摘 要

随着地下空间结构的迅速发展，以及近些年来这类结构在地震中震害的发生，在长大型地下结构不断涌现的大背景下，地下结构的抗震性能和震害机理正受到越来越多学者的关注。由于土体的变形是地下结构震害的主要原因，特别是长大型地下结构不可避免的会穿越复杂地层以及长距离地下结构在地震时的非一致效应明显，因此本文以自由场土体作为研究对象，建立数值模型，主要探讨非一致地震作用中的行波效应下土体的响应规律，并与一致激励下自由场土体地震响应结果进行对比。

首先建立自由场土体模型，并进行模态分析，得到场地的自振特性。然后采用等价线性化模型—Davidenkov模型，分别将两种地震波（EL-Centro波、Kobe波）按不同加速度幅值，不同输入方式（一致和非一致）进行输入和计算，并根据计算结果对比分析各工况的加速度时程及频谱，峰值加速度，相对位移响应，得到了不同种类、不同加速度幅值的地震波作用下一致和非一致激励时的土体响应规律。结果表明：

1. 在一致输入下，地震波的加速度幅值和类型对土体响应的影响与非一致输入下其对土体响应的影响规律基本一致；
2. 在相同条件下，非一致激励下的土体响应小于一致激励下的土体响应；
3. 非一致激励不仅会导致土体的加速度响应出现明显的时滞效应，还会显著改变不同时刻的加速度响应的幅值；
4. 深度方向各点相对于底面点的最大位移随高度的增加呈非线性增大的趋势，但其增量在逐渐减小，当地震波的加速度幅值增大时，各测点最大相对位移的放大呈现出非线性特征。

论文的研究方法和结果对进行非一致激励下的土体及结构的地震响应研究有一定的意义

关键词：行波效应；自由场土体；非一致激励；地震响应；

Abstract

With the rapid development of the underground space structure and the occurrence of earthquake damage in this type of structure in recent years, the anti-seismic properties and the mechanism of earthquake damage of the underground structure are attracting more and more attention of scholars under the background of the continuous emergence of long and large underground structures. Because the deformation of soil is the main reason for the earthquake damage of underground structures, especially the long and large underground structure that will inevitably cross the complex strata and the obvious inconsistency of long-distance underground structures during the earthquake. As a result, the free-field soil is taken as the research object in this paper, a numerical model is established to investigate the response law of soil under the effect of traveling wave in non-uniform seismic action, and compared with the results of seismic response of free-field soil under uniform excitation.

Firstly, a free-field soil model is established and modal analysis is performed to obtain the site's self-vibration characteristics. Then using the equivalent linearized model—Davidenkov model, the two types of seismic waves (EL-Centro waves and Kobe waves) are input and calculated according to different acceleration amplitudes and input methods（uniform and non-uniform）, and the response including time history of acceleration, frequency spectrum, peak acceleration and relative displacement of each working condition is compared and analyzed according to the calculation results. The response law of soil under seismic waves with different types and different acceleration amplitude by uniformly and non-uniformly excitated is obtained. The results show that:

1. Under the uniform input, the influence of acceleration amplitude and type of seismic wave on soil response is basically the same as the effect on soil response under non-uniform input；
2. Under the same conditions, the soil response under non-uniform excitation is less than that under uniform excitation；
3. Non-uniform excitation will not only lead to a significant time-lag effect on the acceleration response of the soil, but also significantly change the amplitude of the acceleration response at different times；
4. The maximum displacement of each point in the depth direction with respect to the bottom point increases non-linearly with increasing height, but the increment of each measuring point gradually decreases. When the acceleration amplitude of the seismic wave increases, the maximum relative displacement of each measuring point is amplified non-linearly.

The research methods and results of the dissertation have a certain significance for the study of seismic responses of soils and structures under non-uniform excitation.

Keywords: traveling wave effect; free-field soil; non-uniform excitation; seismic response;

目 录

第1章 绪论.........................................................................................................................1

1.1 引言.......................................................................................................................1

1.2 国内外研究现状...................................................................................................1

1.3 研究内容...............................................................................................................3

第2章 自由场土体计算模型............................................................................................5

2.1 计算范围及边界条件...........................................................................................5

2.2 本构模型及计算参数...........................................................................................6

2.3 地震波输入...........................................................................................................7

2.4 工况设置及测点布置...........................................................................................8

2.5 小结.....................................................................................................................10

第3章 数值计算结果分析...............................................................................................11

3.1 模态分析……………………………………………………………………….11

3.2 一致激励下地震响应分析.................................................................................12

3.2.1 地表加速度响应分析..............................................................................12

3.2.2 场地放大效应分析..................................................................................14

3.2.3 沿土层深度方向峰值加速度分析..........................................................15

3.2.4 沿土层深度方向最大相对位移分析......................................................16