摘要
四分量钻孔应变观测产出了丰富的近地表连续地壳应变变化资料,使用这些资料时需要正确解析。在四分量钻孔应变观测的力学换算方法基础上,提出了在张-压应力、张应力和压应力3种应力环境下利用四分量钻孔应变观测判定观测区域应力应变状态的方法。以中国青海省门源M 6.9地震为例,用此方法研究了震中附近区域的背景应力应变状态,结果表明应力应变集中区在近地表可能会出现应变拉张现象;分析了门源站主张应变方向的动态变化,初步确定震前5 d出现的主张应变方向变化速率增强现象为震前异常;对四分量钻孔应变记录的同震应变状态与基于弹性位错理论模拟的同震应力场变化特征进行了对比分析,结果表明实测结果与模拟结果吻合度较高。应用分析表明,所提出的判定钻孔观测区域应力应变状态的方法可行有效。
Objectives:Data on near-surface continuous crustal strain variation are produced in large quantities by the 4-component borehole strainmeter,but correct analysis is needed when using these data.Methods:Based on the mechanical conversion method of 4-component borehole strainmeter,we propose a method to determine the stress-strain state by using 4-component borehole strain observations under three stress environments:Tension-compression stress,tension stress,and compression stress.Results:Taking the M 6.9Menyuan earthquake in Qinghai Province,China as an example,we investigate the background stressstrain state near the epicenter by the proposed method.The results show that the stress-strain concentration area may have strain tension near the surface.After analyzing the dynamic change of the strain direction of the Menyuan station,we suggest that the increasing rate of the strain direction change that occurred five days before the earthquake was an anomaly before the earthquake.Following the comparison between the coseismic strain state measured by the borehole strainmeter and the modeled results according to elastic dislocation theory,the results show that the observed results are in good agreement with the modeled results.Conclusions:The application analysis shows that the proposed method to determine the stress-strain state of borehole area is feasible and effective.
作者
唐磊
邱泽华
李玉江
李瑜
樊俊屹
TANG Lei;QIU Zehua;LI Yujiang;LI Yu;FAN Junyi(China Earthquake Networks Center,Beijing 100045,China;National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China)
出处
《武汉大学学报(信息科学版)》
北大核心
2025年第1期63-73,共11页
Geomatics and Information Science of Wuhan University
基金
国家自然科学基金(41974018)。
关键词
四分量钻孔应变观测
应变换算
应力应变状态
应变阶
同震应力场
4-component borehole strainmeter
strain conversion
stress-strain state
strain step
co mic stress field
