考虑竖向摩阻作用的陡坡段桥梁桩基侧向受力分析

Analysis on lateral mechanical behaviors of bridge pile in steep slope considering vertical friction

为分析陡坡段桥梁桩基的力学特性,根据桩身特征段的不同受力特征,将桩身划分为自由段、被动段和主动段,考虑桩身竖向摩阻的影响,基于三参数地基模型,建立桩身响应微分控制方程,并采用Laplace变换结合传递矩阵法推导出桩身响应的半解析解.然后,通过现场试验和文献算例验证了该方法的合理性,并通过某工程实例分析了桩身被动段竖向摩阻和长度对桩身响应的影响.结果表明:桩身被动段竖向摩阻对桩身响应具有折减效应,但该效应随着被动段竖向摩阻的增加逐渐减弱;被动段长度在被动段临界长度内增长将显著增加桩身响应,且被动段临界长度随着被动段土体刚度的增大而减小;增强桩身被动段3~5倍桩径深度范围内的土体刚度能明显减小桩身响应.

To analyze the mechanical characteristics of the bridge pile in the steep slope,according to the different mechanical characteristics of pile sections,the pile was divided into the free section,the passive section and the active section.Considering the vertical friction influence of the pile,the differential equations of the bridge pile were established by using the tri-parameter model.The semi-analytical solution of the pile response was deduced by Laplace inverse transformation with the matrix-transfer method.Then,the rationality of the proposed method was verified by field tests and literature examples.The influence of the vertical friction and the length of the pile passive section on the response of the pile was analyzed by an engineering example.The results show that the vertical friction of the pile passive section has a reduction effect on the pile response,but the effect decreases gradually with the increase of the vertical friction.The increase of the length of the passive section within the critical length of passive section can increase the pile response significantly,and the critical length of the passive section decreases with the increase of the soil stiffness in the passive section.The increase of the soil stiffness in the depth range of 3 to 5 times pile diameter in the pile passive section can reduce the pile response significantly.