摘要
为探讨均质砂土地基中桩顶水平简谐荷载H(t)与扭矩T联合作用下的单桩承载特性,基于改进的有限杆单元法,考虑桩周土的刚度贡献及H(t)-T的耦合作用,建立出桩身综合刚度矩阵,再利用MATLAB求解桩身的内力、位移,进而通过参数分析获得桩身长径比(L/D)、桩土刚度比(Ep/Es)、H(t)的无量纲频率a0与幅值Q0以及桩底边界条件等对H(t)-T联合受荷桩内力、位移的影响曲线,研究表明:随入土深度增加,桩身弯矩先增大后急剧减小,而扭矩和变形急剧减小直至为0,即存在一有效桩长ld,ld与桩身内力、位移受Ep/Es的影响较大。当Ep/Es从1500增至3500时,ld从27.3D增至44.1D,且桩身弯矩最大值相对增大23.5%,而地面处桩身水平位移与扭转角分别减小19.0%及26.0%;减小H(t)的无量纲频率a0或增大幅值Q0均可适当提高桩身受扭承载力;桩底边界条件只对有限长桩的内力、位移有影响。
To investigate the bearing behavior of a single pile in uniform sand under the combined action of horizontal harmonic load H(t)and torque T,the modified finite bar element method is used to establish the comprehensive stiffness matrix of the pile shaft with consideration of the stiffness contributed by the surrounding subsoil and the coupling effect between H(t)and T.Then,the internal forces and deformations of H(t)-T combined loaded pile are solved by MATLAB,and a detailed parametric analysis is carried out to discuss the influence of length-diameter ratio(LID),pile-soil stiffness ratio(Ep/Es),dimensionless frequency(a0)and amplitude(Q0)of the horizontal harmonic load,and boundary conditions of the pile toe on the bearing behavior of pile shaft.The results show that as the depth of the pile increases,the bending moment along the pile shaft first increases and then decreases sharply,while the torque and deformation reduce drastically to almost zero in the end,i.e.,there is an effective pile length ld.The ld,internal forces and displacements are greatly affected by Ep/Es.When Ep/Es increases from 1500 to 3500,ld rises from 27.3 D to 44.1 D,and the maximum bending moment of the pile increases by 23.5%,but the horizontal displacement and torsional angle at the ground surface decrease by 19.0%and 26.0%,respectively.Decreasing a0 or increasing Q0 can relatively improve the torsional bearing capacity of the pile shaft.The boundary conditions of the pile toe only affect the internal forces and deformations of finite-length piles.
作者
覃玉兰
邹新军
曹雄
QIN Yu-lan;ZOU Xin-jun;CAO Xiong(College of Civil Engineering,Hunan University,Changsha,Hunan 410082,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2020年第1期147-156,共10页
Rock and Soil Mechanics
基金
国家自然科学基金项目（No.51578231,No.51378197）~~
关键词
单桩
均质砂土
水平简谐荷载
扭矩
承载特性
single pile
uniform sand
horizontal harmonic load
torque
bearing behavior
