多分辨率地震信号反褶积

基于二进小波变换提出了一种新的反褶积方法─-多分辨率地震信号反褶积．在地震信号二进小波变换域中的各尺度上分别进行其分辨率随小波尺度变化的反褶积,利用不同分辨率反褶积结果之间的相关性,以及测量噪声随尺度的衰减特性,从低分辨率反褶积结果逼近高分辨率反褶积结果．理论分析和实验表明,该方法有较高的精度,并且在较低信噪比情况下有好的效果．     

A model for the seismic analysis of a periodic viaduct when considering the pile–soil–structure interaction

In this study, a new model is developed for the aseismic design of a periodic viaduct when the pile–soil–structure interaction is considered. To account for the influence of the pile–soil–structure interaction, a wavenumber domain boundary element method (WDBEM) model for the periodic pile row supporting the viaduct is developed using the sequence Fourier transform as well as the boundary element method for the elastic medium. By using the WDBEM model for the pile row, the transfer matrices for the beams and piers, the joint conditions at the beam–beam–pier (BBP) junction as well as the periodicity condition for the viaduct, the wavenumber domain response of the periodic viaduct to spatially harmonic waves is determined. Based on the wavenumber domain response of the viaduct, the space-domain response of the viaduct to an arbitrary seismic wave can be obtained by invoking the inverse sequence Fourier transform method. Numerical results show that when the periodic viaduct is exposed to the spatially harmonic wave, resonances may occur at the bounding frequencies of the passbands of the characteristic waves of the viaduct. Also, it is found that the coincidence between the traveling seismic wave and characteristic waves of the viaduct will generate additional resonant frequencies located in passbands of the characteristic waves.     

均匀黏弹性地基中现浇X形桩低应变动测响应数值模拟

建立现浇X形桩(XCC桩)桩-土体系三维有限元模型,对XCC桩低应变检测动力响应进行数值模拟,得到完整桩和缺陷桩的桩顶速度响应结果,并分析完整桩及缺陷XCC桩桩顶速度响应特性及规律。计算结果表明:XCC桩低应变瞬态动测时桩顶速度响应存在明显的三维效应,桩心(激振点)附近点的入射波峰值较大,且到达时间较早;距离桩心越远点的入射波峰到达时间越滞后,入射波峰值从桩心到尖角边界先减小后增大。桩顶距桩心距离相同的环向上各点的入射波和反射波区别不大,而各点所受的高频干扰情况并不相同。变模量桩的入射波和完整桩相同,反射波峰值较完整桩小,反射波峰对应时间较完整桩滞后。局部缺陷桩桩顶距桩心距离相同环向各点的第一个缺陷反射波有微小差别,而第二个缺陷反射波有较大差别。     

奇异值分解(SVD)实现地震波场分离与去噪新思路

依据不同性质的地震信号（反射波、折射波、直达波、面波、VSP上\下行波、多次波、随机干扰等）之间在运动学、视速度和相干性上的差异,借助某种数学变换、SVD分解与重构联合、时域与频域结合的方式,通过这些间接的处理手段,把要提取的目标信号或要剔除的干扰信号转换到一种相干性更好的空间域中,再进行SVD分解与重构,最充分利用SVD滤波技术特点,实现地震波场分离与去噪,而不是直接对信号进行SVD分解与重构来实现地震波场分离与去噪,这样做可有效地避免以往对SVD波场分离与去噪技术应用空间狭窄、有效信号损失严重等缺陷性.     

Dynamic response of an offshore pile to pseudo-Stoneley waves along the interface between a poroelastic seabed and seawater

A coupled model is developed to investigate the dynamic interaction between an offshore pile, a porous seabed and seawater when subjected to the pseudo-Stoneley wave along the seabed and the seawater interface. The pile and the seabed are treated as the porous medium governed by Biot's theory, while the seawater is considered as an acoustic medium and is described by the conventional Helmholtz equation. The free field solution of the incident pseudo-Stoneley wave is obtained using Biot's theory and the potential method. Based on the boundary element method (BEM) for the porous medium and the acoustic medium, three BEM formulations are constructed for the pile, the seabed and the seawater, respectively, which are combined together using the continuity conditions between the pile, the seabed and the seawater to formulate the coupled model for the system. As shown in numerical examples, when the system is subjected to the pseudo-Stoneley wave, the maximum pore pressure of the seabed usually occurs at the region near the interfaces between the seabed and the seawater.     

Capacity evaluation of statnamic tested long piles

A procedure that uses the structural damping (SD) concept for estimating the capacity of a pile based on the Statnamic (STN) pile load test results, formerly used by the authors for short piles, is extended in this paper for the STN tested long piles. Similar to segmental unloading point method procedures for long piles, the shaft length is divided into several segments and each segment is assumed to behave as a mass of a single degree of freedom. The SD concept is then applied to each segment to consider the displacement related soil damping instead of the velocity dependent damping. Instrumented strain gauge data at different levels of the shaft are required for the interpretation method. Three case studies are presented in this paper to study the validity and applicability of the present method. The predicted results are also compared to the available test or analytical data.     

利用相关域小波变换进行SWD资料预处理

随钻地震(SWD)的波场十分复杂,对钻头有效信号和地表机械干扰成分的分析是SWD重要的资料预处理步骤.本文利用有效信号和噪声带有周期性或时延差异等时间结构特征,引入相关域小波变换进行SWD信号检测和分析.有效信号在钻柱内往复多次传播,因而带有严格的周期性,泥浆泵等机械发出的噪声也是周期性的,这些成分在自相关域内可以得到很好的凸显.SWD波场的各种成分,由于到达各个接收道的时延不同,在互相关域的特定时延处也能够得到凸显.利用小波变换对这些在相关域内得到凸显的成分进行多分辨分析,能够获得优势频率范围、周期、衰减等主要特征.根据这些信息,设计出合理的SWD处理方法,初步得到了有效信号的直达波.数据试处理结果表明,相关域小波变换是随钻地震的一个有效的预处理方法.     

Analyses on normal background characteristics about deformation observation data on the basis of wavelet transform method

Introduction Fourier transform that summed up a series discomposed sin functions of signal has been one of the widely used methods in the field of signal process all along. While for time information be-ing thrown away by this transform, it is difficult for us to judge when a special signal occurs on the way. Though short time Fourier transform (STFT) was developed later, which can probe local features of signals, it can not reveal what is really there because uniform window functions de-fin…     

声子波及其在地震波资料分解中的应用

声子波是由声波波动方程的解构成的一种物理子波,如果不考虑吸收和散射,声子波的传播是相当简单的;相反地,数学子波的传播即使在均匀介质中也是极其复杂的.作为波动方程的解,声子波比一般的数学子波更能有效地应用于复杂声波和地震波的分解和分析.本文从Kaiser的声子波理论出发,给出了通过分别引入点源波形的复时间函数和点源虚时间坐标来构成声子波的两种解释,并对点源模型的合成地震图和实际复杂模型的地震波资料进行了时-空域的声子波变换,说明了声子波应用于地震波资料分解的有效性.     

Method for Identifying Micro-seismic <Emphasis Type="Italic">P</Emphasis>-Arrival by Time-frequency Analysis Using Intrinsic Time-Scale Decomposition

A method to identify the P-arrival of microseismic signals is proposed in this work, based on the algorithm of intrinsic timescale decomposition (ITD). Using the results of ITD decomposition of observed data, information of instantaneous amplitude and frequency can be determined. The improved ratio function of short-time average over long-time average and the information of instantaneous frequency are applied to the time-frequency-energy denoised signal for picking the P-arrival of the microseismic signal. We compared the proposed method with the wavelet transform method based on the denoised signal resulting from the best basis wavelet packet transform and the single-scale reconstruction of the wavelet transform. The comparison results showed that the new method is more effective and reliable for identifying P-arrivals of microseismic signals.     

自适应Kalman滤波反褶积的快速实现方法

提出了以二进小波变换为基础的自适应Kalman滤波反褶积(AKFD)新方法，针对该方法的计算复杂程度，提出了一种快速实现方法.二进小波变换的AKFD抛弃了传统预测反褶积对信号平稳性的假设，克服了提高分辨率而信噪比明显降低的问题，具有很好的抗噪性能.在小波域进行的AKFD在压制假反射以及提高分辨率方面比时间域的AKFD好，克服了在时域内进行AKFD抬升低频成分的缺陷.利用二维地震数据的局部平稳性的假设提出了快速实现方法，通过分段求取自适应预测算子，分别于横向及纵向采用样条插值的方法进行插值，来减少求取自适应预测算子的计算量，达到快速实现的目的.经过大量实验表明计算速度提高数百倍，仍能保持原来的计算效果.     

利用小波变换方法分析形变观测资料的正常背景变化特征

为定量刻画数字化形变观测资料中背景信息和噪声的时 频分布特征, 本文应用二进小波变换方法, 通过对小波分解的主模特征和随机白噪声识别因子变化特征分析, 剖析了山东数字化形变观测资料的正常动态背景和噪声变化规律. 结果表明, 当尺度取2, 3和4时, 分解后的细节部分存在着1/4日波、 半日波、 日波和半月波等准循环周期信号, 其中尤以尺度为3时的信号波幅最大; 尺度取1和5时的细节部分主要包含着噪声; 通过分析和追踪指定尺度的数字化形变观测资料小波变换的非震异常特征变化, 可望捕捉到与强地震孕育过程有关的前兆异常信息.      

Surface wave attenuation based polarization attributes in time-frequency domain for multicomponent seismic data

In the paper, we propose a surface wave suppression method in time-frequency domain based on the wavelet transform, considering the characteristic difference of polarization attributes, amplitude energy and apparent velocity between the effective signals and strong surface waves. First, we use the proposed method to obtain time–frequency spectra of seismic signals by using the wavelet transform and calculate the instantaneous polarizability at each point based on instantaneous polarization analysis. Then, we separate the surface wave area from the signal area based on the surface-wave apparent velocity and the average energy of the signal. Finally, we combine the polarizability, energy, and frequency characteristic to identify and suppress the signal noise. Model and field data are used to test the proposed filtering method.     

MCZT在气枪震源信号频谱分析中的应用

气枪震源信号是短时非平稳信号,采用频谱细化算法能提高频谱分析的准确性。首先进行了改进线性调频Z变换(MCZT)和FFT两种频谱分析算法的误差仿真计算,然后进行气枪震源的水下子波信号和地震波信号的对比计算。结果表明MCZT计算误差较小、计算时间较少,能有效提高气枪震源信号频率和幅度特征提取的准确性,是气枪震源信号频谱特征分析的一个有效方法。     

基于小波分频叠前相干噪声压制方法

基于小波分析的去噪方法在地震资料叠前处理中得到了广泛应用.本文主要介绍利用小波变换的分频特性来压制相干噪声.通过小波分频技术将叠前地震信号分解为不同频带,然后利用有效波和相干干扰波的频谱差异来区分有效信号和噪声,最后利用加权方法去掉不需要的噪声信息来达到去除相干噪声的目的.实际资料的处理结果表明：基于小波分频方法能很好地压制相干噪声,从而提高地震资料信噪比和分辨率.     

桩身材料阻尼对波传播特性影响的小波分析方法

理论计算及实测资料表明,反射波法基桩动测激振信号近似为半周期正弦波,不同激振方式产生的桩顶速度脉冲信号宽度不同,相应频率成分也就不同。桩身内阻尼对不同频率谐波的幅值衰减及频散规律不同,使得不同激振方式产生的复合脉冲在同一桩中会有不同变化规律,为了使不同激振方式测试资料具有可比性,应采用相同频带进行对比。为此利用小波分析的时-频特性,通过对测试信号进行时频分解,就桩身内阻尼对不同频带信号的吸收系数及波速的影响规律进行了研究。对实测资料分析的结果表明,预制桩不同频带信号波速变化不大,但衰减系数随频率增大近似线性增加。     

GNMF小波谱分离在地震勘探噪声压制中的应用

地震勘探资料噪声压制及信噪比提高是整个地震勘探信号处理过程中的重要任务,随着地震勘探深度的增加及其复杂性,人们对地震数据质量的要求越来越高.勘探环境的复杂化使得采集到的地震资料中有效信号被大量噪声淹没,无法清晰辨识,严重影响后续的数据处理与解释.小波去噪是地震勘探中常用且发展较成熟的一种方法,但是其涉及到的阈值函数选取问题一直令人困扰,虽然已有多种阈值函数被提出,但仍存在各自的缺陷.本文利用小波分解在时域及频域良好的信号细节体现特性,引入模式识别中的非负矩阵分解(NMF)谱分离思想,针对小波系数阈值优化问题,提出了一种小波域图非负矩阵分解(GNMF)消噪算法.该方法首先在小波分解基础上,利用GNMF算法实现小波分解系数谱中信号分量与噪声分量的谱分离,然后通过反变换重构各分离子谱对应的子信号,最后利用K均值聚类算法将得到的多个子信号划分为信号类及噪声类,最终得到重构信号及分离噪声.合成记录和实际地震资料的消噪结果验证了新方法在提高信号与噪声分离准确性和精度方面的有效性,同时新方法避免了阈值选取造成的噪声压制不理想或有效成分损失问题.与小波消噪结果的对比及数值分析也说明了新方法在噪声压制及有效成分保持方面的优势.     

Gauss linear frequency modulation wavelet transforms and its application to seismic phases identification

Introduction The accurate gradual change style seismic phases identification is an older new question for discussion. Wavelet transform has good localization properties in time-frequency domain, and is a effective tool to analyze seismic signal which has been applied to detection of many kinds of signal, picture processing and other fields. When a kind of new signal stack up another kind of signal, more high frequency signal components will happen at onset time of new signal. Based on the wave…     

高斯线调频小波变换及其在地震震相识别中的应用

基于地震渐变信号在起始点附近信号高频分量比较丰富，但信号幅度较小的特点，本文选取高斯线调频小波作为基函数，研究了不同小波参数和信号参数对其变换结果的影响规律，找出了直接利用变换峰值进行震相识别的误差来源，提出了一种从背景噪声中实现渐变地震震相识别的有效方法——定尺度小波变换比方法，给出了模拟数字信号和实际地震震相识别的实例．