青藏铁路接触网异型桩基抗冻拔模型试验研究  

Experimental of Anti-Frost Jacking Model of Grotesque Pile Foundations of Overhead Contact System Mast of Qinghai–Xizang Railway

作　　者：周亚龙 王旭[1,2] 蒋代军[1,2] 刘德仁[1] 何菲[1] 晏昌 牛富俊 ZHOU Yalong;WANG Xu;JIANG Daijun;LIU Deren;HE Fei;YAN Chang;NIU Fujun(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;Key Laboratory of Road&Bridge and Underground Engineering of Gansu Province,Lanzhou Jiaotong University,Lanzhou 730070,China;Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China)

机构地区：[1]兰州交通大学土木工程学院,甘肃兰州730070 [2]兰州交通大学甘肃省道路桥梁与地下工程重点实验室,甘肃兰州730070 [3]西北生态资源环境研究院,甘肃兰州730000

出　　处：《西南交通大学学报》2024年第3期677-684,共8页Journal of Southwest Jiaotong University

基　　金：国家自然科学基金(41902272);甘肃省优秀研究生“创新之星”项目(2021CXZX-571)。

摘　　要：保证接触网支柱桩基础的冻拔稳定性是青藏铁路格拉段电气化改造工程建设中的关键问题之一,为研究不同截面形式桩(等截面圆形桩Z1、直锥柱形桩Z2及曲锥柱形桩Z3)的抗冻拔性能,以青藏线路基填料为试验土体,进行3个冻融循环的室内模型试验,得到冻融作用下接触网支柱桩基础的地温、桩顶位移及桩身应力的分布规律.试验结果表明:路基体的冻结(融化)是二维冻结(融化),接触网支柱桩基础附近的冻结深度约为30 cm;路肩处土体的竖向冻胀位移为4.30 mm,Z1的竖向冻拔量为0.26 mm,Z2与Z3的竖向冻拔量分别为Z1的46%、58%,3根桩的桩顶均产生约0.1 mm的水平位移;冻结过程中桩基整体受拉,冻深附近桩身轴力最大;切向冻胀应力的最大值出现在地表附近,曲锥柱形桩切向冻胀总力最小,抗冻拔效果最好.One of the key problems in the construction of the electrification reconstruction project of Gela section of Qinghai−Xizang Railway is to ensure the frost jacking stability of the pile foundation of the overhead contact system mast(OCSM).In order to study the anti-frost jacking performance of piles with different sections(equalsection circular pile(Z1),straight-cone cylindrical pile(Z2),and curved-cone cylindrical pile(Z3)),the indoor model tests with three freeze-thaw cycles were carried out by using the subgrade filling materials of Qinghai-Xizang Railway as the test soil sample.The distribution laws of ground temperature,pile-top displacement,and pile body stress of the OCSM pile foundations under the influence of freezing and thawing were obtained.The test results show that the freezing(thawing)of the subgrade is two-dimensional,and the depth of freezing near the OCSM pile foundations is about 30 cm.The vertical frost-heave displacement at the subgrade shoulder is 4.30 mm,and the vertical frost jacking displacement of Z1 is 0.26 mm.In addition,the vertical frost jacking displacement of Z2 and Z3 is only 46%and 58%of Z1,respectively.The top of the three piles has a horizontal displacement of about 0.1 mm.During the freezing process,the pile is under tension as a whole,and the axial force is greatest near the depth of freezing.The maximum value of tangential frost-heave stress occurs near the ground surface.The total tangential frost-heave force of the curved-cone cylindrical pile is the smallest,with the best anti-frost jacking effect.

关 键 词：多年冻土 接触网支柱桩基础 异型桩 模型试验 冻融作用 冻拔特性 

分 类 号：TU445[建筑科学—岩土工程]