桩-土-结构相互作用分析的等效计算桩长简化模型

A simplified model of equivalent calculated pile length for soil-pile-structure interaction analysis

在一定程度上,桩长是影响桩-土-结构体系动力分析复杂程度的关键因素之一,在桩-土-结构相互作用的数值模拟中对桩长进行适当简化可以提高计算效率,尤其对具有大量长桩基础的结构体系。基于Boulanger模型和OpenSees软件,分析了软粘土地基-单桩结构体系地震反应中桩身的位移、弯矩、剪力的分布特点以及桩顶上部结构的加速度响应,探讨了结构体系振型及振型周期随桩长的变化特点,进一步提出了等效计算桩长的桩-土-结构模型。研究表明,当结构体系前3阶的振型周期的变化率控制到2.5%时,对应的等效计算桩长分析模型能实现较高的动力响应计算精度,其动力响应误差已降低至5%以内;等效计算桩长可以通过动力响应误差控制精度要求确定,对于软粘土地基中的单桩基础结构,建议将前3阶振型周期的变化率控制到2.5%时的计算桩长作为等效计算桩长。

To a certain extent,the pile length is one of the key factors affecting the complexity of the dynamic analysis of the pile-soil-structure system.A proper simplification for the pile length can improve the calculation efficiency,especially for a structural system with a large number of long pile foundations.Based on Boulanger model and OpenSees,this study analyzed the earthquake response of the single pile-soil-structure system in the soft clay site,including the displacement,bending moment,shear force of the pile and the acceleration response of superstructure,and investigated the variation of vibration modes and mode periods with different pile length,and then proposed a pile-soil-structure model with equivalent calculated length pile.The results show that the model with equivalent calculated length pile has a high simulating accuracy,and the calculation error of the dynamic response of structure system is less than 5%when the change rate of the first three-mode periods of structure system is low than 2.5%;the equivalent calculated pile length can be determined by the accuracy requirement of the dynamic response error,and for the single pile structure in the soft clay site,it is suggested that the corresponding calculated pile length should be regarded as the equivalent calculated pile length when the change rate of the first three-mode periods is controlled to 2.5%.