气温条件和不同含冰量类型冻土的地基温度状况以及季节活动层厚度变化进行了模拟;利用温度场有限元数值试验结果和已有承载力试验数据分析了不同类型冻土地基的力学性质对气温变化敏感性,评估了气温变化对各类冻土地基承载力的影响。气候变化对多年冻土地区构筑物稳定性影响程度取决于两个环节:其一,冻土地基温度状况对气候变化的响应;其二,冻土地基力学性质对地基温度变化的敏感性。研究结果表明,冻土地基含冰量和温度状态对其承载力随气温变化的敏感性具有显著的影响。含土冰层地基承载力对气温变化最为敏感,气温变化对高温冻土地区浅层地基承载力以及桩-土冻结强度影响较大;而深基础桩端冻土地基承载力受气候变化影响相对较小。更多还原

【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.更多还原