倾斜液化场地−桩基−结构体系在近场脉冲与非脉冲地震动下地震响应差异分析

Difference analysis of seismic responses of inclined liquefaction site-pile-structure system under near-field pulsed and non-pulsed ground motions

对比研究了倾斜液化场地−桩基−结构体系在近场脉冲和非脉冲地震动作用下的响应。首先基于OpenSees有限元平台建立了倾斜液化场地−桩基−结构体系的有限元模型,与大型振动台试验结果进行对比,验证了数值模型的可靠性。在此基础上,建立典型倾斜液化场地−桩基−结构体系的有限元模型,对比分析近场脉冲与非脉冲地震作用下体系的地震响应规律,并开展地震动强度指标与地震响应之间的相关性分析。结果表明:与非脉冲地震动相比,近场脉冲地震动作用下,场地残余位移明显增加,在松砂层顶部最为明显,约增大40%;桩身弯矩和桩身残余位移显著增加,尤其是桩顶位置处;非脉冲地震动下地震动强度指标与各响应之间的相关性高于脉冲地震动作用,选取3个相关性较好的强度参数:峰值速度/峰值加速度(PGV/PGA)、阿里亚斯强度AI、平均周期Tm,可在一定程度上表征地震动对液化场地−桩基−结构体系破坏反应的影响。

In this paper,the seismic responses of inclined liquefaction site-pile-structure system under near-field pulsed and non-pulsed ground motion were studied.Firstly,a finite element model of inclined liquefaction site-pile-structure system was established based on the finite element platform OpenSees,and the reliability of the numerical model was verified by comparing with the results of large-scale shaking table test.On this basis,the finite element model of typical inclined liquefaction site-pile-structure system was established,the seismic response laws of the system under near-field pulsed and non-pulsed ground motion were compared and analyzed,and the correlation analysis between ground motion intensity index and seismic response was carried out.The results show that compared with the non-pulsed ground motion,the residual displacement of the site increases obviously under the near-field pulsed ground motion,especially at the top of the loose sand layer,which increases by about 40%.Pile bending moment and pile residual displacement increase significantly,especially at the pile top.The correlation between the ground motion intensity index and the response under non-pulsed ground motion is higher than that under pulsed ground motion.Three strength parameters with good correlation,i.e.PGV/PGA(peak ground velocity/peak ground acceleration),AI(Arias intensity)and Tm(mean period),can indicate the influence of ground motion on the failure response of liquefaction site-pile-structure system to a certain extent.