波形拟合法在人工挖孔扩底桩承载力测试中的应用          下载免费PDF全文

吕芝全  潘纪顺  刘长来  海蕊  王碧辉  孙方宇 《地震工程学报》2002,24(1):78-84

从人工挖孔扩底桩的工作机理和波形拟合法的基本原理出发 ,结合工程实例阐述了波形拟合法在确定人工挖孔扩底桩承载力中的应用特点及可行性 .  相似文献   

地闪回击辐射场波形的重构及地闪放电参量的估算   总被引：4，自引：0，他引：4  

张其林  郄秀书 《高原气象》2003,22(3):252-258

根据地闪回击传输线电流模式重新确立了地闪回击辐射场与电流之间的关系式,并在观测实验的基础上,重构了不同距离范围内(15～50km,50～100km,100～150km)的地闪回击辐射场波形,重构波形与实测波形之间有很好的一致性。同时在合理的假定下,将回击辐射电场与电流之间的关系进一步推广到先导过程,并估算了地闪先导放电过程中的三个参量。发现首次回击前最后一个先导脉冲电流为2.7kA,通道的电荷密度为(0.135～1.35)×10-3C·m-1,负地闪回击过程中和电荷量为2.06C。  相似文献   

Feasibility of waveform inversion of Rayleigh waves for shallow shear-wave velocity using a genetic algorithm   总被引：1，自引：0，他引：1  

Chong Zeng  Jianghai Xia  Richard D. MillerGeorgios P. Tsoflias 《Journal of Applied Geophysics》2011,75(4):648-655

Conventional surface wave inversion for shallow shear (S)-wave velocity relies on the generation of dispersion curves of Rayleigh waves. This constrains the method to only laterally homogeneous (or very smooth laterally heterogeneous) earth models. Waveform inversion directly fits waveforms on seismograms, hence, does not have such a limitation. Waveforms of Rayleigh waves are highly related to S-wave velocities. By inverting the waveforms of Rayleigh waves on a near-surface seismogram, shallow S-wave velocities can be estimated for earth models with strong lateral heterogeneity. We employ genetic algorithm (GA) to perform waveform inversion of Rayleigh waves for S-wave velocities. The forward problem is solved by finite-difference modeling in the time domain. The model space is updated by generating offspring models using GA. Final solutions can be found through an iterative waveform-fitting scheme. Inversions based on synthetic records show that the S-wave velocities can be recovered successfully with errors no more than 10% for several typical near-surface earth models. For layered earth models, the proposed method can generate one-dimensional S-wave velocity profiles without the knowledge of initial models. For earth models containing lateral heterogeneity in which case conventional dispersion-curve-based inversion methods are challenging, it is feasible to produce high-resolution S-wave velocity sections by GA waveform inversion with appropriate priori information. The synthetic tests indicate that the GA waveform inversion of Rayleigh waves has the great potential for shallow S-wave velocity imaging with the existence of strong lateral heterogeneity.  相似文献   

数字化地震记录波形线性度的分析处理方法及其初步应用     

冯德益  虞雪君 《地球物理学进展》1993,8(1):75-81

探讨了数字化地震记录P 波初始部分波形线性度的两种分析处理方法,即波形的时间线性度和波形的空间线性度的分析处理方法,并着重介绍了这两种方法在地震预报研究中的初步应用结果.  相似文献   

2014年8月3日云南鲁甸M_W6.1（M_S6.5）地震破裂过程          下载免费PDF全文

张勇  许力生  陈运泰  刘瑞丰 《地球物理学报》2014,57(9):3052-3059

2014年8月3日云南鲁甸（M_W6.1,M_S6.5）地震是一次规模不大、但灾害严重的走滑型地震事件.受走滑型地震辐射图型的影响,远震地震资料在特定方位上信噪比不高,给此次地震发震断层面的确定造成了一些干扰.本文概述了鲁甸地震发生后2.4小时发布的作为地震应急响应的破裂过程快速反演工作,以及随后对反演结果的修订工作.修订结果中,两个双力偶节面的反演都显示破裂方向朝地表和走向方向扩展.结合现有的烈度分布和余震精确定位结果,根据破裂方向和烈度与余震分布的优势方向的一致性,确定鲁甸地震是发生在走向162°,倾角86°的近乎垂直于地面的以左旋走滑为主的断层面上的一次破裂事件.根据破裂过程反演得到的震源时间函数,大部分地震矩在破裂开始后2~5 s内集中释放. 比较集中的地震矩释放过程可能是此次地震面波震级明显高于矩震级,且造成严重地震灾害的原因之一.  相似文献   

利用sPn震相测定芦山M_S7.0级地震余震的震源深度          下载免费PDF全文

孙茁  吴建平  房立华  王未来  王长在  杨婷 《地球物理学报》2014,57(2):430-440

利用南北地震带南段密集流动地震台阵的观测数据,采用波形互相关方法拾取Pn波走时,应用滑动时窗相关法识别sPn震相,通过sPn与Pn震相之间的走时差测定了芦山地震序列中28个M_L4.0级以上余震的震源深度.结果表明,震源深度集中在10~20 km范围内,垂直余震带的北西-南东向震源深度剖面揭示,余震分布表现出西深东浅的特点,倾角大约为39°.这些余震在空间上具有较好的线性分布特征,推测可能发生在与主震有关的破裂面上或邻近位置,由此推测主震的破裂面倾角大约为39°.根据余震的空间分布特征,认为芦山地震的发震断层并非双石-大川断裂,可能是其东侧的一条隐伏断层.  相似文献   

The April 24, 2013 Changning M_s4.8 earthquake: a felt earthquake that occurred in Paleozoic sediment     

Xiangfang Zeng  Libo Han  Yaolin Shi 《地震学报(英文版)》2014,(1):107-115

The dense broadband seismic network provides more high-quality waveform that is helpful to improve constraint focal depth of shallow earthquake. Many shallow earthquakes occurring in sediment were regarded as induced events. In Sichuan basin, gas industry and salt mining are dependent on fluid injection technique that triggers microseismicity. We adopted waveform inversion method with regional records to obtain focal mechanism of an Ms 4.8 earthquake at Changning. The result suggested that the Changning earthquake occurred at a ESE thrust fault, and its focal depth was about 3 km. The depth phases including teleseismic pP phase and regional sPL phase shows that the focal depth is about 2 km. The strong, shortperiod surface wave suggests that this event is a very shallow earthquake. The amplitude ratio between Rayleigh wave and direct S wave was also used to estimate the source depth of the mainshock. The focal depth(2–4 km) is far less than the depth of the sedimentary layer thickness(6–8 km) in epicentral region. It is close to the depth of fluid injection of salt mining, which may imply that this event was triggered by the industrial activity.  相似文献   

波形相关意义“重复地震”研究综述   总被引：2，自引：0，他引：2  

李宇彤  蒋长胜 《中国地震研究》2012,26(3):277-291

波形相关意义的“重复地震”在自然界中普遍存在,其数量远远超过我们的预期。近年来由于数字地震观测技术的普及和发展,有关“重复地震”的研究引起越来越多的关注,目前“重复地震”研究已被广泛应用于检测地壳介质性质变化、评估地震台网的定位精度、估计地震“复发”的概率和断层深部滑动速率的估算方面的估计;在提高定位和震相识别精度、断层结构、震源物理及地震预测研究等方面也都显示出值得关注的应用潜力。本文对有关“重复地震”的最新研究及应用成果进行了总结和归纳。  相似文献   

利用重复地震观测地壳介质变化   总被引：11，自引：1，他引：10  

周龙泉  刘桂萍  马宏生  华卫 《地震》2007,27(3):1-9

利用天然重复地震观测地壳介质速度随时间的变化, 其精度主要受地震定位精度、 重复地震位置不一致以及震相读取误差等影响, 这限制了其在实际中的应用。 文中提出利用射线追踪方法对重复地震进行位置归一处理, 并且采用波形互相关技术消除震相读取误差影响, 从而达到提高精度的目的。 根据上述方法原理, 利用大姚地区重复地震观测该地区地壳介质随时间的变化。 结果表明, 该方法能够有效地提高测量的精度, 并且显示在2003年大姚6.2级、 6.1级地震前出现了短期的地壳介质速度明显升高的现象。  相似文献   

Validation of 3-D basin structure models for long-period ground motion simulation in the Osaka basin, western Japan     

Asako Iwaki  Tomotaka Iwata 《Journal of Seismology》2008,12(2):197-215

We studied the applicability of two types of existing three-dimensional (3-D) basin velocity structure models of the Osaka basin, western Japan for long-period ground motion simulations. We synthesized long-period (3–20 s) ground motions in the Osaka basin during a M6.5 earthquake that occurred near the hypothetical Tonankai earthquake source area, approximately 200 km from Osaka. The simulations were performed using a 3-D finite-difference method with nonuniform staggered grids using the two basin velocity structure models. To study the ground motion characteristics inside the basin, we evaluated the wave field inside the basin using the transfer functions derived from the synthetics at the basin and a reference rock site outside the basin. The synthetic waveforms at the basin site were obtained by a convolution of the calculated transfer function and the observed waveform at the reference rock site. First, we estimated the appropriate Q values for the sediment layers. Assuming that the Q value depends on the S wave velocity V _S and period T, it was set to Q = (1/3V _S)(T ₀/T) where V _S is in m/s and the reference period T ₀ is 3.0 s. Second, we compared the synthetics and the observations using waveforms and pseudovelocity response spectra, together with a comparison of the velocity structures of the two basin models. We also introduced a goodness-of-fit factor to the pseudovelocity response spectra as an objective index. The synthetics of both the models reproduced the observations reasonably well at most of the stations in the central part the basin. At some stations, however, especially where the bedrock depth varies sharply, there were noticeable discrepancies in the simulation results of the models, and the synthetics did not accurately reproduce the observation. Our results indicate that the superiority of one model over the other cannot be determined and that an improvement in the basin velocity structure models based on simulation studies is required, especially along the basin edges. We also conclude that our transfer function method can be used to examine the applicability of the basin velocity structure models for long-period ground motion simulations.  相似文献