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Shear strength, internal friction, and friction between soil and metal in different soil types, as affected by moisture content
Journal of Terramechanics, 1969, Vol. 6, No. 4, pp. 65 to 71. Pergamon Press Printed in Great Britain.
ABSTRACTS 78.
F . O . Aboaha. Effects of time on compaction of soils by rollers. Trans. ASAE, 12 (3), 302-304 (1969). The main object of the work discussed in this paper was to find the effect of speed on soil compaction. Previous workers concerned with this subject had attributed low compaction at high speeds to a bouncing effect. This study was designed to roll on a flat surface (hence eliminating bounce) and find if there is correlation between speed and compaction.
79.
M . G . Bekker. Introduction to terrain-vehicle systems. Part I : The terrain. Part 1I : The vehicle. Michigan Univ. Ann Arbor, 865 pp. (1969). Systems analysis is applied to off-the-road locomotion. Existing knowledge and literature on terrain-vehicle systems are reviewed and integrated from the practical engineering viewpoint. Facilities and equipment required for systems evaluation are described and its management discussed. Mathematical models allow speculation on future developments including terrain measurements, soil-vehicle interface definition, design and performance parameters optimization and cost effectiveness. Related problems and possible developments in agriculture, earth moving, and industrial and military operations are considered. (U.S. Gov. Res. Dev. Rep., 25.7.69, AD-687599.)
80.
H. Benkenstein and H. Lindner. Shear strength, internal friction, and friction between soil and metal in different soil types, as affected by moisture content. Albreeht-Thaer-Arch. 13, 351-359 (1969). The decrease in shear strength of soils in situ with increasing moisture content followed a quadratic function, due to the decreased cohesion between soil particles. A similar but increasing trend in internal friction occurred with increasing moisture content. In the dry state, slightly loamy sands possess low shear strengths, whereas soils rich in material in the silt and clay fractions show high shear strengths; in such soils the decrease in shear strength on wetting is slight or marked, respectively. The coefficients of friction between soil and metal reach maxima in the range of minimum field capacity in light soils and lower moisture levels Jn heavy soils. (Soil and Fertilizers, 1969.)
81.
G . P . Boutwell Jr. On the yield behaviour of cohesionless materials. Soil Mechanics series No. 7, Duke University, Durham, N.C. (1968). A series of drained and undrained triaxial extension and compression tests were used to investigate the concept of critical state for failure of a sand. Samples of Chattahoochie and Ottawa Sands were prepared at varying initial densities and tested at varying initial effective radial stresses. Conclusions are: (1) At large strains, the Mohr-Coulomb yield criterion adequately describes interrelations of effective stresses in the critical state. (2) Density attained when critical state is reached in the drained condition depends only on the octahedral normal effective stress in that state. (3) Octahedral normal effective stress attained when critical state is reached in undrained condition depends only on the sample's density when the undrained condition is imposed. (4) Relation between density and octahedral normal effective stress in critical state is the same whether this state is attained in drained or undrained condition, and is unaffected by preconsolidation or anisotropic consolidation. An analytical relationship is given for pore pressure parameters which describe pore pressure changes developed in undrained condition during yield as a function of deviatoric stress state causing that yield. This relationship is a simple function of yield criterion and initial effective stress state. (J. Soil Mech. Fndns Div., July 1969.)
82.
Max L. Calhoon. Pressure-meter field testing of soils. Civil Engng ASCE, 71-74 (July 1969). Most soil mechanics design in the U.S. is done without the benefit of stress-strain information, which would permit predicting settlement. In the past there was no reliable method to estimate settlement in granular and silty deposits. Also, there are many soil formations which defy conventional, rational analysis due to the inability to recover undisturbed samples for laboratory testing. An in situ testing device, called the pressure-meter, is now available to do these tasks, quickly and in the field. It is an expansible, cylindrical probe which is inserted into a 65
ABSTRACTS 78.
F . O . Aboaha. Effects of time on compaction of soils by rollers. Trans. ASAE, 12 (3), 302-304 (1969). The main object of the work discussed in this paper was to find the effect of speed on soil compaction. Previous workers concerned with this subject had attributed low compaction at high speeds to a bouncing effect. This study was designed to roll on a flat surface (hence eliminating bounce) and find if there is correlation between speed and compaction.
79.
M . G . Bekker. Introduction to terrain-vehicle systems. Part I : The terrain. Part 1I : The vehicle. Michigan Univ. Ann Arbor, 865 pp. (1969). Systems analysis is applied to off-the-road locomotion. Existing knowledge and literature on terrain-vehicle systems are reviewed and integrated from the practical engineering viewpoint. Facilities and equipment required for systems evaluation are described and its management discussed. Mathematical models allow speculation on future developments including terrain measurements, soil-vehicle interface definition, design and performance parameters optimization and cost effectiveness. Related problems and possible developments in agriculture, earth moving, and industrial and military operations are considered. (U.S. Gov. Res. Dev. Rep., 25.7.69, AD-687599.)
80.
H. Benkenstein and H. Lindner. Shear strength, internal friction, and friction between soil and metal in different soil types, as affected by moisture content. Albreeht-Thaer-Arch. 13, 351-359 (1969). The decrease in shear strength of soils in situ with increasing moisture content followed a quadratic function, due to the decreased cohesion between soil particles. A similar but increasing trend in internal friction occurred with increasing moisture content. In the dry state, slightly loamy sands possess low shear strengths, whereas soils rich in material in the silt and clay fractions show high shear strengths; in such soils the decrease in shear strength on wetting is slight or marked, respectively. The coefficients of friction between soil and metal reach maxima in the range of minimum field capacity in light soils and lower moisture levels Jn heavy soils. (Soil and Fertilizers, 1969.)
81.
G . P . Boutwell Jr. On the yield behaviour of cohesionless materials. Soil Mechanics series No. 7, Duke University, Durham, N.C. (1968). A series of drained and undrained triaxial extension and compression tests were used to investigate the concept of critical state for failure of a sand. Samples of Chattahoochie and Ottawa Sands were prepared at varying initial densities and tested at varying initial effective radial stresses. Conclusions are: (1) At large strains, the Mohr-Coulomb yield criterion adequately describes interrelations of effective stresses in the critical state. (2) Density attained when critical state is reached in the drained condition depends only on the octahedral normal effective stress in that state. (3) Octahedral normal effective stress attained when critical state is reached in undrained condition depends only on the sample's density when the undrained condition is imposed. (4) Relation between density and octahedral normal effective stress in critical state is the same whether this state is attained in drained or undrained condition, and is unaffected by preconsolidation or anisotropic consolidation. An analytical relationship is given for pore pressure parameters which describe pore pressure changes developed in undrained condition during yield as a function of deviatoric stress state causing that yield. This relationship is a simple function of yield criterion and initial effective stress state. (J. Soil Mech. Fndns Div., July 1969.)
82.
Max L. Calhoon. Pressure-meter field testing of soils. Civil Engng ASCE, 71-74 (July 1969). Most soil mechanics design in the U.S. is done without the benefit of stress-strain information, which would permit predicting settlement. In the past there was no reliable method to estimate settlement in granular and silty deposits. Also, there are many soil formations which defy conventional, rational analysis due to the inability to recover undisturbed samples for laboratory testing. An in situ testing device, called the pressure-meter, is now available to do these tasks, quickly and in the field. It is an expansible, cylindrical probe which is inserted into a 65