利用热棒阵对多年冻土区桥墩进行主动热防护研究  

Study on active thermal protection for bridge pier in permafrost regions by using thermosyphon group

作　　者：孙田 郭宏新[1] 周天宝 索华宁 董添春 张明国 SUN Tian;GUO Hongxin;ZHOU Tianbao;SUO Huaning;DONG Tianchun;ZHANG Mingguo(Jiangsu Sunpower Technology Co.,Ltd.,Nanjing 210003,China;China Railway Qinghai-Tibet Group Co.,Ltd.,Xining 810007,China;College of Transportation Engineering of Nanjing Tech University,Nanjing 211816,China)

机构地区：[1]江苏中圣高科技产业有限公司,江苏南京210003 [2]中国铁路青藏集团有限公司,青海西宁810007 [3]南京工业大学交通运输工程学院,江苏南京211816

出　　处：《冰川冻土》2023年第5期1555-1563,共9页Journal of Glaciology and Geocryology

基　　金：冻土工程国家重点实验室开放基金项目(SKLFSE202009);江苏省资助招收博士后人员资助计划项目(2019Z016);国家自然科学基金项目(52108324)资助。

摘　　要：为解决青藏铁路沿线多年冻土区各大桥的桥梁桥墩沉降问题,以K1401特大桥桥墩为研究治理对象,设计出一种主动热防护的热棒阵治理方法。热棒阵设计思想是利用外侧热棒使土体冻结形成冰幕,保护和维持内侧热棒冻结区的稳定发展,降低桥墩桩基附近多年冻土温度,使桩基承载力增强,保护桥墩长期热稳定性。在典型桥墩周围内外侧平行布置热棒阵,热棒埋深依据初始冻土上下限决定,且埋设间距不超过2 m。开展了现场监测,用2个冻融循环周期的监测数据分析地温和沉降变形时空效应,研究热棒阵主动热防护方法的降温效能和治理效果。结果表明:桥墩外侧热棒水平方向3 m范围内降温明显,经过两个冬季后热棒周边3 m范围内平均降温幅度为1.1℃;竖直方向上随深度增加,降温幅度有所减小,冻土上限至埋深15 m范围内平均降幅超过0.4℃;整治前桥墩每年沉降量超过10 mm,布置热棒阵后年沉降量小于3 mm,热棒阵整治后沉降变形得到有效控制。本研究可为寒区同类桥梁桩基融沉病害整治提供借鉴。Pile foundations are widely used to support dry bridges crossing large extents of warm and ice-rich permafrost regions along the Qinghai-Xizang(Tibet)Railway.The performance of these pile foundations are re⁃lated to permafrost conditions surrounding the piles.The thickness of permafrost surrounding the piles has signif⁃icantly decreased and artesian sub-permafrost groundwater has been observed around the middle-lower part and below the piles.As a consequence,due to the sub-permafrost groundwater occurrence significantly reducing the friction between the pile surface and thawed ground and the end bearing capacity,large settlements of pile foun⁃dations are currently occurring.Ensuring the stability of bridges in warm and ice-rich permafrost regions is of great significance to the sustainable and safe operation of the Qinghai-Xizang Railway.In order to solve the set⁃tlement problem of bridge piers in permafrost regions along the Qinghai-Xizang Railway,taking Bridge K1401 as an example,the thermosyphons as an active thermal protection method were arranged in two arrays in paral⁃lel,forming thermosyphon group.The core idea is to make use of the outside thermosyphon leads to the forma⁃tion of the ice curtain,which effectively prevent the external thermal erosion between sub-permafrost groundwa⁃ter and outer environment,also directly protect and maintain stable development of the inner thermosyphon freez⁃ing zone.Thermosyphon group cool down the permafrost around the pile foundation and strengthens the freezing force between pile surface and permafrost and bearing capacity of the pile foundation,which effectively protects the long-term stability of the bridge pier.Around the typical pier,thermosyphon group were installed.In order to meet the requirement,the depth of the thermosyphon is determined by the base and table of permafrost and the distance is not more than 2 m between the thermosyphon.Field monitoring was carried out to analyze the tempo⁃ral and spatial effects of ground temperature and subsid

关 键 词：多年冻土 桥墩 热棒阵 沉降 青藏铁路 

分 类 号：P642.14[天文地球—工程地质学] U443.22[天文地球—地质矿产勘探]