摘要
中国地震局"十五"期间建立的四分量钻孔应变观测台网运行已经超过9年,至今大部分台站仍然工作正常.对所有这些台站的全部观测数据的分析结果表明:这些四分量钻孔应变仪的观测变化非常稳定,主方向大体不变,剪应变速率保持在一个相当恒定的水平上.这应该是地壳构造运动造成的应变变化的表现.这种对构造应变变化主方向和应变速率的精确观测,可以为地球动力学等多方面的研究提供可靠的数据.以理论固体潮作为标准进行实地标定,最大剪应变的应变速率除少数台站达到每年几个微应变外,大多数台站都小于1个微应变;面应变的应变速率比较大,个别台站超过10个微应变,大多数为几个微应变,可能受到"孔缩"影响.多方面的证据表明:观测漂移主要与水泥耦合有关,而水泥耦合过程其实是逐渐调整到适应围岩应变场的过程,只影响最初1~2年的观测结果.
The network to monitor changes in ground strain field with YRY-4 Four-Gauge-Borehole Strainmeters(FGBS) in China has been established since nearly one decade ago. A majority of the instruments are still working well. Our analysis of the data from these sites shows that all observed long term variations are fairly steady, that is, the principal orientations remain roughly constant and the shear strain rates keep at nearly unchanged levels. Such observation results are related to the tectonic motion which is thought extremely slow except during earthquakes. This observation of the tectonic strain rates and the principal orientations are quite precise and supply credible data for studies in the fields of geodynamics. Theoretic earth tides being applied to the in-situ calibration, the observed maximum shear strain rates are usually less than one μs per year except for a few sites being a little above, and the observed areal strain rates for most of the sites are at the level of several μs per year with the rest to reach even higher, probably affected by unknown long-term borehole shrinking. The impact of drift due to the grout coupling process to fit along with the surrounding strain field is concluded to affect only for the beginning one year or two.
作者
邱泽华
唐磊
郭燕平
张宝红
QIU Ze-hua();TANG Lei;GUO Yan-ping;ZHANG Bao-hong(Institute of Crustal Dynamics,China Earthquake Administration,Beijing 100085,China)
出处
《地球物理学进展》
CSCD
北大核心
2020年第5期1688-1701,共14页
Progress in Geophysics
基金
中国地震局地壳应力研究所中央级公益性科研院所基本科研业务专项资助项目(ZDJ2017-10,ZDJ2018-09)资助.
关键词
钻孔应变仪
四分量钻孔应变观测
构造应变
应变速率
主方向
Borehole strainmeter
Four-Gauge-Borehole-Strainmeters(FGBS)
Tectonic strain
Strain rate
Principal orientation
