MICRO TREMOR MEASUREMENTS AT MOGAO GROTTOES,DUNHUANG, CHINA FOR PRELIMINARY DYNAMIC CHARACTERIZATION FOR PERFORMANCE UNDER EARTHQUAKE
Mogao Grottoes,Dunhuang,China,is a world heritage of UNESCO created in steep cliff with 50 ~ 60m in height.Micro-tremor measurements and seismic refraction surveys have been carried out as a preliminary study to obtain dynamic characteristics.The site surface geology consists of young sediment of conglomerate in Pleistocene period above granite rock.A velocity sensor with a natural period of 0.5s was used to monitor the micro-tremors at several points on the top terrace of the cliff and the lower plain in front of the cliff.Two survey lines of some 40m for refraction survey were performed along which P and S waves were monitored.The velocities obtained from the both refraction lines are in the range of 500 ~ 700rn/s and 1.6 ~ 4.0km/s for S and P waves respectively.The monitored micro-tremors were in less than a few m kines and the intensities of the motions were changed with time.Particle motions at the most observed sites shows the perpendicular direction to the cliff of EW is the predominant direction irrespective the intensity of the motions.Predominant period of spectral ratio of SW to UD direction shows about 2s at the top terrace of the cliff and 1 second at the lower plain in front of the cliff.The thickness of the top surface layer of conglomerates is estimated about 125 ~ 180m below the lower plain and 250m or more.Another characteristic period was found at a period of 0.3 ~0.4s.that might be caused by cliff-edge vibration.
mogao grottoes protection of cultural heritage micro-tremor active fault
Y.IWASAKI K.NAKAGAWA Y.ISHIKAWA C.TANIMOTO K.KOIZUMI K.OIKE LM.WANG XD.WANG QL.GUO
Geo Research Int.,Osaka,Japan Osaka City Univ.,Osaka Japan Shizuoka University,Shizuoka,Japan International Institute for Advanced Studies,Kizu,Japan Osaka Univ.,Suita,Japan Lanzhou Institute of Seismology,Lanzhou,China Deputy Director,Dunhuang Academy,Dunhuang,China
国际会议
5th China-Japan Geotechnical Symposium(第五届中日岩土工程学术会议)
成都
英文
172-179
2013-05-18（万方平台首次上网日期，不代表论文的发表时间）