- Email: [email protected]
Experimental investigations for an algorithm simulating the effect of normal stiffness on discontinuities shear strength
6A 911038 In site density measurement with nuclear cone penetrometer Sully, J P; Echezuria, H J Proc 1st International Symposium on Penetration Testing, ISOPT-I, Orimulo,20-24 March 1988 V2, PIO01-1005. Publ Rotterdam: A A Balkema, 1988
lnsitu nuclear density tests have been carried out for many years as a routine part of petroleum exploration programmes. However, use in geotechnical studies has been limited due to inadequate equipment and procedures and problems associated with interpretation of results. A brief description of a penetrometer which is capable of measuring in situ soil density via a nuclear source and detector is presented. Results obtained from tests in the east coast of Lake Maracaibo, Venezuela, are presented and compared to laboratory tests on undisturbed samples. 911039 Properties and engineering behavinur of a residual soil from the Commonwealth of Deminica Hartford, D N D; Doff, D H Proc International Conference on Engineering Problems of Regional Soils, Beijiug, 11-15 August 1988 P592-597. Publ Beijing: International Academic Publishers, 1989
Soils from eastern and central highlands regions of Dominica have been studied. X ray diffraction analysis, engineering classification, and laboratory strength and deformation testing are described. The mineralogy was not consistent with that of other weathering products of intermediate and basic igneous rocks, a complex illite-smectite structure resembling rectorite being found. The soil is heterogeneous and difficult to sample. Problems are found in measuring the friction angle, and dilatancy at low stress levels influences undrained shear strength. Results are examined within a hyperbolic Cam clay model. 911040 Preparation of reconstituted sand specimens Vaid, Y P; Negussey, D Proc Symposium on Advanced Triaxial Testing of Soil and Rock, Louisville, 19-20 June 1986 P405-417. Publ Philadelphia: ASTM, 1988 ( ASTM Special Technical Publication 977)
Review and assessment of sand sample preparation techniques from both theoretical and experimental viewpoints are presented. Sample densities obtained by air pluviation are shown to be sensitive to rate of pouring and drop height. Terminal velocity is reached at a very small drop height,and homogeneous samples of the same initial density can be formed by pluviation of uniform sand in water. Uniformly dense samples obtained by vibration of loose pluviated samples show similar behaviour to those densified by control of drop height only.
Deformation and strength characteristics See also: 911248, 911249, 911250, 911280, 911283, 911285, 911041 Failure criterion for stiff soils and rocks exhibiting softening Yoshida, N: Morgenstern. N R; Chan, D H Can Geatech J V27, N2, April 1990, P195-202
A simple nonlinear failure criterion is proposed which is expressed in terms of maximum and minimum principal stresses, uniaxiai compression strength, and three easily measurable strength parameters. It is shown tO be in excellent agreement with published data. It can be used to describe
observed behaviour of overconsolidated clays and soft rocks. Strain softening is represented in the criterion through time dependent reduction in strength parameters. Behaviour from initial to fully softened can be described. 911042 Experimental investigations for an algorithm simulating the effect of normal stiffnem on discontinuities shear strength Archambault, G; Fortin, M; Gill, D E; Aubertin, M: Ladanyi, B Proc International Symposium on Rock Joints, Locn, 4-6 June 1990 P141-148. Publ Rotterdam: A A Balkema. 1990
Goodman (1980) proposed a graphical method to construct the stress displacement curves of joints under conditions of partial or total inhibition of dilatancy from results of standard direct shear tests. An algorithm based on this approach is presented to give improved predictions of joint shear behaviour. Shear tests on artificial rock joints under conditions of constant normal stress and constant normal stiffness were carried out to validate the algorithm procedure. Relatively good agreement is found between predictions and laboratory results. 911043 Shear strength of rock joints reinforced with flexible bolts based on physical modeling Bakhtar, K; Zahra, T; Chitty, D P r o c International Symposium on Rock Joints, Locn, 4-6 June 1990 P157-161. Publ Rotterdam: A A Balkema, 1990 Small scale model tests were carried out on 4 blocks with and without model tunnels and containing a single through-going simulated joint. The blocks were cast in model material and a constant joint roughness was maintained. Two blocks were reinforced with flexible bolts installed at about 20 deg with respect to the horizon. The blocks were loaded under uniaxial stress. Shear strength of the joint was increased due to the reinforcement by 21% and 400% respectively for blocks with and without the structures. 911044 Scale effects in the shear behavior of joints in welded tuff Blejwas, T E; Hansen, F D Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P185-189. Publ Rotterdam: A A Balkema, 1990
Instabilities in the rock mass around the proposed repository at Yucca Mountain, Nevada, may arise from movements along pre-existing joints. Some potential for joint sliding is indicated, but there is little information on joint behaviour at large scale under realistic rock mass conditions for comparison. Scale effects on joint frictional properties are discussed. The large scale, in situ testing program which has been initiated at Yucca Mountain is described. 911045 Behaviour of reinforced jointed models under multinxiul Ioadings Egger, P; Pellet, F Proc International Symposium on Rock Joints, Locn, 4-6 June 1990 P191-194. Publ Rotterdam: A A Balkema, 1990
A series of tests was carried out to examine the effect of reinforcement of smooth rock joints under stress paths simulating in situ conditions. Large scale models were made by assembling plaster plates to give bedding at 45deg to the specimen axis and reinforcing with passive horizontal steel rods. Specimens were tested under biaxial and uniaxial Ioadings and plane strain conditions. Deformational response was significantly influenced by stress path.
© 1991 Pergamon Press pie. Reproduction not permitted
lnsitu nuclear density tests have been carried out for many years as a routine part of petroleum exploration programmes. However, use in geotechnical studies has been limited due to inadequate equipment and procedures and problems associated with interpretation of results. A brief description of a penetrometer which is capable of measuring in situ soil density via a nuclear source and detector is presented. Results obtained from tests in the east coast of Lake Maracaibo, Venezuela, are presented and compared to laboratory tests on undisturbed samples. 911039 Properties and engineering behavinur of a residual soil from the Commonwealth of Deminica Hartford, D N D; Doff, D H Proc International Conference on Engineering Problems of Regional Soils, Beijiug, 11-15 August 1988 P592-597. Publ Beijing: International Academic Publishers, 1989
Soils from eastern and central highlands regions of Dominica have been studied. X ray diffraction analysis, engineering classification, and laboratory strength and deformation testing are described. The mineralogy was not consistent with that of other weathering products of intermediate and basic igneous rocks, a complex illite-smectite structure resembling rectorite being found. The soil is heterogeneous and difficult to sample. Problems are found in measuring the friction angle, and dilatancy at low stress levels influences undrained shear strength. Results are examined within a hyperbolic Cam clay model. 911040 Preparation of reconstituted sand specimens Vaid, Y P; Negussey, D Proc Symposium on Advanced Triaxial Testing of Soil and Rock, Louisville, 19-20 June 1986 P405-417. Publ Philadelphia: ASTM, 1988 ( ASTM Special Technical Publication 977)
Review and assessment of sand sample preparation techniques from both theoretical and experimental viewpoints are presented. Sample densities obtained by air pluviation are shown to be sensitive to rate of pouring and drop height. Terminal velocity is reached at a very small drop height,and homogeneous samples of the same initial density can be formed by pluviation of uniform sand in water. Uniformly dense samples obtained by vibration of loose pluviated samples show similar behaviour to those densified by control of drop height only.
Deformation and strength characteristics See also: 911248, 911249, 911250, 911280, 911283, 911285, 911041 Failure criterion for stiff soils and rocks exhibiting softening Yoshida, N: Morgenstern. N R; Chan, D H Can Geatech J V27, N2, April 1990, P195-202
A simple nonlinear failure criterion is proposed which is expressed in terms of maximum and minimum principal stresses, uniaxiai compression strength, and three easily measurable strength parameters. It is shown tO be in excellent agreement with published data. It can be used to describe
observed behaviour of overconsolidated clays and soft rocks. Strain softening is represented in the criterion through time dependent reduction in strength parameters. Behaviour from initial to fully softened can be described. 911042 Experimental investigations for an algorithm simulating the effect of normal stiffnem on discontinuities shear strength Archambault, G; Fortin, M; Gill, D E; Aubertin, M: Ladanyi, B Proc International Symposium on Rock Joints, Locn, 4-6 June 1990 P141-148. Publ Rotterdam: A A Balkema. 1990
Goodman (1980) proposed a graphical method to construct the stress displacement curves of joints under conditions of partial or total inhibition of dilatancy from results of standard direct shear tests. An algorithm based on this approach is presented to give improved predictions of joint shear behaviour. Shear tests on artificial rock joints under conditions of constant normal stress and constant normal stiffness were carried out to validate the algorithm procedure. Relatively good agreement is found between predictions and laboratory results. 911043 Shear strength of rock joints reinforced with flexible bolts based on physical modeling Bakhtar, K; Zahra, T; Chitty, D P r o c International Symposium on Rock Joints, Locn, 4-6 June 1990 P157-161. Publ Rotterdam: A A Balkema, 1990 Small scale model tests were carried out on 4 blocks with and without model tunnels and containing a single through-going simulated joint. The blocks were cast in model material and a constant joint roughness was maintained. Two blocks were reinforced with flexible bolts installed at about 20 deg with respect to the horizon. The blocks were loaded under uniaxial stress. Shear strength of the joint was increased due to the reinforcement by 21% and 400% respectively for blocks with and without the structures. 911044 Scale effects in the shear behavior of joints in welded tuff Blejwas, T E; Hansen, F D Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P185-189. Publ Rotterdam: A A Balkema, 1990
Instabilities in the rock mass around the proposed repository at Yucca Mountain, Nevada, may arise from movements along pre-existing joints. Some potential for joint sliding is indicated, but there is little information on joint behaviour at large scale under realistic rock mass conditions for comparison. Scale effects on joint frictional properties are discussed. The large scale, in situ testing program which has been initiated at Yucca Mountain is described. 911045 Behaviour of reinforced jointed models under multinxiul Ioadings Egger, P; Pellet, F Proc International Symposium on Rock Joints, Locn, 4-6 June 1990 P191-194. Publ Rotterdam: A A Balkema, 1990
A series of tests was carried out to examine the effect of reinforcement of smooth rock joints under stress paths simulating in situ conditions. Large scale models were made by assembling plaster plates to give bedding at 45deg to the specimen axis and reinforcing with passive horizontal steel rods. Specimens were tested under biaxial and uniaxial Ioadings and plane strain conditions. Deformational response was significantly influenced by stress path.
© 1991 Pergamon Press pie. Reproduction not permitted