考虑泊松效应的单桩竖向承载变形特性研究  

Study on vertical bearing deformation behavior of single pile considering Poisson’s effect

作　　者：余棚 谢唯实 傅旭东[1,2] YU Peng;XIE Weishi;FU Xudong(School of Civil Engineering,Wuhan University,Wuhan 430072,China;Hubei Key Laboratory of Safety for Geotechnical and Structural Engineering,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学土木建筑工程学院,湖北武汉430072 [2]武汉大学岩土与结构工程安全湖北省重点实验室,湖北武汉430072

出　　处：《铁道科学与工程学报》2021年第4期901-907,共7页Journal of Railway Science and Engineering

基　　金：国家自然科学基金面上资助项目(51978540)。

摘　　要：单桩在承受上拔或下压荷载时,其桩侧极限摩阻力相差较大,桩身泊松效应是重要的影响因素之一。考虑泊松效应对桩-土界面法向应力的影响,推导得到上拔与下压荷载作用导致的桩侧极限摩阻力改变量的表达式;根据双曲线荷载传递模型,得到考虑泊松效应的的τ-z曲线;在位移协调法的基础上,通过迭代更新桩底位移使桩顶轴力与桩顶荷载相等,提出各级荷载作用下桩身位移响应的计算方法;基于Matlab开发平台编制单桩在竖向荷载作用下Q-S曲线和抗拔系数的计算程序,通过与现场试验数据对比验证了本文计算方法的可靠性。研究结果表明:单桩的抗拔系数随着桩土平均模量比的增大而增大,但其增长速率逐渐减小;随着长径比的增大,单桩的抗拔系数线性减小。随着桩土平均模量比的增大,抗拔系数受长径比的影响逐渐减小,当桩土平均模量比为6 000时,抗拔系数几乎不随长径比的改变而变化。The ultimate side friction resistance is quite different for uplift and compressive piles,and the Poisson’s effect is one of the most important influencing factors.With the influence of the Poisson’s effect on the normal stress at the pile-soil interface considered,the expression of the change in the ultimate side friction resistance due to the action of uplift and download was derived;according to the hyperbolic load transfer model,anτ-z curve which can consider the Poisson's effect was proposed;on the basis of the method for harmony of displacement,the axial force of pile top was made to be equal to the load of pile top by iteratively updating the displacement of pile bottom,in which case,a calculation method of pile body displacement response under various levels of load was proposed;the calculation program of Q-S curve and uplift coefficient of single pile under vertical load was proposed on the basis of Matlab,and the reliability of the calculation method was verifed in this paper by comparing the result with the field test data;the results of uplift coefficient which is influenced by the average pile-soil modulus ratio and slenderness ratio show that:1)The uplift coefficient of a single pile increases with the increase of the pile-soil average modulus ratio,but its growth rate gradually decreases;2)As the slenderness ratio increases,the uplift coefficient of the single pile decreases linearly.With the increase of average pile-soil modulus ratio,the influence of slenderness ratio on the uplift coefficient gradually decreases,when the pile-soil modulus ratio is 6000,the uplift coefficient hardly varies with the change of the slenderness ratio.

关 键 词：极限摩阻力 泊松效应 τ-z曲线 抗拔系数 

分 类 号：TU473[建筑科学—结构工程]