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886039 Estimation of fracture aperture using hydraulic and tracer tests
266A 886038 In situ density measurements by nuclear backscatter for an offshore soil investigation Tjelta, T I; Tieges, A W W; Smits, F P; Geise, J M; Lunne, T A Norw Geotech Inst Publ N169, 1987. 5P
A nuclear backscatter density probe, designed to be used with standard cone penetration methods and equipment, is described. In situ tests were undertaken offshore at Gullfaks to determine the density of the upper 35m of soil, using the density probe, piezocone penetration testing and borehole sampling. Results obtained from the 3 techniques show good correlation. 886839 Estimation of fracture aperture using hydraulic and tracer tests Smith, L; Mase, C W; Schwartz, F W Proc 28th US Symposium on Rock Mechtmics, Tucson, 29 June-l July 1987 P453-463. Pub1 Rotterdam: A A Balkema, 1987
Techniques to obtain in situ estimates of fracture aperture from hydraulic and tracer tests are examined. 3 estimates are considered: hydraulic aperture, tracer aperture and volume balance calculation, all derived for an assumed axisymmetric flow field established during a steady state withdrawal test. Results are presented as contour plots of aperture values, estimated as a function of the location of an injection well, and analysed as networks of parallel plate fractures and networks of rough-walled fractures.
Deformation and strength characteristics See also: 886232, 886297, 886420
Normalii behaviour of offshore clay under uniform cyclic loading Vucetic, M Can Geotech J V25. NI, Feb 1988, P33-41 A procedure for cyclic characterisation of normalised behaviour of normally consolidated and overconsolidated clays subjected to cyclic strain-controlled simple shear loading is presented. The method is illustrated with cyclic results for an offshore clay and is verified by accurately predicting the initial backbone curve, cyclic stiffness degradation, and pore pressure variation for the same clay. Consistent relationships between cyclic shear strain and other cyclic parameters obtained by cyclic strain-controlled testing confirm that cyclic shear strain is probably the most fundamental parameter governing the undrained cyclic behaviour of clay. 886041 Constant-volume friction angle of granular materials Negussey, D; Wijewickreme, W K D; Vaid, Y P Can Geotech J VZS. Nl, Feb 1988, P50-S5 Various granular materials were subjected to large shear displacements until a lower bound friction angle was mobilised, using a ring shear device. The tests indicate that the constantvolume friction angle is a lower bound on shear resistance and is independent of particle size, confining pressure and density, that mobilised friction angle at maximum contraction is dependent on initial density and confining pressure, and that a close agreement exists between constant-volume friction angle and mobilised friction angle at phase transform and steady state. The steady state and critical state friction angles seem to be equivalent and unique to a granular material. 0
886042 Theoretical bearing capacity of clay under shallow footings: verifying whether it is realistic Chapuis, R P; Silvestri, V; Soulie, M Can Geotech J V25. NI, Feb 1988, P62-75
Traditionally the bearing capacity and settlement of footings on clay are determined by theoretical analyses. A method is proposed for determining validity of calculated bearing capacity, by comparison of a calculated load-settlement curve with a field test. Bearing capacity and settlement are discussed with respect to deformability of clay and its influence on the bearing capacity of shallow footings. The proposed method is numerical oedometric, taking into account the initial state of stress before loading, the consolidation state and the variation of the clay compressibility. Four case studies are presented, showing the groundwater conditions have a major influence on the bearing capacity of highly compressible, slightly overconsolidated clays, but little influence on the bearing capacity of clays with low compressibility. 886043 Profiling of overconsolidation ratio in clays by field vane: technical note Mayne, P W; Mitchell, J K Can Geotech J V2.5, NI, Feb 1988. PIjO-157 The field vane (FV) is much used to measure the direct in situ undrained shear strength in soft to medium clays. It is proposed that empirical correction factors be applied to Fv data to account for effects of strain rate, anisotropy and disturbance on measured shear strength, and that the FV may be calibrated to develop profiles of overconsolidation ratio (OCR) with depth. A review of consolidation data and field vane strengths from 96 clays shows a general correlation between OCR and normalised undrained strength to overburden ratio.
Liquid limit of kaolinitic soils Sridharan, A; Rao, S M; Murthy, N S Geotechnique
V38, N2, June 1988, P191-I98
The relation of liquid limit of natural kaolinitic soils to surface area, % clay size fraction, shrinkage, sediment volume in water, and exchangeable sodium content was studied in the laboratory. Results confirm earlier work on purified systems which suggested that interparticle forces which determine the clay fabric regulate liquid limit. Soils with high liquid limit have high sedimentation volume and low shrinkage. Poor correlation between exchangeable sodium and liquid limit indicates that the latter is not related to double layer thickness. 886045 Interpretation of flaf plate dilatometer tests in sands in terms of the state parameter Konrad, J M Geotechnique
V38, N2, June 1988, P263-277
In situ tests yield index parameters which are converted to design values by means of empirical correlations. Key parameters which govern the expansion stage of the flat plate dilatometer (DMT) test are assessed. Deformation characteristics inferred from DMT tests in sands in a calibration chamber agree well with those from triaxial tests, if interpreted in terms of the state parameter. A framework based on interpretation of DMT tests based on the normal&d state parameter is proposed.
1988 Pergamon Press plc. Reproduction
not permitted
A nuclear backscatter density probe, designed to be used with standard cone penetration methods and equipment, is described. In situ tests were undertaken offshore at Gullfaks to determine the density of the upper 35m of soil, using the density probe, piezocone penetration testing and borehole sampling. Results obtained from the 3 techniques show good correlation. 886839 Estimation of fracture aperture using hydraulic and tracer tests Smith, L; Mase, C W; Schwartz, F W Proc 28th US Symposium on Rock Mechtmics, Tucson, 29 June-l July 1987 P453-463. Pub1 Rotterdam: A A Balkema, 1987
Techniques to obtain in situ estimates of fracture aperture from hydraulic and tracer tests are examined. 3 estimates are considered: hydraulic aperture, tracer aperture and volume balance calculation, all derived for an assumed axisymmetric flow field established during a steady state withdrawal test. Results are presented as contour plots of aperture values, estimated as a function of the location of an injection well, and analysed as networks of parallel plate fractures and networks of rough-walled fractures.
Deformation and strength characteristics See also: 886232, 886297, 886420
Normalii behaviour of offshore clay under uniform cyclic loading Vucetic, M Can Geotech J V25. NI, Feb 1988, P33-41 A procedure for cyclic characterisation of normalised behaviour of normally consolidated and overconsolidated clays subjected to cyclic strain-controlled simple shear loading is presented. The method is illustrated with cyclic results for an offshore clay and is verified by accurately predicting the initial backbone curve, cyclic stiffness degradation, and pore pressure variation for the same clay. Consistent relationships between cyclic shear strain and other cyclic parameters obtained by cyclic strain-controlled testing confirm that cyclic shear strain is probably the most fundamental parameter governing the undrained cyclic behaviour of clay. 886041 Constant-volume friction angle of granular materials Negussey, D; Wijewickreme, W K D; Vaid, Y P Can Geotech J VZS. Nl, Feb 1988, P50-S5 Various granular materials were subjected to large shear displacements until a lower bound friction angle was mobilised, using a ring shear device. The tests indicate that the constantvolume friction angle is a lower bound on shear resistance and is independent of particle size, confining pressure and density, that mobilised friction angle at maximum contraction is dependent on initial density and confining pressure, and that a close agreement exists between constant-volume friction angle and mobilised friction angle at phase transform and steady state. The steady state and critical state friction angles seem to be equivalent and unique to a granular material. 0
886042 Theoretical bearing capacity of clay under shallow footings: verifying whether it is realistic Chapuis, R P; Silvestri, V; Soulie, M Can Geotech J V25. NI, Feb 1988, P62-75
Traditionally the bearing capacity and settlement of footings on clay are determined by theoretical analyses. A method is proposed for determining validity of calculated bearing capacity, by comparison of a calculated load-settlement curve with a field test. Bearing capacity and settlement are discussed with respect to deformability of clay and its influence on the bearing capacity of shallow footings. The proposed method is numerical oedometric, taking into account the initial state of stress before loading, the consolidation state and the variation of the clay compressibility. Four case studies are presented, showing the groundwater conditions have a major influence on the bearing capacity of highly compressible, slightly overconsolidated clays, but little influence on the bearing capacity of clays with low compressibility. 886043 Profiling of overconsolidation ratio in clays by field vane: technical note Mayne, P W; Mitchell, J K Can Geotech J V2.5, NI, Feb 1988. PIjO-157 The field vane (FV) is much used to measure the direct in situ undrained shear strength in soft to medium clays. It is proposed that empirical correction factors be applied to Fv data to account for effects of strain rate, anisotropy and disturbance on measured shear strength, and that the FV may be calibrated to develop profiles of overconsolidation ratio (OCR) with depth. A review of consolidation data and field vane strengths from 96 clays shows a general correlation between OCR and normalised undrained strength to overburden ratio.
Liquid limit of kaolinitic soils Sridharan, A; Rao, S M; Murthy, N S Geotechnique
V38, N2, June 1988, P191-I98
The relation of liquid limit of natural kaolinitic soils to surface area, % clay size fraction, shrinkage, sediment volume in water, and exchangeable sodium content was studied in the laboratory. Results confirm earlier work on purified systems which suggested that interparticle forces which determine the clay fabric regulate liquid limit. Soils with high liquid limit have high sedimentation volume and low shrinkage. Poor correlation between exchangeable sodium and liquid limit indicates that the latter is not related to double layer thickness. 886045 Interpretation of flaf plate dilatometer tests in sands in terms of the state parameter Konrad, J M Geotechnique
V38, N2, June 1988, P263-277
In situ tests yield index parameters which are converted to design values by means of empirical correlations. Key parameters which govern the expansion stage of the flat plate dilatometer (DMT) test are assessed. Deformation characteristics inferred from DMT tests in sands in a calibration chamber agree well with those from triaxial tests, if interpreted in terms of the state parameter. A framework based on interpretation of DMT tests based on the normal&d state parameter is proposed.
1988 Pergamon Press plc. Reproduction
not permitted