Instability Underground - Causes, Costs and Controls

8/10/2019 Instability Underground - Causes, Costs and Controls

1/13

hapter

INSTABILITY UNDERGROUND CAUSES COSTS AND CONTROLS

John E. Udd

A s s o c ia t e P r o f e s s o r

Depar tment of Mining and Met a l lu rg ic a l Engineer ing

M c i l l Universi ty Montreal Quebec Canada

In t roduc t i on

During the very long pe r i od i n which man has mined mi ne ra l s

from t he c r us t of t he e a r t h f a l l s of g round a nd c o l l a pe s o f unde r-

ground workings have been t he causes of a s i g n i f i c an t p a r t o f tho se

a c c i d e n t s which have r e s u l t e d i n e i t h e r de a th o r i n i n j u r y . At

presen t because of improvements i n th e approaches t o the des ign

of underg round s t r uc t u r e s i n e qu ipm en t a nd i n a t t i t u d e s t ow ards

a c ci d en t p re ve nt io n t h e p r o p o r ti o n of a c c i d e n t s due t o i n s t a b i l i t y

of rock i s p ro bab ly f a r l e s s t h an i t was h i s t o r i c a l l y . N onethe -

l e s s i n s p i t e of the many advances which have been made in s ta -

b i l i t i e s s t i l l

accou nt f o r a bo ut on e- qu ar te r of a l l f a t a l i t i e s

and o ne- ten th of a l l of t h e i n j u r i e s i n t h e m i ne r al s i n d u s t r y .

The means must be found whereby bo th t h e numbers of a c c i d e n ts and

t he a c c i de n t

rates

due t o f a l l s o f g round c an be re duce d t o t he

l ow es t l e v e l s poss i b l e .

At the ou t s e t i t s h ou ld b e s t a t e d t h a t s h o r t o f s us p e n si o n o f

a l l mining a c t i v i t y i t w i l l p ro b ab l y n ev e r b e p o s s i b l e f o r

us

t o

e l im ina t e acc i den t s comple te ly . Most human en te rp r i se inv olv es

unknowns and r i s k s and min ing

i s

no except ion . A ce r t a in number

of acc iden t s then must be v iewed a s th e in ev i t ab le consequence

of our a t temp t ing t o work wi t h unknowns and t o make de cis io ns t h a t

i nvo l ve unc e r t a i n t i e s .

However i n r e t r o s p e c t many i n s t a b i l i t i e s can b e a t t r i b u t e d t o

fa c t or s which could have been wi th in our c on t ro l .

T he p r e ve n t a b l e

accident must be el iminated.

t

sh ou ld be our goa l t h a t we make

e ve ry e f f o r t t o d i r e c t o u r s k i l l s and t ec hn ol og y t o t h e c r e a t i o n o f

a s a f e r wo rk in g en vir on me nt a n d s h o u l d b e c o n s t a n t l y s t r i v i n g t o


2/13

24 STABILITY IN UN DER GR OU ND MINING

e n su r e t h a t a c c i d e n t s due t o i n s t a b i l i t i e s a r e r educed t o th e

sm al le s t number po ss i b le .

Causes of i n s t a b i l i t i e s

Pr io r t o t he exc ava t ion of an underground opening th e pa r t of

t h e e a r t h s c r u s t t h a t w i l l be a f f e c t e d , a lt ho ug h f ra c t u r ed and

s t r e s s e d ,

i s

proba bl y i n a s t a t e of e qu il i br i um .

t

i s the develop-

ment of th e opening, and th e means by which th i s

i s

achieved, which

c a use s d i s t ruba nc e s t o t h e p r e - e x i s t i ng c ond i t i ons i n t he rock mass.

I n th e f i n a l a n a l ys i s ,

i n a m i ni ng c on t e x t ,

i t

i s a c t i o n s f o r

which man i s r e s po n s ib l e t h a t r e s u l t i n i n s t a b i l i t i e s . We may

or may no t be aware of th e r e l a t io ns h i p between cause and e f fe c t

b e f o r e t h e ev e n t b u t , most c e r t a i n l y , a f t e r t h e e v en t one can

p r ob a bl y i d e n t i f y t h e a c t i o n s a n d / or l a c k of a c t i o n s t h a t were

res pon s ib le . These may range a l l

th e way f rom a l ac k of p r io r

knowledge t o unsa fe working pr ac t i ce s .

The w r i t e r sugges t s then ,

t h a t t he c a use s of i n s t a b i l i t i e s may be t r a c e d t o one o r more of

th e s ta ge s i n t he development of a n underground opening.

Likewise,

i t i s

b e l i ev e d t h a t i n o r d e r t o a c h ie v e a g r e a t e r de gr ee of c o n t r o l

o v e r i n s t a b i l i t i e s , a c t i o n s must t a k e p la c e on s e v e r a l f r o n t s .

I n p u rs u in g t h i s a p p ro a ch , w i t h a v iew t ow ar ds i n i t i a t i n g d i s -

c uss i on ,

l i s t s

of

tho se ac t i on s which might u l t i ma te ly be th e causes

of i n s t a b i l i t i e s h av e b ee n p r ep a re d .

These a r e g iven i n Tables

and 2

I n b o th of t h e s e t a b l e s , w hic h r e f e r t o s tr u c t ur a l ly - i n d uc e d

and t o s t r e s s -i n d u ce d f a i l u r e s , r e s p e c t i v e l y , t h e c au s es have been

a ss i gne d t o c a t e g o r i e s wh ic h de s c r i be t he s t a ge s i n t he development

of an underground opening o r op er a t i on . These ar e : the explora-

t i o n , d e s i g n a nd e x p l o i t a t i o n p h a s es .

F u rt he rm ore , f o r r e a sons w hi ch a r e e v i de n t , t he se l i s t s a r e by

no means mutual ly exclusive . T he re a r e many f a c t o r s i n t h e t h r e e

ca te go r i es which must be common t o a l l .

Because of th e very natu re

o f t h e i n s t a b i l i t i e s , h ow ev er , t h e r e m ust, by d e f i n i t i o n , b e a few

pos s i b l e c a use s w hic h a r e un i que t o one pa r t i c u l a r c a te go ry.

To i l l u s t r a t e t h i s p o i n t ,

i t

i s poss i b l e t h a t t he c ause of a

f a i l u r e c o ul d b e t r a c e d b ack t o a l a c k of i n fo r ma ti on a t e i t h e r

t h e e x p l o r a ti o n o r d e si g n s t a g e .

t t h e e x p l o i t a t i o n s t a g e , i t

i s l i ke l y t ha t d i f f e r e n t f a c t o r s would have bee n i nvo lved . S t r e s s -

i nc ud ed f a i l u r e s r e s u l t when t h e s t r e n g t h s of t h e n a t u r a l g e o l o gi c a l

m a t e r i a l s a r e e xc ee de d, w h i l s t s t r u ct u r a ll y - in d u c e d f a i l u r e s a r e

caused by weaknesses i n t he rock mass.

One o t he r po i n t t h a t shou ld be t a ke n i n t o c ons i de ra t i on

i s

t h a t

t h e l i s t s a l s o i n d i c a t e t h o s e a c t i o n s which s h o ul d be av oi ded i f

t h e p o s s i b i l i t i e s of f a i l u r e s a r e t o be minimized. The o p p o s it e s

t o a l l of t h e c a u s es i n d i c a t e d a r e t ho s e a c t i o n s which s h ou l d b e

t a k e n i n t h e i n t e r e s t s o f c r e a t i n g a s a f e r wo rk in g en vir on me nt.


3/13

INST BILITY UNDE RGR OUN D

TABLE

Causes of St ructural ly-I nduced Fa i l ur es

both shallow and deep mining)

Explorat ion stage

Incomplete geotechnical da t a pr io r t o des ign

undetected weaknesses i n th e rock mass

unknown thickness and properties of overburden

unexpected groundwater

unexpec ted de t e r io ra t i on or wea ther ing

Design stage

Design according t o economic and op er at io na l consi der at i ons only

lack of knowledge regar din g pr op er t i es of

weaknesses and ro ck s)

improper mining tact ics

non-opt imal loc a t i on s and openings and p i l l a r s

non-optimal or i e nt a t io ns of openings and p i l l a r s

non-optimal dimensions of openings and p i l l a r s

f a i l u r e t o ev a lu a te ki ne ma ti c p o s s i b i l i t i e s

inadequate support

improper se l ec t i o n of equipment

improper design of b la st in g system

Exploi t a t ion s t age

Mining wi thout regard t o loc a l con di t ion s

poorly t ra ine d personne l

unsafe working pract ices

unreported loose rock or de te r i or a t io n

la ck of mon itoring

improper use of equipment

improper i n s t a l l a t i o n and maintenance of supp or t s

f a i l u r e t o i n s t a l l s u pp ort

p oor b l a s t i n g p r a c t i c e s

inadequate drainage


4/13

STABILITY IN UN DER GRO UND MINING

T BLE

Causes of S t ress-Induced Fa i l ur es

(usual ly wi th deep mining)

E x p lo r at i on s t a g e

Inc om ple te ge o t e c h n i c a l d a t a p r i o r t o de s i gn

undet e ct e d s t r e s s - r a i s e r s i n t h e roc k mass

unknown va r i a t io ns and d i f f e re nc es i n rock s t r en gt h

a nd de fo rm a t i ona l p rope r t i e s

unknown appl i ed ( t ec ton ic ) s t re sses

unexpected groundwater

Des ign s t age

Design accord ing t o economic and oper a t ion a l cons ide r a t ion s on ly

i m prope r m i n i ng t a c t i c s

a bsence of ov e r a l l s t r a t e g y f o r c om ple te e x t r a c t i on

non-opti ma l o r i e n t a t i o ns of ope ni ngs and p i l l a r s

non-optimal sh ape s of openings

non-optimal dimensions of o penings and p i l l a r s

la ck of sequencing

e x ce s si v e e x t r a c t i o n

f a i l u r e t o c o ns i de r s t r e s s c o n ce n tr at io n s

i na de qua t e suppor t

improper des ign of b la s t in g sys tems

E x p l o i t a t i o n s t a g e

M ining w i t hou t r e ga rd t o l oc a l c ond i t i ons

p o o rl y t r a i n e d p e r so n n el

unsa fe w ork i ng p r a c t i c e s

u nr ep or te d e f f e c t s of h ig h s t r e s s e s ( i . e . s p a l l i n g ,

p i l l a r d e t e r i o r a t i o n , c or e d i sc i ng )

lac k of mo ni tor ing

dep ar tur es f rom sequencing

produc t ion of h igh ly- s t re ssed remnants

l a c k of d e - s t r e s s i n g

f a i l u r e t o i n s t a l l s up po rt s

im proper i n s t a l l a t i o n and ma in te na nc e o f s uppor t s

poor b l a s t i n g p r a c t i c e s

i na de qua t e d r a i na ge


5/13

INST BILITY UNDE RGR OUN D

Whilst obvious t o those who a r e p rac t io ner s of th e sc ie nc e of

rock mechanics, i t

i s

a s a d f a c t t h a t , a l l t o o o f t e n , many of

t h e s e a ct i o n s a r e n o t t a ke n f o r r e as o n s o f c o s t , t im e and a t t i t u d e s .

The re s u l t s o f such omiss ions can be ve ry c os t l y indeed

C os ts of i n s t a b i l i t i e s

The t rue co s t o f an ac c id en t can never be s t a t e d because of a

number of intangibles.

t i s

a lmost inhuman, f o r example, t o a t t em pt

t o p l a ce a va l ue on t he pa i n a nd s u f f e r i ng w hich i s borne by th e

persons su f fe r in g acc ide n t s and by t h e i r fam i l i e s . One can never

place a value on the changes

t o l i f e s t y l e which may r e s u l t f ro m

an accident .

L ik ew is e, i n a d d i t i o n t o t h e u n q u a n t i f i a b l e human c o s t s , i t

i s

a l s o i m po ss ib le t o e s t i m a t e t h e i n d i r e c t c o s t s w hich may r e s u l t

f rom a l t e r e d product ion pl an s and sch edu les , and damage t o image

and p u b l i c r e l a t i o n s . T he re can b e l i t t l e d ou bt t h a t t h e s e must

be considerable .

The ot he r elements of th e c o s t s of ac ci de n ts , however, may be

more t a ng i b l e . Gibbs and P i n t u s ( I ) , r e f e r r i n g t o t h e work o f

Brooks and Berry 2), have summarized these (Table 3).

n

exam in ing t he c os t com ponen ts t ha t a r e l i s t e d i n t h e T a b l e

t

w i l l be immedia te ly recognized th a t , even though the se a r e

s t a t e d a s " t an g ib l e" , i t would b e a n i m p os s ib l e t a s k t o a t t e m p t

t o e x t r a c t , c o l l e c t , an d p r e s e n t t h e i n fo r m at io n r e q u i r e d f o r an y

de t a i l ed an a ly s i s i n a meaningfu l way. There a r e simply to o many

governments , agenc ies , and or ga ni za t io ns t h a t would be involv ed.

Moreover, there

i s

no c e r t a i n t y t h a t p r e c i s e , o r e ve n c om p ar ab le ,

d a t a would b e a v a i l a b l e . Given t h a t t h e r e a r e d i f f e r e n c e s i n t h e

ways i n which acc id en t s a r e de f in ed and repo r ted i t

i s

c e r t a i n t h a t

any inv es t ig a t i on would inv olve con s ide r ab le judgement on th e pa r t

o f t h e i n v e s t i g a t o r .

To i l l u s t r a t e t h i s p o i n t , t h e C anad ian C e nt re f o r O c c u p at io n a l

Heal th and Safe ty (3) has s ta ted:

" . . . t he re a r e many concept ions of t h e na tu re o f an

a c c i de n t and t he c onc ep t i on se l e c t e d w i l l i n f l ue nc e

th e measurement pr oc ed ur e employed. For example,

t h e b e l i e f t h a t a c c i d e n t s a r e a ch an ce e v e n t , o r

'Act of God", would l e a d t o no atte mp t b ei n g made

t o t a b u l a t e in c i de n c e, s i n c e t would s er ve no

purpose . S i m i l a r l y t h e c onc e p ti on t h a t a c c i d e n t

i nvo l ve s i n j u ry w i l l l e a d t o t a bu l a t i o ns o f numbers

of i n j u r i e s o r i n j u r y r a te s. ' '


6/13

ST BILITY IN UND ERG ROUND MINING

TABLE

The Tangible Costs of Accidents

modif ied af t e r Gibbs

and P intus 1) )

To in di v i du a l s

los t income

medical expenses

l o s t s e r v i ce s

To th e indu st r y

l o s t p r od u ct io n

compensat ion

r e c r u i t i n g

r e t r a i n i n g

medical expenses

material damages

To th e pu bl ic

Welfare

medical expenses

l o s t t a x e s

r e s c u e s e r v i c e s


7/13

INST BILITY UND ERG ROUND

29

l l of the informati on which t he wr i t e r has se en has been based on

the l a t t e r c once pt . The on ly da ta which th e wr i t e r ha s found r e l a t e s

t o a c ci de nt s which r e s u l t e d i n e i t h e r d e at h s o r d i s a b l i n g i n j u r i e s .

Thus, a major component of the co st s of i n s t a b i l i t i e s cannot be

determined, o r even est ima ted. One can only surmise t h a t th e co st s

of inc iden ts must be ve ry h igh . The co s t of rep lac ing o r reh abi l i -

t a t in g a s ing le c o l l a pse d o re -pa ss ,

f o r example, c an be i n t he o rde r

of mi l l ions of do l la r s . The cos ts of produc t ion l o s t due t o in s t a -

b i l i t i e s i n s t op e s can be e q u a l ly s e v e re .

Such c o s t s , a t p r e s e n t ,

a r e ne i t he r r e po rt e d no r c o l l e c t e d a nd a r e known only to ind i v idu a l

opera t ions .

With the se d i f f i c u l t i e s i n mind the n ,

i t

i s c e r t a i n t h a t t h e

f a c t s which a r e a v a i l a b le t o the pu b l i c c ompri se only a sma l l p a r t

of a much la rg e r s to ry . Ac tual co s t s , i nc l ud ing in ta ng ib le s , must

be considerably higher than would be in fe rr ed f rom publish ed dat a .

There

i s

t he r e fo r e , a c l e a r nee d fo r f u r th e r work c once rn ing , no t

only t he ways i n which info rma tion

i s

gathered , bu t a ls o the means

by which da ta a re r e t r i ev ed .

R egardles s of the d i f f i c u l t i e s w i th f ig u re s , however,

t i s

c e r t a i n tha t f a l l s of ground a r e one o f the p r i nc i pa l c a uses of

acc idents in min ing. The w r i te r has been to ld (4) , f o r example ,

th a t du ring the pe r iod from 1960 t o 1981 ( in c lu s iv e ) , 111 persons

were k i l l e d by f a l l s o f ground i n th e Province of Onta r io . These

r e pr e se n te d a bo ut 24% o f a l l of t h e f a t a l i t i e s i n t h e O n t a ri o m in in g

i nd us tr y d ur in g t h e p er io d . I n th e s t a t i s t i c s p r es e nt e d i n t h e

repor t of th e Inqui ry C o d s s i o n (Burke t t Cormnission) (7) , f a l l s o f

g round, which ca used 15 .5% o f a l l f a t a l a c c i de n t s i n On ta r io du r ing

the 1975 1980 per iod , was l i s t e d a s the th i r d most impor tan t cause .

Fa l l s of persons and haulage ac ci de nt s were th e most im portant

causes , a t 32.1% and 21.4%, resp ect i vel y.

L ikewise, i n the same r e por t ( 8 ) , f a l l s of g round was l i s t e d a s

be ing the cause of 7.3% of a l l los t - t ime acc ide nts i n Onta r io mines

dur ing the ye a r 1979. I n s t a b i l i t i e s was the f i f t h most impor tan t

of a l l t he c auses l i s t e d . Types of a c c id e n t s c aus ing g r e a te r

numbers of in ju r i es were: s l i p s and f a l l s (27.9%); overex er t ion

(25.5%); s t r i ki ng , and being s t ru ck by, ob je ct s (12.7%); and caught

I n t h i s p ap er, t h e w r i t e r h a s u se d s t a t i s t i c s fr om t h e P r ov i nc e of

Ontar io exc lus ive ly . The reason f o r t h i s i s t h a t , i n comparison

with other Canadian provinc es, th e data a r e more complete. In

addi t ion t o the long-s tanding e f f o r t s o f the Mines Acc ident Preven-

t i o n Ass oc ia ti on of O nt ar io (MAL'AO), two Commissions of i n q u i r y

have iss ued repor ts wit hi n th e pa st f i v e yea rs (Ham, 1976 (5) ;

Burkett , 1981 (6 )) .


8/13

ST BILITY IN UND ERG ROUND MINING

TABLE

Numbers of a cc id en ts due t o f a l l s of ground,

t o t a l number o f compensable a cc ide n t s i n mining ,

and paym ents made by t h e Workmen s Compensation Board

i n t he P rov i nce of O n t a r i o

(da ta cour tesy of J C l u f f , MAPAO)

Year Number of a c c i - T o t a l number of T o ta l payments by

d e n t s r e l a t e d

t o com pens able a c c i - Workmen s Compensa-

loose ground

d e n t s , i n c l u d i n g t i o n Board f o r

he a r i n g c l a i m s m i n ing -r e la t ed a c c i -

i n d u s t r i a l d i s e a s e s de n t s ( i n cl ud e s

medical a i d and

compensations)

N ot e: 1979 f i gu re s r educ ed by s t r i k e s .


9/13

INST BILITY UND ERG ROU ND 3

between ob je ct s (8.2%). Causes t h a t were

l ess

important were:

f a l l i n g o b j ec t s (6.9% ) ; f l y in g o b j ec t s (5 .6 % ) ; ext rem es o f tempera-

tu re (1 .6%) and o thers

(4.3 ) .

s

a summary, the

d a ta pre sent ed i n Table 4 show t he number of

acc id en t s a t t r i b u t e d t o l o o s e grou nd i n On ta r io m ines d u r in g t h e

p as t t h ree y ea r s , t h e t o t a l number o f com pens ab le acc id e n t s i n t h e

m ining i n d u s t ry i n t h e p ro v in ce , and t h e t o t a l paym ents t h a t we re

made by t h e Workmen's Com pensation Board. By im p l i c a t i o n , abo ut

1 .5 t o 2 m i l l i o n d o l l a r s h a s been expended i n each o f t h e p a s t t h re e

year s on d i r e ct compensat ion payments which may be a t t r i b u t e d to

a c c i de n t s i n v ol v i ng f a l l s of g round. I n d i r e c t c o s t s f o r t h e s e

a c ci d en ts a r e e s t im a te d a t a b ou t f i v e

t i m e s

th es e amounts (4 ) .

Thus, t h e c o s t s of a c c i d e n t s r e s u l t i n g fr om i n s t a b i l i t i e s , i n

O nt ar io a l o ne , a r e p ro b ab ly a t

le s t

1 0 m i l l i o n d o l l a r s p e r annum.

These co s t s , on a n a t i o n a l o r g lo b a l s ca l e , i n c lu d i n g t h o s e of

fa i l u r es which do no t invo lve i n ju r i e s , must be enormous.

Having s tu d i ed t h e d a t a , however , t h e w r i t e r p o in t s o u t t h a t t h e

e n t i r e e x e r ci s e e xe m pl if ie s t h e d i f f i c u l t i e s t h a t a r e i n vo lv ed i n

working w i th acc id e n t - r e l a t ed d a t a . Up t o t h e p re s en t , no acco u n t in g

has been

m d e i n Ontar io , and app are n t ly e l sewhere , o f th e compensa-

t i on payments t h a t have been made i n resp ec t o f f a l l s of g round

a lon e . Fur th ermo re , t h e t o t a l s which a r e g iven i n Tabl e 4 ( f o r

both a ccid ents and payments) in cl ude c la i ms which were made f o r

m in in g- re la te d a c c i d e n t s i n c l u d i n g l o s s e s o f h e a r i n g a n d i n d u s t r i a l

d i s ea s e s . Ad d i t i o n a l l y , i t

i s

ce r t a in t h a t some of t h e paym ents i n

any g iv en y ea r r e l a t e t o c l a im s made d u r in g t h e p rev io u s y ea r ( s ) .

Fin all y, because th e consequences of f a l l s of ground may be more

ser ious , on average , than th e consequences o f o th er typ es o f ac c i -

d en t s , i t

i s

l i k e l y t h a t t h e e s t i m a t e s w hich t h e w r i t e r h a s made

a r e very conservat ive .

In summary, t h e w r i t e r b e l i ev e s t h a t

i t

can be shown th a t th e

c o s t s of i n s t a b i l i t i e s a r e v e r y h i g h i nd e ed . W ith t h i s , a nd m ost

i m po r ta nt , t h e a l l e v i a t i o n of human s u f f e r i n g i n mind, t h e r e a r e

co n sid e rab l e i n cen t iv e s t oward s t h e r ed u c t i o n o f ac c id en t s du e t o

f a l l s of ground t o th e lowes t p os s i b l e numbers.

C on tr ol of i n s t a b i l i t i e s

Recognizing th a t most human a c t i v i t y invo lve s some r i s k , and

t h a t

i t i s

n ot l i k e l y t h a t a l l of t h e f a c t o r s c an b e known b e f o r e

a n a c t i o n

i s

t a ke n and t h i s

i s

e s p e c i a l l y t r u e i n mining

i t

would

b e i n a c cu r a t e i f t h e im p re ss io n was gi v en t h a t i n s t a b i l i t i e s u nd er -

ground could be e l imina t ed . Given th e na tu re of th e geo log i ca l

ma te r i a l s wi th which man must work , and t h e co ns tr a i ns of t im e and

economics which must app ly , t h a t

i s

c l e a r l y i m p o s s i b l e .

e

can, however , pur sue th e ambit ion of us in g our knowledge i n

o rd e r t o r edu ce t h e numbers o f l o o s e - r e l a t ed acc id e n t s t o t h e


10/13

32 ST BILITY IN UN DE RG RO UN D MINING

g r ea t e s t p o s s ib l e ex t e n t . The g o a l s m ust b e t h e c r ea t io n o f t h e

s a f e s t p o s s ib l e w o r king en v ir on ment .

I n a d d r e s s i n g t h i s p oi n t , t he n , t i s su gg es te d t h a t s t a b i l i t y

m ust be a c o n ce rn of a l l of t h e s t a k e h o l d e r s i n an e n t e r p r i s e .

The a t t i t u d e s and under s tand ing of a l l , f rom top management to

w o r k e r -ap p r en ti c e , a r e v i t a l l y im p o r t an t . The r o l e of t h e ground

c o n t r o l s p e c i a l i s t , a nd t h e way i n w hi ch he o r s he i s b e s t a b l e t o

fun ct i on , must be known and be sup por ted i f the b e s t environment t o

c o n t r o l i n s t a b i l i t i e s i s t o be c re a te d . In fo rmat ion must be

a n a ly z e d a nd d i s c u s s e d by b o th t e c h n i c a l and pr o du c t io n s p e c i a l i s t s .

Re f e r r in g b ack t o T ab le s and i n w hich th e caus e s of i n s t ab i l -

i t i e s were l i s t e d ,

i t

s h ou l d b e c l e a r t h a t e a c h i t em h a s a n i m pl i-

c a t i o n a s r eg a rd s p o s s i b l e c o n t r o l s . I t

i s

n o t t h e w r i t e r ' s

i n t e n t i o n t o l i s t the se , however, a s l i s t s of a n a l y t i c a l t e c hn i qu e s ,

i tem s of equipment , and sup por t sys tem s would only pre sen t informa-

t ion wh ich

i s

a v a i l a b l e e l s ew h e re . Thus, t h e p r e s e n t d i s c u s s i o n

i s

l i m i t e d t o t h e f o ll o w i ng p o i n t s .

1 ) I t

i s

a l l t oo o f t e n ev id en t a f t e r t he f a c t t h a t i n s t a b i l i t i e s

migh t have been p re ven t ed had more in fo rmat ion been av a i la b l e and

h ad more an a ly s e s b een done b e fo r eh and . I n p a r t , a s a r e a c t i o n to

s uc h s i t u a t i o n s , r e v i s e d l aw s r e l a t i n g t o o c c up a ti on al s a f e t y have

been , o r a r e bei ng , in t rod uc ed by some governments . B i l l 70, i n

th e P ro v in ce o f O n ta r io , i s a good example . I n essen ce, one p a r t

o f t h e l a w r e q u i r e s t h a t t h e s t a b i l i t y of u nderground ex c a va t io n s

s h a l l b e s uc h t h a t a w or ke r

i s

n o t

l i k e ly t o b e end an ge red 9).

R e s p o n s i b i l i t i e s , w h i l e p r i n c i p a l l y d i r e c t e d t o owners , a r e a l s o

a s s ig n ed t o b o th s u p e r v i s o r s an d w o rk e rs ( 10 ).

With t h i s example i n mind, i t

i s

ev id en t t h a t more emphasis must

be p laced on th e geo t echn ica l as pe c t s of t he des ign of underg round

e x c av a t io n s. T h i s w i l l n e c e s s i t a t e t h a t more i n fo r m at i on c on ce rn in g

t h e s t r e n g t h an d s t r u c t u r a l p r o p e r t i e s of r o ck m asse s b e a c q ui r ed

a t e a r l i e r s t a g e s i n t h e development o f p r o j e c t s . I n p a r t i c u l a r ,

t h e r e i s a r e a l need t o expand and improve bo th co re d r i l l i n g and

l o g gi n g p r a c t i c e s . r ev ie w of t h e l i t e r a t u r e ve ry r a p i dl y

e s t a b l i s h e s t h e f a c t t h a t t h e r e a r e t ec hn iq ue s v a s t l y s u p e ri o r

t o thos e commonly be in g used . Mul t ip le - tube co re d r i l l i n g , on - s i te

i n d e x p r o p e r t y t e s t i n g , and g e o t e c h n i c a l lo g gi n g a r e b ut a few

examples.

A t

t h e d es i g n s t a g e ,

i t i s

c e r t a i n t h a t m ore e mph asis w i l l b e

p l a ce d on b o t h s t r u c t u r a l a nd

s t r e s s

a n a ly s e s. The development of

pe rso na l computers and new a n a l y t i c a l methods , such a s th e boundary

e le m en t a pp ro ac h, h a s r e s u l t e d i n t h e o p en in g up of p o s s i b i l i t i e s

w hich d id n o t e x i s t ev en f i v e y e a r s ago . Con sequ en tly, much th a t

was fo rm e rl y a l mo st t h e e x c l u s i v e r e s p o n s i b i l i t y of t h e s p e c i a l i s t

s h o u ld become a v a i l ab l e f o r r e g u la r u s e by t h e d e s ig n en gin ee r .


11/13

INSTABILITY UN DER GRO UND

l l of t h e above taken toge the r though can prov ide no complete

a ss ur an ce t h a t i n s t a b i l i t i e s w i l l n o t oc cu r. T he re a r e si mp ly t o o

many unknowns p resen t. At b e s t more co mp le te an d improved info rma -

t i o n and a na ly se s w i l l r e s u l t i n a r e d uc t io n o f t h e p o s s i b i l i t i e s .

2

For t h e p a s t s e v e r a l y e a r s

t h e w r i t e r has been impressed by

the approach t o desig n which invo lves both eng ine erin g and geolo-

g i c a l sp ec i a l i s t s and p ro du c t io n p e r so n n el . T he re

i s

no doubt

th a t each h as something to co n t r ib u te and t h a t su p e r io r p l an n ing

must r e s u l t . As an example of t h i s approach

i t i s

a r o u t i n e

p r a c t i c e a t one l a r g e Canadian o p e r a t i o n t h a t e v a l u a t i o n s u s i n g

f i n i t e e lement methods a r e made o f th e e f f e c t s th a t proposed

ex t ra c t io n w i l l have on th e d eve lo pment of s t r e s s d i s t r i b u t i o n s .

The re su l t an t p lans a r e based on bo th p roduct ion and geo t echn ic a l

c o ns id e ra t io n s. T hi s c a n o nl y r e s u l t i n improvements t o s t a b i l i t y .

3

t i s

s ug ge st ed t h a t g r e a t e r c o n t r o l of s t a b i l i t y ca n b e

achieved through th e con tin uin g development of monitoring and

r e p o r ti n g sys te ms . R es ea rc h e f f o r t s s h o ul d b e d i r e c t e d t o t h e

des ign of ins t ruments which w i l l enab le min ing eng ine ers t o de te c t

zones of h ig h s t r e s s e s a nd d i s c o n t i n u i t i e s a s e a r l y a s p o s s ib l e .

With respec t to moni to r ing th er e i s now much a c t i v i t y i n connec-

t i on with microseismic methods and wit h i ns t r ume nts f o r th e detec-

t io n of loose p ieces o f rock . At p re sen t microse ismic systems a r e

b e in g in s t a l l e d i n a t l e a s t two major Canadian o p e ra t io n s . Resea rch

i n r e s p e c t of l o o s e d e t e c t i o n

i s

a l s o i n p r o g r es s . The work i n

both a re as however must be regarded a s be ing i n th e res ear ch /

development stage.

With respec t t o re po r t in g sys tems

i t i s

s u g g e s t e d t h a t t h e r e

a r e many oppo r tu n i t ies f o r th e development o f in format ion d a t a

banks

through which one could main tain an awareness of co nd i t io ns

as these develop th roughout an opera t ion . At p re sen t the w r i t e r

i s

invo lved i n th e des ign of a system which w i l l be based on da i l y

ap p ra i s a l s of a l l working p l aces . t i s v i s u a l i ze d th a t a number

of months w i l l be req u i red before th e da ta base can be cons ide red

t o be adequate t o permi t de t a i le d eva lua t io ns . Beyond th a t po in t

though t

i s

b e li e ve d t h a t t h e s ys te m i f s u c c e s s f u l w i l l p er mi t

a l l c on ce rne d t o a c q u i r e a much more de t a i l e d unders ta nding of b ot h

l o c a l and g e ne r a l s t a b i l i t y c o n d i t io n s .

F i na l l y t h e w r i t e r s u gg es ts t h a t g r e a t e r c o n t r o l over s t a b i l i t y

can be achieved through edu cat ion and t r ai n i ng .

Recogniz ing tha t

some i n s t a b i l i t i e s r e s u l t from p oo r w or ki ng p r a c t i c e s t i s

c e r t a i n

th a t t h e re a re many ways i n which s t a b i l i t y c o n d i t i o n s co u ld b e

improved through th e improved t r a i n i n g of workers. No doubt rock

mechanics en g in ee r s and grou nd co n t ro l s p e c i a l i s t s co u ld co n t r ib u te

s i g n i f i c a nt l y i n t h i s r e s p e ct


12/13

STABILITY IN UND ERGR OUN D MINING

Conclusion

I n w r i t i n g t h i s p ap er , on a p a r t i c u l a r l y b ro ad s u b j e c t ,

t

h a s

b ee n a bu nd an tl y c l e a r t h a t t h e r e would b e d i f f i c u l t i e s i n c on f in i ng

t h e ma n usc ri p t t o a r e a so n a b l e l e n g t h .

I n t h e i n t e r e s t s of b r e v i t y , t h e n , t h e w r i t e r ha s at te mp te d t o

provid e an overview on th e th re e a s pe c t s which have been chosen

t h e c au se s, c o s t s and c o n t r o l of i n s t a b i l i t i e s .

Whi le t h e r e must be p o in ts which have no t been covered,

i t

i s

hoped t h a t t h i s p ap er w i l l c o n t r i b u t e t o t h e d i s cu s s io n of t h i s

i m p o r t a n t t o p i c .

Acknowledgement

The a u t h o r would l i k e t o e x p r e s s h i s a p p r e c i a t i o n t o h i s

c o l l e a g u e , D r . N Rowlands, f o r h i s review of th e manuscript and

c o n s t r u c t i v e c r i t i c i s m s .

References

1 Gibbs, G. W and P i n t us , P . , 1978. Hea l th and Sa fe ty in the

Canadian Mining In du st ry , Cent re f o r Resource Stu die s ,

Queen ' s Unive rs i ty , Kings ton , Onta r io .

2. Brooks,

D.B.

and Berry, D .R . 1972. ''Mine He alt h and Sa fet y

a s an An a ly t i c Problem , Mine ral B u l l e t i n 125 , In fo rmat ion

Canada, Ottawa (quoted a s a s ou rc e by Gibbs and P in tu s) .

3. Canadian Ce nt re f o r Occ upa t ion al He al th and Saf ety (November

1980) .

A Review of th e L i t e r a tu re on At t i tu de s and Roles and

t h e i r E f f e c t s on S a f e t y i n t h e w ork place . Repor t of the Jo in t

Fe der a l - Pro vin c ia l Inq ui r y Commission i n t o Saf e ty i n Mines and

Min ing P la n t s i n Onta r io , Volume 2 , Queen' s P r i n te r fo r

On tar io , Toron to , pp. 62 63.

4 .

C lu ff , J . , June 1982. Per so nal communicat ion.

5. Ham, J.W., 1976. Re po rt of th e Royal Commission on th e He alt h

and Sa fe ty o f Workers i n Mines , Queen 's P r i n t e r f o r Onta r io ,

Toronto.

6 . B u r k e t t ,

K.M.

e t a l . , 1 98 1. R ep or t of t h e Jo i n t Fed er al -

P l a n t s i n O n t a r i o , Q ueen 's P r i n t e r f o r O n t a r i o , To ro nto .


13/13

INST BILITY UNDER GRO UND 35

7. Shannon,

H.

and Snyder,

D .

Januar y 1981. An Update of

S t a t i s t i c s Found i n th e Report of th e Royal Commission on th e

Health and Saf ety of Workers i n Mines , Report of th e J o i n t

Federal-Provincial Inq uiry Commission i n t o Safe ty i n Mines

and Mining Pl an ts i n Ontar io , Volume 2, Queen 's P r i n t e r f o r

Ont ario, Toronto, Table 15, page 23.

8. Shannon, H. and Snyder,

D .

Ja nu ary 1981. An Update of S t a t i s -

t i c s Found in th e Report of th e Rova l C o d s s i o n on the Hea lth

-

and Safet y of Workers i n Mines , Report of th e J o in t Fed era l-

Pro vin cia l Inquiry Commission i n t o S afe t y i n Mines and Mining

Pla nts i n Onta rio , Volume 2 , Queen 's P r in te r f o r Onta r io ,

Toronto, Table 23, page 27.

9. Anon., 1978. An Act Re sp ec ting t h e Occ upa tional He al th and

Occupational Safety of Workers , B i l l 70, 2nd Ses sio n, 31 st

Legis la ture , O nta r io , Queen 's P r in te r fo r Onta r io , Toronto ,

Se ct io n 28- (1) (k) page 29.

10. Anon., 1978. An Act Res pec tin g t h e Oc cup ati on al Hea lth and

Occupational Sa fet y of Workers , B i l l 70, 2nd Se ss io n, 31 st

Legis la ture , Onta r io , Queen 's P r in te r fo r Onta r io , Toronto ,

Sect ion s 14 18 , pp. 14 19.

Documents

Instability Underground - Causes, Costs and Controls