多年冻土区接触网桩基础冻拔试验分析  

Experimental Analysis on Freezing and Pulling out of CatenaryPile Foundation in Permafrost Area

作　　者：晏昌 夏琼[1,2] 周亚龙 王旭 YAN Chang;XIA Qiong;ZHOU Yalong;WANG Xu(School of Civil Engineering,LanzhouJiaotong University,Lanzhou 730070 China;National Local Joint Engineering Laboratory for Disaster Prevention and Control Technology of Road and Bridge Engineering,Lanzhou 730070,China)

机构地区：[1]兰州交通大学,土木工程学院,甘肃兰州730070 [2]道桥工程灾害防治技术国家地方联合工程实验室,甘肃兰州730070

出　　处：《兰州工业学院学报》2022年第3期7-13,共7页Journal of Lanzhou Institute of Technology

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：以青藏铁路格拉段电气化改造项目为工程背景,对多年冻土区接触网桩基础在冻融循环作用下与土体相互作用进行模型试验,分析3个冻融循环周期内,桩周土体及边坡温度场,桩土位移及桩身应力的变化规律。结果表明:试验中所施加的温度能较好地模拟现场的冻融变化过程,各深度处地温随时间呈正弦曲线分布,冻土上限约为0.3 m;在1个冻结期内土体明显发生冻胀,最大冻胀量的关系为:路肩>边坡>路基,桩周土体的冻胀量远大于桩基的冻拔量;在冻结过程中,桩基础整体受拉,从桩顶到桩底,轴力先增大后减小,最大值出现在深0.3 m处;桩侧切应力在模型桩的上部分为方向向上的冻胀应力,下半部分为方向向下的冻结应力,最大值出现在地表附近,且大致平衡。Taking the electrification reconstruction project of Gela section of Qinghai Tibet Railway as the engineering background,the model test of the interaction between OCS pile foundation and soil in permafrost area under the action of freeze-thaw cycle is carried out.The variation laws of soil around the pile and slope temperature field,pile-soil displacement and pile stress in three freeze-thaw cycles are studied.The results show that the temperature applied in the test can better simulate the field freeze-thaw change process.The ground temperature at each depth presents a"sinusoidal"curve distribution with time,and the upper limit of frozen soil is about 0.3 M.In a freezing period,the frost heave of the soil is obvious,and the relationship of the maximum frost heave is:shoulder>slope>subgrade.The frost heave of the soil around the pile is much greater than that of the pile foundation.During the freezing process,the pile foundation is tensioned as a whole.From the pile top to the pile bottom,the axial force first increases and then decreases,and the maximum value appears at the depth of 0.3 M.The shear stress in the upper part of the model pile is the frost heave stress in the upward direction,and the lower part is the frost stress in the downward direction.The maximum value appears near the surface and is roughly balanced.

关 键 词：多年冻土区 冻融循环 接触网桩基础 模型试验 

分 类 号：U213.13[交通运输工程—道路与铁道工程]