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Compressive strength of tuff as a function of strain rate. Technical note
269A 915029
It is used with the numerical-graphical code ANABELA II to model the self boring pressuremeter test. It is possible to determine the curve of friction angles mobilised at each deformation step in the test. Friction angle at the critical state can probably be determined if it is reached during the test.
A structural model, the long range interaction theory, has been developed (Stepkowska, 1988) on a semi-theoretical, semi-empirical basis to explain the behaviour of smectitic clay. Scanning and transmission electron microscopy has been used to provide evidence of the proposed structure, a parallel arrangement of smectitic particles in domains, and their possible delamination and collapse, and their gradual aggregation under external and internal pressures with the formation of plane-parallel fissures.
915033 Prediction of oil saod failure due to steam-iodoced stress Tortike, W S; Farouq Ali, S M Can Pet Technol V30. Nl I Jan-Feb 1991. P87-96
VerIikatlon of the str~2~1l model of clay-water system Stepkowska, E T Proc 12th International Conference on Soil Mechanics and Foutukuion Engineering, Rio a%Janeiro, 13-18 August 1989 VI, P659-662. Pub1 Rotterdam: A A Balkema, 1989
915030 Recent soils of the PO River: statistical analysis of geoteclmical properties
Favaretti, M; Previatello, P Froc 6th International Congress International Association of Engineering Geology, Amsterdizm, 6-10 August 1990 VI, P609-615. Pub1 Rotterdam: A A Balkema. 1990 During work in the PO valley, several boreholes were drilled over a relatively small area of a sedimentary sequence. Statistical analysis of laboratory measured soil properties is presented. Frequency distribution curves relative to liquid limit, plastic limit, plasticity index, water content, specific gravity, undrained shear strength, compressive index, size distribution, uniformity coefficient, and curvature coefficient of granular soils were determined. Possible linear regressions between these parameters were evaluated. High scatter about mean values, frequency distribution curves tending to the Beta distribution, and statistically significant influence of liquid limit on other properties were seen. 915031 Engineering-geologicalclassification of clay microstroctures Sokolov, V N Proc 6th International Congress Znternational Association of Engineering Geology, Amsterdam, 6-10 August 1990 VI, P753-760. Pub/ Rotter&m: A A Balkema, 1990 A microstructural classification of clays is described which includes size and shape of structural units, orientation of structural units, and energy of structural bonds. Classes and subclasses are distinguished on the basis of dispersion and anisotropy coefficient. Groups are identified according to value of strength and character of deformation. Three microstructural classes (fine, medium, coarse), three degrees of structural orientation (high, medium, low), and three energy groups (coagulative, mixed, cemented) are developed. Based on the combination of these factors, strength and deformation characteristics can be predicted.
Deformation and strength characteristics See also: 915001, 915010, 915201, 915237. 915239, 915278, 915283. 915032 RadIaI expansion of cylindrical cavities in sandy soil application to pressoremeter tests de Sousa Coutinho, A G F Can Geotech J V27, N6, Dee 1990, P737-748 A solution for radial expansion of a cylindrical cavity in a sandy medium is developed. The constitutive model is rigidplastic, but not perfectly plastic, and is valid for finite strains.
A numerical model of oil sand including steam/water-oil-gas flow and geomechanical behaviour of the porous medium in the mobilized zone has been developed. It can be used to predict distributions of fluid saturation and pressure, temperature, and stress, and thus to forecast the type of failure expected, shear or parting. It is demonstrated in conjunction with a conventional numerical reservoir model and used to assess three steam injection cycles. 915034 Cohesive soil for huge-size laboratory deposits McManus, K J; Kulhawy, F H Geotech Test J V14. Nl, March 1991, P26-34 Large laboratory samples of cohesive soils can be prepared using the slurry method, if suitable soil materials are available. The requirements of such a soil are discussed. 6 artificial soil mixtures were evaluated, including consolidation of the slurry in a special apparatus. The properties of the selected material, a kaolin/fine ground silica mixture termed Cornell Clay, are presented. Consolidated undrained triaxial test results demonstrate that Cornell Clay has strength parameters similar to many natural cohesive deposits. 915035 Compressive streogth of tatT as a function of strain rate. Technical oote Olsson, W A Int J Rock Mech Min Sci V28, Nl, Jan 1991, Pll5-118 Strain rate dependence of the compressive strength of a tuff from the Nevada Test Site was measured over a strain rate range of 9 orders of magnitude, up to lOOO/sec.Air dry cylindrical specimens aligned parallel to the bedding were used. A conventional electrohydraulic closed loop testing machine was used for strain rates up to 4/set, and a split Hopkinson pressure (Kolsky) bar at rates above 130/set. There is a weak dependence of strength on strain rate up to values of 76/set, then the dependence is on cube root of strain rate. This is consistent with rate effect determined by the crack propagation vs intensity factor relation at slower rates and by a statistical crack model at higher rates. 915036 Direct measurement of the effective pressme law: deformation of joints subject to pore nod confining pressores Boitnott, G N; Scholz, C H J Geophys Res V95, NB12, Nov 1990, Pl9279-19298 Deformation of poroelastic materials is usually analyzed using the concept of effective pressure. In geological materials, loading path dependence (hysteresis) complicates matters and it is difficult to describe properties which exhibit hysteresis by a single stress state variable. An experimental technique for measuring the effective pressure law which can be applied for many properties of interest is presented. It is applied to an experimental study of the effective pressure law of joint closure, and a relation is derived which describes values of pore and confining pressures consistent with a given joint closure for a loading path of constant closure.
0 1991 Pergamon Press plc. Reproduction not permitted
It is used with the numerical-graphical code ANABELA II to model the self boring pressuremeter test. It is possible to determine the curve of friction angles mobilised at each deformation step in the test. Friction angle at the critical state can probably be determined if it is reached during the test.
A structural model, the long range interaction theory, has been developed (Stepkowska, 1988) on a semi-theoretical, semi-empirical basis to explain the behaviour of smectitic clay. Scanning and transmission electron microscopy has been used to provide evidence of the proposed structure, a parallel arrangement of smectitic particles in domains, and their possible delamination and collapse, and their gradual aggregation under external and internal pressures with the formation of plane-parallel fissures.
915033 Prediction of oil saod failure due to steam-iodoced stress Tortike, W S; Farouq Ali, S M Can Pet Technol V30. Nl I Jan-Feb 1991. P87-96
VerIikatlon of the str~2~1l model of clay-water system Stepkowska, E T Proc 12th International Conference on Soil Mechanics and Foutukuion Engineering, Rio a%Janeiro, 13-18 August 1989 VI, P659-662. Pub1 Rotterdam: A A Balkema, 1989
915030 Recent soils of the PO River: statistical analysis of geoteclmical properties
Favaretti, M; Previatello, P Froc 6th International Congress International Association of Engineering Geology, Amsterdizm, 6-10 August 1990 VI, P609-615. Pub1 Rotterdam: A A Balkema. 1990 During work in the PO valley, several boreholes were drilled over a relatively small area of a sedimentary sequence. Statistical analysis of laboratory measured soil properties is presented. Frequency distribution curves relative to liquid limit, plastic limit, plasticity index, water content, specific gravity, undrained shear strength, compressive index, size distribution, uniformity coefficient, and curvature coefficient of granular soils were determined. Possible linear regressions between these parameters were evaluated. High scatter about mean values, frequency distribution curves tending to the Beta distribution, and statistically significant influence of liquid limit on other properties were seen. 915031 Engineering-geologicalclassification of clay microstroctures Sokolov, V N Proc 6th International Congress Znternational Association of Engineering Geology, Amsterdam, 6-10 August 1990 VI, P753-760. Pub/ Rotter&m: A A Balkema, 1990 A microstructural classification of clays is described which includes size and shape of structural units, orientation of structural units, and energy of structural bonds. Classes and subclasses are distinguished on the basis of dispersion and anisotropy coefficient. Groups are identified according to value of strength and character of deformation. Three microstructural classes (fine, medium, coarse), three degrees of structural orientation (high, medium, low), and three energy groups (coagulative, mixed, cemented) are developed. Based on the combination of these factors, strength and deformation characteristics can be predicted.
Deformation and strength characteristics See also: 915001, 915010, 915201, 915237. 915239, 915278, 915283. 915032 RadIaI expansion of cylindrical cavities in sandy soil application to pressoremeter tests de Sousa Coutinho, A G F Can Geotech J V27, N6, Dee 1990, P737-748 A solution for radial expansion of a cylindrical cavity in a sandy medium is developed. The constitutive model is rigidplastic, but not perfectly plastic, and is valid for finite strains.
A numerical model of oil sand including steam/water-oil-gas flow and geomechanical behaviour of the porous medium in the mobilized zone has been developed. It can be used to predict distributions of fluid saturation and pressure, temperature, and stress, and thus to forecast the type of failure expected, shear or parting. It is demonstrated in conjunction with a conventional numerical reservoir model and used to assess three steam injection cycles. 915034 Cohesive soil for huge-size laboratory deposits McManus, K J; Kulhawy, F H Geotech Test J V14. Nl, March 1991, P26-34 Large laboratory samples of cohesive soils can be prepared using the slurry method, if suitable soil materials are available. The requirements of such a soil are discussed. 6 artificial soil mixtures were evaluated, including consolidation of the slurry in a special apparatus. The properties of the selected material, a kaolin/fine ground silica mixture termed Cornell Clay, are presented. Consolidated undrained triaxial test results demonstrate that Cornell Clay has strength parameters similar to many natural cohesive deposits. 915035 Compressive streogth of tatT as a function of strain rate. Technical oote Olsson, W A Int J Rock Mech Min Sci V28, Nl, Jan 1991, Pll5-118 Strain rate dependence of the compressive strength of a tuff from the Nevada Test Site was measured over a strain rate range of 9 orders of magnitude, up to lOOO/sec.Air dry cylindrical specimens aligned parallel to the bedding were used. A conventional electrohydraulic closed loop testing machine was used for strain rates up to 4/set, and a split Hopkinson pressure (Kolsky) bar at rates above 130/set. There is a weak dependence of strength on strain rate up to values of 76/set, then the dependence is on cube root of strain rate. This is consistent with rate effect determined by the crack propagation vs intensity factor relation at slower rates and by a statistical crack model at higher rates. 915036 Direct measurement of the effective pressme law: deformation of joints subject to pore nod confining pressores Boitnott, G N; Scholz, C H J Geophys Res V95, NB12, Nov 1990, Pl9279-19298 Deformation of poroelastic materials is usually analyzed using the concept of effective pressure. In geological materials, loading path dependence (hysteresis) complicates matters and it is difficult to describe properties which exhibit hysteresis by a single stress state variable. An experimental technique for measuring the effective pressure law which can be applied for many properties of interest is presented. It is applied to an experimental study of the effective pressure law of joint closure, and a relation is derived which describes values of pore and confining pressures consistent with a given joint closure for a loading path of constant closure.
0 1991 Pergamon Press plc. Reproduction not permitted