【摘要】：場(chǎng)地效應(yīng)直接影響地震災(zāi)害的嚴(yán)重程度,一直以來(lái)都是地震工程領(lǐng)域的研究熱點(diǎn)。場(chǎng)地非線性反應(yīng)作為場(chǎng)地效應(yīng)之一,也備受國(guó)內(nèi)外學(xué)者的關(guān)注。大量研究結(jié)果表明,土體在強(qiáng)地震動(dòng)作用下的應(yīng)變幅值增加,剪切模量隨之降低而阻尼比增強(qiáng),引起場(chǎng)地卓越頻率向低頻段移動(dòng),場(chǎng)地放大在長(zhǎng)周期段顯著提升。因此,研究場(chǎng)地發(fā)生非線性反應(yīng)現(xiàn)象對(duì)于工程結(jié)構(gòu)選址、抗震理論的完善,尤其是規(guī)范設(shè)計(jì)反應(yīng)譜的標(biāo)定是必須考慮的關(guān)鍵問題。同時(shí)研究場(chǎng)地非線性反應(yīng)的特征以及產(chǎn)生非線性的地震動(dòng)閾值至關(guān)重要。我國(guó)數(shù)字強(qiáng)震動(dòng)觀測(cè)臺(tái)網(wǎng)在2007年至2013年期間捕獲了大量高質(zhì)量的主余震加速度記錄,為研究場(chǎng)地非線性提供了良好的契機(jī)。本文以上述理論和數(shù)據(jù)資料為基礎(chǔ),對(duì)我國(guó)強(qiáng)震動(dòng)臺(tái)站場(chǎng)地非線性反應(yīng)展開研究,完成的主要工作與取得的結(jié)論如下:1、按照一定原則篩選出50個(gè)臺(tái)站的強(qiáng)震動(dòng)觀測(cè)記錄,并對(duì)所有選取記錄進(jìn)行數(shù)據(jù)處理,基于傅里葉振幅H/V譜比法,將記錄按照PGA值分檔類計(jì)算傅氏譜比平均值曲線并識(shí)別卓越頻率。結(jié)果表明,通過對(duì)比各檔類HVSR曲線對(duì)應(yīng)的卓越頻率可以初步判斷出臺(tái)站場(chǎng)地是否發(fā)生非線性反應(yīng),譜比法對(duì)于非線性識(shí)別具有良好的適用性和可靠性。2、研究50個(gè)臺(tái)站場(chǎng)地非線性反應(yīng)四種參數(shù)(Rfp、DNL、ADNL、PNL)與地面加速度峰值(PGA)的對(duì)應(yīng)關(guān)系及其相關(guān)性,并選用相應(yīng)的值判斷發(fā)生場(chǎng)地非線性反應(yīng)的臺(tái)站,確定發(fā)生場(chǎng)地非線性反應(yīng)的參數(shù)閾值。結(jié)果顯示,對(duì)于大部分臺(tái)站四個(gè)參數(shù)規(guī)律均體現(xiàn)了強(qiáng)震動(dòng)作用下場(chǎng)地非線性反應(yīng)的顯著特征,并識(shí)別出24個(gè)臺(tái)站發(fā)生了場(chǎng)地非線性反應(yīng)。本文建議發(fā)生場(chǎng)地非線性反應(yīng)的PGA閾值為100gal,ADNL閾值為0.2,PNL閾值為0.2,Rfp的閾值為0.75。3、利用臺(tái)站捕獲的不同時(shí)間段地震記錄和2007年、2009年臺(tái)站地脈動(dòng)數(shù)據(jù),結(jié)合臺(tái)站場(chǎng)地條件等因素,分析記錄不同時(shí)間段非線性反應(yīng)參數(shù)變化規(guī)律,以及識(shí)別到的弱震記錄卓越頻率變化趨勢(shì),結(jié)果表明,中硬場(chǎng)地土或者弱震作用下的臺(tái)站場(chǎng)地對(duì)應(yīng)了線性地震響應(yīng)或發(fā)生了短暫的非線性反應(yīng)行為,卓越頻率在短周期內(nèi)即可恢復(fù)。中軟場(chǎng)地土或者強(qiáng)震動(dòng)作用下的臺(tái)站場(chǎng)地則對(duì)應(yīng)非線性地震響應(yīng),卓越頻率通常以1年為恢復(fù)周期。
[Abstract]:Site effect, which directly affects the severity of earthquake disaster, has always been a hot topic in the field of seismic engineering. As one of the site effects, the site nonlinear response has also attracted the attention of scholars at home and abroad. A large number of results show that the shear modulus decreases and the damping ratio increases with the increase of the strain amplitude of the soil under strong ground motion, which causes the excellent frequency of the site to move to the low frequency band and the amplification of the site to increase significantly in the long period. Therefore, the study of nonlinear site response is a key problem to be considered for site selection, seismic theory improvement, especially the calibration of the response spectrum of the code design. At the same time, it is very important to study the characteristics of site nonlinear response and to produce nonlinear threshold of ground motion. The digital strong motion observation network in China captured a large number of high quality aftershock acceleration records from 2007 to 2013, which provides a good opportunity for the study of site nonlinearity. Based on the above theory and data, the nonlinear response of strong motion stations in China is studied in this paper. The main work and conclusions are as follows: 1. According to certain principles, 50 observational records of strong motion are selected. Based on the Fourier amplitude H / V spectral ratio method, the average value curve of the Fourier spectrum ratio is calculated according to the class of PGA value and the excellent frequency is recognized. The results show that the nonlinear response of the station site can be preliminarily determined by comparing the superior frequency corresponding to the HVSR curves of each class. The spectral ratio method has good applicability and reliability for nonlinear identification. The relationship between the four parameters (Rfp,DNL,ADNL,PNL) of nonlinear response of 50 stations and the peak (PGA) of ground acceleration and its correlation are studied. At the same time, the corresponding values are selected to judge the station where the site nonlinear reaction occurs, and the parameter threshold of the site nonlinear reaction is determined. The results show that for most of the stations, the four parameter laws reflect the obvious characteristics of the site nonlinear response under strong vibration, and 24 stations have been identified to have the site nonlinear response. In this paper, we suggest that the threshold value of PGA for site nonlinear response is 0.2g / a, and the threshold is 0.75.3.Using the seismic records of different time periods captured by the station and the seismic pulsation data of the stations in 2007 and 2009, combining with the station site conditions and so on, The variation of nonlinear response parameters in different time periods is analyzed, and the dominant frequency variation trend of weak seismic records is identified. The results show that, The intermediate hard soil or the station site under the action of weak earthquake corresponds to the linear seismic response or the transient nonlinear response behavior, and the excellent frequency can be recovered in a short period. The seismic response of the medium soft soil or the station site under strong vibration is corresponding to nonlinear seismic response, and the excellent frequency usually takes one year as the recovery period.
【學(xué)位授予單位】：中國(guó)地震局工程力學(xué)研究所
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：P315.9

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本文編號(hào)：2226699