- Email: [email protected]
Fractal estimation of joint roughness coefficients
266A
PROPERTIES:PHYSICO-CHEMICAL
956116 Fractal estimation of joint roughness coefficients He Ping Kie & W. G. Pariseau, Science in China, Series B, 37(12), 1994, pp 1516-1524. Based on the triadic Koch curve, a generalized fractai model of joint profiles is established to simulate joint roughness. The fractal dimension of a joint profile can be directly obtained from the two parameters, L+ and h+, the average base length and average height of asperities of the joint, respectively. This fractal dimension is strongly correlated with the value of the joint roughness coetlicient (JRC). (from Authors) 956117 Identi5cation of preexisting cracks on soil fracture surfaces using dye P. D. Hallett, A. R. Dexter 8~ J. P. K. Seville, Soif & Tillage Research, 33(3-4), 1995, pp 163-184. A significant strength-controlling property of aggregated soils is structural porosity such as cracks. A technique is presented to identify structural porosity on fracture surfaces using methylene blue dye. Soil aggregates were immersed in the stain, returned to their original water content, and equilibrated. They were then fractured under a dynamic load using an impact rig. The fragments were collected and sieved to selected size ranges. The proportion of the fragment surface that was stained from each size range was measured using a colour image analyser adapted for this experiment. Results obtained illustrate that compaction reduces both structural porosity and fragmentation. (Authors)
Time dependent
behaviour
956118 Continuoos retardation spectrom for solidification theory of concrete creep Z. P. Baxant & Yunping xi, Journal of Engineering A4echanics - AXE, 121(2), 1995, pp 281-288. The basic creep of concrete is the time-dependent strain caused by a sustained stress in absence of moisture movements. It is dependent on the age of concrete, as a consequence of long-time chemical reactions associated with the hydration of cement. This paper formulates the solidification theory with a continuous retardation spectrum, and shows how this spectrum can be readily and unambiguously identified from arbitrary measured creep curves and how it can be easily converted to a discrete spectmm for numerical purposes. (from Authors) 956119 Discretization influence in strainaoftening problems L. J. Sluys, M. Cauvern & R. De Borst, Engineering Computations, 12(3), 1995, pp 209-228. The dispersive behaviour of waves in softening problems is analysed. Attention is focused on the influence of the numerical scheme on the dispersion chamcteristics in the process of localization of deformation. Distinction has been made between softening models defined in a standard plasticity framework and in a gradient-dependent plasticity theory. By carrying out the dispersion analysis on the discretixed system the influence of numerical dispersion on material dispersion can be quantified. For a modelling with and without the inclusion of strain gradients accuracy considerations with respect to mass discretixation, finite element size, time integration scheme and time step have been carried out. (Authors)
Physico-chemical
properties
956120 Fully coupled analysis of heat, moisture, and air transfer in unsatur8ted soil H. R. Thomas 8c M. R. Sansom, Journal of Engineering Mechanics - AXE, 121(3), 1995, pp 392-405. This paper presents a new theoretical formulation of coupled heat, moisture, and air transfer in unsaturated soil. A mechanistic approach is adopted that extends a previous potential-based formulation of coupled heat and moisture/air transfer and coupled heat/moisture transfer at constant pressure. An application of the model to an example test problem is presented, making use of thermophysical soil parameters that have been independently established for a range of the soil properties specified in the formulation. A number of features of interest related to the interaction between elevated temperatures, induced increased air pressure, and infiltration rates are described. The importance of including the air phase is thus identified. (Authors) 956121 Discreteelement method for simulating behavior of cobesive soil A. Anandarajah, Journal of Geotechnical Engineering AXE, 120(g), 1994, pp 1593-1613. The discrete-element method is applied in this paper to cohesive soils, where in addition to mechanical forces, them are physicochemical forces between particles, and there is significant bending of individual particles. By employing suitable force-displacement laws for the mechanical contacts, formation of new contacts, deletion of existing contacts, and slip between particles are modeled. (from Author) 956122 Qoantitative determination of potential distribution in Stern-Guy doable-layer model J. Q. Shang, K. Y. Lo 8c R. M. Quigley, Canadian Geotechnical Joumul, 31(5), 1994, pp 624-636. A quantitative determination of the potential distribution in the Stem-Gouy double-layer model for clay-waterclectrolyte systems is presented. The surface potential, Stern potential, thickness of the Gouy diffuse layer, and distribution of electrical potential can be computed by knowing the required parameters, such as the cation exchange capacity, specific surface 8128, electrolyte concentration, and valence, temperature, and permittivity of the solvent (pore fluid). The factors influencing the potential distribution in the double layer are discussed. To demonstrate the applications of the Stem-Gouy model, two examples are presented. (from Authors) 956123 Poladution and conduction of clay-water-electrolyte systems J. Q. Shang, K. Y. Lo & I. I. In&et, Journal of Geotechnicaf Engineering - AXE, 121(3), 1995, pp 243-248. The polarization and conduction of clay-water-electrolyte systems in a low-frequency electric field can be presented in terms of the Dukhin-Shilov double-layer polarization model and a resistor-in-series model. In an experimental program, the pennittivity and conductivity of two natural Leda clays were measured at a frequency of 60 Hz. The results of permittivity measurements were in good agreement with the Dukhin-Shilov theory. The surface conductivity of clay particles was estimated though the measurements to clay mass and pore fluid based on the resistor-in-series model. (Authors)
PROPERTIES:PHYSICO-CHEMICAL
956116 Fractal estimation of joint roughness coefficients He Ping Kie & W. G. Pariseau, Science in China, Series B, 37(12), 1994, pp 1516-1524. Based on the triadic Koch curve, a generalized fractai model of joint profiles is established to simulate joint roughness. The fractal dimension of a joint profile can be directly obtained from the two parameters, L+ and h+, the average base length and average height of asperities of the joint, respectively. This fractal dimension is strongly correlated with the value of the joint roughness coetlicient (JRC). (from Authors) 956117 Identi5cation of preexisting cracks on soil fracture surfaces using dye P. D. Hallett, A. R. Dexter 8~ J. P. K. Seville, Soif & Tillage Research, 33(3-4), 1995, pp 163-184. A significant strength-controlling property of aggregated soils is structural porosity such as cracks. A technique is presented to identify structural porosity on fracture surfaces using methylene blue dye. Soil aggregates were immersed in the stain, returned to their original water content, and equilibrated. They were then fractured under a dynamic load using an impact rig. The fragments were collected and sieved to selected size ranges. The proportion of the fragment surface that was stained from each size range was measured using a colour image analyser adapted for this experiment. Results obtained illustrate that compaction reduces both structural porosity and fragmentation. (Authors)
Time dependent
behaviour
956118 Continuoos retardation spectrom for solidification theory of concrete creep Z. P. Baxant & Yunping xi, Journal of Engineering A4echanics - AXE, 121(2), 1995, pp 281-288. The basic creep of concrete is the time-dependent strain caused by a sustained stress in absence of moisture movements. It is dependent on the age of concrete, as a consequence of long-time chemical reactions associated with the hydration of cement. This paper formulates the solidification theory with a continuous retardation spectrum, and shows how this spectrum can be readily and unambiguously identified from arbitrary measured creep curves and how it can be easily converted to a discrete spectmm for numerical purposes. (from Authors) 956119 Discretization influence in strainaoftening problems L. J. Sluys, M. Cauvern & R. De Borst, Engineering Computations, 12(3), 1995, pp 209-228. The dispersive behaviour of waves in softening problems is analysed. Attention is focused on the influence of the numerical scheme on the dispersion chamcteristics in the process of localization of deformation. Distinction has been made between softening models defined in a standard plasticity framework and in a gradient-dependent plasticity theory. By carrying out the dispersion analysis on the discretixed system the influence of numerical dispersion on material dispersion can be quantified. For a modelling with and without the inclusion of strain gradients accuracy considerations with respect to mass discretixation, finite element size, time integration scheme and time step have been carried out. (Authors)
Physico-chemical
properties
956120 Fully coupled analysis of heat, moisture, and air transfer in unsatur8ted soil H. R. Thomas 8c M. R. Sansom, Journal of Engineering Mechanics - AXE, 121(3), 1995, pp 392-405. This paper presents a new theoretical formulation of coupled heat, moisture, and air transfer in unsaturated soil. A mechanistic approach is adopted that extends a previous potential-based formulation of coupled heat and moisture/air transfer and coupled heat/moisture transfer at constant pressure. An application of the model to an example test problem is presented, making use of thermophysical soil parameters that have been independently established for a range of the soil properties specified in the formulation. A number of features of interest related to the interaction between elevated temperatures, induced increased air pressure, and infiltration rates are described. The importance of including the air phase is thus identified. (Authors) 956121 Discreteelement method for simulating behavior of cobesive soil A. Anandarajah, Journal of Geotechnical Engineering AXE, 120(g), 1994, pp 1593-1613. The discrete-element method is applied in this paper to cohesive soils, where in addition to mechanical forces, them are physicochemical forces between particles, and there is significant bending of individual particles. By employing suitable force-displacement laws for the mechanical contacts, formation of new contacts, deletion of existing contacts, and slip between particles are modeled. (from Author) 956122 Qoantitative determination of potential distribution in Stern-Guy doable-layer model J. Q. Shang, K. Y. Lo 8c R. M. Quigley, Canadian Geotechnical Joumul, 31(5), 1994, pp 624-636. A quantitative determination of the potential distribution in the Stem-Gouy double-layer model for clay-waterclectrolyte systems is presented. The surface potential, Stern potential, thickness of the Gouy diffuse layer, and distribution of electrical potential can be computed by knowing the required parameters, such as the cation exchange capacity, specific surface 8128, electrolyte concentration, and valence, temperature, and permittivity of the solvent (pore fluid). The factors influencing the potential distribution in the double layer are discussed. To demonstrate the applications of the Stem-Gouy model, two examples are presented. (from Authors) 956123 Poladution and conduction of clay-water-electrolyte systems J. Q. Shang, K. Y. Lo & I. I. In&et, Journal of Geotechnicaf Engineering - AXE, 121(3), 1995, pp 243-248. The polarization and conduction of clay-water-electrolyte systems in a low-frequency electric field can be presented in terms of the Dukhin-Shilov double-layer polarization model and a resistor-in-series model. In an experimental program, the pennittivity and conductivity of two natural Leda clays were measured at a frequency of 60 Hz. The results of permittivity measurements were in good agreement with the Dukhin-Shilov theory. The surface conductivity of clay particles was estimated though the measurements to clay mass and pore fluid based on the resistor-in-series model. (Authors)