ISSN 1062-7391, Journal of Mining Science, 2013, Vol. 49, No. 4, pp. 521–536. © Pleiades Publishing, Ltd., 2013. Original Russian Text © V.N. Oparin, A.F. Emanov, V.I. Vostrikov, L.V. Tsibizov, 2013, published in Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, 2013, No. 4, pp. 3–22.

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Kinetics of Seismic Emission in Coal Mines in Kuzbass V. N. Oparina,c, A. F. Emanovb, V. I. Vostrikova, and L. V. Tsibizovc a

N.A. Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Krasnyi pr. 54, Novosibirsk, 630091 Russia b Altay-Sayan Division of Geophysical Service, Siberian Branch, Russian Academy of Sciences, pr. Akad. Koptyuga 3, Novosibirsk, 630090 Russia c Novosibirsk Sate University, ul. Pirogova 2, Novosibirsk, 630090 Russia Received June 17, 2013

Abstract—The article gives the experimental evidence of effective use of the kinematic criterion χ , derived by Oparin for “apparent” velocities of pendulum waves based on deterministic description of seismic energy release in the Norilsk mine fields, in assessment of stresses and strains in coal beds in terms of the Polysaevskaya Mine, Kuzbass. Keywords: Seismic release development, kinematic characteristics, coupled pendulum waves, coal beds Breevsky and Tolmachevsky, Kuzbass, rockburst hazard criterion χ .

INTRODUCTION

Exploratory search of deep level Talnakhsky and Oktyabrsky Polymetal Mines revealed oscillatory mode seismic energy release in highly stressed rock mass, pendulum-like movement of fronts of the mining-induced seismicity in the vicinity of zones of clustered seismic events, with velocity of the order of 10–6—10–5 m/s along the rays from the seismic release zone center to the periphery, and migration of concurrent seismic events inside the clusters, with the velocity of the order of 10–2–10–1 m/s [1–4]. This discovery was scientifically explained and quantitatively described within the theory of pendulum waves [5–9]. According to this theory, a seismic process shall be analyzed as in a certain manner deterministic geomechanical–geodynamic process rather than a random chain of seismic events. On this ground, a mine seismicity data scanning method was proposed to detect slow pendulum waves [10] and a kinematic expression was derived for nearly all groups of pendulum waves in a highly stress rock mass structured as a hierarchy of rock blocks [11]. A criterion of stress– strain state of rock masses was introduced as a kinematic ratio of velocities of concurrent pendulum waves groups [1]: V χ (t ) = E (t ) , (1) VК where VE is the mean monthly velocity of migration of reduced seismic energy release center; VK is the “apparent” velocity of migration of the t-ordered series of seismic events within a monitored site of a rock mass (source zone). As shown in [1, 5, 6], this ratio characterizes connection between diameters of rock blocks and openings of joints—the statistically invariant distribution [12]. Pendulum waves are not carried by inconcrete “volume units” [13] but by rock blocks quite specific in size [11], being in translation and rotation motion nourished by the blocks themselves as in the chain reaction of falling dominoes. Kinetic theory of gases defines temperature as a value proportional to kinetic energy of atomic motion [13], but in the case discussed, it is the kinetic energy of rock blocks that move in space-limited environment as perfectly rigid bodies. In this content, the normalized inverse value of (1) may be assumed a “geomechanical temperature” of nucleating sites of high stress concentration. This theoretical research branch development is on the way [15]. 521

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1. ROCKBURST HAZARD CRITERION AND ITS ADAPTATION TO WORKING CONDITIONS IN COAL MINES IN KUZBASS

The method developed in [1–4] for geomechanical–geodynamic and seismic monitoring is based on “migration” velocity of seismic events in limited zones of higher seismic activity. The input data for the migration velocity calculation are VE and VK . According to [7], the translation and rotation motion of rock blocks and local redistribution of stresses induce seismic release (and electromagnetic release), propagation of which in space shows direction and velocity of displacement waves or strain waves. It is reputed, large rock block displacements recorded as energy-intensive seismic events are initiated by smaller internal block displacements recorded as less energy-intensive time-ordered seismic events. So, out of total series of seismic events, we can choose series limited in terms of energy criterion: Ei < E0 , where E0 is the “trigger” event energy; Ei is an i-th “trigger” event energy. Then, the “apparent” migration velocity of the i-th seismic event is: ( x j − x0 ) 2 + ( y j − y0 ) 2 + ( z j − z0 ) 2 VК = , (2) t j − t0

where x j , y j , z j , t j are the coordinates and time of a j-th seismic event; x0 , y0 , z0 , t0 are the coordinates and time of the strong trigger seismic event entailing lower energy seismic events. The mean monthly migration velocity VE of a reduced seismic events cluster is: ( xi −1 − xi ) 2 + ( yi −1 − yi ) 2 + ( zi −1 − zi ) 2 , (3) VЕ = ∆t where i is the number of a period; ∆t is the period duration; xi , yi , zi are the coordinates of the seismic cluster for the i-th period. The reduced seismic cluster is calculated as the weighted average (the weight is the energy of an event) geometrical center of seismic events recoded in the period ∆t0 . As the stress–strain state and rockburst hazard criterion, we use the ratio (1) as consisted with [1]. We tested the described approach in the conditions of Polysaevskaya Mine, Kuzbass, which is illustrated below. 1.1. Subject of the Research

Polysaevskaya Mine is the underground black coal mine located in Kuzbass, Kemerovo Region. The Kuznetsk Basin (Kuzbass) is the region of high-rate open and underground coal mining, which evidently exerts impact on the earth crust and stress state of rock masses and evokes increased seismic activity in the area [16–18]. On the top of it, the Kuzbass adjoins the tectonically active Altay–Sayan folded area. The seismicity analysis in the area of Polysaevo township [19, 20] showed three seismicity clusters that are spatially correlated with coal longwalls. The monitoring period (Aug 13, 2007 till Sep 11, 2007) covered longwalling in Breevsky coal seam and Tolmachevsky coal seam at the depth of 410 and 440 m below surface, respectively. 1.2. Geological and Mining Conditions

Enclosing rocks are interbedded layers of sandstone, argillite and siltstone. Between the operating seams and the daylight surface there are 4–5 worked out seams. Figure 1 shows the stratigraphic sections of the analyzed seams and enclosing rocks and their mechanical characteristics. The Breevsky coal seam operation started in 1974, the seam is methane and dust hazardous, rockburst hazardous downward from 150 m, methane and coal outburst hazardous downward from 560 m, is not prone to spontaneous ignition, ranked as gas coal, water inflow rate is 51 m3/h. The Tolmachevsky coal seam operation started in 1979, the seam is methane and dust hazardous, rockburst hazardous downward from 150 m, methane and coal outburst hazardous downward from 560 m, is not prone to spontaneous ignition, ranked as gas coal, water inflow rate is 17 m3/h. JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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Fig. 1. Enclosing rocks of (a) Breevsky and (b) Tolmachevsky coal seams: Protodyakonov’s hardness f ranges as 0.8–3.5 and 1.5–6.0, respectively.

Fig. 2. Routine maintenance schedule in (a) Breevsky and (b) Tolmachevsky longwalls: of routine maintenance.

shows periods

The round-the-clock operation takes 4 shifts/6 hours (see Fig. 2). One of the shifts is routine maintenance, no coal cutting is performed, between 8 am and 2 pm local time (GMT 0–6 am). The Breevsky longwall advance is 5 m/day (5·10–3 m/s), the coal cutter runs shuttle operation. The longwall width is 220 m, the coal cutter velocity is 100 m/h. The mine-out void roof is caved. The Tolmachevsky longwall advance is 5 m/day (5·10–3 m/s); the coal cutter breaks coal in the forward run, the backward run is idle. The longwall width is 260 m, the coal cutter velocity is 100 m/h. The mined-out roof is caved. 2. SEISMIC MONITORING AND GEOMECHANICAL INTERPRETATION

The Altay-Sayan Division of the Geophysical Service of the Siberian Branch of the Russian Academy of Sciences accomplished the comprehensive report on seismic activity in the Polysaevo township area. In the zone where underground shocks were felt, 8 seismic recorders Baikal-AS [21] were arranged; the other seismic recorders were placed 2–7 km away from the supposed seismic cluster area (Figs. 3 and 4), with the aim to improve location of seismicity sources and obtain more precise estimates of energy of the seismic events. Total seismic array used 20 recorders. Besides, regional seismic network stations courteously provided their data for the analysis. The seismic monitoring period lasted from Aug 13 to Sep 11, 2007. The data on seismic waves velocities were obtained with the help of the records of large-scale blasting in the Mokhovsky open pit located 5–6 km away from the zone of felt seismicity. The blasting was carried out on Aug 18, 2007 at GMT 05:33. JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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Fig. 3. Seismic activity recording array: 1:100 000).

is the station that recorded the open pit blasting on Aug 18, 2007 (S

Fig. 4. Map of clusters of seismic events.

Based on the processed seismic records, catalog of seismic events and map of their clusters were prepared. Nearly 400 seismic events had energy class 2–7. Figure 5 shows coordinates of seismic epicenters obtained using the method of seismic tomography with double differences [22]. 2.1. Calculation of Kinematic Characteristics

Interpretation of data on location of clusters of seismic events showed two seismically active zones in the area of the operating Breevsky and Tolmachevsky coal longwalls (Fig. 6). The time was reduced to Aug 13, 2007 GMT 00:00, i.e. prior to the recording of seismic activity began. The energy class of seismic events was calculated from the formula K = log10 E , where E is the energy of a seismic event, J. The wanted kinematic characteristics VE , VK were calculated for each seismically active zone. The temporal development of seismic activity is illustrated in Fig. 7. JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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Fig. 5. Clusters of seismic events by the seismic tomography method.

Fig. 6. Map of the seismic clusters:

seismic events.

Fig. 7. Temporal development of seismic activity: (a) cluster 1 (Breevsky longwall); (b) cluster 2 (Tolmachevsky longwall).

Calculation of VK is complicated in a certain degree as selecting seismic events groups is laborious because of wide range of energies of seismic events, and a trigger seismic event can be a triggered JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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event if it is an aftershock of a stronger seismic event, whereas low energy seismic events that are not aftershocks even more scatter the values of VK . In [22] such groups of seismic events were selected manually, and the apparent velocities were calculated using appropriate scripts and Excel. The present study authors processed the obtained catalog of seismic events using special Matlab program that greatly simplified the calculation of VK . The algorithm of apparent velocities is based on the assumption that the wanted VK is the peak value of distribution of all possible apparent velocities of all events inside the series composed of aftershocks of a strong seismic event (within a day after the trigger event) and lower energy class events. All seismic events recorded within a day after a stronger event, with lower energy class, are named a group. The aftershocks are assumed the evens that show in time t at a distance d from the trigger event so that VK = d / t assumes close values for all of the events. In this case, it is reasonable to assess the order of the value and track its temporal development. To do so, we are to plot distribution of the apparent velocities in each seismic event group. An example of the plotted distribution for a randomly chosen trigger event with energy class 5–6 is shown in Fig. 8. To estimate the order of the value of VK , we calculate a number of the apparent velocity values inside the interval with its center at the maximum of distribution log10 VK with the width 1. Then, the wanted distribution will be as shown in Fig. 9. Having calculated distributions for all seismic events, we plotted an overall distribution of actual apparent velocities with accuracy of the order for each defined cluster (see Figs. 10 and 11). Widths of the vertical bars in the plots are conventionally equal to unit; each vertical bar corresponds to a seismic event and, in point of fact, is a distribution of apparent velocities in the group of this event as in Fig. 9. This allows accurate to an order estimation of the value consistent with the maximum of distribution of VK values for each of the events.

Fig. 8. Distribution of apparent velocities in the seismic events group triggered by the seismic event with energy class 5–6 in cluster 1: means the number of the velocity values in the bin.

Fig. 9. Estimate of the peak value in the distribution of apparent velocities in the seismic events group triggered by the seismic event with energy class 5–6 in cluster 1: in the center the interval a is the bin composed of the values of VK that fall inside the interval; means the number of the velocity values in the bin.

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Fig. 10. (a) Distribution of apparent velocities for all events inside cluster 1; (b) number of these events; (c) classes of these events.

Fig. 11. (a) Distribution of apparent velocities for all events inside cluster 2; (b) number of these events; (c) classes of these events. JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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Fig. 12. Apparent velocities VK for the trigger events with energy class ≥ 6: (a) cluster 1; (b) cluster 2.

Withdraw trigger events with energy class less than 6 from the resultant plots, as well as the trigger events of the seismic series composed of less than 3 events. Maximum of the distributions of apparent velocities for the remaining events are shown in Fig. 12. As seen, the values of VK weakly change within the monitoring period; therefore, we assume the value of VK constant and equal its average value in each cluster: Cluster 1: VK = 〈VK 〉 = const = 0.0114 m/s; Cluster 2: VK = 〈VK 〉 = const = 0.0218 m/s. To assess time dependence of the kinematic criterion χ (t ) as put by (1), we follow temporal development of its part VE (t ) . It is worthy to note that VK assumes values close to those obtained in [1–4]. 2.2. Migration Velocities of Reduced Seismic Energy Release Centers

The kinematic characteristic VE was calculated from the formula: ( xi +1 − xi ) 2 + ( yi +1 − yi ) 2 + ( zi +1 − zi ) 2 , (3′) VE = ∆t 0 where i is the number of a period; ∆t0 is the period duration; xi , yi , zi are the coordinates of the energy release center for an i-th period. The period length ∆t0 varies versus temporal development of seismic events, frequency of the events and sizes of the seismic clusters. In the case discussed in the present article, seismic energy release sharply decreased in the routine maintenance period (see Figs. 13 and 14) [19]. For this reason, we assume a day period optimal for the calculations of the seismic energy release and the reduced seismic energy release center migration. In our case, each period contains at least on period of routine maintenance, and the effect of coal cutter operation mode on the seismic energy release is leveled to a certain extent. The i-th center of seismic energy release is taken the weighted mean center of energy release of events (similarly to center of mass) occurred in the i-th period: ( t0 + ti ; t0 + ti + ∆t0 ), t0 is the zero time (in our case, Aug 13, 2007 GMT 00:00), ti is the i-th period start time; t i +1 = t i + s , where s < ∆t0 is the time shift of the period. JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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Fig. 13. Hourly seismic energy release in cluster 1:

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routine maintenance periods.

Fig. 14. Distribution of seismic events versus time.

The reduced seismic energy release center coordinates ri = ( xi , yi , zi ) are found from the formula [10]: n

ri =

∑ rj E j j =1 n

Ej ∑ j =1

,

(4)

where n is the number; r j = ( x j , y j , z j ) are the coordinates; E j is the energy of the events recorded in the i-th period. The calculated values of the reduced seismic energy release center migration velocities are presented in Fig. 15. The average values of VE in the Breevsky and Tolmachevsky coal seams, respectively, were 5.6·10–3 andи 6.4·10–3 m/s. Figures 16 and 17 show migration trajectories of the reduced seismic energy release centers in clusters 1 and 2 for 1 day and 5 days period, respectively, to understand the general trend of migration of the seismic energy release within the analyzed seams. Typical size of migration domain of the seismic energy release centers is 500 m in cluster 1 and 400 m in cluster 2, and clusters 1 and 2 themselves are 1500 and 900 m in size, respectively. The ratio of the diameter of the seismic energy release area, D(i ) , to the diameter of the reduced seismic energy release center, ∆(i ) , for clusters i = 1, 2 is denoted as γ i = D (i ) / ∆ (i ) . Then, for cluster 1, γ ≈ 3 , for cluster 2, γ ≈ 2 . This characteristic describes localized state of the energy release center, that may be related with the mechanism of initiation of activation of seismic events and needs further analysis in terms of specific mining conditions. JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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Fig. 15. Migration velocity of reduced seismic energy release center versus time: (a) cluster 1; (b) cluster 2.

Fig. 16. Migration path of reduced seismic energy release center: (a) cluster 1; (b) cluster 2.

Fig. 17. Migration path of the reduced 5-day seismic energy release center: (a) cluster 1; (b) cluster 2.

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Fig. 18. Daily seismic energy release per time: (a) cluster 1; (b) cluster 2.

Fig. 19. Daily seismic energy release and higher energy events: (a) cluster 1; (b) cluster 2.

In general, direction of the migration path of the reduced seismic energy release center coincides with the assigned direction of the longwall advance as seen in Fig. 17, at the rate from 0 to 20 m per day (on the average 4 m/day), which also agrees with the average rate of the longwall advance. Hence, it is possible to deduce on the determinate connection between the parameters of longwalling and the concurrent seismic release. 2.3. Seismic Energy Release and Its Connection with Kinematic Criterion

Daily energy release inside the chosen zones is related with time as follows: n

W (ti ; ti + ∆t0 ) = ∑ E j ,

(5)

j =1

where n is amount of seismic events; E j is energy of seismic events recorded in the i-th period. Daily energy release characterizes overall geomechanical situation in rocks surrounding excavations (see Figs. 18 and 19). For instance, increased energy release raises probability of stronger seismic events with energy class above 6 (Fig. 19), that show as rock bursts and endanger mine safety. For the convenient comparison, the coupled plots of the energy release W (t ) and the seismic energy release center migration velocity VE (t ) are shown in Fig. 20. As seen in Fig. 20, increased seismic energy release is generally associated with the higher energy events, e.g. 21st day in cluster 1 and 6th day in cluster 2. It is shown in [1–4] that rockburst hazard in the Norilsk mines relates with the decrease in the kinematic criterion χ (t ) = VE / VK . According to the above data, VK (t ) = const in each monitored zone in the coal seams, therefore, χ (t ) and VE (t ) behave the same way. JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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Fig. 20. Seismic energy release center migration velocities VE and daily energy release W : (a) cluster 1 (Breevsky coal seam); (b) cluster 2 (Tolmachevsky coal seam).

The lower VE (t ) fit the peaks of W (t ) in Fig. 20. We correlate these parameters using the grad correlation coefficient by Spearman in each cluster zone [24]: c = 1−

where

∑d2

6∑ d 2 n(n 2 − 1)

,

(6)

is the sum of squared differences of grades; n is quantity of the values to be compared.

After the calculations using (6), we have c1 = − 0.44 in cluster 1 and c 2 = − 0.53 in cluster 2. These values suit the average closeness of the found relationship. 3. DISCUSSION AND GENERALIZATION OF THE RESULTS

So, it has been found in terms of the monitored Breevsky and Tolmachevsky coal seams in the Polysaevskaya Mine that migration velocities of reduced centers of daily seismic energy release correlate with the overall level of seismic energy release (the grade correlation coefficients are 0.44 and 0.53, respectively). In this case, the rockburst hazard criterion χ appears of use to forecast strong seismic events within the coal mine field. The kinematic parameter VK (t ) in expression (1) for χ is the constant value: 〈VK 〉 ≈ 0.014 m/s in the Breevsky coal seam and 〈VK 〉 ≈ 0.0218 m/s in the Tolmachevsky coal seam. Consequently, the rockburst hazard in the monitored seams can be described by the other kinematic characteristic in (1), i.e. the daily migration velocity of the reduced seismic energy release center, VE (t ) . In the observation time period, VE (t ) ranges to 4.5·10–3 m/s in JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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the Breevsky coal seam ( 〈VE 〉 ~ (0.5 ÷ 1) ⋅ 10 −2 ) and to 2.8·10–3 m/s in the Tolmachevsky coal seam ( 〈VE 〉 ~ 0.005 − 0.01 ). Finally, place 〈VK 〉 and 〈VE 〉 in (1) and obtain: 〈V 〉 ⎧0.36 ÷ 0.71 (average 0.54), 〈χ〉 = E ≈ ⎨ 〈VK 〉 ⎩ 0.23 ÷ 0.46 (average 0.35) in the Breevsky and Tolmachevsky coal seams, respectively. Thus, by χ , the Tolmachevsky seam is more rockburst-hazardous than Breevsky (0.35 < 0.54). Within the boundaries of the Tolmachevsky coal seam, energy classes of major seismic events are high, from 3 to 7, which also implies higher rockburst hazard in this seam. The increased seismic energy release in the discussed coal seams, as against the Talnakhsky and Oktyabrsky polymetal ore mines [1–4], is explained by different mining rates and technologies applied, as well as different physico-mechanical properties of rocks and occurrence depth [25, 26]. On this base, we introduce a new definition—relative seismic energy release hardness coefficient λ for seismically active zones i and j:

∑ λ (i, j ) =

N (i ) k =1

E k (i )

V (i ) N (i )

∑ /

N ( j) k =1

E k ( j)

V ( j) N ( j)

,

(7)

where i and j are seismically active zones under comparison; V(…), N(…) and E(…) are, respectively, volume of a zone (m3), amount of seismic events and their energy (J) within these zones. Normalizing in a certain manner denominator in (7) will allow introduction of the absolute seismic energy release hardness. With reference to the seismic energy release hardness, under notice come the relations of characteristic linear dimensions of analyzed zones in projections individually for each of the discussed coal seams: diameter of total area of seismic energy release, D1 ; diameters of on-day seismic energy release center migration, D2 , and 5-day seismic energy release center migration, D3 ; and the longwall width D0 (refer to Figs. 6, 16 and 17). These diameters are assessed by the length of the diagonals of the minimum area rectangles containing the described domains. • For the Breevsky coal seam: D0 = 220 m, D1 ≈ 2121 m, D2 ≈ 846 m, D3 ≈ 265 m. It follows thence: D1 D2 D3 ≈ 9 .6 ; ≈ 3 .9 ; ≈ 1 .2 . D0 D0 D0 As seen, the diameter of the induced seismicity cluster in the Breevsky seam is 10 times larger than the working longwall width and the diameter of the 5-day seismic energy release center migration domain is almost equal to the longwall width. • For the Tolmachevsky coal seam: D0 = 260 m, D1 ≈ 2121 m, D2 = 500 m, D3 = 150 m. It follows thence: D1 D2 D3 ≈ 4; ≈ 1.92 ; ≈ 0.58 . D0 D0 D0 In this case, the diameter of the induced seismicity cluster is 4 times larger than the longwall width whereas the 5-day seismic energy release center migration domain is nearly twice as little the longwall width. JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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Using canonical scale of structural hierarchy imaging with the base 2 [27, 28] and Di (i = 0, 1, 2, 3) allows: • for the Breevsky seam: D1 ≈ D0 ( 2 ) 6 ; D2 ≈ D0 ( 2 ) 4 ; D3 ≈ D0 ( D0 ≈ 220 m); • for the Tolmachevsky seam: D1 ≈ D0 ( 2 ) 4 ; D2 ≈ D0 ( 2 ) 2 ; D3 ≈ D0 ( 2 ) −2 ( D0 = 260 m). It is apparent that the exponent at the base 2 can be used as the measure of “attraction” (minimum values) and overall influence (maximum values) exerted by the working longwall on the nonlinear geomechanical processes in the surrounding rock mass. Linear scales of the influence domains in the considered seams differ nearly two times despite the close values of widths of the working longwalls. This means that the high stress concentration area is two times nearer to the working longwall in the Tolmachevsky seam than in the Breevsky seam. Taking this into account together with the different occurrence depths of the studied seams allows explaining the harder seismic energy release mode in the Tolmachevsky coal seam. In the context of the cause and effect, of interest are the relations of the kinematic characteristics of the compared coal seams: average longwall advance rate 〈 v1 〉 , average cutter-loader velocity 〈 v2 〉 , 〈VE 〉 and 〈VK 〉 in the monitored zones. • In the Breevsky coal seam (see Fig. 15a): 〈 v1 〉 ≈ 5 m/day ≈ 5.8·10–5 m/s; 〈 v2 〉 ≈ 100 m/h ≈ 2.8·10–2 m/s; 〈VE 〉 ~ 7.5·10–3 m/s; 〈VK 〉 ≈ 1.4 ⋅ 10 −2 m/s. These estimates imply that 〈 v2 〉 , 〈VE 〉 and 〈VK 〉 not only belong to the same order but have close absolute value, 0.5–3)·10–2 m/s, within the confidence interval limits. On the other hand, we have: 〈 v1 〉 ∈ (0.2 ÷ 1.2) ⋅ 10 − 2 ( j = 2, E, K). 〈v j 〉 • In the Tolmachevsky coal seam (see Fig. 15b): 〈 v1 〉 ≈ 5 m/day ≈ 5.8·10–5 m/s; 〈 v2 〉 ≈ 100 m/h ≈ 2.8·10–2 m/s; 〈VE 〉 ~ 7.5·10–3 m/s; 〈VK 〉 ≈ 2.2 ⋅ 10 −2 m/s and the same estimate: 〈 v1 〉 ∈ (0.2 ÷ 1.2) ⋅ 10 − 2 ( j = 2, E, K). 〈v j 〉 The presented estimates of the kinematic characteristics 〈 v1 〉 and 〈 v2 〉 almost coincide with the geomechanical invariant µ ∆ (δ ) in high stress geomedia [12], which is the statistic distribution of ratio of the average opening of joints to the size of geoblocks, besides, it greatly depends on the stress–strain state of rocks [7]. CONCLUSIONS

The experimental research and its analysis allows the conclusion that the criterion χ offered to assess rockburst hazard in polymetal ore mining with drilling-and-blasting in the Talnakhsky and Oktyabrsky Mines is applicable to coal mines in Kuzbass. The expression of χ contains kinematic JOURNAL OF MINING SCIENCE Vol. 49 No. 4 2013

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characteristics of migration of seismic emission clusters within the bounds of the coal seams Breevsky and Tolmachevsky of the Polysaevskaya Mine are directly connected with the longwalling regime in the mine. This connection is based on the geomechanical invariant µ ∆ (δ ) that describes statistical ratio of average opening of joints and dimensions of rock blocks in high stress rock masses and is a key element of the pendulum waves theory now under development [8, 29]. ACKNOWLEDGMENTS

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