四分量钻孔应变对气压响应的传递函数及围岩力学参数估算——以江苏江宁台为例  

FOUR-COMPONENT BOREHOLE STRAINMETER TRANSFER FUNCTIONS AND ROCK PROPERTIES ESTIMATION: A CASE OF JIANGNING STATION, JIANGSU, CHINA

作　　者：杨小林 杨锦玲 苏利娜[3] 冯静[4] 王军[5] YANG Xiao-lin;YANG Jin-ling;SU Li-na;FENG Jing;WANG Jun(Jinggangshan University,Ji'an 343009,China;Minjiang University,Fuzhou 350108,China;Shaanxi Earthquake Agency,Xi'an 710068,China;Sichuan Earthquake Agency,Chengdu 610041,China;Yunnan Earthquake Agency,Kunming 650224,China)

机构地区：[1]井冈山大学,吉安343009 [2]闽江学院,福州350108 [3]陕西省地震局,西安710068 [4]四川省地震局,成都610041 [5]云南省地震局,昆明650224

出　　处：《地震地质》2023年第5期1170-1186,共17页Seismology and Geology

基　　金：陕西省自然科学基础研究(2022JQ-225);中国地震局地震科技星火计划项目(XH20056Y);中国地震局2022年度震情跟踪任务(2022020203);国家自然科学基金(42104091)。

摘　　要：目前中国有60余处四分量钻孔应变测点,这些测点的观测数据在地球动力学和地震前兆等研究中均发挥着重要作用。但在实际观测中,不少四分量钻孔应变仪会受到不同周期气压波的干扰。截至目前,还鲜有关于该类仪器对气压频响效应研究的报道。文中以江宁台为例,尝试采用传递函数对其进行系统诊断;在此基础上,进一步利用双衬套力学模型反演其钻孔围岩的力学参数。结果表明:1)在0.1~30cpd频带内,气压和钻孔应变的相干性较好;2)低频带(0.1~0.5cpd)的气压响应最好,高频带(>8cpd)次之,中频带(0.5~8cpd)则略差;3)若不考虑日波和半日波频段的影响,在整个频带内,4个分量的应变和面应变气压系数谱近线性平稳;4)在高频带,钻孔应变对气压响应的相位谱呈指数形式上升,平均滞后约24.2°,频率依赖性明显;5)利用面应变低频气压系数均值反演的钻孔围岩弹性模量和泊松比分别为33.9GPa和0.27。以上结果将不仅有助于气压效应的分频改正,同时还能为钻孔围岩力学参数的定量反演提供新方法。To date,more than 60 four-component borehole strainmeters have been deployed in China to provide more data on geodynamics and earthquake precursors.In practice,the strain signals recorded by the four-component borehole strainmeters are greatly disturbed by the effect of barometric pressure at different frequencies.Therefore,precisely deciphering the frequency-dependent strain response to barometric pressure changes in the frequency domain is very significant for continuous high-resolution borehole strainmeter measurements.However,no much related research has been conducted in this day.For these more than 60 four-component borehole strainmeters being operated in China's Mainland,the study of properties(e.g.,Young's modulus and Poisson's ratio)of borehole surrounding rock are seldom probed via rock mechanical testing has not been given enough attention,compared that with in the USA and Japan,consequently,which makes it difficult in the understanding of the driving mechanism of atmospheric effects.Beginning at 2006,a YRY-4 type borehole strainmeter was installed approximately at 50m depth in the Jiangning area to precisely monitor the earthquake precursors and tectonic movements in Jiangsu Province.For daily observation,the atmospheric effect is quite obvious in different frequency bands.Therefore,we applied transfer function to uncover features,such as barometric pressure coefficient and phase shift,of frequency dependence observed at Jiangning station in Jiangsu Province in high-(>8cpd),intermediate-(0.5~8cpd),and low-frequency(0.1~0.5cpd)bands.Furthermore,the double bush mechanical model was adopted to estimate the parameters of elastic modulus and Poisson's ratio for the borehole surrounding rock.The results show that:1)The values of coherence in the frequency band(0.1~30cpd)are higher than in others.2)The barometric pressure responses were very stable and valid in the low-frequency band,and remained stable in the high-frequency band(8~30cpd),but significantly fluctuated in the intermediate-frequency band.3)If t

关 键 词：四分量钻孔应变仪 江宁台 气压 传递函数 钻孔围岩 弹性模量 安山岩 

分 类 号：P315.727[天文地球—地震学]