缺陷桩-梁系统的动力特性应用研究

Dynamic characteristics of defective pile-beam system and its application

提出了缺陷桩-梁系统的理论模型。桩周土采用了三维连续介质模型,桩身则采用Rayleigh-love杆件,以考虑大直径桩的横向惯性效应。为了模拟桩身的缺陷段,采用了不同于正常桩身半径的桩段。通过结合阻抗函数递推法、虚土环法(ring soil pile theory,简称RSPT)和修正的阻抗函数递推法(amended impedance function transfer method,简称AIFTM),得到了桩-土系统的桩顶阻抗。桩顶梁采用了Timoshenko杆件进行模拟,同时在桩-梁连接处施加瞬态激振。成功求得了桩-梁系统动力响应在频域内的解析解,并利用离散傅里叶变换获得了时域内的半解析解。为了验证模型的合理性,将获得的半解析解与试验数据和有限元法结果进行了对比。研究结果显示,桩-梁系统较为适合的激振拾取点通常为桩梁连接处,同时需要综合考虑桩梁参数的影响。最后,通过参数分析方法探讨了在桩-梁系统上使用低应变测试的注意事项。

A theoretical model of the defective pile-beam system has been proposed.A three-dimensional continuous medium model is adopted for the surrounding soil,while a Rayleigh-love rod is employed for the pile shaft to account for the transverse inertial effect.The pile defect is simulated using segments with a radius different from the normal one.The impedance function recursive method,in conjunction with ring soil pile theory(RSPT)and amended impedance function transfer method(AIFTM),is used to obtain the impedance function at pile head.The beam is simulated using Timoshenko beam,and transient excitation is applied at the pile-beam connection.The analytical solution for the dynamic response of the pile-beam system in the frequency domain is obtained,and a semi-analytical solution in the time domain is derived using the discrete Fourier transform.The obtained semi-analytical solution is compared with experimental and finite element method results to validate its reasonability.It is found that the pile-beam system is more suitable for excitation pickup at the pile-beam connection,although the influence of pile-beam parameters must also be considered.Finally,precautions for using low-strain testing on the pile-beam system are studied through parameter analysis.