【作者】 王玉石；

【导师】 周正华；

【作者基本信息】 中国地震局工程力学研究所 ， 防灾减灾工程及防护工程， 2010， 博士

【摘要】 地震动的强度,一般用烈度或地面峰值加速度、地面峰值速度等地震动参数表示。但是,地面运动是一种典型的非平稳信号,幅值和频率成分均随时间变化,瞬时的幅值最大值并不能完全代表其破坏能力。统计资料已表明,地面峰值加速度或地面峰值速度与烈度间的对应关系具有很大的离散性,很难仅仅根据一个地区强震记录的地面峰值加速度或地面峰值速度可靠地估计其遭受的烈度影响。在地震应急救援中,为快速可靠地估计烈度分布,需要探求与烈度间对应关系紧密的地震动参数,并利用相应的地震动参数衰减关系进行仪器烈度空间插值,以求提高速报烈度的可靠性。除了地面加速度时程,地面速度时程和地面位移时程也是重要的地震动强度表征,但是由于部分近场加速度记录存在基线漂移现象,致使速度时程和位移时程并不能由加速度时程直接积分获得。而采用滤波去除基线漂移将带来误差且无法得到地面同震永久位移,这与观测资料不符。本文收集了近年来我国西部获得的破坏性地震加速度记录及其对应的烈度资料,利用假设检验的方法,对比分析了多个强地震动参数与烈度间的相关性,统计结果表明谱烈度与震害烈度间对应关系最好。本文对谱烈度进行了修正,采用修正谱烈度所确定的台站仪器烈度,与震害烈度完全一致的比例接近70%,约99%的台站仪器烈度与震害烈度相差在1度以内,具有较高的可靠性。本文利用近年来多次破坏性地震及汶川地震强余震中获得的加速度记录,统计获得了我国川滇地区的谱烈度、修正谱烈度、地面峰值加速度和35个周期点的加速度反应谱衰减关系,而以往我国采用的地面峰值加速度和加速度反应谱衰减关系大多是由参考地区的地震动衰减关系利用转换方法得到。本文经推导获得了强震记录仪一阶误差项公式,发现强震加速度记录的一阶误差与其位移时程成比例,据此提出一种加速度记录基线校正方法,并利用校正后加速度记录经积分运算获得了数个台站的强震位移时程。因迭代过程存在发散问题,本方法尚需改善。本文基于单个余弦波移动卷积(SCW变换)与Hilbert变换,提出一种时频分析方法,并对数条结构强震记录进行了尝试性分析。总之,本文通过统计分析强震记录,获得了我国西部地区仪器烈度确定方法和川滇地区数个地震动参数的衰减特征,并尝试性地提出了一种加速度基线校正方法和一种强震记录时频特征分析方法。更多还原

【Abstract】 The strength of strong ground motion was generally scaled by intensity, or strong ground motion parameters like Peak Ground Acceleration(PGA) and Peak Ground Velocity(PGV). However, as a typical non-stationary signal whose amplitude and frequency components varied with time, the instantaneous peak amplitude of strong ground motion could not represent its destructive power perfectly. Statistical analyses had proved that whether PGA or PGV was linked closely to intensity, which indicated that reliable estimation of intensity distribution could not be available soon after PGA and PGV were determined.Meanwhile, rapid and reliable distribution of intensity was strongly needed by emergency rescue for destructive earthquakes. Parameters much more significantly related to intensity should be chosen, and the corresponding attenuation relationships should be determined in order to improve the reliability of the instrumental intensity distribution.Besides the acceleration history, the velocity history and the displacement history were another two important characteristics of strong ground motion. But because of baseline shifts, sometimes the velocity history and the displacement history of ground could not be achieved by simple integration of acceleration. Filtering in frequency domain could obviate baseline shifts, but could not achieve co-seismic permanent displacement for any record, which was inconsistent with the observation data.In this article, accelerograms and their corresponding intensity materials of recent destructive earthquakes in West China were collected. The relativity between various strong ground motion parameters and intensity was compared with a method based on hypothesis testing, which indicated that Spectral Intensity(SI0.2) was the parameter that most significantly related to intensity. As an improvement, SI0.2 was modified depending on the predominant period of spectral acceleration and the site condition of the station. The instrumental intensity determined by modified SI0.2 was identical with the actual intensity for 70 percents of the stations, and the difference between instrumental intensity and actual intensity for 99 percents of the stations was within 1 degree of intensity.By statistical analyses of acceleration records obtained in several destructive earthquakes and after shocks of Wenchuan MS8.0 earthquake, attenuation relationships for SI0.2, modified SI0.2, PGA and spectral acceleration in Sichuan-Yunnan region of China were determined. This might be the first time that reliable attenuation relationships for strong ground motion parameters were determined by statistics of accelerograms in China. In this article, the first order error term of acceleration recorder was found to be proportional with the ground displacement history. A baseline correction method was suggested based on this finding, with which ground velocity and ground displacement of several stations were obtained. But this method needed improvement because of the divergence in its iterative process.A time-frequency analysis method based on Single-Cosine Wave(SCW) convolution and Hilbert transform was proposed, with which several acceleration records of tall buildings were analyzed.In summary, an instrumental intensity determination method for West China and the strong ground motion attenuation characteristics for Sichuan-Yunnan region were obtained by statistical analyses, and an explorative attempt was made on the acceleration baseline correction method as well as on the time-frequency analysis method.更多还原