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Nonlinear model for the dynamics of penetration into geological targets
46A
842047 Coal strength evaluation from boreholes Jeremlc, M L int Assoc Engng Geol Bull N26-27, Dec 1982-June 1983, P95-99 (Paper to the International Symposmm on Sozl and Rock Imestzgatlons by In Sttu Testing, Parts, 18-20 May 1983) The exploration bonng of the coal fields in Western Canada suggest the possibility of evaluating m-seam coal strength by (1) logging of coal core, (2) geophysical borehole logging and (3) phenomenological observations of boreholes Four categories of coal strength and associated stability are proposed (1) excessive strength - sudden and violent deformations, (2) moderate strength - stable yielding deformations, (3) low strength unstable fracturing and (4) very low or no strength - coal extrusion The categories of coal could be determined by criteria based on proposed ln&ces
842048 Suggested methods for determining the strength of rock materials in triaxial compression: revised version ISRM Comm on Standar&zatlon of Laboratory and FmldTests lnt J Rock Mech Min Sci V20, N6, Dec 1983, P283-290 Three types of tnaxlal compression test are described the hndlvldual test', the 'mulUple failure state test', and the 'contmuous failure state test'
842049 Influence of core sample geometry on the axial point-load test. Technical note Forster. I R lnt J Rock Mech Min Sei V20. N6. Dec 1983. P291-295 Three main problem areas in point load strength testing are the effects of rock amsotropy, sample geometry, and the ratio of umaxlal compressive strength to the standard diametral point load strength Index A senes of tests was c a m e d out to study the influence of sample thickness on the axial point load strength index of drill core samples of different diameters
842050 Penetration experiments for normal impact into geological targets Forrestat, M J, Grady, D E lnt J Solids Struct 1/18. N3. 1982. P229-234 A laboratory procedure which determines resultant forces on penetrators for normal impact into geological targets is described Seven experiments usmg conical-nosed penetrators and targets of foundry core, a simulated sandstone, were performed Rigid body velocity of the penetrators was measured with laser lnterferometry and maxlmum decelerations and resultant force~ were obtained from these data It is concluded that this laboratory procedure can help evaluate the validity or weaknesses of theoretical models
842052 Penetration of targets described by a Mohr-Coulomb failure criterion with a tension cutoff Longscope. D B. Forrestal. M J J Appi Mech (Tram ASME, Set E) VS0. N2 June 1983 P327-333 A model is developed to estimate the force on a conical-nosed penetrator for normal entry into geological targets that have linear hydrostats and fail according to a Mohr°Coulomb criterion with a tension cut off The model is applicable to targets with shear strength which either increases with pressure (dry rocks) or is constant (sea ice, concrete, saturated rock) Results from a field test on a dry rock target are compared with predictions using the model, reasonable agreement is shown
842053 Effect of stress release on shear modulus of clays Athanasopoulos, G A, Rlchart. F E J Geotech Engng Div ASCE V109, NGTIO, Oct 1983 P12331245 An experimental study using resonant column tests determined the effect of a temporary release of confining pressure on the low-amphtude shear modulus, G, of two cohesive soils The soils tested were a remoulded kaolinite clay and a natural "undisturbed' silty clay It was found that a temporary release of confining pressure induces disturbances which are mafilfested by a drop in the value of G After reapphcatlon of the original confining pressure the cohesive soil regains the lost amount of G It is suggested that the findings be used for estimation of the secondary time that must be taken into account in a resonant column test on 'undisturbed' samples, to establish G representative of the m-situ value
842054 Mechanisms of strength for frozen sand Tmg. J M, Torrence Martin. R. Lad& C C J Geotech Engng Div A$CE V109. NGTIO, Oct 1983. P1286I302 Various physical mechamsms controlhng the strength of frozen sand are proposed, evaluated and quantified by drawing upon an extensive literature survey, unconfined creep data on frozen sand and frozen saturated wetting and nonwettmg glass beads The principal mechanisms are ice strength and strengthening, soil strength, and ice matrix-soil skeleton interaction through dllatancy effects and structural hindrance Auth
842055 Shear strength of clay in centrifuge models. Technical note Davies, M C R, Parry, R H G J Geoteck Engng Div ASCE V109. NGTIO, Oct 1983. P13311337
842051 Nonlinear model for the dynamics of penetration into geological targets Norwood, F R, Sears, M P J Appi Mech (Tram ASME, Set E) V49, NI, March 1982, P26-30
In order to get reasonable test times m the centrifuge, clays of relatively high permeability must be used As a result, on stopping the centrifuge any excess water available is rapidly drawn into the clay by the negative pore pressures, softening the clay In-flight vane tests, m clay cakes consisting of an overconsolidated upper half over a normally consolidated lower half, give strength values equal to or higher than values calculated from critical state theory Vane tests conducted after stopping the centrifuge show strength drops of 50-60" 0 compared to In-flight values
A general theory is developed for predicting stress and force h~stones for normal impact and penetration of geological targets by conical-nosed projectiles Using the cyhndncal cawty approximation the problem reduces to that of radially symmetric stress wave propagation
842O56 SPT-CPT correlations Robertson, P K; CampaneUa, R G, Wtghtman, A J Geoteeh Engng Div ASCE VI09, NGTI 1, Nov 1983. P1449-1459
842047 Coal strength evaluation from boreholes Jeremlc, M L int Assoc Engng Geol Bull N26-27, Dec 1982-June 1983, P95-99 (Paper to the International Symposmm on Sozl and Rock Imestzgatlons by In Sttu Testing, Parts, 18-20 May 1983) The exploration bonng of the coal fields in Western Canada suggest the possibility of evaluating m-seam coal strength by (1) logging of coal core, (2) geophysical borehole logging and (3) phenomenological observations of boreholes Four categories of coal strength and associated stability are proposed (1) excessive strength - sudden and violent deformations, (2) moderate strength - stable yielding deformations, (3) low strength unstable fracturing and (4) very low or no strength - coal extrusion The categories of coal could be determined by criteria based on proposed ln&ces
842048 Suggested methods for determining the strength of rock materials in triaxial compression: revised version ISRM Comm on Standar&zatlon of Laboratory and FmldTests lnt J Rock Mech Min Sci V20, N6, Dec 1983, P283-290 Three types of tnaxlal compression test are described the hndlvldual test', the 'mulUple failure state test', and the 'contmuous failure state test'
842049 Influence of core sample geometry on the axial point-load test. Technical note Forster. I R lnt J Rock Mech Min Sei V20. N6. Dec 1983. P291-295 Three main problem areas in point load strength testing are the effects of rock amsotropy, sample geometry, and the ratio of umaxlal compressive strength to the standard diametral point load strength Index A senes of tests was c a m e d out to study the influence of sample thickness on the axial point load strength index of drill core samples of different diameters
842050 Penetration experiments for normal impact into geological targets Forrestat, M J, Grady, D E lnt J Solids Struct 1/18. N3. 1982. P229-234 A laboratory procedure which determines resultant forces on penetrators for normal impact into geological targets is described Seven experiments usmg conical-nosed penetrators and targets of foundry core, a simulated sandstone, were performed Rigid body velocity of the penetrators was measured with laser lnterferometry and maxlmum decelerations and resultant force~ were obtained from these data It is concluded that this laboratory procedure can help evaluate the validity or weaknesses of theoretical models
842052 Penetration of targets described by a Mohr-Coulomb failure criterion with a tension cutoff Longscope. D B. Forrestal. M J J Appi Mech (Tram ASME, Set E) VS0. N2 June 1983 P327-333 A model is developed to estimate the force on a conical-nosed penetrator for normal entry into geological targets that have linear hydrostats and fail according to a Mohr°Coulomb criterion with a tension cut off The model is applicable to targets with shear strength which either increases with pressure (dry rocks) or is constant (sea ice, concrete, saturated rock) Results from a field test on a dry rock target are compared with predictions using the model, reasonable agreement is shown
842053 Effect of stress release on shear modulus of clays Athanasopoulos, G A, Rlchart. F E J Geotech Engng Div ASCE V109, NGTIO, Oct 1983 P12331245 An experimental study using resonant column tests determined the effect of a temporary release of confining pressure on the low-amphtude shear modulus, G, of two cohesive soils The soils tested were a remoulded kaolinite clay and a natural "undisturbed' silty clay It was found that a temporary release of confining pressure induces disturbances which are mafilfested by a drop in the value of G After reapphcatlon of the original confining pressure the cohesive soil regains the lost amount of G It is suggested that the findings be used for estimation of the secondary time that must be taken into account in a resonant column test on 'undisturbed' samples, to establish G representative of the m-situ value
842054 Mechanisms of strength for frozen sand Tmg. J M, Torrence Martin. R. Lad& C C J Geotech Engng Div A$CE V109. NGTIO, Oct 1983. P1286I302 Various physical mechamsms controlhng the strength of frozen sand are proposed, evaluated and quantified by drawing upon an extensive literature survey, unconfined creep data on frozen sand and frozen saturated wetting and nonwettmg glass beads The principal mechanisms are ice strength and strengthening, soil strength, and ice matrix-soil skeleton interaction through dllatancy effects and structural hindrance Auth
842055 Shear strength of clay in centrifuge models. Technical note Davies, M C R, Parry, R H G J Geoteck Engng Div ASCE V109. NGTIO, Oct 1983. P13311337
842051 Nonlinear model for the dynamics of penetration into geological targets Norwood, F R, Sears, M P J Appi Mech (Tram ASME, Set E) V49, NI, March 1982, P26-30
In order to get reasonable test times m the centrifuge, clays of relatively high permeability must be used As a result, on stopping the centrifuge any excess water available is rapidly drawn into the clay by the negative pore pressures, softening the clay In-flight vane tests, m clay cakes consisting of an overconsolidated upper half over a normally consolidated lower half, give strength values equal to or higher than values calculated from critical state theory Vane tests conducted after stopping the centrifuge show strength drops of 50-60" 0 compared to In-flight values
A general theory is developed for predicting stress and force h~stones for normal impact and penetration of geological targets by conical-nosed projectiles Using the cyhndncal cawty approximation the problem reduces to that of radially symmetric stress wave propagation
842O56 SPT-CPT correlations Robertson, P K; CampaneUa, R G, Wtghtman, A J Geoteeh Engng Div ASCE VI09, NGTI 1, Nov 1983. P1449-1459