场地特征对强地震动特征参数的影响

发布时间：2018-03-12 17:12

本文选题：地震预警　切入点：局部场地　出处：《北京交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：地震预警是指在地震发生以后,利用电磁波的传播速度大于地震波的速度、P波传播速度大于S波的特点,提前向破坏性S波尚未到达的地区发出预警,使得不同地区的人们有着数秒甚至数十秒的预警时间,采用有效的防灾措施,尽可能地减少人员伤亡和财产损失。本文首先介绍了地震预警系统的发展和研究现状,主要针对地震预警基础理论中研究的不足,提出了场地特征的影响作用。本文主要开展了以下几点工作： (1)本文主要参照地震动参数研究的方法,利用ANSYS软件模拟地震波传播的土层,建立考虑局部场地条件和传播路径的场地反应分析模型,采用地震响应的分析方法,即特征周期的计算方法(瞬时特征周期τp max法和特征周期τc法)来计算地表的地震动参数,并与过滤前的地震动特征参数进行对比,得到传播路径、局部场地条件的影响情况。结果表明,τp max法和τc法都能得到较好的拟合精度,但是τc法优于τp max法。基于P波初至前3s时间窗的位移幅值Pd参数研究,可以看出其与全过程的峰值加速度PGA、全过程的峰值速度PGV都存在着良好的拟合关系,达到一定的拟合精度。 (2)本文建立45种单层匀质弹性土层模型,进一步研究土层类型对地震动幅值、地震动特征参数不同的放大作用。同时也表明,土层类型变化时,特征参数与全过程的峰值加速度都存在良好的线性关系。本文还对比研究了土层厚度,多层土层模型的影响情况。 (3)本文对比了30。、60。斜入射以及垂直入射多层场地情况,结果表明特征参数与反应地震强度的全过程峰值加速度之间有着较好的线性关系。 (4)本文以Coalinga波、El centro波和Mammoth Lakes波的斜入射为例,对比入射角从0°到90°变化过程中,地震波各特征参数的变化情况。峰值加速度PGA,峰值位移P dmax和瞬时卓越周期τp max值都随着入射角度的增大逐渐上升,在入射角度为80°时处于最高点,后下降至90°时处于最低点；而大体上特征周期τc值却逐渐减少至80°时取得最小值,后上升至90°时取得最大值。
[Abstract]:Earthquake warning means that after an earthquake occurs, the propagation speed of electromagnetic wave is faster than that of seismic wave and P wave propagates faster than S wave, and early warning is issued to areas where the destructive S wave has not yet arrived. So that people in different areas have several seconds or even tens of seconds of early warning time, using effective disaster prevention measures, as far as possible to reduce casualties and property losses. First, this paper introduces the development and research status of earthquake early warning system. Aiming at the deficiency of the basic theory of earthquake warning, the influence of site characteristics is put forward. The main work of this paper is as follows:. This paper mainly refers to the research method of seismic parameters, uses ANSYS software to simulate the soil layer of seismic wave propagation, establishes the site response analysis model considering the local site condition and propagation path, and adopts the seismic response analysis method. The calculation method of characteristic period (instantaneous characteristic period 蟿 p max method and characteristic period 蟿 c method) is used to calculate the ground motion parameters, and compared with the characteristic parameters of ground motion before filtering, the propagation path is obtained. The results show that both 蟿 p max method and 蟿 c method have better fitting accuracy, but 蟿 c method is better than 蟿 p max method. It can be seen that it has a good fitting relationship with the peak acceleration of the whole process and the peak velocity PGV of the whole process, and achieves a certain fitting accuracy. In this paper, 45 kinds of homogeneous elastic soil layer models are established to further study the magnification effect of soil types on the amplitude of ground motion and the characteristic parameters of ground motion. At the same time, it is also shown that when the soil type changes, There is a good linear relationship between the characteristic parameters and the peak acceleration of the whole process. The results show that there is a good linear relationship between the characteristic parameters and the peak acceleration of the whole process of response seismic intensity. In this paper, the oblique incidence of Coalinga El centro and Mammoth Lakes is taken as an example to compare the incident angle from 0 掳to 90 掳. The peak acceleration, peak displacement P dmax and instantaneous excellent period 蟿 p max all increase with the increase of incident angle, and are at the highest point at the incidence angle of 80 掳and the lowest point at 90 掳. On the whole, the characteristic period 蟿 c value decreases gradually to 80 掳to obtain the minimum value, and then rises to 90 掳to obtain the maximum value.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.9;TU435

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