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任务书学院 矿业学院 专业 采矿工程 班级 姓名 毕业设计（论文）题目：王楼煤矿16上煤开拓设计 二、毕业设计专题： 大采高工作面顶板破断结构与支护方法研究 三、毕业设计（论文）主要原始资料：（1）王楼煤矿精查地质报告； （2）王楼煤矿矿井初步设计；（3）现生产采区工作面回采作业规程、掘进作业规程等；（4）王楼煤矿16煤层底板等高线图及其他相关资料。四、毕业设计（论文）应解决的主要问题：（1） 16上煤开拓方案选择； （2）采区巷道布置及采煤方法选择； （3）通风与安全； （4）主要生产系统设备选型； （5）大采高工作面顶板破断结构与支护方法研究。 五、毕业设计（论文）附件（图纸、软件、译文等）：（1）开拓方式平剖面图； （2）采区巷道布置平剖面图； （3）大采高工作面顶板破断结构与支护方法研究； （4）译文。 六、任务发出日期： 毕业设计（论文）完成日期： 指导教师签字： 系主任签字： FROM: PURE AND APPLIED GEOPHYSICS,1998.6,10（1）：4165附录Use of Microseismic Source Parameters for Rockburst Hazard AssessmentJANE M. ALCOTT1, PETER K. KAISER1 and BRAD P. SIMSER2 1.Geomechanics Research Centre, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada. 2.Noranda Mining and Exploration Ltd., Brunswick Mining Division, P.O. Box 3000, Bathurst, New Brunswick, E2A 3Z8, Canada. Abstract：Since 1994 Norandas Brunswick #12 Mine has complemented their MP250/Queens Full Waveform seismic systems with an ISS (Integrated Seismic System). Time histories of ISS source parameter information form a component of the daily ground control decision-making. This paper discusses a methodology for microseismic hazard assessment, which filters ISS data using energy, apparent stress and seismic moment criteria to identify those events that are relevant for the assessment and decision-making process. Seismic events are classified into four groups: (1) no or minor hazard; (2) seismically-triggered, gravity-driven hazards; (3) stress-adjustment-driven hazards resulting in bulking due to rock mass fracturing; and (4) deformation-driven hazards exploiting existing rock mass damage. Three case histories from 19941996, for the 1000 Level South and the 850 Level at Brunswick Mine, are analyzed using this technique to calibrate and verify the proposed methodology.Key words: Rockbursts, hazard assessment, microseismicity, source parameters.Introduction Many research efforts have been directed toward eliminating, mitigating and minimizing rockburst hazard by improved mine design methods, design of energy absorbing or yielding rock support systems, and by better rockburst anticipation techniques (CAMIRO, 1997). Bursting conditions are usually not experienced early in a mines life; and thus little effort may be placed on preventing burst-prone conditions during mine planning. If problems are encountered later in mine life, it is often not possible to alter the mining method or sequence and ground control engineers may be forced to live with seismicity, requiring procedures to identifypotential rockburst hazards and to ensure adequate ground support to minimize risk. Norandas Brunswick no.12 Mine, located in Bathurst, NB, Canada, is a 9000 tonnes per day, zinc-lead-copper-silver operation. Brunswick has a history of microseismicity and has experienced rockburst-related damage to underground excavations. The mine has taken a pro-active approach to mitigating rockburst risk by complementing preventative mine design and ground support initiatives with a ground control program that provides 24-hour access to microseismic monitoring data. Brunswick employs three systems for seismic monitoring: Electrolab MP250 and Queens Full Waveform (FW) systems for event locations, and an Integrated Seismic System (ISS) for event locations and source parameter information. During the study period (19941996), normal daily microseismic activity averaged 400800 FW system triggers and 2040 ISS system triggers; however, these numbers could increase tenfold during periods of intense activity. Typically, 75% of these triggers are cultural noise, stemming from ore passes; fill raises as well as development and production blasts (HUDYMA, 1995). Daily data analyses, at the mine, consist of tracking variations in event location clustering and occurrence frequency, and ISS energy index and cumulative apparent volume time histories analyses. These analyses combined with underground observations currently form the basis for workplace closure and re-opening decisions. Time histories (VAN ASWEGEN and BUTLER, 1993) examine spatial and temporal source parameter variations to monitor rock mass behavior and to predict large magnitude seismic events (potential instabilities). Brunswick has successfully applied this approach, but felt it did not adequately capture or differentiate seismic hazards, largely because seismicity and seismically-induced damage are not restricted to large mangitude events (GIBOWICZ, 1990). HUDYMA (1995) wrote about seismic-ity at Brunswick, on an individual basis there is not a good correlation between the size of a seismic event magnitude and the level of damage that may be done. Accepting that current mining conditions and techniques cannot be changed to eliminate rockburst hazards, these hazards must be properly managed as part of a daily ground control decision-making process (e.g., temporary workplace closures and re-openings rehabilitation, support standard revisions). This paper presents a methodology to assess potential rockburst hazards using microseismic source parameters, which is designed to provide a simple but effective means for incorporating the most relevant source parameters into the daily monitoring and decisionmaking process. The ISS data and observed damage recorded at Brunswick Mine are used to calibrate and verify this methodology.1 Rockburst Hazard Assessment Quantitative seismology (MENDECKI, 1993) can be used to identify stress release(e.g., energy index, seismic energy), stress adjustments (e.g., stress drop or apparent stress) and ground deformation (e.g., apparent volume or seismic moment) indicators which are sensitive to changes in rock mass behavior (stress and strain). By 43 quantifying variations in these parameters within spatial and temporal frames of reference, a Rockburst Hazard Assessment (RHA) methodology was developed. This paper defines a hazard, from a mining perspective, as the potential for damage to an excavation which may impact on operational safety, costs and productivity. Time histories examine events by cumulative or statistical means toascertain overall trends, while minimizing fluctuations associated with individual events. The RHA technique uses an alternative approach whereby key events are identified by filtering data using three assessment criteria and then interprets the remaining events by assigning them to one of three characterstic types. The RHA approach is based on a rationale that links localized rock mass behavior, such as seismically-induced falls of ground due to rock mass shaking or bulking due to rock mass fracturing, to specific seismic events. This linkage implicitly assumes that there is a direct correlation between the source parameters of an individual event and the consequences as observed underground. If treated statistically, such linkages would be camouflaged by the averaging process.The following sections describe the theoretical basis of the methodology and the rationale for selecting energy, apparent stress and seismic moment criteria to describe and differentiate potential rockburst hazards. Ultimately, the goal of the RHA is to arrive at a means to assist the daily decision-making process through definition of operational guidelines to assess progressively worsening and improving conditions in seismically-active workplaces.1.1 Theoretical Considerations The RHA utilizes three assessment criteria: seismic energy; apparent stress; and seismic moment. These criteria were selected because scalar parameters can be more easily handled and thus lend themselves to routine analyses. Use of source model dependent parameters and seismic moment tensors has been deliberately avoided for this reason. The source parameter calculations employed assume that all events are caused by pure shear failure. From published seismological relationships (KANAMORI, 1977), it follows that the seismic energy (E) should be proportional to the product of stress drop (), the co-seismic slip displacement (D) and the area of the fault (A), although the nature of this proportionality depends on the frictional losses during slip. All future references to energy (E) refer to seismic energy as it is calculated by the ISS system and is defined in Equation (2) (MENDECKI, 1997). where P, SH and SV refer to the body wave components. Similarly, the seismic moment (M0) is equal to the co-seismic slip displacement (D), the source area (A) and the rigidity or shear modulus (G) of the rock mass containing these is micsource (AKIandRICHARDS,1980): All future references to seismic moment (M0) refer to seismic moment as it is calculated by the ISS system as an average value from P- and S-wave spectra. The stress drop () is a measure of co-seismic stress adjustment at the source, which is calculated based on a model-dependent source radius (0)(BRUNE, 1970; MADARIAGA, 1976). However, the apparent stress (), which is a measure of the average co-seismic stress adjustment is model independent, and thus a more reliable parameter (WYSS and BRUNE, 1968; GIBOWICZ et al., 1990). For typical conditions encountered in mining situations (URBANCIC et al., 1992) stress drop is proportional to apparent stress ssuch that: Assuming that apparent stress is proportional to stress drop, the co-seismic deformation (AD) can be described (from Equations (1), (3) and (4) in terms of energy and apparent stress or the seismic moment:AD is a measure of co-seismic deformation and the volume of rock it affects. In the energy versus seismic moment space (Fig. 1), the co-seismic deformation increases parallel to the =constant line and the co-seismic stress adjustment increases perpendicular to it. If this co-seismic deformation causes rock mass deformation, then the rockburst hazard potential (i.e., the potential for damage to an excavation) is a function of energy, apparent stress and seismic moment. In practice, an increase in either AD or can be interpreted as an increase in rockburst hazard potential because larger co-seismic deformations strain the rock mass more, or more volume of rock is affected, and larger stress adjustments associated with events of large apparent stress () result in stress redistributions that may bring the rock surrounding the event closer to failure. Hence, the rockburst hazard potential should be a function of energy and apparent stress or energy and seismic moment (Equation (5). The nature of this potential hazard therefore depends on the position of a seismic event in the EM0 space, which can be tracked using a seismic path concept.1.2 Seismic Path Concept Stress paths are commonly used in geomechanics to track changes in loading of an element of rock in the principal stress space. Similarly, the authors have considered the variations of energies and seismic moments, in the log Elog M0 space, using a seismic path concept. A seismic path consists of events, within a specified volume, plotted in energy-seismic moment space and connected sequentially in time (Fig. 2). A detailed analysis of the data presented on Figure 2 reveals two dominant seismic path trends: (1) movement sub-perpendicular to a line of constant , and (2) movement sub-parallel to a line of constant . Therefore, based on the methodology presented earlier and reflected in Figure 1,events exceeding a certain threshold are characteristic of elevated stress adjustments, which may cause damage to excavations in areas of highly stressed rock, and events exceeding a certain M0 threshold are indicative of large ground deformations, which may cause detrimental rock mass degradation and potential falls of ground.1.3 Assessment Criteria and the Establishment of RHA Thresholds The RHA methodology presented here utilizes Equation (5) or the three parameters (energy, apparent stress and seismic moment) coupled with the seismic path trends to assess potential rockburst hazards (i.e., seismically-induced falls of ground, bulking due to rock mass fracturing and deformation-driven hazards). By establishing thresholds for each of these three parameters, the potential hazards can be classified. The assessment criteria should be widely applicable; however, the thresholds employed by the RHA methodology will be site-specific. Each of the assessment criteria is explained in general terms and then selection of its threshold value for the calibration and verification case studies is described. It is anticipated that the criteria thresholds described in this paper would have to be adjusted for different rock mass and stress conditions. Aside from assessing rockburst hazard potential, the three criteria may also be employed to identify seismic events which have minor hazard potential. If there is insufficient co-seismic deformation or stress adjustment, conditions are not critical (Fig. 3a) (i.e., seismic activity poses only a minor hazard). Events with very low energy content cause little ground motion or low peak particle velocities and thus damage is unlikely. Similarly, an event having a small apparent stress will generate little co-seismic stress adjustment, and fracturing will be unlikely, and small seismic moments will result in minor rock mass deformation.Seismic path for the events recorded during the time period 15 December 1994 (1000 Level South).1.4 Energy Criterion As the energy level increases, so does the ground motion or peak particlevelocity (ppv). PERRET (1972) established that energy (E) is proportional to the product of the distance from source (R) and the peak particle velocity (v), and KAISER and MALONEY (1997) developed a scaling law to describe this relationship:where R is in m2/s and E is in MJ . KAISER et al.(1996) related the ground motion level (ppv) to anticipated rockburst hazards (e.g., falls of ground, bulking due to rock mass fracturing and ejection) and illustrated that as the ppv increases, the potential and type of hazard changes. First, low ground motion levels can trigger seismically-induced falls of ground. As the level increases, bulking due to rock fracturing is encountered, and at even higher levels rock ejection must be anticipated (Fig. 4). Therefore, the energy criterion is selected to characterize the trigger limit for the most prevalent or most critical rockburst hazard at a mine. Energies recorded at Brunswick vary from 101 to 107J. Based on this range of energy values, Figure 4 identifies seismically-induced falls of ground as the most likely rockburst hazard. This is consistent with the predominant observed damage mode (falls of ground, back failure and caving). Hence, an energy threshold for triggering of falls of ground must be chosen to cover the most sensitive or critical hazard type (Fig. 3b). Fracturing with rock mass bulking for higher energy events at close distances must also be anticipated as a potential hazard, again consistent with observations. However, this hazard will be assessed by an apparent stress criteria (Fig. 3c). According to Figure 4, rock ejection is an unlikely cause of damage at Brunswick Mine. BUTLER and VAN ASWEGEN (1993) demonstrated with data from two South African gold mines, that peak particle velocities of less than 0.001 m/s could trigger failures of marginally-stable blocks of rock. At a distance from the source of R=100 m with 6=0.001 m/s, Equation (6) yields an energy criterion of 1000 J. This value is shown on Figure 4 as ECRITICAL. When compared to the trigger limit for falls of ground, shown as 0.015 m/s (KAISER et al., 1996), this threshold should provide a reasonable filter for events that are not likely to cause falls of ground of the type experienced at Brunswick Mine. The energy criterion threshold (1000 J) was established to filter out events that have little impact at the workplace and thus was defined to identify events generating peak particle velocities in excess of 1 mm/s at a design distance of 100 m. From experiences in hard rock mines, these events are considered sufficient to trigger seismically-induced failures of a marginally stable block rock. This energy criteria threshold is supported by the case studies presented later in this paper.1.5 Apparent Stress Criterion The first trend identified by the seismic path analysis (Fig. 2) represents an increase in apparent stress or co-seismic stress adjustment with little accompanying change in seismic moment or co-seismic deformation. This is indicative of conditions in regions where stresses build-up and suggests an elevated fracturing potential (Fig. 3c). Although, apparent stress alone does not uniquely define an event in the EM0 space, it does fundamentally relate energy and seismic moment (Equation(4). Apparent stress is not a measure of absolute stress, however it is a measure of stress change and its magnitude has rockburst and support design implications. As apparent stress increases, larger energy dissipation demands are imposed on the rock and the ground support, and increases beyond its capacity will lead to an enhanced rockburst damage and fracturing potential. Since apparent stress is stress adjustment or stress change and additional increments of stress change lead to rock mass fracture and bulking, deformation of, and imposition of higher load demands on ground support. The impact of an increase in apparent stress on an opening or excavation depends on several factors. In the case of a stable, relatively-undamaged opening, large co-seismic stress adjustments would be required to cause fracturing. Whereas, for openings at depth or in areas of high extraction ratio, which have already experienced rock mass damage and deformation, minor co-seismic stress adjustments may result in damage. An apparent stress criterion of 7500 Pa was selected as threshold for stressrelated damage at Brunswick Mine. The apparent stress threshold was defined based on calibration with field observations to identify larger stress changes or adjustment events, which were considered sufficient to cause fracturing or rock mass bulking. The threshold was calibrated against the larger apparent stress and smaller seismic moment events that were observed on the abutment regions following failure, the migration of seismicity and the redistribution of stresses to those regions. Its effectiveness will be explored in the three case studies presented later.1.6 Seismic Moment Criterion The second trend, identified by the seismic path analysis (Fig. 2), represents sudden increases in seismic moment or deformation (AD; Equation (3).These events with large co-seismic deformation strain the rock mass. The impact of these strains depends on the degree to which the rock mass has already been damaged. If cumulative straining or deformation is high then the additional increment of deformation creates conditions conducive to deformationdriven hazards and enhances their potential (Fig. 3d). Aside from these hazards, large seismic moment events are indicative of major shear movements (fault slip) and thus pose an additional rockburst hazard (larger magnitude event). A seismic moment threshold of 8.81010 Nm was selected to filter theseevent types at Brunswick Mine. The seismic moment threshold was defined based on calibration with field observations to identify deformation-driven hazards and was calibrated against the larger seismic moment events that were observed in the stoping area where waste stringer crushing and large-scale failures occurred.Again, this threshold will be evaluated by the following case studies.1.7 Source Parameter Data Errors The Rockburst Hazard Assessment assesses rock mass behavior relative to critical thresholds of energy, apparent stress and seismic moment. In order to assess individual event source parameter values relative to critical thresholds, one must have a reasonable degree of confidence in the calculated event source parameters. It is recognized that variations in radiation pattern, attenuation and system sensitivity will affect these source parameter values. Even if one assumes an error of one order of magnitude on the calculated source parameter values, this should have little effect on selected energy and seismic moment threshold values, which were defined for energies and seismic moments that varied over eight and seven orders of magnitude, respectively. However, if microseismic data beyond event locations are to be of any use for mining and ground control decision-making, one must be able to use source parameter data either as calculated by the system or as calculated after manual processing, accepting the errors inherent in those calculations. 2 Assessment Methodology The three criteria and their thresholds are combined and applied to ISS data within regional polygons to filter out minor hazard potential events, and to classify the remaining events in one of the three categories: (1) seismically-triggered gravity-driven hazard potential, (2) stress-adjustment-driven hazard potential; and (3) deformation-driven hazard potential (Fig. 5a). Events exceeding the energy criterion (E) are considered indicative of a seismically-triggered, gravity-driven hazard potential (e.g., seismically-induced fall of ground). Events exceeding both the energy and the apparent stress criteria (E &) are considered indicative of a stress-adjustment-driven hazard potential (e.g., bulking due to rock mass fracturing). Events exceeding both the energy and the seismic moment criteria (E & M0) are considered indicative of a deformation-driven hazard potential (e.g., caving, back failure or large magnitude fault-slip rockburst). Events meeting or exceeding these criteria are plotted on Log Energy versus Time plots. The criteria employed,and symbols used to represent them, are shown in Figure 5a and a sample Log Energy versus Time plot is shown in Figure 5b. Blast times are shown by plus signs above the time axis. These plots are analyzed for precursory, failure and decay trends correlated to observed damage (shown as vertical dashed lines; Fig. 5b). Precursory trends are defined as warning signals consisting of a sequential spatial and temporal build-ups of indicators (i.e., EE & E& M0). For example, first exceeding a critical energy level, then a critical energy and apparent stress, and eventually, a critical energy and moment threshold; in short EE &E & M0. These trends identify the area as a region of elevated rockburst hazard potential, and indicate a progressive worsening of conditions and potential hazards from shakedown (E) to fracturing (E &) to deformation (E & M0) resulting in the exploitation rock mass damage. Conversely, decay trends refer to a progressive improvement of conditions represented by the sequential disappearance indicators (i.e., E & M0E & E). Events corresponding to these trends are then plotted on plans and sections for further analysis to identify regions of elevated rockburst hazard potential. The usefulness of the RHA is demonstrated in its application to three case histories, which consider two mining blocks and several time periods.(a) Characterization of microseismic events: exceeding the energy criterion (EECritical) as indicative of a potential for seismically-triggered, gravity-driven hazards; exceeding the energy and apparent stress criteria (EECritical and Critical) as indicative of a potential for stress-adjustment driven hazards;or exceeding the energy and seismic moment criteria (EECritical and M0M0Critical) as indicative of a potential for deformation-driven hazards. (b) Sample hazard assessment showing a precursory sequential build-up of indicators (E E &E & M0) prior to a failure (indicated by the dashed line) and followed by a sequential decay of indicators (E & M0 E & E) . 3 Case Histories Brunswick operates on three main production levels (725, 850 and 1000 meter levels). Three case histories are examined in this paper, two from 1000 Level South and one from the 850 Level (Fig. 6). Constant criteria thresholds (i.e., E=1000 J, =7500 Pa, M0=8.81010Nm) were employed in all three analyses. These thresholds were first selected empirically for one part of Brunswick Mine applying source parameter data and observed damage, and then calibrated for other parts of the mine.Vertical long-section of the Main Ore Zone (MOZ), looking West, indicating mining blocks. Stope caving and overbreak are indicated by lighter hatching. The rectangles indicate the 1000 Level South and 850 Level study areas. Geologically, the 1000 Level South consists of sulphide ore interfingered with waste meta-sediments and a porphyry dyke, and bounded by footwall and hangingwall sediments. Traditionally, ground control concerns have been attributed to the contrast between weaker meta-sediments and the more competent ore, resulting in squeezing of the meta-sediments and fracturing and seismicity in the ore. A typical fall of ground type failure at an intersection affected by a meta-sediment waste stringer is shown in Figure 7.3.1 The geology of the 850 block is similar to the 1000 Level. Ground control concerns are related to stope backs caving into the sill and hourglassing of stope sidewalls due to the creation of unfavorable mining geometries (i.e., slender pillar geometries for the secondary stopes).Intersection in 2387 Cross-Cut (X/C) (1000 Level South) following failure along the waste stringer.(a) Assessment criteria applied to all events; the rectangle highlights events meeting the criteria. (b)rockburst hazard assessment; dashed lines indicate failures and crosses indicate blasts.3.1 Case 1: 1000 Le6el SouthSeptember 1994 to January 1995 A total of 489 events from the time period 25 November 199425 January 1995 were analyzed. The events were filtered by applying the three criteria introduced earlier: energy (1000 J), seismic moment (8.81010Nm) and apparent stress (7500Pa)Figure 8a. This filtering identified 70 events which met at least the energy criterion. The assessment highlights a period of major activity associated with blast-triggered waste stringer mobilization (crushing) (Fig. 8b). Blast and failurelocations and dominant geological structure (waste stringer) discussed later are shown in Figure 9a. Figure 9b illustrates all 1000 Level South events recorded during this period. Two failures occurred during this period.A fall of ground in 33683cross-cut(X/C) and continued pillar deterioration in 2368 occurred on 30 November, 1994(indicated by the first dashed line in Fig. 8b). Two E & M0 indicators were recorded, one 5 days prior to the failure and another on the day of the failure. Neither of which was consistent with the failure location. The subsequent failures, 3358 Stope Back, continued failure of 3368 X/C and significant ground deterioration along 348 through 398 Stopes on 2 and 3 sub-levels, occurred on 5 December 1994 (second dashed line in Fig. 8b). In the five days prior to these failures, 10 indicators (6E, 2E & and 2E & M0) were recorded. These indicators corresponded to a systematic build-up of indicators or precursor (i.e., E E & E & M0) and were consistent with the subsequent failure locations, delineating these areas as regions of elevated rockburst hazard potential (Fig. 10a). On 5 December 1994, the day of the failures, 20 indicators were recorded(10E, 6E &, 4E & M0). These event locations are consistent with the significant ground deterioration observed between the 348 and 398 stopes on #2 and 3 sub-levels (Fig. 10b), and with the waste stringer (HW sediments and tuffs) orientation (Fig. 9a). Following the failures, December 6 to 26, 1994, there was a systematic decay of indicators (E & M0E & E) (Fig. 10c). E & M0 indicators decayed first over 9 days, then the E & |a events decayed over 16 days and E only events decayed over 21 days. These indicator locations corresponded to the decay of hazard indicators in the failed region and a migration of seismicity along the waste stringer to the adjacent abutments. The large deformation criteria events (E & M0), located along the Waste Stringer (Fig. 10c) are indicative of a deformation-driven hazard associated with crushing of the stringer and seismic migration to adjacent abutments (Figs. 10c and 8b). Interestingly, events located on the South Regional Abutment (Fig. 10c) satisfy the E &criteria; indicating loading without much accompanying deformation. This is indicative of a potential for a stress-adjustment-driven or fracturing hazard rather than a deformation-driven one, and implies a need for energy absorption capacity in HW access support. The rockburst hazard assessment technique significantly reduces data (to 14% in this case) for high activity periods while focusing attention on key events,which clearly pinpoint areas of elevated risk, allowing the ground control personnel to take appropriate actions.1000 Level South #2 Sub-level plan (a) Blasting (B), failure (F) and waste stringer locations. (b) All recorded events (25 November 199426 December 1994).Rockburst hazard assessment indicator event locations shown on #2 Sub-level plan and Main Ore Zone long section. (a) 25 Nov. 19944 Dec. 1994. (b) 5 December 1994. (c) 6 Dec. 199426 Dec. 1994. The thick black circle indicates the location of the 5 December 1994 failures.3.2 Case 2: 1000 Level SouthSeptember 1995 to January 1996 A total of 904 events recorded from 1 October 1995 to 31 January 1996 was analyzed. The events were filtered by applying the same criteria thresholds as before. Filtering results in 103 events, which met at least the energy criterion. Three failures occurred during this period. Blasting and failure locations and critical geology (waste stringer) referenced in the following discussion are shown in Figure 11.1000 Level #2 Sub-level plan blasting (B), failure (F) and waste stringer locations shown. In the three days prior to a 300 tonne rockburst in the back of 2398, 7 indicators were recorded (5E, 1E & and 1E & M0). On 29 November 1995, the day of the rockburst, 2 indicators were recorded (1E and 1E & M0). One energy indicator was recorded 4 days after the failure. Precursor, failure and decay events correspond to and clearly delineate the rockburst location as an area of elevated rockburst hazard potential (Figs. 12a,b).1000 Level South rockburst hazard assessment (26 November 19953 December 1995) indicator locations shown on (a) #2 Sub-level plan and (b) Main Ore Zone long section. The thick black circle indicates the location of the 28 November 1995 rockburst. There were few precursory indicators in the 5 days prior to 19 December 1995 failures (2378 Back Failure, 1398 Back Failure, 2388 HW ACC Back Failure and 2358 continued Back and HW Failure). Only 3 indicators (1E and 2E & M0) were recorded, one of which was located in the area of the subsequent 2388 HW Access Back Failure location (Fig. 13a). However, on the day of the failures, 41 indicators (22E, 7E & and 12E & M0) were recorded (Fig. 13b). The indicators recorded between 8 am12 pm on December 19 exhibited the typical precursory sequence (E E &E & M0) (Fig. 14). Many of these event locations corresponded to the waste stringer and were located in the affected failure areas, identifying these areas as having an elevated rockburst potential (Figure 13b).Rockburst hazard assessment indicator event locations shown on #2 Sub-level plan and Main Ore Zone long section. (a) 14 Dec. 199518 Dec. 1995, (b) 19 Dec. 1995, (c) 20 Dec. 19956 Jan 1996. The thick black ellipse indicates the location of the 19 December 1995 failures. There was a post-failure decay period (20 December6 January). During this period, events were primarily constrained to the waste stringer and there was again a visible migration of seismicity to both abutment regions (Fig. 13c). The decay pattern was as follows: E & over 2 days, E & M0 over 10 days; and E over 17 days.Hazard assessment indicator sequence on 19 December 1995, the day of the failures. Between 28 January 1996, a fall of ground occurred in 3348; however, there were no indicators directly associated with this failure location and time. The possibility that the failure could have been triggered by an event below the energy criterion was investigated (note that this area was affected by large deformation events in December 1994 (Fig. 10c). All recorded events within 100 m of the 3348 stope were examined in order to identify potential fall of ground trigger events, which would have been filtered out by the energy criterion (Fig. 15a). The identified events caused ppv(s) on the order of 0.1 mm:s. During the entire analysis period no ISS events were recorded in 348 (Fig. 15b); however, seismicity was recorded in the surrounding stopes, despite the fact that the waste stringer was being mobilized and was present within the stope. Based on the seismic evidence, 348 is interpreted as a failure due to gradual rock mass which yielded around the stope causing stress relaxation, which promoted gravity-driven failures. This failure in 3348 was most likely not seismically-triggered by an event occurring in the 1000 Level South.All events (a) 28 January 1996 and (b) 14 December 19956 January 1996 plotted on the c2 Sub-level plan.3.3 Case 3: 850 Le6el SouthSeptember 1994 to January 1995 A total of 578 events recorded from 21 September 1994 to 25 January 1995 were analyzed. The events were filtered by applying the same criteria thresholds as before. Filtering results in 40 events, which met at least the energy criterion. Two failures were recorded during this period. Blasting and failure locations discussed are shown in Figure 16. On 9 December 1994, there was a wall failure in the 2853 X:C. One precursory energy indicator was consistent with the location of the subsequent failure (Fig.17a). During the failure, 3 indicators (1E and 2E &) were recorded. These indicators delineated the 2853 X/C failure location (Fig. 17b), an area of elevated rockburst hazard potential. Failure and decay intervals run concurrently. The failure was both small, 23 tons, localized, occurring along a waste sediment/dyke contact, and resulted in neither seismic migration nor subsequent damage, suggesting that little stress adjustment was involved in this failure.850 Level 4 Sub-level plan blasting (B) and failure (F) locations shown. On 10 December 1994 failures were recorded in 2797 Cemented Rock fill (CRF) Wall Failure:3797 Hanging wall (HW) Failure. No indicators were consistent with these failure locations (Fig. 17a) and neither the 3797 HW nor the 2797 CRF locations were identified as areas of elevated rockburst hazard potential. The 2797 CRF failure was unlikely to have generated seismicity, although both failures could potentially have been seismically-triggered (e.g., shakedown failures). The possibility of seismically-induced failure triggered by an event below the energy criterion was again investigated. Inscribing a sphere of 100 m about 2797/3797 stopes, two events fell within the 100 m radius (Fig. 18a). The most likely trigger event occurred on December 10 (the failure date) at a distance of 56m from the failure location, with an energy of 53.1 J, which translates to a ppv of 0.33 mm/s (Equation (6). This event cannot conclusively be ruled out as a potential trigger for seismically-induced failure. Nevertheless, this example suggests that the rock mass was sufficiently damaged or deformed and that rather minor shaking could cause gravity-driven instabilities. From 19 December 1994 to 19 January 1995, there were no recorded failures. However, build-up and decay indicator trends were observed (i.e., E E &M0E). Indicator locations correspond to a band of pillars between 2801 and 2883 stopes (Fig. 17c), and identify them as areas of elevated rockburst hazard potential. E & M0 indicators (deformation) correspond to these pillar locations and locate along a waste (HW sediments and tuffs):ore contact. Therefore, these events may be indicative of pillar crushing or waste stringer crushing inside the pillar or in the footing of the pillar.Rockburst hazard assessment indicator event locations shown on #4 Sub-level plan and Main Ore Zone long section. (a) 24 Nov. 19948 Dec. 1994. The thick black circle indicates the location of the 9 December 1994 failure. (b) 911 Dec. 1994. (c) 19 Dec. 199419 Jan. 1995. The thick black ellipse indicates the location of the secondary stope pillars.All 850 Level events (a) 811 December 1994; the large circle indicates potential trigger events for the 2797/3797 failures and the black dot indicates the most likely trigger event, (b) 24 November 199419 January 1995 plotted on the #4 Sub-level plan. Figure 18b shows all 850 Level events recorded from 24 November 1994 to 19 January 1995. In total, 283 events were recorded of which 28 events met indicator criteria (10%).3.4 SummaryThe observed damage, the RHA indicators (precursory, failure and decay), the indicator sequences and the success of the RHA methodology, for the three case studies, are summarized in Table 1. Broadly, the failures analyzed can be classified as instances:（1）where seismicity leads to failure (e.g., rockburst damage to excavations) and the seismicity can be used to anticipate the failure and its precursor (e.g., the development of a state of elevated hazard potential); or （2）where previous seismicity has resulted in rock mass degradation and the failure occurs as the result of the degradation as opposed to seismicity recorded at the time of the failure. In these cases the seismicity is not likely useful for anticipating the failure or its precursor. Of the seven failures analyzed, five fall into the first category, and in four of the five cases the failure location was successfully identified by the RHA as an area of elevated rock burst hazard potential. The remaining two cases fall into the second category, where the failures appeared to be the result of progressive rock mass degradation leading to the loss of the rocks self-support capacity and resulting in gravity-driven failures. As such these failures were not identified as areas of elevated rockburst hazard potential by the RHA assessment. The RHA identifies both precursory (i.e., E E & E & M0) and decay (i.e., E & M0E & E) trends, which are indicative of a progressive worsening and improving, respectively, of conditions in seismically active areas.These trends and their indicators vary as a function of level of rock mass degradation. Typically, as degradation accumulates, the rock mass loses its capacity for stress transfer (e.g., stress redistribution and the migration of seismicity). This is captured by the absence of E & indicators in both the precursory and decay sequences (i.e., E E & M0 E). In addition to the absence of E &indicators, as rock mass degradation accumula tes, the duration of both the precursory (i.e.,from days to hours prior to failure) and decay intervals (i.e., from weeks where stress redistribution and migration occur to days where they do not) are shortened. The ability to identify areas of elevated rockburst hazard potential, coupled with rock mass condition dependent precursory and decay trends, makes the Rockburst Hazard Assessment ideally suited as a basis for closure/reopening and support requirement decision-making in seismically-active workplaces.4 Conclusions A rockburst hazard assessment technique is presented that is able to successfully delineate areas of elevated rockburst hazard potential, and which identifies precursory (EE &E & M0) and decay trends (E & M0 E & E) indicative of progressive worsening and improving conditions in seismically-active workplaces, at Brunswick Mine. The RHA establishes source parameter performance criteria and thresholds which can be (and have been) easily incorporated into the daily ground control decision-making process. This technique is intended for use with existing time history and event location analysis techniques. Linking hazard indicators with event locations provides a means to delineate indicators by mechanism; stress-adjustment-driven/abutment failures characterized by E & indicators, or deformation-driven/waste stringer instability defined by E & M0 indicators. The three cases presented illustrate the robustness and applicability of unique threshold criteria to different mining blocks. The same threshold values were shown to be applicable for the three case study areas, however different thresholds may have to be established for other mines or rock mass conditions. Differences in precursor and decay trends highlight variations in rock mass condition and failure mechanisms. This assessment procedure provides the basis for assessing support requirement because areas affected by critical seismicity can be identified. It also assists in defining a workplace closure/reopening policy based on spatial and temporal precursory trends and decay intervals. One caution is offered. An assessment of this nature places increased emphasis on source parameters; the quality of which relies on the quality of the acquisition and the data processing system. Lack of high quality data may lead to erroneous interpretations.FROM: PURE AND APPLIED GEOPHYSICS,1998.6,10（1）：4165译文：使用微震震源参数对冲击地压危险性进行评估摘要：1994年以来诺兰达的布伦瑞克12号矿使用MP250/全波地震系统与ISS（集成地震系统），取得了不错的成效。ISS的源参数信息成了日常地面控制决策的一个组成部分。本文讨论了微地震危险性评估，使用视应力与地震矩来对事件的相关性进行评估，并确定过滤ISS数据的方法。地震事件分为四组：（1）无或轻微的危险;（2）地震触发，重力驱动的危害;（3）由于岩体破裂膨胀，压力变化诱发灾害;（4）变形驱动增加现有岩体损伤的危险。1994-1996年三年的实践中，布伦瑞克矿的1000m水平南部与850m水平，使用这种技术来校准和验证，提出方法并进行了分析。关键词：冲击地压，危险评估，微震，源参数 引文 很多研究工作已经开始面向消除，减轻和尽量减少冲击地压危害，改良矿山设计方法，并通过更好的冲击地压预测技术（CAMIRO，1997）来吸收能量或设计岩石支撑系统。爆破条件通常影响矿工的日常工作，所以矿山的规划过程中要防止突发事件。如果后续工作中遇到问题，往往不可能改变开采方法或顺序，地面控制工程师可能也要被迫忍受地震，所以必须要求监测程序的严格，以确定潜在的冲击地压带来的危险，并确保有足够的地面保障以减少风险带来的损失。诺兰达布伦瑞克的12#矿，位于巴瑟斯特，加拿大，产量为9000吨/天，矿产铅锌铜银等。布伦瑞克有微震的历史，经历了与地下冲击地压有关的灾害。该矿采取了积极主动的方法，通过完善地面控制程序，提供24小时微震监测数据，采取有针对性的煤矿设计及地面保障措施来减轻冲击地压危险。布伦瑞克使用三个地震监测系统： MP250和奎因全波形（FW）定位系统，并且集成地震系（ISS）的活动地点和来源的参数信息。研究期间（1994-1996年），正常的微震活动在FW系统的触发器上平均为400-800， 在ISS系统触发器上平均为20-40;然而，这些数字可能会在激烈的活动期间增加十倍。通常情况下，这些触发器接收的75是生产的噪音，是矿石运输引起的，部分还来自于掘进和生产爆炸（HUDYMA，1995）。每日矿山的数据分析，包括跟踪变化的事件定位集群和发生频率，ISS累计能量数。这些分析结合地下观察决定基本工作面的关闭和重新开放。 时间历程（VAN ASWEGEN和BUTLER，1993）通过研究空间和时间源参数的变化来监测岩体的变化，并预测较大震级的地震（潜在的不稳定性）。这种方法已成功应用于布伦瑞克，但它没有充分反映或区分地震的危害，主要是因为地震和地震引发的危害不仅仅局限于大震级事件中（GIBOWICZ，1990年）。HUDYM（1995）在布伦瑞克的基础上写了一段关于地震的分析，“没有一个人可以把地震事件的大小（幅度）和破坏的程度之间的关系分析透彻。”目前的开采条件和技术，不能消除冲击地压的危害，这些危害必须作为日常地面控制管理过程（例如，临时工作面关闭和重新开放，使用修订的图纸）所考虑的一部分。本文提出了一种利用微震震源参数的方法，其目的是为了整合最有联系性的源参数纳入日常监管和决策过程中，利用简单有效的方法来评估潜在的冲击地压的危险。记录布伦瑞克矿ISS数据和观察到的损害来校准和验证这种方法。 1 冲击地压灾害评估 定量地震学（MENDECKI，1993）可用于识别应力释放（例如，能源指数，地震能量），应力调整（例如，应力降或表观应力）和地面变形（例如，表观体积或地震矩），它们是岩体活动（应力和应变）敏感的指标。通过定量变化的参考空间和时间框架内的43个参数，开发了一个评估冲击地压灾害（RHA）的方法。本文中，定义了一个危害，从开采的角度来看，作为危害，掘进可能对运营安全，成本和生产率产生影响。时间历程统计的方法，以确定总体趋势，同时尽量减少个别事件的影响。RHA技术使用一种替代方法，即关键事件是使用三个评估标准来筛选识别数据，然后将它们分配到三个特征类型中的一种，并解释其余的事件。RHA方法是基于局部岩体行为，如由于岩体摇动或岩体压裂填充剂，以特定的地震事件引起的突然变化。假定有一个单独的事件源参数和后果观察地下有着直接的关系。在统计处理过程中，这种联系将被做平均处理。以下部分描述了该方法的理论依据和选择能量，视应力与地震矩的标准来描述和区分潜在的冲击地压灾害的理由。RHA的最终目标是通过标准的定义协助日常决策过程，提高地震活跃工作场所的生产条件的一种手段。1.1 理论思考 RHA利用三个考核标准：地震能量，明显的压力和地震矩。这些标准被选中是因为可以更容易地处理标量参数，有利于常规分析。使用源模型相关的参数和地震矩张量就是刻意回避这个原因。源参数的计算假定所有的事件都是由纯剪切破坏引起的。从已出版的地震关系（KANAMORI，1977年），它遵循的地震能量（E）是与应力降（），同震滑动位移（D）和断层的区域面积（A）成正比的，这个比例取决于滑动期间的摩擦损失。E指地震的能量，因为它是由ISS系统计算和公式（2）（MENDECKI，1997）定义的。其中P，SH和SV指能量波分量。同样地，地震矩（M0）等于同震滑动位移（D），刚性或剪切模量（G），岩体含有地震源（AKI和Richards，1980）源区面积（A）的乘积：地震矩（M0）引用的所有参考地震矩是由ISS系统从P和S波光谱的平均值计算得出的。应力降（）是衡量同震应力调整的来源，它基于一个依赖模型的源半径0来计算（BRUNE，1970; MADARIAGA，1976）。然而，明显的应力（）是测量平均同震应力调整的独立模型所获得的更可靠参数（WYSS和BRUNE，1968； GIBOWICZ等人，1990）。在采矿的情况下遇到的典型条件（URBANCIC等人，1992）应力降正比于视应力：假定表观应力和应力成正比下降，同震形变（AD）可描述为（来自等式（1），（3）和（4）中的能量和视应力或地震矩的术语）：AD用来衡量同震变形和它对岩石体积的影响。在能源与地震矩的空间（图1）中，共震形变增大方向平行于（线性常数），地震应力增大方向垂直于共震形变。如果此同震变形导致岩体变形，那么冲击地压的潜在危险（为了发现潜在危险）是一个能量函数，即表现应力和地震矩的函数。在实践中，在任一AD或的增加可以解释为冲击地压的危险性变大了，因为较大的同震应变岩体变形更多，或者岩石的体积受到更大影响，更大的应力调整表示有明显应激事件发生（）。在应力上的重新分布可能会带来周边活动岩石的破裂。因此，发生岩爆的潜在危险应该是一种和表观应力或能量，地震矩有关的函数（见方程（5）。因此，这种潜在的危险性取决于可以使用路径追踪的EM0地震事件的空间位置。1.2 地震路径的概念 应力路径通常用于地质力学，用来跟踪在主应力空间内，一个岩石单元加载的变化。同样，研究人员考虑了能量和地震的矩变化，在E-M0研究日志中利用了地震路径的概念。地震波路径包括在指定的体积内发生的事件，绘制在能源地震矩的空间和时间顺序（图2）。对图2中数据的详细分析显示两个主要的地震路径的发展趋势：（1） 运动的路径恒定单调的垂直于；（2） 移动的路径恒定平行于因此,基于前面给出并反映在图1中的方法,事件超过某一阈值，是应力升高地调整，对发掘区的高应力岩石造成损害，事件超过某一阈值M0的特性是表示，可能导致状况不好的岩体破碎和地面沉陷。1.3评估标准和RHA阈值的建立 这里提出的分析方法，利用方程（5）或三个参数（能量，视应力，地震矩），加上地震路径趋势评估潜在的冲击地压灾害（地震引起的地面沉降，岩体破裂膨胀变形）。通过建立这三个参数的阈值，可区分潜在的危害。评价标准是广泛适用的，所采用的方法将分析特定的阈值。每个评价标准是对一些数据的解释和其阈值选择的校准，并验证所描述的研究案例。为获得标准的阈值，本文中将不断改变岩体的应力条件。1994年12月1-5日记录的地震路径（1000m水平南部） 除了评估冲击地压的潜在危险性，这三个标准也可以用来识别有轻微潜在危害的地震事件。如果没有足够的同震变形或应力调整，那么条件就变得不重要了（如图3a）（地震活动带来的只是一个次要风险）。非常小的能量引起小范围或低速度的地面运动，所以不可能避免损害。同样，一个小的应力变化会产生小的同震应力调整，虽然不会发生压裂，但发生小地震的同时会导致轻微的岩体变形。1.4 能量判据 随着能量水平的增加，地面运动和质点峰值速度（PPV）也变大。 PERRET（1972）发现能量（E）正比于能量源的距离（R）和质点峰值速度（v）的乘积。PERRET，KAISER和MALONEY（1997）开发了一种对数法来描述这种关系：其中，R的单位是m2/ S，E的单位是MJ。Kaiser等人（1996年）将地面运动水平（PPV）和预测冲击地压的危险（例如，地面沉陷，岩体膨胀和压裂）联系起来，还发现随着 PPV的增加，潜在的风险也会改变。首先，较轻的地面运动可以引发地面地震感应的变化。随着开采水平的增加，由于岩石压裂，必须在更高水平的岩石中预先喷射填充剂（图4）。因此，该选择能量准则用于在矿井中发现最普遍的或最主要的冲击地压危险。布伦瑞克矿记录的能量变化范围在10-1107J之间。基于该范围内的能量值，图4所示的冲击地压最可能带来地面沉陷。这与观察到的主要损伤模式（地面沉陷，崩踏和垮落）相一致。因此，必须选择用于触发地面沉陷的能量阈值来概括最敏感或严重的危险型（图3b）。岩体受到近距离高能量压裂而膨胀，必须作为一个潜在的危险来进行观测。这种危险将会由表观应力条件（图3c）进行评估。根据图4，岩石的抛射可能是造成布伦瑞克矿危害的原因。BUTLER和VAN ASWEGEN（1993）根据两个南非金矿矿山的数据证实，小于0.001米/秒的峰值质点速度就可能影响岩石的稳定。当R= 100米， = 0.001米/秒时，根据方程（6）得到1000J能量准则。图4显示的该值为关键。相比于触发地面沉陷的上限，如图为0.015米/秒（Kaiser等人，1996），此阈值不可能对布伦瑞克的地面沉陷做出一个合理的解释。能量准则的阈值（1000 J）的设立是为了筛选出对工作场所的具有影响很小的变化以确定危险的发生，因此该阈值被定义为在100米的距离内峰值粒子速度超过1毫米/秒所需要的能量。从坚硬岩石矿山的经验来看，通过矿山中的经验，一个稍微被破坏稳定的岩块是足以引发地震的。这种能量的标准阈值将支持研究本文在后面介绍的案例。1.5 表面应力准则 由地震路径分析确定的第一个趋势（图2）表明增加表面应力或同震应力，地震矩或共震形变也将变化。这表明在区域发生应力堆积的条件下，破裂水平位置会升高（图3c）。虽然，表面应力本身并不唯一地限定在E-M0空间的事件中，但是它从根本上涉及到能量和地震矩（式（4）。表面应力不是绝对压力的尺度，但它是应力变化的尺度，其大小对冲击地压和支护设计有影响。由于应力明显的增大，更大的能量消耗强加在岩石和地面支持上，超出了其承受能力将导致发生冲击地压危害和压裂的可能性增大。由于表面应力的调整和变化，应力变化的额外增量导致岩体产生裂隙和膨胀变形，并提高对地面支撑的负载要求。表面应力的影响取决于几个因素。在稳定的，相对完好开口的情况下，需要较大的同震应力调整才能引起压裂。而对于开口在深部或高回采率的区域，其已经经历岩体损坏和变形，较小的同震应力调整就有可能导致破坏。在布伦瑞克矿，7500Pa被选定为应力准则的损伤阈值。基于校准与实地观察，7500Pa被认为是足以引起破裂或岩体膨胀的明显压力，用来预测较大的应力变化或调整。阈值针对较大表观应力和在相邻区域观察到的以下故障：较小的地震时间，地震活动的迁移，并对这些区域的应力重新分配进行校准。其效果将在稍后给出的三个案例中进行研究探讨。1.6 地震矩标准 由地震路径分析确定第二个趋势（图2），表示地震矩或变形量突然增加（方程（3）。这些事件与大地震同震应变的岩体相关。这些岩石的影响取决于岩体已损坏到何种程度。如果累积应变或变形增加，那么有利于创造变形驱动条件和提高他们的潜在危害（图3）。除了这些危害，主要剪切运动（断层）会造成一个额外的冲击地压危险（幅度较大的事件）。在布伦瑞克矿中，过滤这些事件类型的地震矩阈值是8.81010 Nm。通过实地观察校准来定义地震矩阈值，以确定变形运动带来的的危险，针对在停止区域中观察到的更大的地震事件（纵梁破裂和大规模事故二次发生）来进行校准，该阈值将由下面的案例研究进行评估。1.7 源参数数据错误 评价冲击地压的灾害，评估岩体的行为与能量临界值，表观应力和地震矩有关。为了评估个别事件源参数的相对临界值，必须有一个合理事件的源参数的置信度计算。人们认识到，在变化的过程中，系统的衰减和灵敏度会影响这些源参数值。即使我们假设计算出的源参数值分别超过7和8个数量级的错误，对能量和地震矩阈值的影响不大。然而，如果任何活动超出开采和地面控制决策所使用的地点，微震数据必须使用源参数数据进行系统计算或手动处理，并接受计算固有的误差。2 评估方法 三个标准和它们的阈值结合起来，应用于多边形区域内，过滤掉较小的潜在危险性活动的ISS数据，并在三个类别外的其余的事件进行分类：（1）地震引起的潜在危险，（2）应力调整引发的潜在危险,（3）变形引发的潜在危险（图5a）。事件超过能量准则（E）被认为是引发地震和重力驱动的潜在危险的标识（例如地震引起的地面沉降）。事件能量超过表观应力的条件（E）被认为是应力调整引发潜在危险（例如，由于岩体压裂填充剂）的征兆。事件能量超过地震矩的标准（EM0）被认为是变形驱动引发潜在危险（例如，空间塌方，大幅度断层滑动，冲击地压）的征兆。达到或超过这些标准的事件都绘制在能量随时间变化曲线上。这些图是根据观察到的相关破坏前兆，衰竭和衰减趋势分析（用垂直虚线表示出;图5b）得出的。前兆趋势定义为连续的集中指标性预警信号（即，EEM0）。例如，临界能量超过第一水平，则临界能量和表观应力最终达到一个关键的能量和阈值；总之EE EM0。这些趋势表明随着冲击地压的升高，潜在危险的区域的面积也随之增加，而且来自震荡（E）的条件和潜在的危害逐步恶化压裂（E）变形（EM0）导致开采岩体遭受破坏。相反，衰减趋势是指由于连续降低的指标（即EM0EE）为代表的条件逐步改善。对应于这些趋势的事件，绘制图表并进行更深层次的分析，以确定冲击地压潜在危险高发的区域平面图和剖面图。RHA的用处体现在其应用到三个案例中的历史，其中考虑两个采矿区域和几个时期。（a）微震事件的特性：特定的标准（E ECritical）作为触发地震，引发重力危害的指标；特定的能量和视应力标准（E ECritical andCritical）作为应力调整引发潜在的危害的指标，或特定的能源和地震矩的标准（E ECritical和M0 M0）作为严重变形引发的潜在危害的标准。（b）评估样品的危险性表明一个前后积聚顺序的指标（EEEM0），之前发生的动态（用虚线表示）和随后的指标依次衰变（E M0EE）。3 历史案例 布伦瑞克矿有三个主要的生产水平（725m，850m和1000m水平）。在本文中分析三个案例的历史：两个来自1000m水平南部，一个来自850m水平（图6）。恒定的标准阈值（即E =1000J，=7500Pa，M0=8.81010Nm）使用于三个分析之中。这些标准首次使用布伦瑞克矿的一部分凭经验得出的源参数数据和观察到的破坏，然后对矿井的其他部分进行校准。主矿带纵长部（MOZ）中，向西部看，指向开采区域。采场崩落和超前开拓部分用轻微阴影表示。矩形表示1000m水平南部与850m水平的研究区域。 从地质学角度来看，1000m水平南部由硫化矿夹杂废物沉积物和斑岩脉，并被下盘和上盘的沉积物限制。传统上，地面控制更关注软弱沉积物和坚硬矿石，造成沉积物与矿石之间的挤压和压裂，造成地震。典型的地面沉降，在沉积物废弃物作用