不同升温模式下冻土地区装配式基础热稳定性研究  

Thermal Stability of Fabricated Foundations with Different Warming Patterns in Permafrost Regions

作　　者：陈赵育 李国玉[1] 穆彦虎[1] 俞祁浩[1] 毛云程[1,3] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所冻土工程国家重点实验室,甘肃兰州730000 [2]中国科学院大学,北京100049 [3]甘肃省交通科学研究院有限公司,甘肃兰州730050

出　　处：《地震工程学报》2013年第4期877-884,共8页China Earthquake Engineering Journal

基　　金：国家重点基础研究发展计划(973项目)(2012CB0261061);国家自然科学基金创新群体(4112106);国家电网公司科技项目(SGJSJS(2010)935-936);冻土工程国家重点实验室自主研究项目(SKLFSE-ZY-11)

摘　　要：以IPCC SRES A2、A1B、B1三种气候变化模式为基础,利用数值方法研究了青藏直流联网工程冻土区装配式基础的冻融过程以及活动层、融化深度、地温的变化规律。结果表明:工程扰动和气候变暖改变了冻土的热状态,促进了冻土退化,均为影响基础长期稳定性的重要因素,其中混凝土桩基的强化导热作用加剧了冻融过程,气候升温导致活动层厚度增加,土层温度升高;随着深度的增加,冻土响应减弱,冻土温度变化幅度越小;在三种升温模式下50年后融化深度分别达到3.12 m、5.07 m和6.02 m,而同期天然场地活动层厚度为2.07 m、4.37m、5.62m,说明冻土对不同升温模式的响应程度不同,且中心冻土在气候变暖和工程扰动双重影响下退化更快;从第10年到第50年,这三种模式下桩基中心融化速率分别为1.5 cm·α^(-1),6.2 cm·α^(-1),8.6 cm·α^(-1),即随着升温速率的增加,土层融化深度增加,冻土退化速度加快;低升温率时冻土变化主要受工程作用,而在较高升温模式下冻土退化则主要受气候变暖的影响。Climate warming and engineering activities could cause changes in the thermal conditions of permafrost,mainly in two ways：warming of the permafrost and increasing the thickness of the active layer,which will lead to a marked change in the thermal stability of foundations in permafrost regions.Generally based on the IPCC SRES A2,A1B,and B1 climatic changes,this study uses numerical methods to research the freezing and thawing process,the changes in the active layer,the thaw depth and the soil temperature of fabricated foundations in permafrost regions along the ± 400 kV Qinghai-Tibet power transmission line.The results show that engineering activities and climate warming change the thermal conditions of permafrost and promote degradation; these are important factors affecting the long-term stability of foundations.Enhanced heat conduction from concrete pile foundations aggravates the freezing and thawing process,and climatic warming leads to a decrease in the thickness of the active layer and a rise in soil temperature,With increasing depth,the permafrost response decreases,and the rate of change of temperature becomes small.The permafrost response increases and the rate of change of temperature is greatly altered closer to the active layer.Under three warming patterns,after 50 years,the soil temperature at 1 m depth increases to 2.80 ℃,4.66 ℃,and 5.60 ℃ from 1.90 ℃,the soil temperature at 2 m depth increases to 1.22 ℃,3.66 ℃,and 4.82 ℃ from 0.50 ℃,and at 10 m depth,the permafrost temperature will rise from-0.70 ℃ to -0.42 ℃,-0.35 ℃,and-0.30 ℃.With the three warming patterns,IPCC SRES B1,A1B,and A2,the maximum thaw depths under the centers of foundations are 3.12 m,5.07 m,and 6.02 m after 50 years,while the thicknesses of the active layers of natural ground are 2.07 m,4.37 m,and 5.62 m.The maximum thaw depth of natural ground is much shallow than the maximum thaw depth under the centers of foundations.This shows that permafrost has different responses to different warming patterns,and th

关 键 词：青藏直流输电工程 升温模式 装配式基础 热稳定性 多年冻土 

分 类 号：TV445[水利工程—水工结构工程]