共查询到20条相似文献,搜索用时 78 毫秒
1.
我国钻孔应力-应变地震前兆监测台网的现状 总被引:10,自引:3,他引:10
当今的地震成因理论表明:地震是地应力(应变)积累到一定程度,使断层滑动而发生的。由此可见地应力-应变观测的重要性。我国的钻孔应力-应变地震前兆监测网,是全国地震前兆监测台网的一个组成部分。观测对象包括:体应变,分量应变,分量应力和钻孔应力-应变差应变。文章通过分析调查结果,比较详细地介绍了我国的钻孔应力-应变地震前兆监测台网的现状。 相似文献
2.
3.
介绍了体应变观测潮汐因子和勒夫数 h2 之间的线性关系 ,h2 的变化幅度较体应变观测潮汐因子震前异常变化大 7.5倍。同时 ,昌平台剪应变观测潮汐因子 O1波与体应变观测潮汐因子M2 波震前异常有较好的一致性 ,研究钻孔应变观测潮汐因子的变化有可能是取得地震前兆的有效途径之一。 相似文献
4.
5.
姑咱台的YRY-4型四元件钻孔应变仪是2006年底安装的,至今仍在正常工作,已经有十多年的分钟值观测数据.姑咱台的这种观测的高质量,首先体现在连续性上,除仪器本身的耐久性外,认真有效的运维管理是一个重要原因.这种高质量观测的另一个特点是稳定性,十年来耦合系数保持稳定,说明观测系统的稳定.这种观测数据保持了良好的自洽性,作为四元件钻孔应变观测,这是一项关键指标.所有这些指标(连续性、稳定性和自洽性),说明了观测技术和产出数据的可靠性.根据这十多年的可靠观测数据,得到两个重要认识:一个是这种仪器可以观测长期的构造应变速率,改变了过去对钻孔应变观测频响性能的认识,有助于对现今构造运动特别是地震断层现今活动性的研究;另一个是汶川地震前观测到的异常变化得到进一步确认,这为地震前兆研究提供了一个可靠的个案.不仅如此,姑咱台还进行了这种钻孔应变仪的高频观测实验,采样率达到每秒100次,与摆式地震仪相同.结果表明,这种应变仪在高频端的观测表现非常好.这为地震波研究提供了新手段.更重要的是,它说明这种钻孔应变观测是一个地球动力学的全频段观测技术.这种观测创造了一种可能性,就是将地震孕育以及发生的过程完整... 相似文献
6.
从大地测量技术、地震观测技术和钻孔应变观测技术3种地面运动观测方法在观测频频带和观测精度方面的互补性,探讨了钻孔应变观测技术的发展方向,指出钻孔应变观测应将观测重点放在周期数十秒到数十天的短临信息频段,同时指出,钻孔应变观测可以同时用于声和高频地震观测,以获取更多的短临信息。 相似文献
7.
8.
9.
选取易县地震台YRY-4型分量式钻孔应变仪2012—2020年观测数据,进行Venedikov调和分析,并对2015—2020年四分量数据S1、S2、S3、S4进行自洽检验,发现应变观测数据连续性、可靠性较高。选取该台2018—2019年钻孔应变原始数据S1、S2、S3、S4,利用面应变S1 + S3、S2 + S4相关系数,分析河北省3次ML≥4.0地震前数据异常变化,并利用剪应变S1 - S3、S2 - S4的大小,分析受抽水干扰的NE分量主应力方位角,判断干扰源方位,结果发现:①面应变与剪应变在地震发生前均会出现异常变化,且剪应变异常变化幅度较大,应与震中相对于观测井的位置有关;②对于受抽水干扰的钻孔应变NE分量,利用剪应变固体潮数据推算主应力方位角,可得干扰源在钻孔应变观测室NW80.96°方位,与实际位置存在一定偏差。 相似文献
10.
11.
根据双衬套钻孔应变观测力学模型,推导出平面应力作用下各分量应变观测中两个耦合系数(A、B)的计算公式,为进一步确定地壳应变场最大、最小主应变的数值及方向提供了必需的前提条件,对当前国内外开展的利用钻孔应变进行地震、火山和板块边界的观测研究具有一定积极意义.研究结果表明,A、B与用双环模型和复变函数法解算出的c(面应变响应因子)、d(剪应变响应因子)之间分别存在2倍的关系(c=2A,d=2B),并且二者绘制的曲线完全一致,c、d的物理含义分别是地壳岩石面应变与剪应变观测的井孔耦合系数. 相似文献
12.
对高台地震台2008—2012年的YRY-4分量钻孔应变观测资料进行处理与分析,结果显示:高台台YRY-4分量钻孔应变仪运行良好,产出的观测数据连续、稳定、可靠;各个分量应变潮汐因子及相位变化相对稳定,相对误差较小,符合地壳形变观测技术规范要求;各个分量应变观测数据具有明显的周期特性和同向漂移变化。 相似文献
13.
Introduction The Earth′s crust deforms in the regional tectonic stress field. Borehole strain observation isone important means for studies on the crustal deformation and the stress field. QIU and ZHANG(2002) have introduced the current situation of borehole strain observation in China. OutsideChina, early in September of 1968, Sacks of Carnegie Institution of Washington and Evertson ofUniversity of Texas firstly invented a borehole dilatometer in the world (Sacks, Evertson, 197… 相似文献
14.
Borehole strain observation is playing an increasingly important role in the study on the crustal movements. It has been used
by many countries such as China, USA, Japan, Peru, Australia, South Africa, Iceland and Italy, in research fields of plate
tectonics, earthquake, volcanic eruption, dam safety, oil field subsidence, mining collapse and so on. Borehole strainmeter
has been improved rapidly and tends to get more and more components included in one probe. Based on observations by this kind
of instruments, studies on seismic strain step, slow earthquake, earthquake precursor and volcanic eruption forecasting have
made remarkable achievements. In the coming years, borehole strain observation is going to become one major goedetic means,
together with GPS and InSAR.
Foundation item: National Natural Science Foundation of China (40374011) and Joint Seismological Foundation of China (1040037). 相似文献
15.
苏恺之 《地震地磁观测与研究》2020,41(2):172-180
论文讲述了作者参与的四分量钻孔应力仪的诞生和发展,向读者展示了它的研制到逐步成功的曲折历程,体现了四分量钻孔应力—应变观测给地壳形变观测在数据处理与思想方法带来的有意义的变化。在论文最后,结合21世纪初得到的四分量应变观测的震前异常资料,体会到勇于思考、勇于创新的科学理念,对于建设我国地形变观测体系,做出自己的特色,具有重要的现实意义。 相似文献
16.
钻孔应变观测系统(岩石、 膨胀水泥和应变仪钢筒)存在显著的井孔耦合效应,只有确定这一耦合系数,才能得到地壳岩石的真实应变值,从而实现不同测点数据的可比性.本文根据双衬套理论及弹性力学理论,建立了三维空间应力作用下体应变与面应变观测力学模型,并进一步推导各自井孔耦合系数计算式,发现两组系数与井孔的受力状况密切相关,分别与不同力源引起的应变信号相对应.亦即应力比(钻孔轴向应力与平面应力之比)不同,耦合系数也不一样,体应变随应力比的增大而下降,面应变则上升. 本文结果还表明平面应力作用下的耦合系数与外加应力无关,只与观测系统本身有关,故数值保持恒定. 此外,文中对其影响因素也进行了分析,结果表明,体应变和面应变的井孔耦合系数均随岩石弹性模量和泊松系数的增大而增大,且前者的幅度较大,井孔耦合材料水泥对二者影响均很小. 相似文献
17.
钻孔体应变与面应变观测参数k的计算 总被引:1,自引:0,他引:1
钻孔体应变与面应变观测模型是地壳岩石应变测量资料分析的理论基础,对揭示研究对象的物理本质有所帮助,因为都含有参数k(应变仪钢筒内壁面应变与空孔岩石面应变之比),故k 的解算对模型的正确表述十分关键。考虑到外加应力需在岩石、膨胀水泥和仪器钢筒等3 层介质中传递的实际情况,根据弹性力学中的厚壁圆筒方程,推导出轴对称应力作用下k的计算式,该式与平面应力作用下基于双衬套理论(潘立宙、欧阳祖熙和陈沅俊等建立)的解算结果完全一致,公式的可靠性由此得到互证。又对k 的影响因素进行了系统研究,给出有关变化规律曲线和定量指标。最后,与Evertson 用2 层介质模型(岩石、钢筒)推导的k 值(0. 9)进行了比较,指出二者之间的明显差异和0. 9 的狭窄适用范围。 相似文献
18.
19.
James F. Lewkowicz 《Physics of the Earth and Planetary Interiors》1985,41(1):58-65
Measurements of the Earth tide using tilt and strainmeter data can be used to infer crustal structure. However, in almost all measurements of crustal motion using shallow tiltmeters and strainmeters, reference is made to the degradation of the data implied to be caused by influence of meteorological parameters on near surface layers. For example, studies by Wood and King and Goulty et al. indicated that a substantial portion of measured crustal motion by shallow tilt and strain data may be attributed to the weather. These studies were limited to data outside the tidal band. However, it is important to determine the effects of weather on these data, within the tidal band, if shallow tiltmeters are to be used to determine crustal structure.Collocated deep and shallow borehole tiltmeter arrays were operated by The Air Force Geophysics Laboratory in eastern Massachusetts and provided an opportunity to investigate weather effects on shallow tilt. The tiltmeters installed in deep boreholes (100 m) yielded internally consistent M2 amplitudes (2%) and phases (3%) (Cabaniss and McConnell) but the collocated shallow (4 m) borehole tilt array did not produce the same results. Least squares analyses of the shallow tilt data revealed variations of 20% for M2 tidal amplitude compared to the deep data. A multichannel Wiener filter technique was used to investigate the hypothesis that this discrepancy was due to meteorological influence. Results indicated that approximately one-half of the anomalous M2 power was correlated with air and borehole temperatures. It is suggested that the remaining anomalous power may be due to ground deformation caused by the action of groundwater. If this is true, shallow tiltmeters might not be measuring the same deformation as the deep instruments and, therefore, not capable of measuring the Earth tide with the accuracy required to determine crustal structure. 相似文献
20.
Design parameters for borehole strain instrumentation 总被引:3,自引:0,他引:3
The response of a borehole strain meter to hydrostatic and shear deformations in an isotropic medium is calculated to facilitate optimum instrument design and produce instrument response factors for parameters typically encountered in installed instruments. Results for an empty borehole are first compared with results for an instrument in intimate contact with the surrounding rock. The effects of the grout used to install the instrument are then examined. Where possible, analytic forms for the response factors are given. Results for typical installations are then presented in graphical form for optimizing instrument design in an environment of known elastic parameters. Alternatively, the results may be applied in the measurement of unknown strain signals, to correct for instrument response or to provide in-situ estimates of the elastic properties of the environment by examination of observed strain response to known strain signals. 相似文献