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1.
测震数采仪记录的钻孔应变 总被引：1，自引：1，他引：0
A seismometer data acquisition unit has been used in the Changping seismic station to record the output of a strainmeter.The output of a strainmeter was sampled at a rate of 100/sec by seismometer acquisition from the original rate of 1 per minute.Plenty of high frequency sampled data was recorded.The minute value curve calculated from the seismometer acquisition are consistent with that of the original data sampled by the strain acquisition system.More complete waveforms were recorded with a higher sampling rate,and seismic phase parameters calculated by using higher sampling rate strain seismic waves are also in consistency with the results of its predecessors.Spectra of the strain seismic waves are compared with that of seismic waves recorded by a seismometer in the Shisanling seismic station,and their trends are almost the same.Besides,some lower frequency components still exist in strain seismic waves. 相似文献
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《中国地震研究》1994,(1)
An ASKANIA borehole tiltmeter which consists of a vertical pendulum with two degrees of freedom was installed in Xiangshan station,Beijing,in May 1989 in order to monitor the earthquake-reiated crustal deformations.The preliminary results indicate that the resolution of the instrument is better than 0.05 msec for tidal amplitudes.The daily total tidal amplitude is about 20 msec.The spectral analysis of the first four months data provides a signal-to-noise ratio of > 100 for the main semi-diurnal waves.The non-tidal tilts for one year data are dominated by a long term drift with the rate of 0.9 msec/day for X-component and 1.1 msec/day for Y-component.In addition,the tilt observations are affected by meteorological factors,especially by rainfall.The results of modelings of the fault-creep related tilts and responses of tilts to earthquakes suggest that the tilt measurements are very sensitive to the change in tectonic strain and stress fields near the site where the tiltmeter is installed.The fault-creep 相似文献
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Longshou Zhou Zehua Qiu Lei Tang Baoxiang Kan Institute of Crustal Dynamics China Earthquake Administration Beijing China 《地震学报(英文版)》2009,(1)
Based on the borehole strainmeter recordings immediately before the strong earthquakes(MS≥7.5) during the period from 2001 to 2005 observed at the Taian observation station,Shandong Province,the authors make a systematic and objective examination of the precursor waves of the quakes.The effects of Earth tides with periods larger than 128 min are eliminated through high-pass filtering;and atmospheric-pressure inferences are removed by linear regression.The 2-128 min signals are then separated into six freque... 相似文献
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The Yutian earthquake with Ms7. 3 happened on February 12, 2014. The precursor monitoring ability is weak in that area. We found tendency anomalies and middle- and short-term anomalies from metal pendulum tilt measurements in Hotan seismic station before the earthquake. And we also compared the anomalies with that of the Ms7. 3 Yutian earthquake on March 21, 2008. The tendency anomalies measured by the metal pendulum tiltmeter appeared since 2012 as tilting eastward. While the middle- and short-term anomalies were characterized by acceleration, pause and rapid change of tilt rate in two directions. The tendency anomalies of metal pendulum tilt records are the same before the two earthquakes. They both happened in the east direction. However, there are differences in duration, characteristic and earthquake intervals for the middle- and short-term anomalies. 相似文献
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We report here the observation result of joint observation of long period tremor signals with broadband seismome-ter,tiltmeter and gravimeter at the HUST(Huazhong University of Science and Technology)station.The observed data were compared and analyzed.Since 2005,the several tens of abnormal tremor signals which are weak,com-plex and duration of 2 to 3 days have been synchronously recorded by the different instruments.The tremor signals have the periodic domain in the range of 3 to 5 minutes,20 to 30 minutes and even more than 1 hour.The observa-tion shows such tremors are a physical existence.The analysis indicates that a part of the tremors caused by the typhoon from the western Pacific Ocean.These tremors have a close relationship with wind velocity of typhoon and distance between the typhoon center and the station.Except these,the cause of others is still unclear. 相似文献
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高采样率四分量钻孔应变同震响应分析 总被引：1，自引：0，他引：1
In this paper, we adopt the observation data of two 10Hz YRY 4-component borehole strainmeters and one 100Hz FBS-3B broadband seismometer to study the responses of their observations to the April 11, 2012 Mw 8.6 earthquake off the west coast of northern Sumatra, and compare the response characteristics during the coseismic stage after preprocessing of the data. We analyze the spectrum＇s dynamic process during the coseismic stage with the S transformation method, and discuss the spectrum＇s details in different seismic phases. The S transformation results of the data of seismometer and borehole strainmeter at the same station show that the coseismic spectrum evolution of the two kinds of observation are similar to each other and can be cross-referenced in indentifying the wave signals, which proves that the borehole strainmeter measurements at high frequencies are reliable. 相似文献
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<正>This paper describes an experimental study of the hysteretic behavior of prestressed truss concrete composite beams(PTCCBs) under cyclic loading.Five beam models were designed and tested,in which the testing parameters include the global reinforcement index β_0,the prestress levelλand the ratio of stirrupρ P_ss in the potential plastic hinge zones.Based on the test results,the failure mode and hysteretic behavior of the tested models are obtained.In addition,the P-△and sectional M- hysteretic models for the PTCCBs at the midspan are established.The P-△hysteretic model shows good agreement with the test results. 相似文献
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A modified domain reduction method for numerical simulation of wave propagation in localized regions
A modified domain reduction method(MDRM) that introduces damping terms to the original DRM is presented in this paper. To verify the proposed MDRM and compare the computational accuracy of these two methods, a numerical test is designed. The numerical results of the MDRM and DRM are compared using an extended meshed model. The results show that the MDRM significantly improved the computational accuracy of the DRM. Then, the MDRM is compared with two existing conventional methods, namely Liao's transmitting boundary and viscous-spring boundary with Liu's method. The MDRM shows its great advancement in computational accuracy, stability and range of applications. This paper also discusses the influence of boundary location on computational accuracy. It can be concluded that smaller models tend to have larger errors. By introducing two dimensionless parameters, φ_1 and φ_2, the rational distance between the observation point and the MDRM boundary is suggested. When φ_1 2 or φ_213, the relative PGA error can be limited to 5%. In practice, the appropriate model size can be chosen based on these two parameters to achieve desired computational accuracy. 相似文献
10.
Effects of near-fault ground motions on the nonlinear behaviour of reinforced concrete framed buildings 
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下载免费PDF全文 Mirko Mazza 《地震科学（英文版）》2015,28(4):285-302
The design provisions of current seismic codes are generally not very accurate for assessing effects of near-fault ground motions on reinforced concrete(r.c.)spatial frames,because only far-fault ground motions are considered in the seismic codes.Strong near-fault earthquakes are characterized by long-duration(horizontal)pulses and high values of the ratio α_(PGA)of the peak value of the vertical acceleration,PGA_V,to the analogous value of the horizontal acceleration,PGA_H,which can become critical for girders and columns.In this work,six- and twelve-storey r.c.spatial frames are designed according to the provisions of the Italian seismic code,considering the horizontal seismic loads acting(besides the gravity loads)alone or in combination with the vertical ones.The nonlinear seismic analysis of the test structures is performed using a step-by-step procedure based on a two-parameter implicit integration scheme and an initial stress-like iterative procedure.A lumped plasticity model based on the Haar-Karman principle is adopted to model the inelastic behaviour of the frame members.For the numerical investigation,five near-fault ground motions with high values of the acceleration ratio α_(PGA) are considered.Moreover,following recent seismological studies,which allow the extraction of the largest(horizontal) pulse from a near-fault ground motion,five pulse-type(horizontal)ground motions are selected by comparing the original ground motion with the residual motion after the pulse has been extracted.The results of the nonlinear dynamic analysis carried out on the test structures highlighted that horizontal and vertical components of near-fault ground motions may require additional consideration in the seismic codes. 相似文献
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乌加河地震台水平摆、水管倾斜仪同震响应对比分析 总被引：1，自引：1，他引：0
选取2013—2015年乌加河地震台水平摆和水管仪记录的13个地震资料,对比分析同震响应特征。分析认为:对于同一地震,水平摆最大响应幅度大于水管仪,且响应延迟时间略小;水管仪和水平摆同震响应持续时间与震级成正比。结果表明,该地震台水平摆和水管仪记录同一地震的最大响应幅度、延迟和持续时间,对远震和近震均具有不同程度的响应。 相似文献
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文中以怀来台竖井水平摆倾斜仪的干扰为背景,初步地分析了其干扰机理;并以“气体分子运动说”对其进行解释. 相似文献
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DSQ水管仪和SSQ-2I水平摆效能对比研究 总被引：1，自引：1，他引：0
SSQ-2I型水平摆仪器和DSQ水管仪同属倾斜类前兆仪器,两者观测原理不同,但观测物理量一致.相对于水管仪而言,SSQ-2I型水平摆属于新型仪器,有关其运行效能的评价很少.延庆地震台从2007年开始两种仪器同场地观测,通过年变幅度、滤波残差、周期分析、Venedikov调和分析、相关性分析、抗干扰能力等角度,对两种仪器... 相似文献
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对乾陵地震台2019年7—12月VP型垂直摆倾斜仪和DSQ型水管倾斜仪观测数据进行系统分析,对比研究2套仪器在固体潮记录、数据连续性、观测精度、日均值变化趋势相关性和映震能力等方面的差异,结合乾陵地震台地质构造、台基岩性和仪器自身差异等分析产生差异的可能原因,并分析2套仪器在不同方面的优势。 相似文献
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对于涉县地震台水管倾斜仪观测资料，根据地球物理数据跟踪分析方法，将干扰源按照自然因素、场地环境因素、观测系统、地球物理事件等类型进行分析，并给出数据处理建议。 相似文献
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根据所掌握的仪器映震能力、震前(后)大震特殊捕捉现象,以及对相同地震不同仪器映震的对比,可以看出,VP型宽频带垂直摆倾斜仪具备前兆仪器捕捉(反映)地震孕育及地震发生的相关作用,能够正确、客观的作用于地震前兆数据产出,对地震预测研究具有深远影响. 相似文献
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分析了宁蒗5.5级地震前,永胜地震台FSQ型浮子水管倾斜仪的短临异常特征,总结出短临形变异常的几种类型,并得出若干结论。 相似文献
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对青海省格尔木、门源和乐都地震台水平摆与垂直摆倾斜仪观测资料进行对比分析，论述温度、气压、人为活动（工作人员进入观测山洞）以及大风等干扰因素对观测资料的不同影响，发现垂直摆倾斜仪受温度、大风和人为活动等因素的干扰程度总体低于水平摆倾斜仪，对观测环境的要求相对较低。 相似文献