边坡地形的地震动放大效应预测模型研究

发布时间：2018-03-17 16:17

本文选题：场地效应　切入点：数值分析　出处：《西南交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：地震动由震源效应、路径效应和场地效应三者共同决定。大量现场观测、理论分析、数值模拟和物理试验的研究成果都证实场地效应对地震动有显著影响。其中,地形效应作为场地效应的重要方面,自然起着不可忽视的作用。但是,大量对边坡地形效应的研究是频域内的,这些研究成果无法直接应用于工程抗震设计。本文即是利用数值模拟和统计回归的方法,求出一系列反应谱谱放大的预测模型评估边坡的地震动地形效应。本文的预测模型能够得到坡顶面任意场地的设计反应谱,便于实际工程的抗震设计。具体步骤如下：(1)首先建立80个单面坡数值模型,分别具有不同的模型参数,相应地建立一系列一维自由场模型；(2)通过输入一条基岩地震记录,得到每个边坡模型和对应一维自由场模型上数个场地的地震反应；(3)通过对时域的地震记录进行傅里叶变换,求出各场地地震反应和输入地震动间的频域内传递函数；(4)利用上一步得到的传递函数,计算出每个边坡模型和对应一维自由场模型上各监测点在输入大量地震记录时的地震反应。这一方法很大地提高了计算效率；(5)通过对比边坡模型和对应一维自由场的反应谱,求出反映地震动地形效应的谱放大；(6)利用系统的统计分析和随机效应方法建立起相对简单的地形效应预测模型,模型中只包含四个边坡模型参数：坡高、坡度、场地自坡顶点的距离和坡体材料的剪切波速。利用残差分析法选择模型参数并验证参数在统计意义上是否显著。残差分解为模型内残差和模型间两个部分,模型内残差由不同基岩记录的不同频率成分造成,预测模型对放大效应描述的不精确产生了模型间残差。预测模型的两类残差在线性尺度上相对于模型参数是无偏的：用来拟合残差的直线是水平的。两类残差的标准差都很小,地震参数主要在短周期对模型有影响。两个数值验证实例的结果表明,侧面吸收边界产生的反射波会对谱放大计算的准确性造成影响。但是,这种影响的误差水平在地震动预测模型中是可以接受的。残差分析和误差分析表明：在选定的模型参数范围内,最终的预测模型可以在一阶描述边坡的地震动地形效应。
[Abstract]:Ground motion is determined by focal effect, path effect and site effect. A large number of research results of field observation, theoretical analysis, numerical simulation and physical test all prove that site effect has significant influence on ground motion. Terrain effect, as an important aspect of site effect, naturally plays an important role. However, a large number of researches on slope topographic effect are in the frequency domain. These results can not be directly applied to seismic design of engineering. In this paper, numerical simulation and statistical regression methods are used. A series of prediction models with amplified response spectrum are obtained to evaluate the topographic effect of the slope ground motion. The prediction model in this paper can obtain the design response spectrum of any site on the top of the slope. The concrete steps are as follows: 1) first, 80 single slope numerical models with different model parameters are established, and a series of one-dimensional free field models are established accordingly) by inputting a bedrock seismic record. The seismic response of several sites on each slope model and corresponding one-dimensional free field model is obtained by Fourier transform of seismic records in time domain. The transfer function in frequency domain between the seismic response of each site and the input ground motion is calculated. (4) using the transfer function obtained from the previous step, The seismic response of each monitoring point on each slope model and the corresponding one-dimensional free field model is calculated when a large number of seismic records are inputted. This method greatly improves the calculation efficiency by comparing the slope model with the corresponding one-dimensional free field response spectrum. Based on the statistical analysis of the system and the random effect method, a relatively simple terrain effect prediction model is established. The model contains only four slope model parameters: slope height, slope gradient, slope height, slope gradient, slope height, slope gradient, slope height, slope height, slope gradient, slope height, slope height, slope gradient, slope height, slope height, slope height, slope gradient, The distance of the site from the top of the slope and the shear wave velocity of the material of the slope body. The model parameters are selected by residual analysis and the statistical significance of the parameters is verified. The residual is decomposed into two parts: the residual and the inter-model. The residuals in the model are caused by different frequency components recorded in different bedrock. The two types of residuals of the prediction model are unbiased relative to the parameters of the model on a linear scale: the lines used to fit the residual errors are horizontal, and the standard deviations of the two types of residuals are very small. The seismic parameters mainly affect the model in short periods. The results of two numerical examples show that the reflection generated by the side absorbing boundary will affect the accuracy of spectral amplification calculation. The residual error analysis and error analysis show that the final prediction model can describe the topographic effect of ground motion in the first order within the selected parameters of the model.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU435

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