纵横荷载下单桩地基反力法的半解析解

张磊^1,2, 龚晓南¹, 俞建霖¹

1.浙江大学软弱土与环境土工教育部重点实验室;2.西安建筑科技大学土木工程学院



摘要:

为深入研究纵横荷载作用下的单桩响应,引入地基反力系数的一般形式,通过把地面以下桩身分成很多等长的小段并假定每段上桩身轴力和地基反力系数为常数,求得桩身响应的半解析解.结合已有的地面以上桩身响应的幂级数解,采用Fortran语言编制了计算程序.计算结果表明:桩的最大位移和最大弯矩随水平荷载的增加而大幅度增大;纵向荷载可以引起桩基失稳;地表处土反力和地基反力系数沿深度的分布形式对桩的响应影响很大.特例情况下的解与已有解的计算结果吻合得很好,所得解及程序是可靠的.

关键词:  桩基础  纵横荷载  侧向变形  弯矩  半解析解

DOI：10.11918/j.issn.0367-6234.2011.06.020

分类号:TU473.1

基金项目:国家自然科学基金资助项目(50708093)



Semi-analytical solutions for single piles subjected to combined vertical and lateral loads by subgrade reaction method

ZHANG Lei^1,2, GONG Xiao-nan¹, YU Jian-lin¹

1.Key Laboratory of Soft Soils and Geoenvironmental Engineering,Ministry of Education, Zhejiang University,310058 Hangzhou,China;2.College of Civil Engineering,Xi’an University of Architecrure and Technology,710075 Xi’an,China)

Abstract:

To intensively study the responses of single piles under combined vertical and lateral loads,the common form of the coefficient of subgrade reaction was introduced.The semi-analytical solutions were obtained by dividing the pile shaft under ground into many small segments and supposing the axial force of the pile and the coefficient of subgrade reaction corresponding to each segment to be constants.Together with the pre-existing power series solutions for the pile shaft above ground,the relevant computer program was developed by Fortran programming.The calculation results indicate that the maximum lateral displacement and bending moment increase significantly with the increase of lateral loads.The vertical load can cause the instability of the pile.The soil resistance at the ground surface and the distribution of the coefficient of subgrade reaction along depth play important roles in pile responses.The computed results obtained using solutions corresponding to a special case agree well with those obtained using pre-existing solutions,meaning that the presented solutions are dependable.

Key words:  pile foundation  combined vertical and lateral loads  lateral deflection  bending moment  semi-analytical solution