大变形条件下单桩水平承载性状分析

Behavior Analysis of Laterally Loaded Single Pile under Large Deflection

针对大变形条件下承受水平荷载的单桩基础,采用沿深度线性增加并能较好的反映上部土体抵抗侧向变形能力的地基反力系数,及简化的土体弹塑性本构关系,推导出桩身变形和内力的计算公式,并用FORTRAN语言编制了计算程序。算例表明:桩的水平位移和弯矩随水平力和力矩的增加而非线性增大;桩身位移随距离地面的距离的增加而减小,距地面的距离超过10倍桩径时桩身响应极小,可忽略不计;桩顶约束是桩身响应沿桩身分布的重要影响因素;随着桩周土体力学性质的改善,桩的最大位移和最大弯矩均明显减小。计算值与现场实测值吻合度很高,且比已有解计算结果更优,所得解及程序是可靠的。

Based on the simplified elastoplastic constitutive model of soil,the calculation method for the laterally loaded single pile with large deflection was submitted.The coefficient of subgrade reaction was presumed to increase linearly with depth,which simulates the soil resistance close to ground well.The relevant program was then developed using FORTRAN language.The examples show that（1）the displacement and bending moment increase nonlinearly when the lateral load and the moment load increase.（2）The pile displacement decreases with depth.（3）The pile displacement at the point which is over ten times pile diameter from ground is so small that can be neglected.（4）The pile head condition is the key factor,which influences the distributions of pile responses along depth.（5）By improving the mechanical properties of soil around pile,the maximum lateral displacement and bending moment can be decreased efficiently.The calculation results are in good agreement with the field test results and are better than those obtained using the pre-existing solutions,which shows the presented solutions are reliable.