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Abnormal strain changes observed at Guza before the Wenchuan earthquake

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Science China Earth Sciences 2011年第2期54卷 233-240页

作者： QIU ZeHua ZHANG BaoHong CHI ShunLiang TANG Lei SONG Mo Institute of Crustal Dynamics China Earthquake Administration Beijing 100085 China hebi Seismological Bureau Hebi 458000 China

An YRY-4 type borehole strainmeter at Guza station on the southwest end of the Longmenshan fault zone recorded anomalous changes from time to time since about one year before the Wenchuan earthquake.The anomaly is characterized by steps and/or asymmetrical pulses of short-periods(minutes-hours).Among about one hundred stations over the mainland of China,only Guza,the nearest one to the seismic area,observed such changes.A self-check function of the strainmeter helps confirm the credibility of the observation.The anomalous signals do not correspond to seasonal changes.The consistency in the sense of strain among long-term,anomalous interfering and coseismic changes suggests that they all resulted from the background tectonic movement.Results of an Overrun Rate Analysis further illustrate a close temporal relevance of the anomaly to the Wenchuan earthquake:its increase before,and decrease after the biggest changes during the main shock.The abnormal changes are attributed to local small-scale fractures with an evidential clue that the only Ms4.5 foreshock near Guza station on February 27,2008 produced the biggest anomalous change.By means of Wavelet Decomposition,it is revealed that longer period portion of the anomaly took place later before the main shock,consistent with the idea that scales of small fractures increase during earthquake preparation process.The anomalous strain changes are analogous to the stress changes observed before the 1976 Tangshan earthquake.

关键词：异常信号应变变化地震前汶川钻孔应变仪龙门山断裂带地震孕育过程季节性变化

The strain seismograms of P- and S-waves of a local event recorded by four-gauge borehole strainmeter

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earthquake Science 2015年第3期28卷 209-214页

作者： Zehua Qiu Shunliang Chi Zhenming Wang Seth Carpenter Lei Tang Yanping Guo Guang Yang Institute of Crustal Dynamics China Earthquake Administration earthquake administration of hebi Kentucky Geological Survey University of Kentucky Guza Seismic Station Earthquake Administration of Sichuan Province

At a sampling rate of 100 samples per second,the YRY-4 four-gauge borehole strainmeters（FGBS） are capable of recording transient strains caused by seismic waves such as P and S waves or strain seismograms. At such a high sampling rate, data from the YRY-4 strainmeters demonstrate fairly satisfactory self-consistency. The strain tensor seismograms demonstrate the senses of motion of P waves, that is, the type of seismic wave travels in the direction of the maximum normal strain change. The observed strain patterns of S waves significantly differ from those of P waves and should contain information about the source mechanism. Spectrum analysis shows that the strain seismograms are consistent with conventional broadband seismograms from the same site.

关键词： Four-gauge borehole strainmeter（FGBS） Strain seismogram P-wave S-wave Self-consistency Spectrum analysis

Application of steel fibre reinforced sprayed concrete to a deep tunnel in weak rocks

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Journal of Coal Science & Engineering(China) 2002年第2期8卷 49-54页

作者：周宏伟彭瑞东李振东董正亮陈文伟王健 GuangzhouMetroCorporation Guangzhou510030China hebiCoalMineAdminlstration Hebi458000China InstituteofRockMechanlesandFractals BeijingCampusChinaUniversityofMiningandTechnologyBeijing100083China

Based on an engineering background of a deep tunneling in weak rocks, the numerical modeling is used to compare different support schemes of tunnel at great depth in this paper. Focused on the general behaviors of weak rocks at great depth, a tunneling scheme with rock bolting and steel fibre reinforced sprayed concrete is proposed. This scheme is practiced successfully at a deep tunnel in weak rocks in Coal Mine No 10 of hebi Coal Mining administration.

关键词：钢纤维增强喷射混凝土隧道软弱岩层数学模型煤矿