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Observation of cracks propagating in diametrically-compressed rock discs
2A
Luminescence can be clearly related to certain concentrations of the transition elements of the periodic system incorporated in a host mineral. During the last decade the energy band model has been replaced by the ligandfield theory for the interpretation of the phenomenon. Cathode luminescence may reveal textures in minerals and rocks that are not recognisable through the transmitted light of a petrographic microscope. Determination of degree of compaction, compaction phases and fracture generation have been reported. A luminoscope is now commercially available, and instrmment design is described, data are surveyed for a wide variety of rock-forming minerals, argl applications of feasible methods are l~esented and critically assessed. 84 refs. 791009 SOME DEFORMATION AND FRACTURE CHARACTERISTICS OF OIL SHALE Cleary, M P Proc 19th US Symposium on Rock Mechanics, Stateline, Nevada, 1-3 May 1978, V2, P7282. Publ Renc: University of Nevada, 1978 Reports tests conducted with homogeneous tension and compression specimens, torsion configurations and suitable fracture geometries on ~ grades of oil shale from Anvil Points, Colorado. Strong directionality and temperature dependence was found in moduli, strengths, and toughness. Fracture toughnesses increased markedly with richness of kerogen content. A mathematical model is developed to link monotonic deformation with dilatancy and other nonlinearities due to microdamage. Mechanics of fracture behaviour are discussed, and the method used in experiment is compared with others, particularly that of Schmidt.
Texture, structure, composition and density
791010 E~'~CT OF IR-I~qAGRA~_R POROSITY ON COMPACTION Saxena, S K; Her~rikson, C J Geotech E r ~ Div ASCE, VI0~, NGTS, 19Y8,
Pl053-1059 The variation in intragranular porosity of limestones often does not allow specified compaction standards to be achieved when limestone aggregates are used as fills. The influence of Intragranular porosity and specific gravity on the maximum dry densities of a number of limestone aggregates are discussed. Practical guidelines for achieving good resuits are given. 791011 INI~RPRETATION OF THE GRAVITATIONAL EFFECT OF A TWO-DIMENsIONAL DYKE BY FOURI~q TRANSFORM Ser~pta, S; Das, S Geoexploration, V15, ~ , Oct 1977, P251-261 An equation is presented for the gravity effect due to an inclined 2-dimensional dyke of finite depth, which is interpreted by using Fourier transforms. It is shown that the parameters associated with dykes can be estimated from the phase and amplitude spectra. The method has so far only been used for theoretical analysis.
791012 ANALYSIS OF JOINT TRACES Barton, C M Proc 19th US Symposium on Rock Mechanics, Statellne, Nevada, 1-3 May 1978, V1, P38-41. Publ Reno: University of Nevada, 1978 Rock Joints can be considered as extremely thin disc-like breaks which cut through rock masses. This paper established a numerical model to determine the salient characteristics of Joint trace l e r ~ s from random intersections of specified populations of Joint discs. Comparisons of field and model data show good correlation.
Fracture processes See also: 791143 791013 OBSERVATION OF CRACKS PROPAGATING IN DIAMETRIcALLY-COMPRESSED ROCK DISCS Yanagldanl, T; Sano, 0; Terada, M Int J Rock Mech Min Sci, V15, N~, Oct 1978,
P225-235 This study considers the cracking mechanism of diametrically-compressed rock discs. The crack initiation point, crack propagation velocity and the stress field due to the dynamic crack running were studied using the strain gages as a crack detector. The troublesome l~oblem in the Brazilian test was solved directly. The experimental results show that the crack is not initiatdd from the loading point but from the tensile stress zone. The results have direct relevance to the validity of the Brazilian test. Auth. 791014 EXP~IMENTAL METHOD TO ESTIMATE THE DYNAMIC FRACTURE STRENC/fH OF OIL SKALE IN THE i0 CUBED TO I0 TO THE FOURT~SEC STRAIN RATE REGIME Forrestal, M J; Grady, D E; Schuler, K W Int J Rock Mech Min Sci, V15, NS, Oct 1978, P263-265 A magnetic pressure loading technique was successfully applied to estimate the dynamic spall strength of oil shale. The strain rate regime is complementary to those achievable with air guns and Hopklnson bar tests. 791015 NEW ASPECTS OF SOIL FRACTURING IN CLAY Massarsch, K R J Geotech Engng Div ASCE, Vl04, NGT8, 1978, PII09-I123 An analysis using cavity expansion theory suggests that soil fracturing can occur within the plastic zone during expansion of a cavity in clay. Results from pore pressure measurements during pile dri~Ing and hydraulic fracturing tests support this conclusion. An analysis shows that fracturing in hydraulic fracturing tests is likely to occur along vertical planes in both normally and overconsolidated clays. 791016 CONTAIh~4ENr OF MASSIVE HYDRAULIC FRACTURES Simonson, E R; Abou-Sayed, A S; Clifton, R J Soc Pet Engr J, V18, N1, Feb 1978, P27-32 Discusses contair~ent in relation to linear elastic fracture mechanics. Three cases are
Luminescence can be clearly related to certain concentrations of the transition elements of the periodic system incorporated in a host mineral. During the last decade the energy band model has been replaced by the ligandfield theory for the interpretation of the phenomenon. Cathode luminescence may reveal textures in minerals and rocks that are not recognisable through the transmitted light of a petrographic microscope. Determination of degree of compaction, compaction phases and fracture generation have been reported. A luminoscope is now commercially available, and instrmment design is described, data are surveyed for a wide variety of rock-forming minerals, argl applications of feasible methods are l~esented and critically assessed. 84 refs. 791009 SOME DEFORMATION AND FRACTURE CHARACTERISTICS OF OIL SHALE Cleary, M P Proc 19th US Symposium on Rock Mechanics, Stateline, Nevada, 1-3 May 1978, V2, P7282. Publ Renc: University of Nevada, 1978 Reports tests conducted with homogeneous tension and compression specimens, torsion configurations and suitable fracture geometries on ~ grades of oil shale from Anvil Points, Colorado. Strong directionality and temperature dependence was found in moduli, strengths, and toughness. Fracture toughnesses increased markedly with richness of kerogen content. A mathematical model is developed to link monotonic deformation with dilatancy and other nonlinearities due to microdamage. Mechanics of fracture behaviour are discussed, and the method used in experiment is compared with others, particularly that of Schmidt.
Texture, structure, composition and density
791010 E~'~CT OF IR-I~qAGRA~_R POROSITY ON COMPACTION Saxena, S K; Her~rikson, C J Geotech E r ~ Div ASCE, VI0~, NGTS, 19Y8,
Pl053-1059 The variation in intragranular porosity of limestones often does not allow specified compaction standards to be achieved when limestone aggregates are used as fills. The influence of Intragranular porosity and specific gravity on the maximum dry densities of a number of limestone aggregates are discussed. Practical guidelines for achieving good resuits are given. 791011 INI~RPRETATION OF THE GRAVITATIONAL EFFECT OF A TWO-DIMENsIONAL DYKE BY FOURI~q TRANSFORM Ser~pta, S; Das, S Geoexploration, V15, ~ , Oct 1977, P251-261 An equation is presented for the gravity effect due to an inclined 2-dimensional dyke of finite depth, which is interpreted by using Fourier transforms. It is shown that the parameters associated with dykes can be estimated from the phase and amplitude spectra. The method has so far only been used for theoretical analysis.
791012 ANALYSIS OF JOINT TRACES Barton, C M Proc 19th US Symposium on Rock Mechanics, Statellne, Nevada, 1-3 May 1978, V1, P38-41. Publ Reno: University of Nevada, 1978 Rock Joints can be considered as extremely thin disc-like breaks which cut through rock masses. This paper established a numerical model to determine the salient characteristics of Joint trace l e r ~ s from random intersections of specified populations of Joint discs. Comparisons of field and model data show good correlation.
Fracture processes See also: 791143 791013 OBSERVATION OF CRACKS PROPAGATING IN DIAMETRIcALLY-COMPRESSED ROCK DISCS Yanagldanl, T; Sano, 0; Terada, M Int J Rock Mech Min Sci, V15, N~, Oct 1978,
P225-235 This study considers the cracking mechanism of diametrically-compressed rock discs. The crack initiation point, crack propagation velocity and the stress field due to the dynamic crack running were studied using the strain gages as a crack detector. The troublesome l~oblem in the Brazilian test was solved directly. The experimental results show that the crack is not initiatdd from the loading point but from the tensile stress zone. The results have direct relevance to the validity of the Brazilian test. Auth. 791014 EXP~IMENTAL METHOD TO ESTIMATE THE DYNAMIC FRACTURE STRENC/fH OF OIL SKALE IN THE i0 CUBED TO I0 TO THE FOURT~SEC STRAIN RATE REGIME Forrestal, M J; Grady, D E; Schuler, K W Int J Rock Mech Min Sci, V15, NS, Oct 1978, P263-265 A magnetic pressure loading technique was successfully applied to estimate the dynamic spall strength of oil shale. The strain rate regime is complementary to those achievable with air guns and Hopklnson bar tests. 791015 NEW ASPECTS OF SOIL FRACTURING IN CLAY Massarsch, K R J Geotech Engng Div ASCE, Vl04, NGT8, 1978, PII09-I123 An analysis using cavity expansion theory suggests that soil fracturing can occur within the plastic zone during expansion of a cavity in clay. Results from pore pressure measurements during pile dri~Ing and hydraulic fracturing tests support this conclusion. An analysis shows that fracturing in hydraulic fracturing tests is likely to occur along vertical planes in both normally and overconsolidated clays. 791016 CONTAIh~4ENr OF MASSIVE HYDRAULIC FRACTURES Simonson, E R; Abou-Sayed, A S; Clifton, R J Soc Pet Engr J, V18, N1, Feb 1978, P27-32 Discusses contair~ent in relation to linear elastic fracture mechanics. Three cases are