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Effects of electroosmotic field treatments on the soil properties of a soft sensitive clay
279A
Deformation and strength characteristics See also: 925005, 925240, 925245, 925239, 925262, 925300, 925046 Effects of electroosmotic field treatments on the soil properties of a soft sensitive clay Lo, K Y; Ho, K S Can Geotech J V28, N6, Dec 1991, P763-770 Electroosmotic strengthening of Champlain Sea clay at the Gloucester Test Fill site was carried out using specially designed copper electrodes. 127ram diameter tube samples were taken for examination before and after treatment. Isotropically consolidated undrained triaxial tests showed the treatment increased strength in terms of effective stress. Consolidation tests showed preconsolidation pressure raised from 53 to 98kPa. Plasticity, carbonate content, and salinity were increased, whilst sensitivity decreased. 925047 Effective stress paths and pore-pressure responses during undrained shear along the bedding planes of valved Fort William Clay Eigenbrod, K D; Burak, J B Can Geoteck J 1/28, N6, Dec 1991, P804-811 Varved clays from the Thunder Bay area of Ontario were subject to consolidated isotropic undrained triaxial tests with pore pressure measurement. Samples were prepared with the varves at an angle to the vertical axis. A variety of stress paths was followed. Different elastic properties, shearing modes, and strength parameters were obtained, depending on whether the specimens were normally or overconsolidated. Unusual results are described and their causes discussed. 925048 Anisotropy of normally consolidated San Francisco Bay mud Kirkgard, M M; Lade, P V Geotech Test J VI4, N3, Sept 1991, P231-246 Large cylindrical block samples of normally consolidated clay (San Francisco Bay mud) were taken and intact cube specimens prepared and subjected to consolidated undrained triaxial tests. Soil fabric and its relation to the stratigraphy of the area were also investigated. Consolidation characteristics, stress strain bchaviour, pore pressure, strength relations, and lateral strains in two perpendicular directions were measured. The clay behaved as an orthotropic material, but for practical purposes can be considered cross-anisotropic. Elastic parameters and their relation to initial inclination of effective stress paths for horizontal and vertical specimens are discussed.
925O5O Side draimL~ill triaxial testing at moderate to high pressures. Technical note Oswell, J M; Graham, J; Lingnau, B E; King, M W Geotech Test J VI4, N3, Sept 1991, P315-319 The function of side drains used to increase rate of consolidation and equalise pore water pressures during triaxial tests has been shown to be influenced by time and effective confining pressure. A survey of side drain practices indicates procedures not recommended by standard references are often used. An experimental investigation of four side drain materials, one geotextile and three filter papers, has been carried out. Flow properties as a function of confining pressure and as a function of time at fixed confining pressure have been examined. Natural clay specimens were also tested to assess influence of side drain material on consolidation behaviour.
925051 Automated electropneumatic control system for direct simple shear testing De Groot, D J; Germaine, J T; Gedney, R Geotech Test J VI4, N4, Dec 1991, P339-348 An automatic electropneumatic system for stress and displacement control during direct simple shear testing is described. It is implemented in the multidirectional direct simple shear (MDSS) apparatus of De Groot (1989). Details are presented of hardware and software. Successful control of stress during consolidation increments is possible, but control of displacements as required for undrained shear of cohesive soils presents problems, primarily as a result of relative lack of rigidity of the equipment. Consequences of this are discussed. The more sophisticated proportional plus integral plus derivative (PID) controller is required to overcome these difficulties.
925052 Piezo film technology and appfications in geotechnical testing Santamarina, J C; Wakim, T N; Tallin, A G; Rab, F; Wong, J Geotech Test J VI4, N4, Dec 1991, P363-370 Thin piezoelectric membranes which generate a voltage output when they undergo deformation (and vice versa) may be adapted to a range of field and laboratory uses by the geotechnical engineer. The fundamental concepts of piezo film technology are outlined and principles behind common applications reviewed. Specific uses as a low cost field sensor and in modified triaxial and oedometer cells to measure low strain moduli in resonant and pulse modes are described.
925049 Some issues in triaxial extension tests Wu, W; Kolymbas, D Geotech Test J VI4, N3, Sept 1991, P276-287
925053 Point load strength: an index for classification of rock material Ghosh, D K; Srivastava, M Int Assoc Eagng Geol Bull N44, Oct 1991, P27-33
Triaxial extension tests can be used to simulate a range of geotechnical situations. Factors influencing results of such tests have been studied. Results are more sensitive to accuracy of axial force measurement, membrane effects, gravity, and inhomogeneous deformation than in triaxial compression tests. Methods to minimise these influences are discussed. Failure mode is largely influenced by initial density. Inhomogeneous deformation (necking) occurs in upper and middle regions of dense and loose specimens respectively. Shear bands develop only in dense specimens.
Point load tests and uniaxial compression tests were carded out on samples of anisotropic granitic rock containing visible planes of foliation. Measured point load strengths and those corrected to platen distance of 50mm were used to predict UCS. Good correlation is seen between laboratory measured and predicted values of UCS. Graphical and mathematical relations between observed and estimated UCS are established. A nomogram for computing point load strength index and a system for classification of the rock material are presented.
© 1992 Pergamon Press Ltd. Reproduction not permitted
Deformation and strength characteristics See also: 925005, 925240, 925245, 925239, 925262, 925300, 925046 Effects of electroosmotic field treatments on the soil properties of a soft sensitive clay Lo, K Y; Ho, K S Can Geotech J V28, N6, Dec 1991, P763-770 Electroosmotic strengthening of Champlain Sea clay at the Gloucester Test Fill site was carried out using specially designed copper electrodes. 127ram diameter tube samples were taken for examination before and after treatment. Isotropically consolidated undrained triaxial tests showed the treatment increased strength in terms of effective stress. Consolidation tests showed preconsolidation pressure raised from 53 to 98kPa. Plasticity, carbonate content, and salinity were increased, whilst sensitivity decreased. 925047 Effective stress paths and pore-pressure responses during undrained shear along the bedding planes of valved Fort William Clay Eigenbrod, K D; Burak, J B Can Geoteck J 1/28, N6, Dec 1991, P804-811 Varved clays from the Thunder Bay area of Ontario were subject to consolidated isotropic undrained triaxial tests with pore pressure measurement. Samples were prepared with the varves at an angle to the vertical axis. A variety of stress paths was followed. Different elastic properties, shearing modes, and strength parameters were obtained, depending on whether the specimens were normally or overconsolidated. Unusual results are described and their causes discussed. 925048 Anisotropy of normally consolidated San Francisco Bay mud Kirkgard, M M; Lade, P V Geotech Test J VI4, N3, Sept 1991, P231-246 Large cylindrical block samples of normally consolidated clay (San Francisco Bay mud) were taken and intact cube specimens prepared and subjected to consolidated undrained triaxial tests. Soil fabric and its relation to the stratigraphy of the area were also investigated. Consolidation characteristics, stress strain bchaviour, pore pressure, strength relations, and lateral strains in two perpendicular directions were measured. The clay behaved as an orthotropic material, but for practical purposes can be considered cross-anisotropic. Elastic parameters and their relation to initial inclination of effective stress paths for horizontal and vertical specimens are discussed.
925O5O Side draimL~ill triaxial testing at moderate to high pressures. Technical note Oswell, J M; Graham, J; Lingnau, B E; King, M W Geotech Test J VI4, N3, Sept 1991, P315-319 The function of side drains used to increase rate of consolidation and equalise pore water pressures during triaxial tests has been shown to be influenced by time and effective confining pressure. A survey of side drain practices indicates procedures not recommended by standard references are often used. An experimental investigation of four side drain materials, one geotextile and three filter papers, has been carried out. Flow properties as a function of confining pressure and as a function of time at fixed confining pressure have been examined. Natural clay specimens were also tested to assess influence of side drain material on consolidation behaviour.
925051 Automated electropneumatic control system for direct simple shear testing De Groot, D J; Germaine, J T; Gedney, R Geotech Test J VI4, N4, Dec 1991, P339-348 An automatic electropneumatic system for stress and displacement control during direct simple shear testing is described. It is implemented in the multidirectional direct simple shear (MDSS) apparatus of De Groot (1989). Details are presented of hardware and software. Successful control of stress during consolidation increments is possible, but control of displacements as required for undrained shear of cohesive soils presents problems, primarily as a result of relative lack of rigidity of the equipment. Consequences of this are discussed. The more sophisticated proportional plus integral plus derivative (PID) controller is required to overcome these difficulties.
925052 Piezo film technology and appfications in geotechnical testing Santamarina, J C; Wakim, T N; Tallin, A G; Rab, F; Wong, J Geotech Test J VI4, N4, Dec 1991, P363-370 Thin piezoelectric membranes which generate a voltage output when they undergo deformation (and vice versa) may be adapted to a range of field and laboratory uses by the geotechnical engineer. The fundamental concepts of piezo film technology are outlined and principles behind common applications reviewed. Specific uses as a low cost field sensor and in modified triaxial and oedometer cells to measure low strain moduli in resonant and pulse modes are described.
925049 Some issues in triaxial extension tests Wu, W; Kolymbas, D Geotech Test J VI4, N3, Sept 1991, P276-287
925053 Point load strength: an index for classification of rock material Ghosh, D K; Srivastava, M Int Assoc Eagng Geol Bull N44, Oct 1991, P27-33
Triaxial extension tests can be used to simulate a range of geotechnical situations. Factors influencing results of such tests have been studied. Results are more sensitive to accuracy of axial force measurement, membrane effects, gravity, and inhomogeneous deformation than in triaxial compression tests. Methods to minimise these influences are discussed. Failure mode is largely influenced by initial density. Inhomogeneous deformation (necking) occurs in upper and middle regions of dense and loose specimens respectively. Shear bands develop only in dense specimens.
Point load tests and uniaxial compression tests were carded out on samples of anisotropic granitic rock containing visible planes of foliation. Measured point load strengths and those corrected to platen distance of 50mm were used to predict UCS. Good correlation is seen between laboratory measured and predicted values of UCS. Graphical and mathematical relations between observed and estimated UCS are established. A nomogram for computing point load strength index and a system for classification of the rock material are presented.
© 1992 Pergamon Press Ltd. Reproduction not permitted