Proceedings of the Institution of Civil Engineers, 2001
This paper is the second in a series of three, describing a research project being carried out at... more This paper is the second in a series of three, describing a research project being carried out at Technion in Israel to study the influence of plant roots on the stability of slopes. In the present paper, the numerical simulation of large, direct shear tests performed on soil samples reinforced with roots, is described. Simulation was performed using the finite difference code, FLAC, and two different soil models were used—the hyperbolic model, and a plastic, strain-hardening model. Soil parameters were obtained from triaxial tests, and root properties from tension and pull-out tests described in the previous paper. The method of preparing the numerical scheme in order to obtain equivalence with the experimental set-up is discussed. Good agreement was obtained between the analyses and the results of the laboratory tests for both soil models, providing confidence in the use of the scheme for slope stability analysis. Cet exposéest le second d'une série de trois, décrivant un projet de recherche menéà Technion en Israël pour é tudier l'influence des racines végétales sur la stabilitédes pentes. Dans cet exposé, nous décrivons la simulation numérique d'essais de grands cisaillements directs, essais réalisés sur des é chantillons de sol renforcés de racines. La simulation a étéréalisée en utilisant le code de différence finie, FLAC; deux modèles de sol différents ont é téutilisés le modèle hyperbolique et un modèle plastique, à durcissement-déformation. Nous avons dérivéles paramètres du sol des tests triaxiaux et les propriétés des racines des tests de tension et d'arrachage décrits dans l'étude précédente. Nous examinons la méthode de préparation du système numérique afin d'obtenir une é quivalence avec les installations expérimentales. Nous obtenons une bonne corrélation entre les analyses et les résultats des essais en laboratoires pour les deux modèles de sol, ce qui nous montre la fiabilitéde ce système pour l'analyse de la stabilitédes pentes.
This paper presents a discussion of the yielding behavior of particulate media during shearing, b... more This paper presents a discussion of the yielding behavior of particulate media during shearing, based on the results of a laboratory investigation of the stress–strain properties of samples of glass microspheres. The test program, carried out on hollow cylinder specimens, studied the effect of functions of the three stress invariants on the stress–strain behavior.It is suggested that a 'yield' point may be defined, below which relatively little interparticle slippage occurs. Below this yield point, stress–strain relations under any particular stress-path may be predicted from superposition of isotropic and deviatoric components. An initial yield point is defined which is shown to occur at a constant ratio of octahedral shear to normal stresses, so obeying an extended Von Mises type criterion.With regards to the post-yield-point behavior, an expression is developed for the yielding behavior, based on an assumed mechanism of energy dissipation within the mass. This yield relation expresses the lack of normality between the strain increment vector and the yield function, known empirically to exist in granular materials, and shows that the deviation from normality is constant, and related to the true angle of interparticle friction, [Formula: see text].
Australian Road Research Board Conference Proc, 1966
THE INFLUENCE OF POROSITY AND OF MINERAL TYPE ON THE COMPRESSIVE AND TENSILE STRENGTHS DEVELOPED ... more THE INFLUENCE OF POROSITY AND OF MINERAL TYPE ON THE COMPRESSIVE AND TENSILE STRENGTHS DEVELOPED IN A SERIES OF CEMENT- AND LIME-STABILIZED FINE, NATURAL MINERALS (INCLUDING KAOLINITE QUARTZ SAND, JASPILITE, MUSCOVITE AND TALC) WAS STUDIED. THE OBSERVED STRENGTHS FOR MATERIAL OF A SIMILAR EFFECTIVE GRAIN ISZE WERE FOUND TO OBEY AN EQUATION IN TERMS OF THE CATION EXCHANGE CAPACITY OF THE MINERALS OR SOIL, AND THE POROSITY. FOR LIME-STABILIZED MATERIALS, THE RATIO OF UNCONFINED COMPRESSIVE STRENGTH TO INDIRECT TENSILE STRENGTH WAS FOUND TO BE HIGHER THAN THAT INDICATED BY FRACTURE THEORY, AND THIS WAS ATTRIBUTED TO THE PRESENCE OF UNREACTED STABILIZER. THE RESULTS WERE APPLIED TO AN INTERPRETATION OF THE FAILURE MODE IN STABILIZED SOILS AND TO THE PREDICTION OF STRENGTH FOR A RANGE OF CEMENT- AND LIME-STABILIZED SOILS FROM THE GREAT SOIL GROUPS OF AUSTRALIA. GOOD AGREEMENT WAS FOUND BETWEEN OBSERVED AND PREDICTED VALUES OF THE UNCONFINED COMPRESSIVE STRENGTH DEVELOPED AT SEVEN DAYS BY HIGH (10 PER CENT) LIME OR CEMENT ADDITION. /AUTHOR/
The pullout capacity of slab anchors in homogeneous sand depends on several factors including the... more The pullout capacity of slab anchors in homogeneous sand depends on several factors including the type and density of the sand, and the depth, size, inclination, and shape of the slab. Although numerous publications have reported results of pullout tests on small models and prototypes, the investigations described have generally been limited to a study of the effects of one or two of the above factors, and no attempt has been made to develop an integrated approach to the problem. This paper presents such an approach by reanalyzing the results of published experimental data as well as those of a series of pullout tests performed on prototype slabs placed at various inclinations and depths in a dense sand profile. A simple theoretical expression is found to reasonably predict the pullout capacity of a continuous, horizontal slab as a function of depth-to-width ratio. Factors to account for shape, and inclination, are then established leading to expressions for the estimation of pullout capacity of any slab anchor. Key words: anchors, field tests, model tests, pullout capacity, sand, slabs, plates.
Soil Dynamics and Earthquake Engineering, Sep 1, 2006
Most design manuals and codes recommend a simple pseudo-static approach for analysis of slope sta... more Most design manuals and codes recommend a simple pseudo-static approach for analysis of slope stability under seismic conditions. Exceptions to this recommendation include problems involving liquefaction, soils exhibiting significant strength loss under cyclic loading, and exceptionally large earthquakes. These unusual situations are not considered in the present work. Conventional applications of the pseudo-static approach are based on slice methods which
Proceedings of the Institution of Civil Engineers, 2000
Research is being carried out at Technion in Israel to study the in¯uence of plant roots on the s... more Research is being carried out at Technion in Israel to study the in¯uence of plant roots on the stability of slopes. The present paper describes the part of the investigation concerned with the determination of the additional shear strength contributed to soil by roots. Speci®cally, results of the following studies are presented: tension tests on roots, pull-out tests of roots from the soil, and direct shear tests on soil and root-reinforced soil. The quantitative results obtained in these investigations provide data which may be used in calculations of slope stability, although this should be done with caution, as pointed out in the paper.
Most constitutive models for unsaturated soils are based on identification of soil-water suction ... more Most constitutive models for unsaturated soils are based on identification of soil-water suction with the capillary component of the matrix potential, ignoring the contribution of adsorption to this potential. Identification of potential (energy per unit volume) with stress (or suction), is questioned, since these quantities have different physical significance despite their common dimensions. It is suggested that the identification of
This paper is the second in a series of three, describing a research project being carried out at... more This paper is the second in a series of three, describing a research project being carried out at Technion in Israel to study the influence of plant roots on the stability of slopes. In the present paper, the numerical simulation of large, direct shear tests performed on soil samples reinforced with roots, is described. Simulation was performed using the finite difference code, FLAC, and two different soil models were used—the hyperbolic model, and a plastic, strain-hardening model. Soil parameters were obtained from triaxial tests, and root properties from tension and pull-out tests described in the previous paper. The method of preparing the numerical scheme in order to obtain equivalence with the experimental set-up is discussed. Good agreement was obtained between the analyses and the results of the laboratory tests for both soil models, providing confidence in the use of the scheme for slope stability analysis. Cet exposéest le second d'une série de trois, décrivant un projet de recherche menéà Technion en Israël pour é tudier l'influence des racines végétales sur la stabilitédes pentes. Dans cet exposé, nous décrivons la simulation numérique d'essais de grands cisaillements directs, essais réalisés sur des é chantillons de sol renforcés de racines. La simulation a étéréalisée en utilisant le code de différence finie, FLAC; deux modèles de sol différents ont é téutilisés le modèle hyperbolique et un modèle plastique, à durcissement-déformation. Nous avons dérivéles paramètres du sol des tests triaxiaux et les propriétés des racines des tests de tension et d'arrachage décrits dans l'étude précédente. Nous examinons la méthode de préparation du système numérique afin d'obtenir une é quivalence avec les installations expérimentales. Nous obtenons une bonne corrélation entre les analyses et les résultats des essais en laboratoires pour les deux modèles de sol, ce qui nous montre la fiabilitéde ce système pour l'analyse de la stabilitédes pentes.
Lateral soil pressures under at-rest conditions are commonly estimated as K0times vertical normal... more Lateral soil pressures under at-rest conditions are commonly estimated as K0times vertical normal pressure, where K0is obtained from generally accepted empirical formulae, related to the soil's friction angle and the stress history. Results of a programme of laterally, rigidly confined, vertical compression and unloading tests on sand and clay are presented, in which two significant experimental techniques were employed: (a) lateral pressures were measured using null pressure gauges, preventing gauge diaphragm deflection; (b) side-wall friction was measured, and minimised using special friction reduction measures. Comparative tests in which one or both of these measures were not employed indicate the significant errors induced in both the vertical and the horizontal pressures used for K0determination. The bank of experimental data, which formed the basis for the commonly accepted empirical formulae, did not take account of these issues, and they are shown to be inconsistent with values measured in the present study.
All measurements of suction in soil water actually measure water energy (potential) rather than t... more All measurements of suction in soil water actually measure water energy (potential) rather than the state of pressure (tension) in the soil water. Matrix potential in unsaturated clays includes capillary and adsorption components. While the capillary component may contribute to the pore stresses, adsorption potential (or adsorption suction), which is due to interaction between the clay particles and the soil water, cannot be considered a stress. The present paper discusses the relevance of this to the shear strength of unsaturated clays. For example, in view of its energetic rather than stress nature, adsorption suction cannot contribute to the frictional component of shear strength, but only to the cohesional component. Published data is used to examine the influence of suction on mechanical behavior of compacted clays, and a relationship is observed between suction, cohesion and the activity of the clay particles.
Proceedings of the Institution of Civil Engineers, 2002
This is the third and final paper describing a research project, carried out at the Technion in I... more This is the third and final paper describing a research project, carried out at the Technion in Israel, to study the influence of plant roots on the stability of slopes. The two previous papers described earlier stages of the research, in which root and soil properties were established, and the reliability of the numerical scheme, based on the use of the finite difference code FLAC, was checked. The present paper uses the previous results as a basis for analysing the stability of root-reinforced chalky slopes under various conditions. It is demonstrated that the stability analysis of root-reinforced slopes must consider the roots as individual elements, and take account of their properties, as well as their interaction with the surrounding soil. Use of the 'equivalent layer ' approach, in which the reinforced soil is replaced by an equivalent soil with strength properties obtained from laboratory shear tests, is likely to be significantly non-conservative. The influence of root inclination is studied, and it is shown that vertical roots do not contribute significantly to slope stability, whereas a considerable contribution is provided by roots that are perpendicular to the slope face. The numerical scheme may be used for the analysis of more complex soil-root interaction problems.
THE VOLUME CHANGE MEASUREMENTS OF GRANULAR SOILS IN TRIAXIAL TESTING ARE GNERALLY AFFECTED BY PEN... more THE VOLUME CHANGE MEASUREMENTS OF GRANULAR SOILS IN TRIAXIAL TESTING ARE GNERALLY AFFECTED BY PENETRATION OF THE MEMBRANE ENCLOSING THE SOIL INTO THE VOIDS BETWEEN THE PARTICLES. THE MAJOR FACTOR INFLUENCING THIS PENETRATION HAS BEEN SHOWN TO BE THE PARTICLE SIZE OF THE SOIL BEING TESTED. ON THE BASIS OF THE RESULTS OF PREVIOUS INVESTIGATINS AND THE PRESENT STUDY, A RELATIONSHIP HAS BEEN FOUND BETWEEN THE MEMBRANE PENETRATION AND PARTICLE SIZE. THIS RELATIONSHIP MAY BE USED TO ESTIMATE THE MEMBRANE EFFECT FOR ANY GRANULAR SOIL. /AUTHOR/
The strain increment resulting from an increment of stress applied to a particulate medium has be... more The strain increment resulting from an increment of stress applied to a particulate medium has been expressed in terms of its elastic and plastic components. The concepts of strain-hardening plasticity have been employed to develop an incremental stress–strain relation, based on a non-associated flow rule. The parameters appearing in the relation have been found using results of three-dimensional shear tests on sands and glass-microspheres. It is suggested that relations of the type developed in the paper could be beneficially incorporated into a finite-element program.
A large portion of the Mediterranean coastal plain of Israel is overlain by thick deposits of cal... more A large portion of the Mediterranean coastal plain of Israel is overlain by thick deposits of calcareous sands, sometimes cemented to varying degrees and forming a cemented sand known locally as kurkar. The paper presentsa review of the geotechnical properties of these deposits, and methods used to evaluate them. Parameters so obtained have been used for the design and analysis of building foundations, cliff slope stability analyses, and liquefaction studies. It is found that in many cases considerable breakdown of calcareous cementing bonds occurs under conditions of high stress, with the result that the soil behaves as an essentially cohesionless material, sometimes having an extremely high compressibility.
Proceedings of the Institution of Civil Engineers, 2001
This paper is the second in a series of three, describing a research project being carried out at... more This paper is the second in a series of three, describing a research project being carried out at Technion in Israel to study the influence of plant roots on the stability of slopes. In the present paper, the numerical simulation of large, direct shear tests performed on soil samples reinforced with roots, is described. Simulation was performed using the finite difference code, FLAC, and two different soil models were used—the hyperbolic model, and a plastic, strain-hardening model. Soil parameters were obtained from triaxial tests, and root properties from tension and pull-out tests described in the previous paper. The method of preparing the numerical scheme in order to obtain equivalence with the experimental set-up is discussed. Good agreement was obtained between the analyses and the results of the laboratory tests for both soil models, providing confidence in the use of the scheme for slope stability analysis. Cet exposéest le second d'une série de trois, décrivant un projet de recherche menéà Technion en Israël pour é tudier l'influence des racines végétales sur la stabilitédes pentes. Dans cet exposé, nous décrivons la simulation numérique d'essais de grands cisaillements directs, essais réalisés sur des é chantillons de sol renforcés de racines. La simulation a étéréalisée en utilisant le code de différence finie, FLAC; deux modèles de sol différents ont é téutilisés le modèle hyperbolique et un modèle plastique, à durcissement-déformation. Nous avons dérivéles paramètres du sol des tests triaxiaux et les propriétés des racines des tests de tension et d'arrachage décrits dans l'étude précédente. Nous examinons la méthode de préparation du système numérique afin d'obtenir une é quivalence avec les installations expérimentales. Nous obtenons une bonne corrélation entre les analyses et les résultats des essais en laboratoires pour les deux modèles de sol, ce qui nous montre la fiabilitéde ce système pour l'analyse de la stabilitédes pentes.
This paper presents a discussion of the yielding behavior of particulate media during shearing, b... more This paper presents a discussion of the yielding behavior of particulate media during shearing, based on the results of a laboratory investigation of the stress–strain properties of samples of glass microspheres. The test program, carried out on hollow cylinder specimens, studied the effect of functions of the three stress invariants on the stress–strain behavior.It is suggested that a 'yield' point may be defined, below which relatively little interparticle slippage occurs. Below this yield point, stress–strain relations under any particular stress-path may be predicted from superposition of isotropic and deviatoric components. An initial yield point is defined which is shown to occur at a constant ratio of octahedral shear to normal stresses, so obeying an extended Von Mises type criterion.With regards to the post-yield-point behavior, an expression is developed for the yielding behavior, based on an assumed mechanism of energy dissipation within the mass. This yield relation expresses the lack of normality between the strain increment vector and the yield function, known empirically to exist in granular materials, and shows that the deviation from normality is constant, and related to the true angle of interparticle friction, [Formula: see text].
Australian Road Research Board Conference Proc, 1966
THE INFLUENCE OF POROSITY AND OF MINERAL TYPE ON THE COMPRESSIVE AND TENSILE STRENGTHS DEVELOPED ... more THE INFLUENCE OF POROSITY AND OF MINERAL TYPE ON THE COMPRESSIVE AND TENSILE STRENGTHS DEVELOPED IN A SERIES OF CEMENT- AND LIME-STABILIZED FINE, NATURAL MINERALS (INCLUDING KAOLINITE QUARTZ SAND, JASPILITE, MUSCOVITE AND TALC) WAS STUDIED. THE OBSERVED STRENGTHS FOR MATERIAL OF A SIMILAR EFFECTIVE GRAIN ISZE WERE FOUND TO OBEY AN EQUATION IN TERMS OF THE CATION EXCHANGE CAPACITY OF THE MINERALS OR SOIL, AND THE POROSITY. FOR LIME-STABILIZED MATERIALS, THE RATIO OF UNCONFINED COMPRESSIVE STRENGTH TO INDIRECT TENSILE STRENGTH WAS FOUND TO BE HIGHER THAN THAT INDICATED BY FRACTURE THEORY, AND THIS WAS ATTRIBUTED TO THE PRESENCE OF UNREACTED STABILIZER. THE RESULTS WERE APPLIED TO AN INTERPRETATION OF THE FAILURE MODE IN STABILIZED SOILS AND TO THE PREDICTION OF STRENGTH FOR A RANGE OF CEMENT- AND LIME-STABILIZED SOILS FROM THE GREAT SOIL GROUPS OF AUSTRALIA. GOOD AGREEMENT WAS FOUND BETWEEN OBSERVED AND PREDICTED VALUES OF THE UNCONFINED COMPRESSIVE STRENGTH DEVELOPED AT SEVEN DAYS BY HIGH (10 PER CENT) LIME OR CEMENT ADDITION. /AUTHOR/
The pullout capacity of slab anchors in homogeneous sand depends on several factors including the... more The pullout capacity of slab anchors in homogeneous sand depends on several factors including the type and density of the sand, and the depth, size, inclination, and shape of the slab. Although numerous publications have reported results of pullout tests on small models and prototypes, the investigations described have generally been limited to a study of the effects of one or two of the above factors, and no attempt has been made to develop an integrated approach to the problem. This paper presents such an approach by reanalyzing the results of published experimental data as well as those of a series of pullout tests performed on prototype slabs placed at various inclinations and depths in a dense sand profile. A simple theoretical expression is found to reasonably predict the pullout capacity of a continuous, horizontal slab as a function of depth-to-width ratio. Factors to account for shape, and inclination, are then established leading to expressions for the estimation of pullout capacity of any slab anchor. Key words: anchors, field tests, model tests, pullout capacity, sand, slabs, plates.
Soil Dynamics and Earthquake Engineering, Sep 1, 2006
Most design manuals and codes recommend a simple pseudo-static approach for analysis of slope sta... more Most design manuals and codes recommend a simple pseudo-static approach for analysis of slope stability under seismic conditions. Exceptions to this recommendation include problems involving liquefaction, soils exhibiting significant strength loss under cyclic loading, and exceptionally large earthquakes. These unusual situations are not considered in the present work. Conventional applications of the pseudo-static approach are based on slice methods which
Proceedings of the Institution of Civil Engineers, 2000
Research is being carried out at Technion in Israel to study the in¯uence of plant roots on the s... more Research is being carried out at Technion in Israel to study the in¯uence of plant roots on the stability of slopes. The present paper describes the part of the investigation concerned with the determination of the additional shear strength contributed to soil by roots. Speci®cally, results of the following studies are presented: tension tests on roots, pull-out tests of roots from the soil, and direct shear tests on soil and root-reinforced soil. The quantitative results obtained in these investigations provide data which may be used in calculations of slope stability, although this should be done with caution, as pointed out in the paper.
Most constitutive models for unsaturated soils are based on identification of soil-water suction ... more Most constitutive models for unsaturated soils are based on identification of soil-water suction with the capillary component of the matrix potential, ignoring the contribution of adsorption to this potential. Identification of potential (energy per unit volume) with stress (or suction), is questioned, since these quantities have different physical significance despite their common dimensions. It is suggested that the identification of
This paper is the second in a series of three, describing a research project being carried out at... more This paper is the second in a series of three, describing a research project being carried out at Technion in Israel to study the influence of plant roots on the stability of slopes. In the present paper, the numerical simulation of large, direct shear tests performed on soil samples reinforced with roots, is described. Simulation was performed using the finite difference code, FLAC, and two different soil models were used—the hyperbolic model, and a plastic, strain-hardening model. Soil parameters were obtained from triaxial tests, and root properties from tension and pull-out tests described in the previous paper. The method of preparing the numerical scheme in order to obtain equivalence with the experimental set-up is discussed. Good agreement was obtained between the analyses and the results of the laboratory tests for both soil models, providing confidence in the use of the scheme for slope stability analysis. Cet exposéest le second d'une série de trois, décrivant un projet de recherche menéà Technion en Israël pour é tudier l'influence des racines végétales sur la stabilitédes pentes. Dans cet exposé, nous décrivons la simulation numérique d'essais de grands cisaillements directs, essais réalisés sur des é chantillons de sol renforcés de racines. La simulation a étéréalisée en utilisant le code de différence finie, FLAC; deux modèles de sol différents ont é téutilisés le modèle hyperbolique et un modèle plastique, à durcissement-déformation. Nous avons dérivéles paramètres du sol des tests triaxiaux et les propriétés des racines des tests de tension et d'arrachage décrits dans l'étude précédente. Nous examinons la méthode de préparation du système numérique afin d'obtenir une é quivalence avec les installations expérimentales. Nous obtenons une bonne corrélation entre les analyses et les résultats des essais en laboratoires pour les deux modèles de sol, ce qui nous montre la fiabilitéde ce système pour l'analyse de la stabilitédes pentes.
Lateral soil pressures under at-rest conditions are commonly estimated as K0times vertical normal... more Lateral soil pressures under at-rest conditions are commonly estimated as K0times vertical normal pressure, where K0is obtained from generally accepted empirical formulae, related to the soil's friction angle and the stress history. Results of a programme of laterally, rigidly confined, vertical compression and unloading tests on sand and clay are presented, in which two significant experimental techniques were employed: (a) lateral pressures were measured using null pressure gauges, preventing gauge diaphragm deflection; (b) side-wall friction was measured, and minimised using special friction reduction measures. Comparative tests in which one or both of these measures were not employed indicate the significant errors induced in both the vertical and the horizontal pressures used for K0determination. The bank of experimental data, which formed the basis for the commonly accepted empirical formulae, did not take account of these issues, and they are shown to be inconsistent with values measured in the present study.
All measurements of suction in soil water actually measure water energy (potential) rather than t... more All measurements of suction in soil water actually measure water energy (potential) rather than the state of pressure (tension) in the soil water. Matrix potential in unsaturated clays includes capillary and adsorption components. While the capillary component may contribute to the pore stresses, adsorption potential (or adsorption suction), which is due to interaction between the clay particles and the soil water, cannot be considered a stress. The present paper discusses the relevance of this to the shear strength of unsaturated clays. For example, in view of its energetic rather than stress nature, adsorption suction cannot contribute to the frictional component of shear strength, but only to the cohesional component. Published data is used to examine the influence of suction on mechanical behavior of compacted clays, and a relationship is observed between suction, cohesion and the activity of the clay particles.
Proceedings of the Institution of Civil Engineers, 2002
This is the third and final paper describing a research project, carried out at the Technion in I... more This is the third and final paper describing a research project, carried out at the Technion in Israel, to study the influence of plant roots on the stability of slopes. The two previous papers described earlier stages of the research, in which root and soil properties were established, and the reliability of the numerical scheme, based on the use of the finite difference code FLAC, was checked. The present paper uses the previous results as a basis for analysing the stability of root-reinforced chalky slopes under various conditions. It is demonstrated that the stability analysis of root-reinforced slopes must consider the roots as individual elements, and take account of their properties, as well as their interaction with the surrounding soil. Use of the 'equivalent layer ' approach, in which the reinforced soil is replaced by an equivalent soil with strength properties obtained from laboratory shear tests, is likely to be significantly non-conservative. The influence of root inclination is studied, and it is shown that vertical roots do not contribute significantly to slope stability, whereas a considerable contribution is provided by roots that are perpendicular to the slope face. The numerical scheme may be used for the analysis of more complex soil-root interaction problems.
THE VOLUME CHANGE MEASUREMENTS OF GRANULAR SOILS IN TRIAXIAL TESTING ARE GNERALLY AFFECTED BY PEN... more THE VOLUME CHANGE MEASUREMENTS OF GRANULAR SOILS IN TRIAXIAL TESTING ARE GNERALLY AFFECTED BY PENETRATION OF THE MEMBRANE ENCLOSING THE SOIL INTO THE VOIDS BETWEEN THE PARTICLES. THE MAJOR FACTOR INFLUENCING THIS PENETRATION HAS BEEN SHOWN TO BE THE PARTICLE SIZE OF THE SOIL BEING TESTED. ON THE BASIS OF THE RESULTS OF PREVIOUS INVESTIGATINS AND THE PRESENT STUDY, A RELATIONSHIP HAS BEEN FOUND BETWEEN THE MEMBRANE PENETRATION AND PARTICLE SIZE. THIS RELATIONSHIP MAY BE USED TO ESTIMATE THE MEMBRANE EFFECT FOR ANY GRANULAR SOIL. /AUTHOR/
The strain increment resulting from an increment of stress applied to a particulate medium has be... more The strain increment resulting from an increment of stress applied to a particulate medium has been expressed in terms of its elastic and plastic components. The concepts of strain-hardening plasticity have been employed to develop an incremental stress–strain relation, based on a non-associated flow rule. The parameters appearing in the relation have been found using results of three-dimensional shear tests on sands and glass-microspheres. It is suggested that relations of the type developed in the paper could be beneficially incorporated into a finite-element program.
A large portion of the Mediterranean coastal plain of Israel is overlain by thick deposits of cal... more A large portion of the Mediterranean coastal plain of Israel is overlain by thick deposits of calcareous sands, sometimes cemented to varying degrees and forming a cemented sand known locally as kurkar. The paper presentsa review of the geotechnical properties of these deposits, and methods used to evaluate them. Parameters so obtained have been used for the design and analysis of building foundations, cliff slope stability analyses, and liquefaction studies. It is found that in many cases considerable breakdown of calcareous cementing bonds occurs under conditions of high stress, with the result that the soil behaves as an essentially cohesionless material, sometimes having an extremely high compressibility.
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