基于自由场局部变形的地下结构抗震Pushover分析方法

对地下结构抗震Pushover分析方法进行了改进,采用自由场局部变形峰值作为目标位移,局部变形峰值时刻对应的土层水平加速度作为等效惯性加速度输入。给出了局部变形峰值和等效惯性加速度确定方式,详细介绍了基于自由场局部变形的地下结构抗震Pushover分析方法实施步骤、使用方法和功能特点。该方法更有针对性地考虑了强地震作用下不同埋深地下结构与土体的非线性特征以及两者之间的相互作用,通过分析变形和受力情况可以得到完整的能力曲线,更好地评估地下结构抗震性能。使用本文方法对3种埋深的地下结构进行计算,并与动力非线性分析结果进行对比研究。结果表明:本方法在计算稳定性和模拟精度方面优于基于自由场整体变形的Pushover方法;对于不同的输入地震波,能力曲线的吻合程度更高;在强震和罕遇地震情况下,对于深埋地下结构,计算结果略大于动力非线性结果,对实际工程而言更加安全。

Seismic Analysis of Underground Structures Based on LocalDeformation of the Free Field via the Pushover Analysis Method

The seismic pushover analysis method of underground structures is improved by applying the local deformation peak of the free field is used as the target displacement and the corresponding horizontal acceleration of the soil layer is used as the equivalent inertial acceleration input. The local peak deformation and method of determining the equivalent inertial acceleration are given, and the implementation steps, application, and functional characteristics of the seismic pushover analysis method for underground structures based on local deformation of the free field are introduced in detail. Compared with the pushover method, the proposed method considers the nonlinear characteristics of different buried underground structures and interactions between the soil and the structure. A complete ability curve can be obtained by analyzing the deformation and stress conditions to better evaluate the seismic performance of the underground structure. For validation, the proposed method and finite element dynamic analysis are performed to analyze three practical subway station structures. Results show that the proposed method is superior to the pushover method based on integral deformation of the free field in terms of stability and simulation accuracy and more consistent with the different input seismic waves. In the case of strong earthquakes, the calculation results are slightly larger than the dynamic nonlinear analysis results for deep buried underground structures.