多年冻土地基单桩冻拔效应的计算方法与分析  

Calculation method and analysis of frost jacking effects of single pile in permafrost soils

作　　者：周亚龙 王旭[1,2,3] 郭春香[1] 刘德仁[1] 蒋代军[1,2,3] 何菲[1] Zhou Yalong;Wang Xu;Guo Chunxiang;Liu Deren;Jiang Daijun;He Fei(College of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;National and Provincial Joint Engineering Laboratory of Road&Bridge Disaster Prevention and Control,Lanzhou Jiaotong University,Lanzhou 730070,China;Key Laboratory of Road&Bridge and Underground Engineering of Gansu Province,Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学土木工程学院,兰州730070 [2]兰州交通大学道桥工程灾害防治技术国家地方联合工程实验室,兰州730070 [3]兰州交通大学甘肃省道路桥梁与地下工程重点实验室,兰州730070

出　　处：《东南大学学报（自然科学版）》2023年第2期295-304,共10页Journal of Southeast University：Natural Science Edition

基　　金：国家自然科学基金资助项目(41902272);甘肃省自然科学基金资助项目(20JR10RA235);甘肃省优秀研究生“创新之星”资助项目(2021CXZX-571)。

摘　　要：为研究多年冻土地基冻结过程中桩基础的冻拔效应,基于桩周土的冻胀变形及桩土之间的变形协调关系,结合剪切位移法构建了一种考虑桩土界面相对滑移效应的单桩冻拔荷载传递的理论模型.采用有限差分法,通过MATLAB编程对桩基受力微分方程求解,获得了冻拔力的发展规律,并采用现场试验与有限元数值模拟验证了模型的合理性.接着分析了冻胀率、桩土界面本构参数及桩长对桩基冻拔响应的影响.研究表明:冻结过程桩身轴力逐渐增大,冻深附近出现轴力峰值,部分桩土界面会产生滑移;冻至最大冻深2.3 m时桩身轴力达到最大值690.3 kN,滑移段长度约为0.65倍冻深;冻拔力随土体冻胀率的增大并非呈线性增大,主要受桩土界面峰值剪切强度与残余强度的影响;桩长越长,抗冻拔效果越好.To study the frost jacking behaviors of pile foundation during permafrost soils freezing,based on the frost heaving deformation of the soil around the pile and the deformation coordination relationship between the pile and the soil,a theoretical model of frost jacking load transfer of single pile in permafrost foundation considering the relative slipping of the pile-soil interface is constructed by using the shear-displacement method.The finite difference method is used to solve the differential equations of mechanic of pile foundation by MATLAB.The distribution law of frost jacking force of pile foundation in the freezing process is obtained.The rationality of the theoretical model is verified by field test and finite element numerical simulation.Then,the effects of frost heaving ratio,constitutive parameters of pile-soil interface and pile length on the frost jacking features of pile foundation are analyzed.The results show that the pile axial force increases gradually during the freezing process,the peak value of axial force appears near the frost depth,and some pile-soil interface will slip.When the maximum frost depth is 2.3 m,the pile axial force reaches the maximum value of 690.3 kN,and the length of the slip section is about 0.65 times the frost depth.The frost jacking force does not increase linearly with the increase of frost heaving ratio of soil,which is mainly affected by the peak freezing strength and residual strength.The longer the pile length,the better the resisting frost jacking effect.

关 键 词：多年冻土 桩基础 剪切位移法 相对滑移 切向冻胀力 有限差分法 

分 类 号：TU475[建筑科学—结构工程]