共查询到20条相似文献，搜索用时 781 毫秒
1.
R. P. Young S. Talebi D. A. Hutchins T. I. Urbancic 《Pure and Applied Geophysics》1989,129(3-4):455-474
Rockbursts and mining-induced seismic events have serious socio-economic consequences for the Canadian mining industry, as their mines are extended to greater depths. Automatic multichannel monitoring systems (Electro-Lab MP250s) are routinely, used to detect the arrival times of seismic waves radiated by mining-induced events and sensed on an array of single component transducers installed throughout a mine. These arrival times are then used to locate the events and produce maps of areas of high activity for use in mine planning and design. This approach has limitations in that, it does not allow a detailed analysis of source mechanisms, which could be extracted if whole waveform signals are recorded and analyzed.A major research project, sponsored by the Natural Sciences and Engineering Research Council of Canada (NSERC) with the collaboration of the Canadian mining industry, is aimed at enhancing existing mine seismic monitoring technology in Canada, in order to carry out more advanced processing of data to obtain fundamental scientific information on mining-induced seismic events This paper describes preliminary results from seismic monitoring experiments carried out in a hard rock nickel mine in Sudbury, Canada. Existing seismic monitoring instrumentation was enhanced with a low cost microcomputer-based whole waveform seismic acquisition system. Some of the signals recorded during this experiment indicate anisotropic wave propagation through the mine rock masses, as observed by the splitting of shear waves and the relative arrival of two shear waves polarized in directions which may be related to the structural fabric and/or state of stress in the rock mass. Analysis of compressional wave first motion shows the predominance of shear events, as indicated by focal mechanism studies and is confirmed by spectral analysis of the waveforms. The source parameters were estimated fro typical low magnitude localized microseismic events during the initial monitoring experiments. The seismic moment of these events varied between 106 N.m and 2.108 N.m. with a circular source radius of between 1 m and 2 m with an estimated stress drop of the order of 1 MPa. 相似文献
2.
This project was started in 1985, after a particularly extensive period of rockburst activity in several Ontario mines. Three parties participated in the project: the Government of Canada, through CANMET, the Ontario Ministries of Labour and Northern Development and Mines, and the Ontario Mining Association.The first two years of the project have been mainly devoted to the design and installation of new seismic monitoring systems. It is intended to install three different types of monitoring systems at the four mining camps experiencing rockbursts (Red Lake, Elliot Lake, Sudbury, and Kirkland Lake). Seismograph units will be installed at each mining camp to obtain permanent records of the larger seismic events and their magnitude. Macroseismic systems are being installed around five mines (Campbell, Quirke, Strathcona, Creighton and Macassa). These systems consist of triaxial, strong-motion geophones with processing units for event detection and data digitization. Complete waveforms are captured to study first motion, peak particle velocity, seismic energy and spectral frequency. At present 13 mines in Ontario operate their own microseismic systems which are used exclusively for real time source location of seismic events.The instrumentation already installed and the present research activities at the mines are described in the paper.Presented at the Fred Leighton Memorial Workshop on Mining Induced Seismicity, Montreal 1987. 相似文献
3.
S. M. Spottiswoode 《Pure and Applied Geophysics》1989,129(3-4):673-680
This paper summarizes seismic and rockburst research activities related to South African deep-level gold mines over the period 1983 to 1987. It covers continued research in directions that were considered in the Seismicity in Mines Symposium in 1982 as well as in several new areas of research. Five broad areas are identified:
- Seismic data acquisition and processing. Improved seismic systems are being developed. Velocity models related to known stratigraphy are being used to provide more accurate estimates of seismic locations.
- Source mechanisms and near-source effects on seismic wave transmission. This work provides fundamental insights into seismicity and rock behaviour and is being applied in rockburst prediction research.
- Mine layouts. Excess shear stress is being investigated as a design parameter by analyzing mining configurations and resultant seismicity. In addition, better understanding of the behaviour of highly stressed remnants and pillars is also being obtained from seismic studies.
- Strong ground motion studies. Evaluation of the performance of support elements, including recently developed backfill materials, requires better knowledge of ground motion around underground excavations during seismic events and rockbursts.
- Rockburst prediction and control. Rockburst prediction research continues with some reported success. In addition, the feasibility of actively triggering fault slip or conditioning the rock ahead of the stope face to ameliorate the rockburst hazard is currently being investigated.
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5.
《Journal of Applied Geophysics》2007,61(1):1-15
The presence of an excavation disturbed zone (EDZ) around an excavation boundary can significantly affect the overall performance of the excavation and the general safety of men and equipment. Hence, it has been an important subject of research in various rock excavation projects. The EDZ is generally defined as the rock zone beyond the excavation boundary where the physical, mechanical and hydraulic properties of the rock have been significantly affected due to the excavation and redistribution of stresses. For LKAB's Kiirunavaara underground iron ore mine in Sweden, the understanding of the EDZ is essential for optimal design of rock support. With this main objective an EDZ investigation was conducted at the mine using seismic measurement techniques. Cross-hole seismics and spectral analyses of surfaces waves (SASW) were the main techniques used. Borehole Image Processing Systems (BIPS) complemented the seismic measurements. The results show that an EDZ with a thickness of 0.5–1. 0 m existed behind the boundaries of the mining drifts being investigated. The magnitude of the Young's modulus of this zone was 50% to 90% of that of the undisturbed rock. 相似文献
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Wide-azimuth seismic data can be used to derive anisotropic parameters on the subsurface by observing variation in subsurface seismic response along different azimuths. Layer-based high-resolution estimates of components of the subsurface anisotropic elastic tensor can be reconstructed by using wide-azimuth P-wave data by combining the kinematic information derived from anisotropic velocity analysis with dynamic information obtained from amplitude versus angle and azimuth analysis of wide-azimuth seismic data. Interval P-impedance, S-impedance and anisotropic parameters associated with anisotropic fracture media are being reconstructed using linearized analysis assuming horizontal transverse anisotropy symmetry. In this paper it is shown how additional assumptions, such as the rock model, can be used to reduce the degrees of freedom in the estimation problem and recover all five anisotropic parameters. Because the use of a rock model is needed, the derived elastic parameters are consistent with the rock model and are used to infer fractured rock properties using stochastic rock physics inversion. The inversion is based on stochastic rock physics modelling and maximum a posteriori estimate of both porosity and crack density parameters associated with the observed elastic parameters derived from both velocity and amplitude versus angle and azimuth analysis. While the focus of this study is on the use of P-wave reflection data, we also show how additional information such as shear wave splitting and/or anisotropic well log data can reduce the assumptions needed to derive elastic parameter and rock properties. 相似文献
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利用FLAC3D软件模拟地震作用下不同岩层倾角的顺倾向边坡,对比坡面峰值加速度放大系数、峰值位移、地震作用结束后坡体剪应变增量的变化规律,探讨岩层倾角对顺倾边坡地震效应的影响。研究表明:(1)在水平地震波作用下,坡面水平峰值加速度放大作用随岩层倾角增大而线性减小;(2)当岩层倾角小于软弱岩层内摩擦角时,坡面峰值位移较小且变化规律受岩层倾角影响不明显,当岩层倾角大于软弱岩层内摩擦角且小于30°时坡面峰值位移增大,大于60°时减小;(3)岩层倾角小于坡角时,残余剪应变增量最大值集中在坡面中下部软弱岩层处,反之,剪应变增量最大值出现在整个坡面并呈弧形区。 相似文献
10.
Navid Hosseini 《Journal of Seismology》2017,21(5):1101-1110
Rockburst is a typical dynamic disaster in underground coal mines which its occurrences relate to the mechanical quality of coal seam and surrounding rock mass and also the condition of stress distribution. The main aim of this paper is to study the potential of rockburst in a longwall coal mine by using of passive seismic velocity tomography and image subtraction technique. For this purpose, first by mounting an array of receivers on the surface above the active panel, the mining-induced seismic data as a passive source for several continuous days were recorded. Then, the three-dimensional tomograms using simultaneous iteration reconstruction technique (SIRT) for each day are created and by employing the velocity filtering, the overstressed zones are detected. In addition, the two-dimensional seismic velocity tomograms in coal seam level by slicing the three-dimensional tomograms are obtained. Then the state of stress changes in successive days by applying the image subtraction technique on these two-dimensional tomograms is considered. The results show that the compilation of filtered three-dimensional tomograms and subtracted images is an appropriate approach for detecting the overstressed zones around the panel and subsequent evaluation of rockburst potential. The research conclusion proves that the applied approach in this study in combination with field observations of rock mass status can effectively identify the rockburst-prone areas during the mining operation and help to improve the safety condition. 相似文献
11.
We provide an overview of the current status of seismic monitoring instrumentation employed in Canadian underground mines. Based on several case studies, we outline how passive seismic monitoring techniques are being used to evaluate fractures and stress conditions associated with ore extraction at depth. It is shown that induced microseismicity allows for the remote monitoring of active fractures, delineating modes of failure with advancing excavation fronts, and identifying variations in principal stress orientations during sequential stages of mining. Advances into the characterization of excavation zone of influence through deformation state analysis and the use of seismic hazard analysis to evaluate the potential for ground instability are also discussed. 相似文献
12.
Bevan M. French 《Bulletin of Volcanology》1970,34(2):466-517
Recent investigations indicate the importance of meteorite impact as a process which has operated throughout geologic time to produce numerous originally circular structures as much as 50 km in diameter. One such structure, at Sudbury, Ontario, is associated with large volumes of internally derived igneous rock. Geological and experimental studies have demonstrated that rocks subjected to intense shock waves produced by hypervelocity meteorite impacts and by nuclear or chemical explosions develop distinctive and uniqueshock-metamorphic features, including: (1) high-pressure minerals such as coesite and stishovite; (2) crystal lattice deformation features such as isotropic feldspar (maskelynite) and « planar features » (shock lamellae) in quartz; (3) ultra-high-temperature reactions not produced by normal geological processes, such as decomposition of zircon to baddeleyite and melting of quartz to lechatelierite. These petrographic features, currently regarded as unequivocal evidence for meteorite impact, can be preserved and recognized even in very old and deeply eroded structures. Such features have now been observed in more than 50 « crypto-explosion » structures ranging in size from 2 km to more than 60 km in diameter. The recent discovery of shock-metamorphic features in rocks of the Sudbury structure, Ontario, indicates that this old and complex structure was also produced by a large meteorite impact. Petrographic shock effects are widespread in inclusions of « basement » rock in the Onaping « tuff », a unit now regarded as afallback breccia deposited in the original crater immediately after impact. Similar shock effects also occur in the footwall rocks around the basin, associated with shatter cones and unusual Sudbury-type breccias. Study of Sudbury specimens has establishedgrades of progressive shock metamorphism comparable to those recognized at younger impact structures (Brent, Ontario; Ries basin, Germany). Igneous activity associated with known meteorite impact structures takes two forms:
- direct production of impact melt. At many structures (e.g., Brent, Ontario; Lake Mien, Sweden; Clearwater Lakes and Manicouagan, Quebec), breccias containing shock-metamorphic features occur with «sills» and «dikes» of fine- to medium- grained crystalline igneous rock. Such units, previously regarded as internal volcanic products, now appear to have been formed by complete fusion, injection, and rapid crystallization of large volumes of target rock during the impact event.
- emplacement of internally derived magma. The presence of the clearly internally-derived Nickel Irruptive within the Sudbury basin indicates that large meteorite impacts may also control the emplacement of internally-generated magmas through « unroofing » or by the production of deeply-extending zones of weakness below the crater.
13.
The study of rock stresses and their changes is of great importance for safety in mines. To detect dangerous stress accumulations in coal mines an empirical method, Jahn's drilling test, is generally used. An experimental survey to solve the same problem by geophysical measurements was undertaken in a Hungarian coal mine. The basic idea was to determine the easily measurable seismic velocities instead of the more difficult to measure stresses in the rocks, since there is a monotonic relation between them. During the survey seismic transmission-type measurements were carried out in the fore-field of longwall faces between the top and tail roads. The seismic velocity data obtained were processed using an iterative algebraic reconstruction technique to determine the ‘velocity field’, i.e., the seismic velocity distribution, of the area covered by the ray paths. By periodically repeating the measurements in the same area, it was possible to follow the changes in the stress conditions caused by mining operations. 相似文献
14.
Andrew J. Feustel Cezar-Ioan Trifu Theodore I. Urbancic 《Pure and Applied Geophysics》1996,147(2):289-304
Intrinsic and scatteringS-wave quality factors (Q
) were estimated using the Multiple Lapse Time Window Analysis (MLTWA) for microseismic events (M<–1) with source-sensor distances of 45 to 120 m, associated with an excavation at 630 m depth in Strathcona Mine, Sudbury, Canada. Additional information on the rock mass was provided by underground structural mapping data. IntrinsicQ
values, at 800 Hz, were on the order of 140, similar to quality factor values obtained in previous studies using Spectral Decay and Coda-Q methods (120 to 170). The scattering quality factor at this frequency was about 520. An observed frequency dependence of the scattering attenuation suggested that a decrease in the density of scatterers, with scale lengths on the order of 2 m, exists at the site. Characteristic fracture scale lengths were considered to range from 4 to 6 m as identified in the mapping data. These observations were supported by the increase in scattering found for seismic waves with frequencies less than 1000 Hz. By assuming that the identified scatters are characteristic faults, these scatterers can then be considered to increase nonsimilar behavior in source scaling. Overall, our results suggest that MLTWA provides a practical method for remotely characterizing the quality of a rock mass when visual observations are not attainable. 相似文献
15.
Research on seismic fluid identification driven by rock physics 总被引：8，自引：0，他引：8
Seismic fluid identification works as an effective approach to characterize the fluid feature and distribution of the reservoir underground with seismic data. Rock physics which builds bridge between the elastic parameters and reservoir parameters sets the foundation of seismic fluid identification, which is also a hot topic on the study of quantitative characterization of oil/gas reservoirs. Study on seismic fluid identification driven by rock physics has proved to be rewarding in recognizing the fluid feature and distributed regularity of the oil/gas reservoirs. This paper summarizes the key scientific problems immersed in seismic fluid identification, and emphatically reviews the main progress of seismic fluid identification driven by rock physics domestic and overseas, as well as discusses the opportunities, challenges and future research direction related to seismic fluid identification. Theoretical study and practical application indicate that we should incorporate rock physics, numerical simulation, seismic data processing and seismic inversion together to enhance the precision of seismic fluid identification. 相似文献
16.
By applying seismic inversion, we can derive rock impedance from seismic data. Since it is an interval property, impedance is valuable for reservoir characterization. Furthermore, the decomposition of the impedance into two fundamental properties, i.e. velocity and density, provides a link to the currently available rock‐physics applications to derive quantitative reservoir properties. However, the decomposition is a challenging task due to the strong influence of noise, especially for seismic data with a maximum offset angle of less than 30°. We present a method of impedance decomposition using three elastic impedance data derived from the seismic inversion of angle stacks, where the far‐stack angle is 23.5°. We discuss the effect of noise on the analysis as being the most significant cause of making the decomposition difficult. As the result, the offset‐consistent component of noise mostly affects the determination of density but not the velocities (P‐ and S‐wave), whereas the effect of the random component of noise occurs equally in the determination of the velocities and density. The effect is controlled by the noise enhancement factor 1/A, which is determined by a combination of stack angles. Based on the results of the analysis, we show an innovative method of decomposition incorporating rock‐physics bounds as constraints for the analysis. The method is applied to an actual data set from an offshore oilfield; we demonstrate the result of analysis for sandbody detection. 相似文献
17.
Induced seismicity in large-scale mining in the kola peninsula and monitoring to reveal informative precursors 总被引：1，自引：0，他引：1
Large volumes of rock mass, mined-out and moved within these deposits, resulted in irreversible changes in the geodynamic regime in the upper earth's crust of the adjacent territory. These changes manifest themselves in a more frequent occurrence of such intensive dynamic phenomena as tectonic rock bursts due to fault movement adjacent to the area which is mined-out and man-made earthquakes which sharply decrease mining safety and result in great material losses.To develop the prediction techniques of such phenomena, a monitoring system is created, based on the program of the Kola Complex of geodynamic measuring stations. Most of this system is realized in the region of the Khibiny apatite mines. The system provides regional seismological monitoring, local prediction of seismicity in separate areas of a rock mass and, determination of stress and strain in rock masses, local geophysical monitoring over the state of rocks in a rock mass as well as physical and mathematical modelling of geodynamic processes in the upper earth's crust.The investigations have resulted in the distinguishing of some regularities in manifestations of induced seismicity and tectonic rock bursts and in the determination of strain precursors of intensive seismic events in the Khibiny mines.The mechanism is provided by the induced seismicity which resulted from the anthropogenic impact on the geological medium. A geodynamic monitoring complex is described, which is used to reveal the precursors of powerful seismic eventsin situ, and monitoring results are shown, obtained in the Kola Complex of geodynamic stations. Methods of preventing tectonic rock bursts and induced earthquakes are presented. 相似文献
18.
Petrophysical evaluation and its application to AVO based on conventional and CMR-MDT logs 总被引：1，自引：0，他引：1
常规测井为 AVO 分析提供了基础的资料, 成为联系岩石物理与地震资料的桥梁。然而如果储层存在有复杂的流体系统, 如地层被严重地层流体侵入、电阻率响应低及盐水矿化度复杂等的现象, 则常规测井无法提供高质量的测井资料, 导致得出错误的弹性计算结果, 使 AVO 结果与地震资料不吻合。中国渤海湾地区第三系裂缝性储层复杂, 我们利用常规测井和核磁共振测井与模块地层动态测试相结合的组合仪完成了地层评价和储层描述。研究结果表明岩石物理学家利用上述方法技术可以获得诸如空隙度、渗透率、含水饱和度、束缚流体以及空隙压力等重要的储层参数并进一步综合应用这些结果和以实验室测量数据为基础的岩性分析结果进行在地震域岩石物理研究和 AVO 分析。 相似文献
19.
近十年来世界在地震各向异性与S波分裂研究领域取得的长足进展,特别是英国科学家将S波分裂理论与观测实验技术逐步引向地震预报研究的努力,说明S波分裂作为体波在各向异性介质中传播的最显著特征,可望提供地震波穿过岩石内部结构最可靠的信息,而震前应力变化最直接的效应将会改变裂纹的几何图象。S波分裂研究是伴随通讯革命在地球物理学领域内发展起来的前沿学科,其形成的高技术反过来又可能产生重大经济效益,特别对石油、地热、煤炭、工程等部门更是如此。通过对国内外大量有关文献的分析、比较和筛选,对无序的情报信息作了有序的浓缩加工,本文将看重概述地震各向异性与S波分裂研究领域的发展历史、S波分裂机理及近期研究成果、S波分裂在地震预报研究中的应用、以及各向异性与S波分裂研究的前景,并给予相应评述。 相似文献
20.
Summary The paper is intended as a contribution to the quantitative analysis of travel-time curves of seismic events recorded in the Ostrava-Karviná District (OKD). The input data represent a set of 2621 seismic events, recorded by the local seismological network of 26 mine stations DSLA and a regional diagnostic polygon consisting of five surface Lennartz stations. All the events were processed automatically in the Operational Seismological Centre of the Czechoslovak Army Mine in Karviná and stored in the seismological data base. The results are presented in the form of graphs of arrival times versus distance for the whole OKD, for two mines and one tectonic block.Travel-time curves of direct P and S waves, as well as of reflected and refracted waves are given. The direct P and S waves propagate well practically throughout the whole region studied, but their apparent velocities of propagation are affected by the properties of the rock medium.As a result of the complicated geological conditions, the recorded wave image is quite complicated. Methods of mathematical modelling, using kinematic and dynamic parameters of seismic waves, will have to be applied to identify the separate wave groups uniquely. 相似文献