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Determination of stresses in deep holes and around tunnels by hydraulic fracturing
12~A
the s t r a i n sensor pipe, s~d from which it is extruded into the space between the geu~e and rock by a plunger. The ~ s ~ e s p e r m i t c o n t i n u o u s o b s e r v a t i o n o f s t r a i n s d u r ln~ overcorin~, ere ~ i s o l a t e d from d r i l l i n g w a t e r , and o p e r a t e s a t i s f a c t o r i l y a t low b o n d s t r e a ~ t ~ w i t h r o c k . They h a v e b e e n u s e d t o measure s t r e s s e s v e ~ - r ~ f r o m 1.~ t o 1 0 0 ~ a a t t e m p e r a t u r e s from l~degC t o ~SdegC.
1167
A L E X A ~ , LG DIV .APP.G~CH., CSIRO,MELB .,AUS Effects of pore water Pressure in two methods of r o c k s t r e s s measurement. PAPER TO ~ I I ~ , I N V E S T I G A T I O N OF STRESS IN ROCK-ADVANCES IN SI~ESS ~ . S Y D N E Y , II-13 AUG,1976,SUPPL. Appreciable time dependent deformation occurred in rock stress measurements in a sandstone b y t h e flat~ack and borehole deformatic~ overcorin~ methods. During tmmellin~, borehole extensometer observations in the tunnel w = ~ e showed, at one location, radial s h r i n k a g e o f t h e surround. An attempt i s made t o account for these as "the dual effects of pore water pressure, shrinkage end consolldatic~, in a saturated porous elastic medium. The p a r a m e t e r s o f t h e medium include a p o r e p r e s s u r e coefficient end a pore water compressibility parameter. ~ROWN, ET IMP.COLL.SC I .TECHNOL,IDNDON,GB HOCKING, G D4P.COLE..SCI .TECH~OL,LONI~ON,GB The u s e o f t h r e e a ~ . ~ n s i o n a l b o u n d a r y i n t e g r a l equation method for determining stresses at tunnel intersectlc~s. 7F,IIR. PAPER TO DESIGN AND CONSTRUCTION OF ~ N E L S AND SHAFTS C O N F ~ C E , MEL~Ot~NE,AUG. 1976,P~5 -6~. The boundary integral equation method offers adventages over o t h e r methods o f 3-D stress analysis in that it does not require the specialist equll~nent end skills of 3-]) photoelastlcity, and has lower computational end data preparation costs then the 3-D finite element method. The potential of the method for 3.D stress analysis of underground openings has been d e m o n s t r a t e d u s i n g a program t o determine the distributions of boundery stresses for Tand Y- ~unctic~s of circular t u n n e l s . Deformations end stresses sws~ from the tunnel boundaries are aASo ~iven by the program.
1171 HAIMISON,BC WISCONSIN UNIV ,MADISON,USA Determinatic~ of stresses in deep holes and around tunnels by hy~ret~lic fracturing. 2 ~ . PROC.RAPID EXCAVATION & TUNNELLI~ C O ~ C E , S A N FRANCISCO, 2~-27 JUNE,197~ ,V2,PI~39-1~60. Using this method, stresses ere calculated directly f r o m t h e f l u i d P r e s s u r e s n e c e s s a r y t o i n i t i a t e and e x t e n d a fracture away from a borehole. Stress determinatlc~ is r a t h e r insensitive to inhomogeneity or e~Isotropy, is not limited in depth except by the length of the hole, requires simple equipment which is com~srcially available, and cs~ be carried out by unskilled personnel. The method has been worked out theoretical~7 and extensively tested snd verified in the laboratory. A n~®ber of field tests in deep holes rangin~ from 300 to 630Oft have yielded good results.
Temporary and permanent supports See also abstract: i142. 1172 DAR, SM U.S .BUR .~P/I~ES,SPOKANE,USA RATES,RC U .S .BUR . M ~ , SPOKANE,USA Analysis of backpacked liners. 12F,3T,Z2R. J .GEOTECH.~GNG DIV .ASCE,VI02,GT7,1976, P739-759. A set of theoretical equations is developed to predict the stresses end d i s p l a c ~ t s everywhere in a linerb e c k p a c k ~ support system of linearly elastic material. It is assumed that the field stresses are applied to the system after the liner has been placed, and the pressures due to the instability of the rock opening itself are not considered. Theoretical work is applicable to any number of concentric layers of material, thereby enabling one to hsndle underground situatians where bac .kpacking can be placed between liner and rock. Graphs shoving the beneflts end limitations of backpacking are given along with an example ~howing the effects of an ultrasoft layer o f m a t e r i a l s u r r o u n d i r ~ t h e l i n e r . These e q u a t i o n s when applied to existing laboratory data show good agreement w i t h measured v a l u e s , +and t h e y h a v e a l s o g u i d e d t h e d e si~ of field liner installatic~s. Auth.
1169 M~RE O F~qRAL,RC K~STE~,RW Stress and fracture develOl~nent around stopes in deep t a b u l a r ore b o d i e s . 7R. ASSN.MIN.MSRS.S.AFR.PAP]'~S & DISCUSSIONS,197~,P3-26. Deals with the basic termlnoio~r end fundamental concepts of the science of rock mechanics as applied to narrow tabular Ore bodies, describing the stress distribution r o u n d a s i n g l e advancing s t o p e f a c e , the s t r e s s e s t h a t cen be expected for r~ent m i n i n g , as w e l l as t h e a f f e c t of overstoping of footwall haulages. 1170 NOORISHAD,J PAHIAVI UNIV,SHIRAZ, IR W I ~ N , PA PAHIAV I U~IV, S~HRAZ, ZR MAINI,YN PAHIAVI t~IV, SHIRAZ, IR Influence of fluid injection on the s t a t e o f stress in the earth's crust. PAPER T2-H TO SD~.ON PERCOLATION THROUGH F ~ ROCK,~,18-19 S ~ T 1~72,11P. A coupled stress flow method is described for enal~zing the s t e a d y state effect of in~ectlng fluid into rock systems where the flow is governed by the behaviour of de.f. orn~ble fractures. The method employs two finite el~,~nt techniques, one for fluid flow end the other for s t r e s s snalysis~ s~d a conver~In~ iteration process. Exan~les of fracture systems with simple gecmetries ere snalyzed t o d e m o n s t r a t e some s u b s u r f a c e c c ~ d i t i o n s u n d e r which injected fluids a r e able either to attenuate or to Concentrate stresses in the earth's crust as distance from the point of injection increases.
ROME,G E q u i v a l e n t r o c k column d e s i g n system f o r t u n n e l l i n e r s end u n d e r g r o u n d s t r u c t u r e s i n c o r p o r a t i n g r o c k restraint. 14F,l~. PAPER TO DESIGN AND CONSTRUCTION OF ~NNELS AND SHAFTS C O N F ~ C E , ~ t ~ q N E , AUG .1976,P41- 5~. An approw1-~te rapid design system for tunnel liners and underground structures is presented which permits the e f f e c t s o f s t r u c t u r e g e o m e t ~ and s t i f f n e s s , r o c k q u a l i t y i n t e r m s of i t s d e f o r m a t i o n modulus, and t h e a p p l i e d s y s t e m l o a d i n g t o be entered as data to ~cod~ce d i r e c t d e s i g n s cc~forming t o s t r e s s l i m i t a t i c ~ s , optimum r e i n forcement requirements and restraints c~ section dimsn. sions. An 'equivalent colu~m' concept is introduced for modelling the rock mass in contact vith the structure. Only the rock treatment is given in detail but the results of sensitivity analyses, with reference to rock quality, for a typical liner design ere given end these results related to a number of e~irical design s ~ s c . hes.
COWLING,R ~DUNT ISA ~I~ES,AUS GONANO,LP CSIRO,I~,AUS Cemented rockfill practice at Mount Isa Mines Limi. ted. 17~,3T, Ta. PROC.SYI~.INFI//D~E EXCAVATION DESIGN GROUND SUPPORT ON UND~GROUND M I N I N G . . . E r C , W O ~ , I 5 MAY,1976,PII-~3. The work d e s c r i b e d d e t a i l s a r a t i o n a l a~proach t o ceme~. ted rockfill deslgn and its-application to the use of
the s t r a i n sensor pipe, s~d from which it is extruded into the space between the geu~e and rock by a plunger. The ~ s ~ e s p e r m i t c o n t i n u o u s o b s e r v a t i o n o f s t r a i n s d u r ln~ overcorin~, ere ~ i s o l a t e d from d r i l l i n g w a t e r , and o p e r a t e s a t i s f a c t o r i l y a t low b o n d s t r e a ~ t ~ w i t h r o c k . They h a v e b e e n u s e d t o measure s t r e s s e s v e ~ - r ~ f r o m 1.~ t o 1 0 0 ~ a a t t e m p e r a t u r e s from l~degC t o ~SdegC.
1167
A L E X A ~ , LG DIV .APP.G~CH., CSIRO,MELB .,AUS Effects of pore water Pressure in two methods of r o c k s t r e s s measurement. PAPER TO ~ I I ~ , I N V E S T I G A T I O N OF STRESS IN ROCK-ADVANCES IN SI~ESS ~ . S Y D N E Y , II-13 AUG,1976,SUPPL. Appreciable time dependent deformation occurred in rock stress measurements in a sandstone b y t h e flat~ack and borehole deformatic~ overcorin~ methods. During tmmellin~, borehole extensometer observations in the tunnel w = ~ e showed, at one location, radial s h r i n k a g e o f t h e surround. An attempt i s made t o account for these as "the dual effects of pore water pressure, shrinkage end consolldatic~, in a saturated porous elastic medium. The p a r a m e t e r s o f t h e medium include a p o r e p r e s s u r e coefficient end a pore water compressibility parameter. ~ROWN, ET IMP.COLL.SC I .TECHNOL,IDNDON,GB HOCKING, G D4P.COLE..SCI .TECH~OL,LONI~ON,GB The u s e o f t h r e e a ~ . ~ n s i o n a l b o u n d a r y i n t e g r a l equation method for determining stresses at tunnel intersectlc~s. 7F,IIR. PAPER TO DESIGN AND CONSTRUCTION OF ~ N E L S AND SHAFTS C O N F ~ C E , MEL~Ot~NE,AUG. 1976,P~5 -6~. The boundary integral equation method offers adventages over o t h e r methods o f 3-D stress analysis in that it does not require the specialist equll~nent end skills of 3-]) photoelastlcity, and has lower computational end data preparation costs then the 3-D finite element method. The potential of the method for 3.D stress analysis of underground openings has been d e m o n s t r a t e d u s i n g a program t o determine the distributions of boundery stresses for Tand Y- ~unctic~s of circular t u n n e l s . Deformations end stresses sws~ from the tunnel boundaries are aASo ~iven by the program.
1171 HAIMISON,BC WISCONSIN UNIV ,MADISON,USA Determinatic~ of stresses in deep holes and around tunnels by hy~ret~lic fracturing. 2 ~ . PROC.RAPID EXCAVATION & TUNNELLI~ C O ~ C E , S A N FRANCISCO, 2~-27 JUNE,197~ ,V2,PI~39-1~60. Using this method, stresses ere calculated directly f r o m t h e f l u i d P r e s s u r e s n e c e s s a r y t o i n i t i a t e and e x t e n d a fracture away from a borehole. Stress determinatlc~ is r a t h e r insensitive to inhomogeneity or e~Isotropy, is not limited in depth except by the length of the hole, requires simple equipment which is com~srcially available, and cs~ be carried out by unskilled personnel. The method has been worked out theoretical~7 and extensively tested snd verified in the laboratory. A n~®ber of field tests in deep holes rangin~ from 300 to 630Oft have yielded good results.
Temporary and permanent supports See also abstract: i142. 1172 DAR, SM U.S .BUR .~P/I~ES,SPOKANE,USA RATES,RC U .S .BUR . M ~ , SPOKANE,USA Analysis of backpacked liners. 12F,3T,Z2R. J .GEOTECH.~GNG DIV .ASCE,VI02,GT7,1976, P739-759. A set of theoretical equations is developed to predict the stresses end d i s p l a c ~ t s everywhere in a linerb e c k p a c k ~ support system of linearly elastic material. It is assumed that the field stresses are applied to the system after the liner has been placed, and the pressures due to the instability of the rock opening itself are not considered. Theoretical work is applicable to any number of concentric layers of material, thereby enabling one to hsndle underground situatians where bac .kpacking can be placed between liner and rock. Graphs shoving the beneflts end limitations of backpacking are given along with an example ~howing the effects of an ultrasoft layer o f m a t e r i a l s u r r o u n d i r ~ t h e l i n e r . These e q u a t i o n s when applied to existing laboratory data show good agreement w i t h measured v a l u e s , +and t h e y h a v e a l s o g u i d e d t h e d e si~ of field liner installatic~s. Auth.
1169 M~RE O F~qRAL,RC K~STE~,RW Stress and fracture develOl~nent around stopes in deep t a b u l a r ore b o d i e s . 7R. ASSN.MIN.MSRS.S.AFR.PAP]'~S & DISCUSSIONS,197~,P3-26. Deals with the basic termlnoio~r end fundamental concepts of the science of rock mechanics as applied to narrow tabular Ore bodies, describing the stress distribution r o u n d a s i n g l e advancing s t o p e f a c e , the s t r e s s e s t h a t cen be expected for r~ent m i n i n g , as w e l l as t h e a f f e c t of overstoping of footwall haulages. 1170 NOORISHAD,J PAHIAVI UNIV,SHIRAZ, IR W I ~ N , PA PAHIAV I U~IV, S~HRAZ, ZR MAINI,YN PAHIAVI t~IV, SHIRAZ, IR Influence of fluid injection on the s t a t e o f stress in the earth's crust. PAPER T2-H TO SD~.ON PERCOLATION THROUGH F ~ ROCK,~,18-19 S ~ T 1~72,11P. A coupled stress flow method is described for enal~zing the s t e a d y state effect of in~ectlng fluid into rock systems where the flow is governed by the behaviour of de.f. orn~ble fractures. The method employs two finite el~,~nt techniques, one for fluid flow end the other for s t r e s s snalysis~ s~d a conver~In~ iteration process. Exan~les of fracture systems with simple gecmetries ere snalyzed t o d e m o n s t r a t e some s u b s u r f a c e c c ~ d i t i o n s u n d e r which injected fluids a r e able either to attenuate or to Concentrate stresses in the earth's crust as distance from the point of injection increases.
ROME,G E q u i v a l e n t r o c k column d e s i g n system f o r t u n n e l l i n e r s end u n d e r g r o u n d s t r u c t u r e s i n c o r p o r a t i n g r o c k restraint. 14F,l~. PAPER TO DESIGN AND CONSTRUCTION OF ~NNELS AND SHAFTS C O N F ~ C E , ~ t ~ q N E , AUG .1976,P41- 5~. An approw1-~te rapid design system for tunnel liners and underground structures is presented which permits the e f f e c t s o f s t r u c t u r e g e o m e t ~ and s t i f f n e s s , r o c k q u a l i t y i n t e r m s of i t s d e f o r m a t i o n modulus, and t h e a p p l i e d s y s t e m l o a d i n g t o be entered as data to ~cod~ce d i r e c t d e s i g n s cc~forming t o s t r e s s l i m i t a t i c ~ s , optimum r e i n forcement requirements and restraints c~ section dimsn. sions. An 'equivalent colu~m' concept is introduced for modelling the rock mass in contact vith the structure. Only the rock treatment is given in detail but the results of sensitivity analyses, with reference to rock quality, for a typical liner design ere given end these results related to a number of e~irical design s ~ s c . hes.
COWLING,R ~DUNT ISA ~I~ES,AUS GONANO,LP CSIRO,I~,AUS Cemented rockfill practice at Mount Isa Mines Limi. ted. 17~,3T, Ta. PROC.SYI~.INFI//D~E EXCAVATION DESIGN GROUND SUPPORT ON UND~GROUND M I N I N G . . . E r C , W O ~ , I 5 MAY,1976,PII-~3. The work d e s c r i b e d d e t a i l s a r a t i o n a l a~proach t o ceme~. ted rockfill deslgn and its-application to the use of