摘要
为了探讨分量钻孔应变地震波测量的可能性,本文引入空孔对入射平面弹性P波散射模型来研究分量钻孔应变观测的理论频响。通过计算空孔对入射波的散射波场,从而得到钻孔直径的变化。类似于分量钻孔应变静态观测,引入不同的钻孔直径变化的组合,来反映入射P波的面应变和最大剪切应变。不同的钻孔直径变化组合的理论频响受入射P波的无量纲波数k1a和钻孔周边介质的泊松比影响。分量钻孔应变波观测等效为低通滤波器,■和■1%频带宽截止k1a为0.061(ν=0.25),■1%频带宽截止k1a为0.037(ν=0.25)。在测量钻孔直径变化的传感器带宽足够高的情况下,可实现入射高频地震应变波的定量测量。
In order to discuss the possibility of measuring seismic strain wave by borehole tensor strainmeters,a model of the scattering of plane elastic P-wave by an empty borehole is introduced to investigate theoretical frequency response of a borehole tensor strainmeter.The calculation of scattering waves around the borehole gives diameter change of the borehole.Similar with the static cases,different gauge combinations are introduced to reflect the areal strain and the maximum shear strain of the incident wave.It is shown that the theoretical frequency responses different gauge combinations are determined by non-dimensional wave numberk1 a of the incident wave and Poisson ratio of surrounding rock.Borehole tensor strain observation is equivalent to a low pass filter.the 1%cut-off k1 aof bandwidth of■and.■.is 0.061(ν=0.25)and 1%cut-off k1 a of bandwidth of■is 0.037(ν=0.25).In the case that the sensor bandwidth is high enough to measure borehole diameter,quantitative measurement of the incident highfrequency seismic strain wave could be realized.
作者
张康华
田家勇
王密
Zhang Kanghua;Tian Jiayong;Wang Mi(Institute of Crustal Dynamics,China Earthquake Administration,Beijing 100085,P.R.China)
出处
《地下空间与工程学报》
CSCD
北大核心
2019年第S01期81-85,共5页
Chinese Journal of Underground Space and Engineering
基金
中国地震局地壳应力研究所基本科研业务专项(ZDJ2018-22,ZDJ2019-15-1,ZDJ2016-20).
