基于非等截面桩体模型的楔形桩动力响应

Dynamic response of tapered pile based on non-equal-section pile model

摘要:

为完善楔形桩的动力响应及应用理论,假设桩为弹性,将桩身划分为非等截面桩段,桩径线性渐变,采用Winkler模型模拟桩周土,建立基桩振动方程,通过换元变换进行简化,依次求得桩顶纵向振动速度的频域响应和时域响应,并通过控制变量法就相关影响因素展开深入讨论,结果表明:当地基土剪切波速较小时,本文模型计算结果与已有简化模型结果相近,随着土体剪切波速提高时,两者出现显著差别；针对3个楔形桩的几何特征参数,计算表明,桩长L主要影响桩底反射信号强度,桩长越长,反射信号峰越低；桩身半长处桩径R_m和楔角α主要影响C区曲线的位置,R_m越大,α越小,C段会更下沉,同时也会小幅影响桩底反射信号强度；桩身纵波速（弹性模量）越大,桩底反射信号越强,频响曲线的震荡幅度越大.

Abstract:

To improve the dynamic response of tapered piles and its application theory, the Winkler model was adopted to simulate surrounding soil, and the frequency domain and time domain responses of longitudinal vibration velocity of the pile top were obtained with the pile vibration equation simplified by changing variable, in which the pile was assumed to be elastic with gradually varied diameter and its body was divided into non-equal-section parts. The variable control method was adopted to investigate the influence factors. Results showed that the calculation results of the proposed model were similar with those of the traditional simplified model when soil shear wave velocity was low. However, the difference between the proposed model and the traditional simplified model became more significant as the shear wave velocity increased. For three geometric feature parameters, calculations showed that pile length L mainly affected the signal intensity of pile bottom. The longer the pile length was, the lower the reflected signal peak was. The radius R_m and cone angle α mainly affected the position of curve in C area, and slightly affected the reflection signal of pile bottom. With the increase of the compressional velocity (elastic modulus), the reflection signal of pile bottom and the amplitude of frequency response curve became more significant.