海上风电升压站平台高程确定标准的合理性研究     

潘晓春 《海洋技术学报》2019,38(6):83-88

为保证海上风电升压电站建设的经济合理与安全可靠,合理确定海上风电升压电站平台高程十分必要。文中从波浪与潮位的遭遇组合、最大波高取值与现行相关标准的比较、最大波峰高度计算的合理性等方面,全面分析了确定海上风电升压站平台高程各组成项取值标准的合理性,研究认为现行标准明显偏高。建议海上升压站平台底部高程按"100年一遇极端高水位+重现期50年波列累积频率1%的最大波峰高度+安全超高"确定。结合工程实例计算分析,按本文建议可使海上升压站平台高程明显降低,从而节省工程造价,还可减轻升压站工程对周边风机的遮蔽影响,以达到多发电量的效果。  相似文献   

Analytical study of ground motion caused by seismic wave propagation across faulted rock masses          下载免费PDF全文

J.C. Li  N.N. Li  S.B. Chai  H.B. Li 《国际地质力学数值与分析法杂志》2018,42(1):95-109

Studying seismic wave propagation across rock masses and the induced ground motion is an important topic, which receives considerable attention in design and construction of underground cavern/tunnel constructions and mining activities. The current study investigates wave propagation across a rock mass with one fault and the induced ground motion using a recursive approach. The rocks beside the fault are assumed as viscoelastic media with seismic quality factors, Q_p and Q_s. Two kinds of interactions between stress waves and a discontinuity and between stress waves and a free surface are analyzed, respectively. As the result of the wave superposition, the mathematical expressions for induced ground vibration are deduced. The proposed approach is then compared with the existing analysis for special cases. Finally, parametric studies are carried out, which includes the influences of fault stiffness, incident angle, and frequency of incident waves on the peak particle velocities of the ground motions.  相似文献   

Application of a cascading filter implemented using morphological filtering and time–frequency peak filtering for seismic signal enhancement     

Yanping Liu  Zhengguo Yan 《Geophysical Prospecting》2020,68(6):1727-1741

Inspired by the idea of the iterative time–frequency peak filtering, which applies time–frequency peak filtering several times to improve the ability of random noise reduction, this article proposes a new cascading filter implemented using mathematic morphological filtering and the time–frequency peak filtering, which we call here morphological time–frequency peak filtering for convenience. This new method will be used mainly for seismic signal enhancement and random noise reduction in which the advantages of the morphological algorithm in processing nonlinear signals and the time–frequency peak filtering in processing nonstationary signals are utilized. Structurally, the scheme of the proposed method adopts mathematic morphological operation to first preprocess the signal and then applies the time–frequency peak filtering method to ultimately extract the valid signal. Through experiments on synthetic seismic signals and field seismic data, this paper demonstrates that the morphological time–frequency peak filtering method is superior to the time–frequency peak filtering method and its iterative form in terms of valid signal enhancement and random noise reduction.  相似文献   

A New Retracking Technique for Brown Peaky Altimetric Waveforms     

Fukai Peng 《Marine Geodesy》2018,41(2):99-125

A new Brown-Peaky (BP) retracker has been developed for peaky waveforms that usually appear within ～10 km to the coastline. The main feature of the BP is that it fits peaky waveforms using the Brown model without introducing a peak function. The retracking strategy first detects the peak location and width of a waveform using an adaptive peak detection method, and then estimates retracking parameters using a weighted least squares (WLS) estimator. The WLS assigns a downsized weight to corrupted waveform gates, but an equal weight to other normal waveform gates. The BP retracker has been applied to 4-year Jason-1 waveform (2002–2006) in two Australian coastal zones. The results retracked by BP, MLE4 and ALES retrackers have been validated against tide-gauge observations located at Burnie, Lorne and Broome. The comparison results show that three retrackers have similar performance over open oceans with the correlation coefficient (～0.7) and RMSE (～13 cm) between altimetric and tide-gauge sea levels for distance >7 km offshore. The main improvement of BP retracker occurs for distance ≤7 km to the coastline, where validation results indicate that data retracked by BP are more accurate (15–21 cm) than those by ALES (16–24 cm) and MLE4 (19–37 cm).  相似文献   

黄土河谷场地地形放大效应的研究     

王良  卢育霞  马林伟  孔德政 《大地测量与地球动力学》2018,38(2):167-171

使用黄土河谷场地模型对地震动峰值加速度和频谱特征进行研究。结果表明，不同工况下各观测点PGA的放大比呈现出不同的变化规律。分析山顶和山谷各点的傅里叶谱以及谱比发现，在地形和土层共同作用下的放大效应是各自单独作用下放大效应的乘积。  相似文献   

Attenuation Characteristics of Earthquake Ground Motion for Large Volume Airgun     

CAI Huiteng  CHEN Yong  JIN Xing  XU Yihe  LI Wen 《中国地震研究》2019,33(4):544-556

In order to further deepen the understanding of seismic wave propagation characteristics induced by the large volume airgun source, experimental data from multiple fixed excitation points in Fujian Province were used to obtain the equivalent single excitation high signal-to-noise ratio velocity and displacement records through linear stacking and simulation techniques. Then the peak displacements of different epicentral distances were used to calculate the equivalent magnitude of the airgun source excitation at different fixed excitation points so as to establish the attenuation relationship between equivalent magnitude,epicenter distance and velocity peak. Our results show that:① Within 270 km of epicentral distance,for the large-volume airgun's single shot,the peak velocity range is about 700-4 nm/s,and the peak displacement range is about 200. 0-0. 2 nm;② The equivalent magnitude of the P-wave from the airgun source with a total capacity of 8,000 in 3 is 0. 181-0. 760,and the equivalent magnitude of the S-wave is 0. 294-0. 832. By contrast,the equivalent magnitude of the P-wave from the airgun source with a total capacity of 12,000 in 3 is 0. 533-0. 896,and the equivalent magnitude of the S-wave is 0. 611-0. 946. The S-wave energy is greater than the P-wave energy, and the excitation efficiency varies greatly with different excitation environment;③ The peak velocity increases with the equivalent magnitude,and decreases with the epicentral distance. The vertical component of the P-wave peak velocity is the largest among those three components,while the S-wave has the smallest vertical component and similar horizontal components. Hence,our research can provide an important basis for the quantitative judgment of the seismic wave propagation distance using the airgun and the design of the observation system in deep exploration or monitoring with airgun.  相似文献   

回填土不确定性对场地地震反应的影响          下载免费PDF全文

张海  陈贺  尤红兵  李克强 《地震工程学报》2019,41(2):370-377

选取某核电场地控制性钻孔的厚度、剪切波速、密度等实际勘探数据,通过改变回填土剪切波速,分析了回填土不确定性对场地地震动参数的影响。研究结果表明:在回填土层厚度不变和模型总厚度不变的情况下,地表的水平向峰值加速度随着回填土剪切波速的增大而减小,但水平向峰值加速度增幅逐渐减小;回填土剪切波速到达一定的波速就不再影响地表水平峰值加速度;随着回填土剪切波速的增加,整个反应谱的谱值都普遍减小。  相似文献   

海底爆破振动强度衰减规律及中华白海豚保护措施研究     

费鸿禄  关福晨  包士杰  肖绍青 《海洋通报》2019,38(4):405-414

为确保海底爆破施工所诱发的振动不对中华白海豚造成危害,基于量纲分析法对萨道夫斯基经验公式进行修正,建立适用于预测海底爆破质点峰值振动速度的相似准数方程。在此基础上根据现场试验数据进行非线性回归运算,得到相关参数并分析了海底爆破振动强度衰减规律。分析表明:海底爆破质点峰值振速主要由单段装药量、监测点距爆心水平距离、覆盖层厚度及海水深度等因素决定。将参数值分别代入萨氏公式及新建公式计算预测值并进行误差估计,其平均误差分别为20.3%和10.0%,新建公式提高了对质点振速预测的准确性。利用新建公式及超压内安全振速估算保护中华白海豚的安全距离并提出相应的保护措施,为同类工程施工提供理论参考依据。  相似文献   

Stormwater control impacts on runoff volume and peak flow: A meta-analysis of watershed modelling studies     

Colin D. Bell  Jordyn M. Wolfand  Chelsea L. Panos  Aditi S. Bhaskar  Ryan L. Gilliom  Terri S. Hogue  Kristina G. Hopkins  Anne J. Jefferson 《水文研究》2020,34(14):3134-3152

Decades of research has concluded that the percent of impervious surface cover in a watershed is strongly linked to negative impacts on urban stream health. Recently, there has been a push by municipalities to offset these effects by installing structural stormwater control measures (SCMs), which are landscape features designed to retain and reduce runoff to mitigate the effects of urbanisation on event hydrology. The goal of this study is to build generalisable relationships between the level of SCM implementation in urban watersheds and resulting changes to hydrology. A literature review of 185 peer-reviewed studies of watershed-scale SCM implementation across the globe was used to identify 52 modelling studies suitable for a meta-analysis to build statistical relationships between SCM implementation and hydrologic change. Hydrologic change is quantified as the percent reduction in storm event runoff volume and peak flow between a watershed with SCMs relative to a (near) identical control watershed without SCMs. Results show that for each additional 1% of SCM-mitigated impervious area in a watershed, there is an additional 0.43% reduction in runoff and a 0.60% reduction in peak flow. Values of SCM implementation required to produce a change in water quantity metrics were identified at varying levels of probability. For example, there is a 90% probability (high confidence) of at least a 1% reduction in peak flow with mitigation of 33% of impervious surfaces. However, as the reduction target increases or mitigated impervious surface decreases, the probability of reaching the reduction target also decreases. These relationships can be used by managers to plan SCM implementation at the watershed scale.  相似文献   

南海北部台风海浪谱的双峰性和成长性     

莫冬雪  刘亚豪  侯一筠  刘泽 《海洋学报(英文版)》2019,38(11):70-80

本论文通过对南海北部三次台风过境期间基于浮标观测的海浪谱进行分析，发现虽然大部分成熟的台风海浪谱为单峰结构，但实际上在台风海浪的成长和衰减阶段，双峰谱占据了很大的比例。双峰谱的形成主要是由于风浪和涌浪的叠加以及不同波分量之间的非线性相互作用，我们可以通过能量密度的成长率对谱型变化进行高效的预报。此外，台风海浪的主要波向依赖于台风中心相对观测点的位置，而波向的分散情况在相距台风中心较远的区域无明显规律。本文提出了一个新的六参数波浪谱型拟合双峰谱，其拟合效果相较于前人的谱型更好。通过验证，形状参数和谱宽度之间的理论关系依然适用于单个谱峰。通过分析谱参量的变化特征，证明了谱参量不仅与台风强度和台风路径相关，还存在很强的交互相关。最后通过拟合海浪谱数据，本文得到了台风影响下海浪有效波高和有效周期之间的成长关系，这对海洋工程实际应用具有重要意义。  相似文献