Sismiscs Effects of Blasting

8/10/2019 Sismiscs Effects of Blasting

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R E S E A R C H O N T H E S E I S M I C

I N T H E M I N I N G I N D U S T R Y

E F F E C T S O F B L A S T I N G

V. N. M o s l n e t s a n d E. I . S h e m y a k i n UDC 622.235:344.3

Contemporary ore mining is one of the most active fields in the use of blasting in the national economy, inwhich theoretical solution and practical realization have been effected for two very important scientific-technicalproblems - to attain a given degree o f crashing of rocks by blasting and to protect engineering constructions andexposed rocks from file seismic action o f the blast. The solution of problems in the seismic effects o f mine blastsis playing an important part in the successful development of contemporary mining production.

1. The impor tance and industrial necessity of solving problems in the seismic effects o f mining blasts incontemporary conditions is due to the fact that at the beginning of the nineteen sixties there were perfected veryefficient high-output roller-bit drills for open-cut mining and pneumatic-percussive and percussive-rotary drillingrigs for underground rocks. As a consequenc e, in the mines there arose the possibility of drill ing lar ge volumes ofrock, and this entailed the necessity of reconsidering the accepted, and creating fundame ntally new, t echnol ogicalmethods of working mineral deposits. Thus, in open -cut mines there appeared systems of working with multirowblasting of benches, blasting in enclosed media, and blasting with preservation of the geological structure of the ore

masses. In underground mining, wi de acce pta nce was obtaine d for systems with massive breaki ng-dow n of ore -sublevel and level forced caving, subdrifts and crosscuts, and caving of strata. The fundam ental dist incti on of thesesystems of working for ope n-c ut underground mine workings is that their e ffe cti ve actio n is possible only under thecondit ion that there is a sharp rise in the amoun t of simultan eously exploded cha rges. In a short time, the weight ofsimultaneously exploded charges necessary to attain an effective mining technology rose from 20-30 to 200-300tons, and in some cases to 500-1000 tons in open-cut mining [1-3]. and from 5-6 to 20-50 tons, in some cases to50-200 tons. in undergound mini ng [4, 5]. The sharp rise in the amount of explosives simultaneous ly detonate dplaced before the blasting theoreticians and practical workers a number of fundamentally new problems in the as-sessment of the seismic action of the blast; though the "Unified Safety Rules" might ensure safety, they did notpermit effective blasting under these conditions.

Th_us, pract ical problems of estimati ng the seismic ef fect o f a blast, arising as a consequence of the devel op-ment o f production, made a powerful impa ct on the broad development o f research on the seismic effects of blast-

ing in many institutes of the Soviet Union. The problem of the seismic action o f blasting in ore mines has been acontinual object of attention by scientists, engineers, and miners.

Together with the problem of attaining a given degree of crushing of the rock by blasting, there has been acomm on front of research on the n ati onal -eco nomi c use of blasting, in which a good deal o f success has recent lybeen achieved.

A great part in the development of research on the seismic effects of mine blasting has been played by the9 Institute of Physics of the Earth of the Acad emy of Sciences of the US~t rIPE A S USSR) where scientists ha ve sy stem ati cal ly

directed the inception and continuation of many investigations [6]. At the First All- Union Seminar on the SeismicEffects of Mine Blasting, orga nized by the IPE AS USSR in February 196,3. M. A. Sadovskii. S. V. Medvede v, D. A.Kharin, and others formulated for the first time those importa nt problems in the study of the se ismic pattern ofblasting to the solution of which many investigations have l ater been directed at the institutes of the Academi es of

Sciences of the USSR. the Ukrai nian SSR. the Kaza kh SSR. and the Klrgiz SSR, toget her with branch institutes ofmining and teaching institutes. An important role in the formulation of problems in research on the seismic actionof blasting has been played by the production undertakings themselves, which have been led by the necessity of

I ns ti tu te f M i n i n g M o s c o w N o v o s i b i r s k. Tr a n s l a t e d f r o m F i z i k o - Te k h n i c h e s k i e P r o b l e m y R a z r a b o t k i P o l e z -

n y k h I s k o p a e m y k h N o . 4 p p . 5 8 - 6 5 J u l y - A u g u s t 1 9 7 4 . O r i g i n a l a r t i cl e s u b m i t t e d A p r l l 2 2 1 9 7 4 .

9 1 9 75 P lenum P ubl ish ing Corporat ion , 22 7 West 17 th S t reet , N ew York , N. Y. 10011 . No par t o f th is pub l icat ion ma y be repduced , s to red in a re tr ieval sy stem, o r t ransmi t ted , in any fo rm or by any means, e lect ron ic , mechan ical , pho toco pying , micrf i lming , record ing or o therwise, wi th ou t wr i t ten permiss ion o f the publ isher. A cop y o f th is ar t ic le is available f rom the pub l i shfor $15 .00 .

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solving practical problems of production, namely, the seismic action of a blast near populated bui lt-up areas or incombined open- cut and underground mining, the stability of the sides o f deep open mines, e tc.

As a consequence of the formulation of the practical requirements of the problems, since the beginning ofthe nineteen sixties, in many undertakings the efforts of the research and teac hing institutes hav e been bent towardsbroad seismological research. The results have been very fruitful and have made a large econo mic saving thanksto the increased weight of simultaneously exploded charges, the preservation of engineering objects surrounding theundertaking, and the add ition al bri nging into p roduction of ore resources which had previously been lost in the ground,in connection with the newly opened possibilities of solving problems in mining seismics of repeated or combinedworking of deposits.

Important results in the seismic effects of mine blasting have been obtained by the Sverdlovsk group of inves-tigators [7-11] who have developed a number of fundamentally new recommendations on the stability of buidings,structures, and quarry sides, and have eluci dated the features o f the sei smic ac tio n of borehole charges spread overthe front of a mi ne working, and also the features of the seismic actio n of blasts with combined open -cut and under-ground mining such as those in the Ural Ore-Mining Combines.

A large contribution to the study of the seismic effects of mining blasts has been made by the Branch Labora-tory of Seismics and Acoustic Measuring Methods of Investigation of the Magnitogorsk Mining-Metall urgical Institute[12, 13], at which there have been developed new ideas on the seismic ac tio n of blasts with short- dela y blasting,on the stability of buildings, structures, and underground pillars; studies have been made on blasting in frozen ground,and some theories have been developed on the control of the seismic action of blasting in relation to the amount offree surfaces and the direction of development of the detonation.

Important research on the seismic action of blasting has been undertakenlby scientists at the Institute of PhysicsandMechanic s of Rocks of the Ac ade my of Sciences o f the Kirgiz SSR [14-17] , who ~have studied the seismic acti onof blasting with propagation of a seismic wave through worked-out mine workings and underground cavities, havedeveloped methods of screening seismic waves in the buildin g-up o f limiting sides of quarries and slopes of hydro-technical constructions, have created theoretical methods of determi ning the parameters o f seismically safe blastingwith combined production in open-cut and underground mine workings over stowed and caved cavities, have createda classification of the seismic stability of structures under the maxi mum permissible elastic deformation and ve loc -ity, and have on this basis calc ulat ed the safe sizes for the charges.

Important research on the seismic effects of mine blasting has been carried out at VNIItsvetmet Instituteat Ust -Kamenogorsk [18-19], where fundamental investigations have been made on the seismic act ion of blastingwith short-delay detonation and on the propagation of seismic waves in fissured media, recommendations have beenmade on the normaliz ation of the parameters of the seismic action, and the spectral characterist ics of the blasthave been deeply studied.

Important research on the seismic effects of mine blasting in open-cut and underground mines has been doneat the Scientific-Research Institute for the Problems of the Kursk Magnetic Anomaly [20, 2t], where scientificallybased recommendations have been developed for estimating the seismic stability of pillars between rooms, blocksof untouched ore, mine workings, sides and slopes of quarries, buildings, and surface structures. An impo rtan t resultof the work of this institute is the creation of the first classification of engineering methods of controlling the seis-mic action of a blast, which is now used by many organizations.

A definite contribution to the solution of production problems in mine blasting seismic effects has been madeby the Institute of Mining of the Academy of Sciences of the Kazakh SSR [22], where work has been done to assessthe seismic stability of pillars and blocks of untouched ore in the operation of blasting in the Dzhe zkazgan Combi neand various other undertakings.

Interesting work on the practical estimation of the seismic action of blasting in open pits has been done inthe UkrNIIproekt Institute [23] and at the Dnepropetrovsk Mining Institute.

A brief survey of the work done by these collectives reveals successes in the study of the seismic effects ofmine bl astin~ the first results of which were reported to the All-Union Conference on the Seismics of IndustrialBlasting in December 1966 at Sverdlovsk. At present we can assert that we have avail able practical scienti ficallybased methods for solving complex engi neeri ng problems in assessing the seis mic act ion of blasting, on the followi ngbases:

a) for quantitati ve estimation o f the parameters of blasting in the general case, the corrected weight of

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c h a r g e s i n o n e d e l a y p e ri o d , a n d i n t h e c a s e o f d i s tr i b u te d c o l u m n c h a r g e s , t h e w e i g h t o f c h a r g e s p e r u n i t l e n g t ho f t h e f r o n t ;

b ) a s a c r i te r i o n o f s e i s m i c s a f e t y, t h e p e r m i s s ib l e v e l o c i t y o n t h e w a v e f r o n t, w i t h a d d i t i o n a l i n f o r m a t i o nt h e p e r i o d o f s e i s m i c v i b r a ti o n s ;

c ) t h e w e i g h t o f t h e c h a r g e f o r o n e d e l a y p e r io d w i t h s u b s e q ue n t b r i e f - d e l a y b l a s t in g is ch o s e n b y t h e t wt h i rd s r o l e f r o m a n i s o la t e d c h a r g e ; o n c o n d i t i o n t h a t th e d e l a y i n t e r v a l e x c e e d s t h e d u r a t i o n o f t h e p o s i t i v e p ho f t h e s e i s m i c v i b r a ti o n s , t h e n u m b e r o f s u c hsu essivelye x p l o d e d c h a r g e s is u n l i m i t e d ; w h e n t h e d e l a y i n t e r v a li s l e ss th a n t h e d u r a t i o n o f t h e p o s i t i v e p h a s e , t h e t o t a l n u m b e r o f c h a rg e s m u s t b e l i m i t e d t o 8 - 9 d e l a y s t e p s ;

d ) t h e p e r m i s s ib l e c h a r g e w e i g h t is li n e a r l y r e d u c e d a s t h e p o t e n t i a l e n e r g y o f t he e x p l o s iv e s i n c r ea s e s i nr e l a t i o n t o A m m o n i t e N o . 6 , a n d v i c e v e r s a ;

e ) i n m u l t i p l e b l a st in g , t h e p e r m i t t e d c h a r g e w e i g h t is r e d u c e d i n p r o p o r t io n t o t h e n u m b e r o f e x p lo s i o n s ;

t9 a s t h e a m o u n t o f fr e e s u r fa c e o n w h i c h t h e e x p l o s i v e c h a r g e a c t s i s i n c r e a s e d , t h e p e r m i s s ib l e w e i g h ti n c r e a s e s i n p r o p o r t i o n t o o n e q u a r t e r o f th e s q u a r e o f th e a m o u n t o f f r e e s u r f a c e s ;

g ) w h e n s e i s mi c w a v e s a r e p r o p a g a t e d t h r o u g h s c r e e n i n g i n t e r l a y e r s , c a v i t i e s , o r u n d e rg r o u n d w o r k i n g s , t hp e r m i s s ib l e c h a r g e w e i g h t c a n b e i n c r e a s e d b y a f a c t o r o f 2 - 4 , a c c o r d i n g t o t h e s c r e e n i n g c a p a c i t y o f th e o b s t a c

I n th e s e c a s e s i t i s d i f f i c u l t t o d e t e r m i n e t h e p e r m i s s i b le v e l o c i t y ; t o e s ta b l i s h t h is , u s e is m a i n l y m a d e o fs t a t i s t i c a l d a t a f r o m l o n g - t e r m o b s e r v a ti o n s .

2 . S o m e p r o gr e ss in t h e s o l u ti o n o f m a n y p r a c t i c a l p r o b l e m s in t h e s e i s m i c s o f m i n e b l a s t i n g h a s r e c e n t l y

f u rt h e re d t h e f o r m u l a t i o n o f im p o r t a n t t h e o r e t i c a l p r o b le m s , s o l u t i o n o f w h i c h m a y p r o v e e x t r e m e l y i m p o r t a n t ff u r th e r d e v e l o p m e n t o f m e t h o d s o f c o n t r o l l i n g t h e s e i sm i c a c t i o n o f b la s t in g , d e v e l o p m e n t o f t e c h n o l o g i e s f o r i nt r ia l b l a s t in g , a n d c r e a t i o n o f m e a n s o f m o n i t o r i n g t h e d e v e l o p m e n t o f a n e x p l o s i o n .

O n e o f t h e c o n c l u s i o n s w h i c h h a s b e e n f u n d a m e n t a l l y c o n f i r m e d i s t h e p r e s e n c e o f tw o m a i n w a v e g r o up s t h e o v e r a l l s e i s m i c m o t i o n d u e t o b l as t i n g n e a r t h e fr e e su r f a c e [2 4 ] . T h e s e g r o u p s h a v e d i f f e r e n t v e l o c i t i e s o fp r o p a g a t i o n a n d d i f f e r e n t r a te s o f a m p l i t u d e a t t e n u a t i o n a n d s p e c t r a l c o m p o s i t i o n s .

W a v e s i n t h e f i rs t g r o u p a r e l o n g i t u d i n a l ( d i r e c t in a h o m o g e n e o u s r o c k ma s s ) o r r e f r a c t e d ( i n a s t r a t i f i e d rw i t h r e f l e c t i o n f r o m t h e s u r fa c e . T h i s g r o u p h a s t h e h i g h e s t s p e c t r a l f r e q u e n c i e s a n d t h e m o s t ra p i d a t t e n u a t i o n[ 2 4 - 2 6 ] ~

Wa v e s i n t h e s e c o n d g r o u p a r e t r a n s ve r s e o r s u r f a ce w a v e s o f v a r io u s t y p es ( i n c l u d in g i n t e r f e r e n c e o f w a v e si n t h e s u r f a c e l a y e r ). T h e a p p a r e n t p e r i o d s w o f v i b r a t i o n i n th i s g r o u p a r e s e v e r a l t i m e s g r e a m r t h a n t h o s e f o r

t h e f i rs t g r o u p , a n d t h e a m p l i t u d e a t t e n u a t i o n i s l e s s. I t i s i mp o r t a n t t h a t t h e s e w a v e s b e c o m p a r a b l e a t t h e b o u no f t h e r a n g e o f s a f e d i s t a n ce s ( 1 - 5 - 1 0 c m / s e c f o r t h e m a x i m u m p a r t i c l e v e l o c i t y a m p l i t u d e ) : a t cl o s e r d i s t a n c et h e a m p l i t u d e s o f t h e f i rs t g r o u p p r e d o m i n a t e , a n d a t m o r e r e m o t e d i s t a n c e s, t h o se o f t h e s e c o n d .

A m o n g t h e m o s t i m p o r t a n t p r o b l e m s a r e t h o se c o n c e r n i n g t h e s o u rc e s o f s e i s m i c v i b r a t i o n s . T h e a c c e p t e dc o n c e p t o f t h e w a v e s o u r c e a s a s p h e r i c a l s y m m e t r i c a l r a d i a t o r g e n e r a t i n g o n l y a c o m p r e s s i o n - t e n s i o n w a v e h a sr e c e n t y e a r s b e e n e x p a n d e d a n d s u p p l e m e n t e d . T h i s i s o f s p e c i a l i m p o r t a n c e in : re s e a r c h o n t h e s e i s m i c e f fe c t s oi n q u a r r i e s a n d o p e n p i t s .

T h u s, i t h a s b e e n s h o w n [2 4 , 2 5 ] t h a t i n b l a s t i n g b y c h a r g e s n e a r t h e f r e e s u rf a c e , t h e r a d i a t o r o f s e i s m i c w as h o u l d r a t h e r b e r e g a r d e d a s a t w o - s t a g e s o u r c e . I n t h e f i r s t s t a g e t h e r e i s t h e u s u a l f o r m a t i o n o f a c a v i t y a n d r at i o n o f t h e l o n g i t u d i n a l w a v e , a n d i n t h e s e c o n d s t a g e t h e r e is a d o m e - s h a p e d h e a v e o f t h e g r o u n d a t t h e e p i c e n to f t h e b l a s t a n d g e n e r a t i o n o f s u r f a c e w a v e s , m n s i o n w a v e s , a n d s h e a r w a v e s . A f u r t h e r d e v e l o p m e n t is f o u n d i n[ 2 9 ] , * i n w h i c h i t is s h o w n t h a t w h e n d i r e c t c o mp r e s s i o n a n d r e f l e c t e d t e n s i o n w a v e s p as s t h r o u g h a me d i u m , c a ub r e a k u p o f t h e m e d i u m , a t t h e b o u n d a ry o f f r a g m e n t a t i o n o f t h e m e d i u m t h e r e m u s t a r i s e ,a n d u n a v o i d a b l y d o a rn e w s o u rc e s o f v i b r a ti o n s w h i c h g e n e r a t e w a v e s o f v a r i o u s ty p e s . F o r t h is r e a so n , t h e f o l l o w i n g t h r e e p r i n c i p a l t hr i es o f t h e n a t u r e o f t h e s o u r c e a n d t h e p o s s i b i l i ty o f i t s u t i l i z a t i o n h a v e b e e n p u t f o r w a r d :

1 ) A s o u r c e o f s e i s m i c w a v e c a n b e r e p r e s e n te d a s a c h a i n o f s u c c e s s i v e l y a c t i n g s o u r c e s g e n e r a t i n g w a v e sv a r i o u s t y p e s .

2 ) Wa v e s o f v a r i o u s t y p e s e m i t t e d b y t h e s a m e s o u r c e a re c h a r a c t e r i z e d b y a c o n s t a n t v i b r a t i o n p e r i o d f o r

* A s i n R u s si a n o r i g i n a l ; t h e r e i s n o [ 2 9 ] f o r th i s a r t i c l e - P u b l i s h e r.

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t h is s o u rc e . A t t h e s a m e r i m e , w a v e s o f t h e s a m e t y p e g e n e r a t e d b y d i f f e r e n t so u r c es h a v e c h a r a c t e r i s t i c i n d i v i dv e l o c i t i e s o f p r o p a g a t i o n a n d a b s o r p ti o n g r a d i e n ts .

3 ) Wa v e s a ri s i n g a t d i f f e r e n t s ta g e s o f t h e b l a s r i n g p r o c e s s a r e p r o p a g a t e d i n d e p e n d e n t l y, a r e s u p e r i mp o s e da n d t hu s t h e s e i s mo g r a m r e p r e s e n t s v i b r a t i o n s w h i c h a r e s u p e r i mp o s e d a c c o r d i n g t o t h e p r i n c i p l e o f s u p e r p o s i t i oa n d m u s t b e d e c i p h e r e d . T h i s a p p r o a c h t o t h e a s se s s m e n t o f a s o u r c e o f s e i s m i c v i b r a t i o n s e n a b l e s u s to s o l v e bt h e d i r e c t a n d t h e c o n v e r s e p r o b le m , i . e ., t o d e t e r m i n e t h e p a r a m e t e r s o f th e w a v e s g e n e r a t e d b y a k n o w n s o u rco r to f in d t h e s o u r c e f r o m t h e o b s e rv e d w a v e s . T h i s i s i m p o r t a n t f o r t h e d e t e r m i n a t i o n o f th e r a d i i o f a c t i o n o fc h a rg e s i n v a r i o u s z o n e s - p l a s t i c d e f o r m a t i o n , f i ss u r e f o r ma t i o n , s h e a r d e f o r m a t i o n , e l a s t i c , a n d s u r f a c e v i b r a t i o n

Ta k e n t o g e t h e r, t h is w o r k s ho w s th a t f u r t h e r d e v e l o p m e n t o f t h e e l u c i d a t i o n o f t h e t r u e n a t u r e o f s o u rc e s os e i s m i c v i b r a t i o n s m a y s e r v e a s a b a si s f or t h e c r e a t i o n o f a n u m b e r o f te c h n i q u e s o f c o n t r o l l i n g t h e e n e r g y o f ab l a s t a n d o f o b t a i n i n g i n f o r m a t i o n o n p h e n o m e n a o c c u r r i n g i n a m e d i u m a t v a ri o u s s t a g e s o f d i s i n t e g ra t i o n : t h em a y b e u s e d a s c o n t r o ll e d p a r a m e t e r s i n t h e c o n v e r s e r e l a t i o n o f t h e p r o c e ss o f fr a g m e n t a t i o n w i t h i ts s o u r c e .

F i n a l ly, a n i m p o r t a n t t h e o r e t i c a l d e v e l o p m e n t i s t h e u s e o f s e i s m i c v i b r a ti o n s t o o b t a i n i n f o r m a t i o n o n t h ef i s su r i n g o f t h e s o li d r o c k , t h e s t r e n g t h s o f w o r k e d r o c k s f o r t h e p u r p o s e o f c h o o s i n g m e a n s a n d t e c h n i q u e s f o r b r ei n g t h e m u p , a n d t h e a c o u s t i c c h a r a c t e r i s t ic s o f ro c k s c o m p o s i n g a c r os s s e c t i o n o f a q u a r r y o r m i n e s i d e . T h a n ks u c ce s s es in t h e d e v e l o p m e n t o f m e t h o d s a nd d e v i c e s f o r s e i s m i c m e a s u r e m e n t s , t h is a p p r o a c h i s b e c o m i n g i n c rei n g l y p o p u l a r i n th e s o l u t i o n o f v a r i o u s e n g i n e e r i n g p r o b l e ms .

A n i m p o r t a n t t h e o r e t i c a l t r e n d i n s e i s m o l o g i c a l i n v e s t i g a t i o n s i s th e r e c e n t w o r k o n t h e s p e c t r a l c o m p o s i t io f s ei s m i c v i b r a ti o n s a n d t h e d i s tr i b u ti o n o f e n e r g y a m o n g t h e w a v e g r o up s a n d v i b r a t io n s p e c t r u m . T h e r e su l ts t h is r e s e a r ch a r e v e r y i m p o r t a n t f o r t h e d e v e l o p m e n t o f m e t h o d s o f c o n t r o l l i n g t h e s e i s m i c e n e r g y o f b l a st s a n d os c r e e n i n g s e i s mi c v i b r a t i o n s , a n d a l s o f o r t h e s tu d y o f t h e g e o l o g i c a l c h a r a c t e r i s t i c s o f t h e w o r k e d d e p o s i t s , t h e o f s t r s s o f t h e r o c k s as t h e d e p o s i t s a r e w o r k e d , t h e d e f o r m a t i o n o f t h e s l o p e s o f h y d r o t e c h n i c a l c u t t i n g s , a n d t h es t a b i l i t y o f q u a r r y si d es , a n d i n e s t i m a t i n g t h e a b s o r p t i o n c a p a c i t i e s o f v a r i o u s s t ru c t u r a l c r o s s s e c t i o n s a n d s o l v io t h e r p r o b l e m s . L o n g - t e r m a c c u m u l a t i o n a n d p r o c e s s in g o f t h is i n f o r m a t i o n o n t h e s p e c tr a l c h a r a c t e r i s t i c s o f s ew a v e s w i l l e n a b l e u s to p r e d i c t a n u m b e r o f p h e n o m e n a w h i c h c a n a r i se a t g r e a t d e p th s i n m i n e s - s h o c k b u m p s a n d i n p r e d i c t i n g d a n g e r o u s s i t u a t i o n s i n q u a r r i e s a n d c u t t i n g s .

O n t h e w h o l e , r e f i n e m e n t o f o ur k n o w l e d g e o f t h e c h a r a c t e r o f th e s o u r c e o f s e i s m i c v i b r a t i o n s i n o p e n a n du n d e r g ro u n d w o r k in g s an d t h e c o m p o s i t i o n o f t h e w a v e g r o u ps a c c o r d i n g to th e i r k i n e m a t i c a n d d y n a m i c c h a r a ct e r is t i cs ) a l r e a d y e n a b l e s u s t o i n d i c a t e a u n i f i e d m e t h o d o f e x a m i n i n g l a r g e q u a rr i es a n d m i n e s f r o m t h e v i e w p oo f s e i s m i c s a f e t y. T h i s e x a m i n a t i o n , b e i n g b a s e d o n a s ta n d a r d m e t h o d a n d ap p a r a tu s , h a s t h e a i m o f r e f i n i n g t hp a r a m e t e r s o f s e i s m i c d i s tu r b a n c e s c h a r a c t e r i s t i c o f g i v e n m e c h a n i c a l c o n d i ti o n s , t e c h n o l o g i e s , a n d e n g i n e e r i n gc o n d i t i o n s a d j a c e n t b u i l d i n g s a n d s t ru c t u r e s ) ; t h e c o s t o f t h i s e x t r a w o r k is u s u a l l y n e g l i g i b l e i n c o m p a r i s o n w i t hi ts e c o n o m i c e f f e c t . T h i s e f f e c t a ri se s o w i n g t o r e f i n e m e n t o f t h e b la s t i n g p a r a m e t e r s t h e w e i g h t s o f s i n g le c h aa n d t h e t o t a l c h a r g e w e i g h t , t h e n e t w o r k p a r a m e t e r s , a n d t h e d e l a y ) a n d t o t h e d e v e l o p m e n t o f m o r e r a t i o n a l b l at e c h n o l o g i e s - t h e s tu d y o f s e i s m i c s a n d t h a t o f b l a s t in g h a v e a c o m m o n b a s is .

A n i m p o r t a n t t h e o r e t i c a l a s p e c t o f w o r k o n th e s e i s m i c e f f e c t s o f m i n e b l a s t i n g is t h e d e t e r m i n a t i o n o f th ec r i t i c a l l y p e r mi s s i b l e d e f o r m a t i o n s , d i s p l a c e m e n t s , a n d a c c e l e r a t i o n s o f b u i l d in g s , s t ru c t u r e s , e x p o s e d r o c k s, m i nw o r k i n g s, a n d s u b q u a r r y, i n t e r r o o m, a n d h y d r o t e c h n i c a l p i l l a r s . O n t h e s u c c e s s a n d v a l i d i t y o f t h e r e s u lt s o f th i sw o r k la r g e l y d e p e n d s t h e a d v a n c e o f g e n e r a l e n g i n e e r i n g s e i s m o l o g y.

A t o u r p r e s e n t l e v e l o f k n o w l e d g e i t is p o s s ib l e t o p o s e q u e s t i o n s, n o t o n th e s e i s m i c d a n g e r o f b l a s ti n g , w hc a n b e f a i r l y p r e c i s e l y p r e d i c t e d , b u t o n t h e e c o n o m i c l o ss e s d u e t o t h e s e i s mi c a c t i o n o f b l a st s , w h i c h s h o u l d b ed e t e r m i n e d i n e a c h p a r t i c u l a r c a s e a n d a d e c i s i o n t a k e n o n th i s b as is - e i t h e r t o g o a h e a d w i t h l a r g e - s c a l e b l a s t sw i t h h i g h t e c h n i c a l - e c o n o m i c i n d i c e s o f t e c h n o l o g i c a l p r o d u c t i o n b u t w i t h d e f i n i t e e c o n o m i c l os s es o n th e r e s t o

t i o n o f b u i l d i n g s , s t r u c tu r e s , a n d w o r k i n g s d a m a g e d b y t h e s e i s mi c v i b r a t io n s , o r to c a r r y o u t s ma l l e r b l a s t s t o p rs e r v e t h e s u r r o u n d i n g st r u c tu r e s , b u t w i t h l i m i t e d t e c h n o l o g i c a l p o s s i b i l i t i e s o f m i n i n g o u t p u t .

S u c e e s s f u l s o l u ti o n o f t h e p r o b l e m s o f t h e s e i a m i e e f f e c ts o f b l a s t i n g i n t h e m i n i n g i n d u s t r y, a r i s in g o u t o f p r o d u ci s a b a si s f or i m p r o v e m e n t i n t h e t e c h n o l o g y o f m i n i n g o p e r a t i o n s a n d f or i n c r e a s e i n t h e o . m . s , d u e t o i n t r o d u c to f a d v a n c e d t e c h n o l o g i e s o f s h o r t - d e l a y b l a s r i n g o f l a r g e m a s s e s o f e x p l o s iv e s i n a c o m p r e s s e d m e d i u m . A n e s pc i a l l y m a r k e d e c o n o m i c e f f e c t o f p o s it i v e so l u t io n o f p r o b l e m s i n m i n i n g s e i s m i c e f f e c t s i s a c h i e v e d b y s e c u r in gs t a b i l i t y o f t h e s i d e s o f q u a r r i e s a n d o p e n p i ts , c u t t i n g f o r h y d r o t e c h n i c a l c o n s t r u c t i o n s , s u b q u a r r y r o o ms , a n d i n tr o o m p i l l ar s , w h e r e , a s w e l l a s s e c u r i n g s af e l a b o r c o n d it i o n s , w e c a n a l s o a c h i e v e a m a r k e d r e d u c t i o n i n t h e a mo f s t r ip p i n g o r o re d r e ss i ng r e q u i r e d . I f w e s u m t h e e c o n o m i c e f f e c t s o b t a i n e d b y r e a l i z a t i o n o f t h e se q u e s t i o n s it h e q u a r ri e s a n d o p e n p i ts o f t h e S o v i e t U n i o n a l o n e , w e g e t a n a m o u n t o f m a n y m i l l i o n s o f r u b ie s .

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A marked economic effect is also attained by positive solution of problems in mining seismic effects due togeneral technological methods of primary or secondary working of deposits by the open-cut method instead of theunderground method. For exampl e, in the successful solution of seismic problems at the Khaidarken Mercury Com-bine, thanks to allowanc e for previously formed underground cavities, it was possible to work out one of its orefields by the open-cut method instead of the underground method, and this was as good as the opening of a new oredeposit. Similar exa mples can be given for some other deposits in the USSR, where deposits have been com ple tel yworked out or are being completely worked out by the open-cut method instead of the underground method thanksto successful solution of problems in the seismic protection of the surrounding structures.

The import ance and industrial necessity of further research on the seismic effects of mine blasting are per-

fectly obvious, because the results will be extremely useful for a general solution of problems in scienti fic- techn icalprogress in winning minerals for the national economy.

8. On the whole, the state of resear ch on m ine blastin g seismic effec ts corresponds quite well to presentproblems in the developmen t of the mining industry and will give realistic bases for the publication of the inte r-depar tmen tal Instructions on Seismic Safety in Blasting during Open -Cut and Underground Mining Operat ions.

The present successes in the solution of practi cal problems of mine blasting seismic effects, which have createda basis for the Inter depar tmen tal Instructions, is largely t he conseque nce of the product ive work carried out at theIPE AS USSR In the provision of all i nvestigat ors with seism ologic al apparatus. At present there is a pressing needto unify methods of seismic measurement and to c reate a unified system of seismometric documentati on of instru-ment al observations on the action of seismic waves in mines and quarries. For this purpose, the Sect ion of MineBlasting Se ismic Effects of the Inte rdepa rtme ntal Commissi on on Blasting has discussed and approved a UnifiedForm of Primary Docu ment ati on of Seismic Observations in Blasting and on this basis has recommen ded to allinterested organizations that they should present their seismometric documentation to the Interdepartmental Com-mission for correl ation and distribution. Also discussed and approved has been the Position Regarding Instrum entalMonitoring and Observations of the Acti on of Blast Waves in Coal Pits; in con nect ion with this, c oal pits mustorganize a service for monitoring and lo ng-t erm observation of the seismic effects of blasting. It is of interest toextend this position to other branches of the nation al ec onom y which use blasting on a large sca le.

L I T E R AT U R E C I T E D

1. M. A. Sadovskii, N. V. Mel' nikov, and G. P. Demidyuk, Princi pal trends in impr ovem ent of blasting in themini ng industry, Fiz. oTekh. Probl. Razrabotki Polezn. Iskop., No. 3 (1973).

2. N. V. Mel'nikov et al., Effective methods of control of processes of blasting crushing and ejec tion, Fiz .-Tekh. Probl. Razrabotki Polezn. Iskop., No. 4 (1971).

3. M. F. Drukovann ii (editor), Han dbook on Drill ing and Blasting in Quarri es and Open Pits [in Russian], Kiev(19q3).4. N. G. Dubynin, Problems of drilling and blasting resulting from the creation of a new technology of ore

mini ng, Fiz .-T ekh . Probl. Razrabotki Polezn. Iskop., No. 8 (19q8).5. V.R . Imenitov et al., Investigation of the effect of screening in the interacti on of blasting waves, Fiz. -

Tektu Probl. Razrabotki Polezn. Iskop., No. 3 (1973).6. M. A. Sadovskii (editor), The Mec han ical Effect of Underground Blasting [in Russian], Nedra, Moscow (1971).7. P. S . Mironov, Blasting and Seismic Safety of Structures [in Russian], Nedra, Moscow (1973).8. L. V. Safonov and G. V. Kuznetsev, The S eismic Effect of Blasting by Borehole Charges [in Russian], Nauka,

Moscow (1967).9. M. I. Kartukhov and A. F. Nozhin, The coefficient of dynami city for buildings and structures, Izv. Vuzov,

Gornyl Zh., No. 12 (1968).10. M. A. Mikuliaskti, A. G. Sisin, G. V. Kuznetsov, and P. S. Mironov, Estimat ion of the actio n of blasting

operations on the stability o f quarry sides, Gornyi Zh., No. 3 (1963).11. P . g . Zurkov, V. F. Bogatskii, and V. T. Ponomarev, On the remits of investi gations of the seismic effe ct

of blasting in the Tomusinskoi 7-8 Open Coal Pit, in: Aspects of Engineerin g Seismology of Mine Blasting[in Russian], No. 53, Magnitogorsk (1968).

12. P. ~. Zurkov, V. F. Bogatskii, V. D. Pechenkin, and V. Kh. Pergament, An eff ect ive method of reducingsetsm icit y and blasts in mining undertaking s, in: Seismics of Blasting and Some Questions of Rock Mechani cs[in Russian]. No. 35, Magnitogorsk (1965).

13. V. N. Mosinets, Yu. Ya. Savel'ev, and A. K. Tokaev, Investigation of seismic safety of methods of carryingout blasting operations in working deposits near engineering structures, in: Technol ogy of Drilling and BlastingOperations [in Russian]. Izd. Ilim, Frunze (1967).

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1 4. S . G . Av e rch in and V. N . Mo,c ine ts , New Eng ineer ing M ethods o f Calc u la t ing the S tab i l i t y o f Rock Bases unthe S eism ic Act io n of Blas t ing [ in Russian], IN TI KirgSSR, Fru nze (1967)o

1 5 . V . N . M o s i ne t s a n d Yu . Ya . S a v e l ' e v , O n th e p r o p a g a t i o n o f s e i s m i c w a v e s i n t h e re g i o n o f m i n e w o r k i nIzv . Akad . Nauk Ki rgSSSR. No . 2 (196 ' / ).

1 6 . V . N . M o s i n et s , Yu . N . S a v e l ' e v, a n d S h t e i n b a k h , A n o m o g r a p h i c m e t h o d o f c a l c u l a t i n g th e s e i s m i c a l l ys a f e d i s t a n c e s f r o m b l a s t in g o p e r a t i o n s i n q u a r r i e s , F i z . - T e k h . P r o b l . R a z r a b o t k i P o l e z n . l ,c ko p. , N o . 4 ( 1

1 7 . B . V . P o z d n y a k o v a n d Yu . V. N e l y u b o v, I n v e s t i g a t i o n o f t h e ,c t a ti s d c al c h a r a c t e r i s t i c s o f t h e s e i, c m ic a c t io f indus t r i a l b l as t s , i n : Se i sm ic Ac t ion o f indus t r i a l Blas ts [ in Russi an ] , M oscow (1966) .

1 8 . K . D . K l e m m - M u s a t o v a n d B. V. P o z d n y a k o v, O n t h e q u e s t io n o f f i l t r a t io n o f s e i s m i c w a v e s b y c r a c k s ,i n : Tr a n s a c t i o n s o f F if t h S e ss io n o f S c i e n t i f i c S o v i e t o n t h e N a t i o n a l - Ec o n o m i c U t i l i z a t i o n o f B la s ti n g [ i nRu,csian], Fmnze (1965)o

1 9 . A . M . P u c h o , Th e s e is m i c a c t i o n o f l a rg e - s c a l e b l a s ts o n m i n e w o r k i n g s , G o r n y i Zh . , N o . 11 ( 1 95 6 ).2 0 . L V S a f o n o v, M e t h o d s o f r e d u c i n g th e s e is m i c a c t i o n o f b l a s t s o n m i n e w o r k i n g s , i n : I n v e s t i g a a o n s o

t h e G e o l o g y, M i n i n g , a n d B e n e f i c i a t i o n o f O r e s f r o m t h e K u r, ck M a g n e t i c A n o m a l y [ i n R u ss ia n] , G o s g o r t ei zda t , Moscow (1962) .

2 1 . O . A . B a i k o n ur o v a n d L . V. Vi n o k u r o v, O n t h e q u e st i o n o f d e t e r m i n a t i o n o f t h e d y n a m i c lo a d s a r i s in g i ne l e m e n t s o f m i n e w o r ki n g s o w i n g to b l a s t i n g , i n: P r o b l e m s o f R o c k M e c h a n i c s [ i n R u ss ia n] , N a u k a , A l m1966).

2 2 . N . U . Tu m t a a n d Yu . L . B l a g o d a re n k o , I n v e s t i g a t i o n s o f t h e s e i s m i c a c t i o n o f l a rg e - s c a l e b l a st s w i t h s h od e l a y e x p l o s i o n an d d i, c tr ib u t io n o f e x p l o s i v e c h a rg e s in q u a r r i e s an d o p e n p i t s , i n: S e i s m i c A c t i o n o f l ndu,ctrial Blast,c [in Russian], Mo scow (196 6).

2 3 . N . V . K u z 'm i n a , A . N . R o m a n o v, B . G . R u l e r, D . A . K h a r i n , a n d E . I . S h e m y a k i n , Th e s e i s m i c e f f e c t o f

e j e c t i o n b l a s t i n g i n c o h e s i v e r o c k , Vo p r o s y I n z h e n e r n o i S e i s m o l o g i i , 6 , N o . 2 1 ( 1 9 62 ) .2 4 . A . N . R o m a s h o v a n d V. M . C h u b a ro v, B l a s t in g n e a r th e f r e e s u r f a c e a,c a s o u r c e o f s e i s m i c w a v e s , F i z . - T

Prob l . Raz rabo tk i Po lezn . I sko p . . No . 4 (1968) .2 5 . B . G . R u le r, Th e d y n a m i c c h a ra c te r i, ct ic ,c o f s e i s m i c w a v e s f r o m u n d e rg r o u n d b l a s t i n g , V z r y v n o e D e l o ,

No. 64/21, Nedra, Moscow (1968).2 6 . N . I . O n i, c 'k o a n d E . I . S h e m y a k i n , M o v e m e n t o f t h e f r e e su r f a c e o f r o c k d u e to u n d e rg ro u n d b l a s t i n g ,

BMTF, No. 4 (1961).2 7 . E . I . S h e m y a k i n , O n t h e b e h a v i o r o f m i n e w o r k i n g s u n d e r d y n a m i c l o a d s , F i z . - Te k h . P r o b l . R a z r a b o t k i

Polezn. I ,ckop. , No. 6 (1966).2 8 . V . N . M o s i n e ts a n d N . P. G o r b a c h e v a , A s e i s m o l o g i c a l m e t h o d o f d e t e r m i n i n g t h e p a r a m e t e r s o f t h e z o n

of def o rm at io n o f rocks due to b l a ,c t ing , F iz . -T ek h . Prob l . Razrab o tk i Po lezn . I ,ckop ., No . 6 (1972) .

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