青海地区S波非弹性衰减Q值、场地响应特征研究     

马建新  姚家骏  陈继锋 《地震地磁观测与研究》2015,(3):38-42

根据地质构造及地震台网分布特征,将青海地区分为柴达木盆地、青海东北部、青海东南部3个区域,运用青海地震台网记录的112条数字地震波形资料,利用Atkinson方法得到3个区域的非弹性衰减Q值随频率的关系,结果表明,柴达木盆地Q值最大,青海东南部Q值最小。采用Moya方法反演得到3个区域24个地震台的场地响应,其中15个台站的场地响应在频率域不平坦,9个台站稳定性相对较好,GOM(格尔木)作为国家基准地震台,具有良好的观测环境,场地响应曲线稳定。  相似文献   

安徽及近邻区地震烈度衰减特征研究   总被引：3，自引：2，他引：1  

丁娟  何琳  叶峰  马犇  张洁 《地震地磁观测与研究》2015,(3):43-48

利用安徽及近邻区地震烈度资料,采用椭圆衰减模型和长轴可转向与近、远场补点方法,通过多元回归方法进行拟合,建立该地区地震烈度衰减关系。该衰减关系用于安徽地震应急指挥技术系统震害快速评估模块,为地震灾害损失快速评估提供基础资料;也可用于安徽地区地震安全性评价、震害预测等防震减灾领域。  相似文献   

Scattering and intrinsic attenuation in Cairo metropolitan area using genetic algorithm     

《Soil Dynamics and Earthquake Engineering》2015

A total number of 46 local earthquakes (2.0≤ML≤4.0) recorded in the period 2000–2011 by the Egyptian seismographic network (ENSN) were used to estimate the total (Q_t⁻¹), intrinsic (Q_i⁻¹) and scattering attenuation (Q_sc⁻¹) in Cairo metropolitan area, Egypt. The multiple lapse time window analysis (MLTWA) under the assumption of multiple isotropic scattering with uniform distribution of scatters was firstly applied to estimate the pair of L_e⁻¹, the extinction length inverse, and B₀, the seismic albedo, in the frequency range 3–24 Hz. To take into account the effect of a depth-dependent earth model, the obtained values of B₀ and L_e⁻¹ were corrected for an earth structure characterized by a transparent upper mantle and a heterogeneous crust. The estimated values of Q_t⁻¹, Q_sc⁻¹ and Q_i⁻¹ exhibited frequency dependences. The average frequency-dependent relationships of attenuation characteristics estimated for the region are found to be: Q_t⁻¹=(0.015±0.008)f ^{(−1.02±0.02)}, Q_sc⁻¹=(0.006±0.001)f ^{(−1.01±0.02)}, and Q_i⁻¹=(0.009±0.008)f ^{(−1.03±0.02)}; showing a predominance of intrinsic absorption over scattering attenuation. This finding implies that the pore-fluid contents may have great effect on the attenuation mechanism in the upper crust where the River Nile is passing through the study area. The obtained results are comparable with those obtained in other tectonic regions.  相似文献   

Field experiment and numerical study on active vibration isolation by horizontal blocks in layered ground under vertical loading     

《Soil Dynamics and Earthquake Engineering》2015

In this paper, a series of field experiments were carried out to investigate the active vibration isolation for a surface foundation using horizontal wave impedance block (WIB) in a multilayered ground under vertical excitations. The velocity amplitude of ground vibration was measured and the root-mean-square (RMS) velocity is used to evaluate the vibration mitigation effect of the WIB. The influences of the size, the embedded depth and the shear modulus of the WIB on the vibration mitigation were also systematically examined under different loading conditions. The experimental results convincingly indicate that WIB is effective to reduce the ground vibration, especially at high excitation frequencies. The vibration mitigation effect of the WIB would be improved when its size and shear modulus increase or the embedded depth decreases. The results also showed that the WIB may amplify rather than reduce the ground vibration when its shear modulus is smaller or the embedded depth is larger than a threshold value. Meanwhile, an improved 3D semi-analytical boundary element method (BEM) combined with a thin layer method (TLM) was proposed to account for the rectangular shape of the used WIB and the laminated characteristics of the actual ground condition in analyzing the vibration mitigation of machine foundations. Comparisons between the field experiments and the numerical analyses were also made to validate the proposed BEM.  相似文献   

Vibration control of piled-structures through structure-soil-structure-interaction     

《Soil Dynamics and Earthquake Engineering》2015

This paper deals with the vibration control of existing structures forced by earthquake induced ground motion. To this aim it is proposed for the first time to exploit the structure–soil–structure mechanism to develop a device, hosted in the soil but detached from the structure, able to absorb part of the seismic energy so to reduce the vibration of neighbourhood structures. The design of the device is herein addressed to protect monopile structures from earthquake induced ground motion. By modelling the ground motion as zero-mean quasi-stationary response-spectrum-compatible Gaussian stochastic process, the soil as visco-elastic medium and the target monopiled-structure as a linear behaving structure the device, herein called Vibrating Barrier (ViBa), has been designed through an optimization procedure. Various numerical and experimental results are produced to show the effectiveness of the ViBa. Remarkably, a significant reduction of the structural response up to 44% has been achieved.  相似文献   

黏弹性介质中瑞利波频散曲线和衰减系数曲线的反演          下载免费PDF全文

常冬梅  刘雪峰 《地震工程学报》2015,37(3):739-742

瑞利波具有能量大、信噪比高等特点,可以用来反演介质内部的力学信息,近年来在浅层地球物理勘探、深层地震学研究以及超声波无损检测等多个领域都有较广泛的应用。目前大多数瑞利波的应用中都假设介质是弹性的,然而实际中岩石、土壤和金属等介质都在一定程度上体现出了黏弹性。当介质的黏弹性较强时仍然采用弹性假设研究其中瑞利波的反演将增大误差,因此有必要考虑黏弹性介质中的瑞利波反演,但是目前这方面的研究仍不够深入。本文研究黏弹性介质中瑞利波频散曲线和衰减系数曲线的反演问题,给出其在半空间中联合反演的方法,并对该方法的误差进行分析。  相似文献   

某石化污染场地含水层自然降解BTEX能力评估   总被引：1，自引：0，他引：1  

蔡婧怡  陈宗宇  蔡五田  高宗军  张敏 《现代地质》2015,29(2):383-389

地下水污染问题是国家关注的重要环境问题之一,监测与评估含水层自然降解污染物能力是防治地下水污染的基本手段,也是国外地下水中修复技术研究热点课题。以华北平原某石油化工类场地为案例,通过调查场地水文地质条件、土壤及地下水污染现状,监测场地地下水中苯系物(BTEX)浓度及相关化学参数变化,运用微生物水文地球化学方法和水文地质方法,估算了该场地含水层自然降解苯系物量。这一研究成果为评估我国石油类场地地下水污染的自然修复能力提供了实证和基础数据。  相似文献   

基于F-K和Radon变换的多次波衰减方法          下载免费PDF全文

张亚伟  严加永  刘振东  张永谦  徐峣 《中国地质调查》2015,2(3):22-27

多次波干扰是地震勘探中最重要的问题之一,其衰减技术也是地震数据处理的难题之一。本文主要介绍了多次波的形成、分类及其特征,并在ProMax系统上对合成地震记录的多次波进行了压制:首先采用合适的速度对时-空域的地震记录进行NMO校正;然后,分别用F-K变换和Radon变换方法将其变换到F-K域和Radon域,对多次波所占据的主要区域进行充零衰减;最后,通过对应的反变换将其变换到时-空域,从而达到多次波衰减的目的。通过在ProMax系统中的应用表明:不同方法对多次波的衰减效果各有优劣,组合滤波方法能达到更好的效果。  相似文献   

基于密度的线数据分组算法研究     

魏海涛  杜云艳  许开辉  吴笛  易嘉伟  莫洋  刘张 《地球信息科学学报》2015,17(5):538-546

目前,地理空间数据面临着由于数据量膨胀和计算量高速增长而引起算法效率低的问题,采用"分而治之"的数据分组策略提高运算效率已成为研究的热点。面向分布不均匀的线数据,本文提出了基于密度的线数据分组算法(简称LGAD)。首先,算法通过查找高密度区提取样本线段,保证了分组算法的起点落到高密区;其次,考虑线空间拓扑关系的复杂性,引用水平、垂直和夹角距离度量线段间距离,创建样本线段与其他线段的距离矩阵;最后,以距离矩阵和最优选择方法实现数据负载均衡分组。实验结果显示,对数据分组和分组后数据进行线段聚类的2个过程中,该算法体现了较好的时间优势,与串行计算相比,在分组数为2-12 时,平均比率达4.3,提高了应用的响应速度,具有较好的实际意义。  相似文献   

四种海水透明度现场测量方法的对比分析及发展趋势研究          下载免费PDF全文

任尚书  周树道 《海洋开发与管理》2017,34(3):99-104

随着海洋探测的不断发展,海水透明度作为海水光学性质的一个重要参量,也越来越受到人们的关注。文章对比分析了4种海水透明度现场测量方法:透明度盘法~([1])、光纤式高光谱剖面测量法~([2])、激光衰减测量法~([3])和基于双光路原理的海水IOPs高光谱测量法~([4]),主要分析了4种方法的测量原理,对比各自的优缺点,并提出了海水透明度测量未来发展设想。  相似文献