scholarly journals Mechanical Effects of Solid Water on the Particle Skeleton of Soil: Mechanism Analysis

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xiaomeng Duan
Keyword(s):  
Effective Stress ◽  
Water Pressure ◽  
Water Layer ◽  
Adsorbed Water ◽  
Interparticle Contact ◽  
Ambient Conditions ◽  
Stress Equation ◽  
Mechanical Effects ◽  
Solid Water ◽  
Interparticle Friction

It is generally accepted that the adsorbed water layer on the surface of the mineral particle has significant effects on the mechanical properties of soils. By defining the concepts of “solid water” and “particle skeleton” after a brief review on adsorbed water, therefore, the mechanical mechanism about how solid water affects the deformation and strength of particle skeleton is theoretically clarified, which could be the physical basis of the reasonability of two assumptive conditions for effective stress equation. Considering solid water as a two-dimensional liquid with appreciable normal strength and lubricity, if soil particles are always wrapped by solid-water layer, the only mechanical effect due to water pressure is to compress particles; while if the interparticle solid water could be extruded undergoing enough force with suitable confinement, the mechanical effects due to increasing water pressure are not only to compress particles more but also to enhance interparticle friction because the indirect interparticle contact could be changed into direct contact to consequently alter the interparticle friction. Because solid water is not likely to be extruded by pressure alone, if the particle compression is negligible relative to the soil-mass compression, two assumptive conditions for effective stress equation are reasonable. Moreover, a simple monitoring test on water content is conducted to certify that the solid-water layer should always exist in soils under ambient conditions, so the ordinarily oven-dried soil samples used in conventional geotechnical tests carried out under ambient conditions could be just “nominally dry” samples with the effects due to solid water.

The influence of high pore-water pressure on the strength of cohesionless soils

1977 ◽  
Vol 284 (1318) ◽  
pp. 91-130 ◽  
Keyword(s):  
Pore Pressure ◽  
Effective Stress ◽  
Quartz Sand ◽  
Pore Water Pressure ◽  
Pore Space ◽  
Water Pressure ◽  
Experimental Studies ◽  
Interparticle Contact ◽  
Particulate Materials ◽  
Shearing Resistance

The influence on the mechanical properties of saturated particulate materials of the component of stress carried by the water filling the pore space is fundamental to both theoretical and experimental studies in soil mechanics. The rôle of pore pressure in controlling compressibility and shear strength is expressed in Terzaghi’s principle of effective stress to a degree of accuracy which is sufficient for most engineering purposes. However, the precise significance of the small but finite area of interparticle contact has remained uncertain in the application of this equation to shearing resistance. In the present paper the possible errors associated with the use of current expressions for intergranular stress and effective stress are examined. These errors are of significant magnitude at high values of pore pressure and low values of the yield stress of the solid forming the particles. A very accurate experimental investigation has been carried out into the sensitivity of shearing resistance to large changes in pore pressure (up to 41.4 MN/m 2 ), using particulate materials ranging in strength from Quartz sand to lead shot. The results indicate that the simple Terzaghi effective stress equation a' - o - u is consistent with all the observations, though for Quartz sand a range of pore pressure changes an order of magnitude higher is desirable for additional confirmatory evidence.

scholarly journals Ion mobility and material transport on KBr in air as a function of the relative humidity

2019 ◽  
Vol 10 ◽  
pp. 2084-2093
Author(s):  
Dominik J Kirpal ◽  
Korbinian Pürckhauer ◽  
Alfred J Weymouth ◽  
Franz J Giessibl
Keyword(s):  
Ion Mobility ◽  
Water Layer ◽  
Adsorbed Water ◽  
Ambient Conditions ◽  
Material Transport ◽  
Surface Conditions ◽  
Force Microscopy ◽  
Atomic Force ◽  
Microscopy Images ◽  
Material Exchange

Surfaces exposed to air can change their structure due to external influences such as chemical reactions or material exchange and movement. The adsorbed water layer that is present under ambient conditions plays an important role especially for highly soluble materials. Surface atoms can easily diffuse into the thin water layer and, when surface conditions are favorable, they can re-attach to the surface. We collected atomic force microscopy images of KBr surfaces in a humidity-controlled glove box at various relative humidities below 40%. By scratching and poking the surface with the AFM tip, we constructed energetically unfavorable holes or scratch sites and material accumulations and recorded the evolution of these defects as a function of the time. We observed an exponential decay of the size of the defects and material accumulations, and from this data we determined energy barriers to dissolution and aggregation of approximately 0.9 eV.

Discussion of “Unified Effective Stress Equation for Soil” by Chao Zhang and Ning Lu

2021 ◽  
Vol 147 (2) ◽  
pp. 07020003
Author(s):  
Sakineh Fazli Ghiyasabadi ◽  
Ehsan Nikooee ◽  
Ghassem Habibagahi
Keyword(s):  
Effective Stress ◽  
Stress Equation

The Principle of Effective Stress Theory Research Based on Channel Rate

2013 ◽  
Vol 275-277 ◽  
pp. 336-342
Author(s):  
Xiao Feng Wu ◽  
Guang Fan Li ◽  
Wan Cheng He
Keyword(s):  
Effective Stress ◽  
Permeability Coefficient ◽  
Cohesive Soil ◽  
Stress Equation ◽  
Jump Problem ◽  
Stress Theory ◽  
Conventional Calculation ◽  
Earth Pressures ◽  
Stress Surface ◽  
Theory Research

Based on the debate of effective stress principle applicability on cohesive soil in recent years and the predecessor's research achievements, this paper puts forward the idea that the effective stress surface including hydrated film surrounding soil particles. And we obtained the extended soil effective stress equation by establishment of the model of channel rate.Combined with the physical significance of permeability coefficient and substantial experimental data, it can establish the fitting equation between permeability coefficient and new proposed physical parameter channel rate. A new calculation method to unify the separate calculation and combined calculation of water and earth pressures is proposed to carry out the transition between results of the two conventional calculation methods and provide a new idea for solving the jump problem between the two results.

Capillary-based effective stress formulation for predicting shear strength of unsaturated soils

2015 ◽  
Vol 52 (12) ◽  
pp. 2067-2076 ◽  
Author(s):  
Jean-Marie Konrad ◽  
Marc Lebeau
Keyword(s):  
Shear Strength ◽  
Effective Stress ◽  
Unsaturated Soils ◽  
Water Retention ◽  
Adsorbed Water ◽  
Soil Strength ◽  
Liquid Films ◽  
Degree Of Saturation ◽  
Stress Parameter ◽  
Effective Stress Parameter

A number of investigations have shown that the shear strength of unsaturated soils can be defined in terms of effective stress. The difficulty in this approach lies in quantifying the effective stress parameter, or Bishop’s parameter. Although often set equal to the degree of saturation, it has recently been suggested that the effective stress parameter should be related to an effective degree of saturation, which defines the fraction of water that contributes to soil strength. A problematic element in this approach resides in differentiating the water that contributes to soil strength from that which does not contribute to soil strength. To address this difficulty, the paper uses theoretical considerations and experimental observations to partition the water retention function into capillary and adsorptive components. Given that the thin liquid films of adsorbed water should not contribute to effective stress, the effective stress parameter is solely related to the capillary component of water retention. In sample calculations, this alternative effective stress parameter provided very good agreement with experimental data of shear strength for a variety of soil types.

The Microscopic Structure of Adsorbed Water on Hydrophobic Surfaces under Ambient Conditions

Nano Letters ◽  
2011 ◽  
Vol 11 (12) ◽  
pp. 5581-5586 ◽  
Author(s):  
Peigen Cao ◽  
Ke Xu ◽  
Joseph O. Varghese ◽  
James R. Heath
Keyword(s):  
Adsorbed Water ◽  
Microscopic Structure ◽  
Ambient Conditions ◽  
Hydrophobic Surfaces

An effective stress model for creep of clay

1995 ◽  
Vol 32 (5) ◽  
pp. 819-834 ◽  
Author(s):  
Mohammed M. Morsy ◽  
D.H. Chan ◽  
N.R. Morgenstern
Keyword(s):  
Finite Element ◽  
Pore Pressure ◽  
Effective Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Surface Model ◽  
Interpolation Technique ◽  
Stress Integration ◽  
Integration Algorithms ◽  
Double Yield

An effective stress constitutive model to study the problem numerically of creep in the field is presented. A double-yield surface model for the stress–strain–time behaviour of wet clay is described. The model adopts the concept of separating the total deformation into immediate and delayed components. The yield surfaces employed are the modified Cam-clay ellipsoid and the Von Mises cylinder inscribed in the ellipsoid. The proposed numerical scheme incorporates the pore pressure based on field observations into a finite element analysis. An interpolation technique is used to determine the pore pressure at every element. A field example is presented to illustrate the interpolation technique procedure. The scheme not only avoids the complexity of making predictions of pore-water pressure, but also allows the analysis to be carried out in terms of effective stresses based on the actual observed pore pressure. Two stress integration algorithms based on the implicit calculation of plastic strain are implemented and tested for the double-yield surface model. A numerical simulation of stress-controlled drained creep tests confirms the numerical procedure. Key words : constitutive equations, creep, finite element, stress integration algorithms, effective stress approach, pore-water pressure.

scholarly journals Implications of the principle of effective stress

2020 ◽  
Author(s):  
Gerd Gudehus
Keyword(s):  
Critical Phenomena ◽  
Pore Water ◽  
Effective Stress ◽  
Critical Points ◽  
Pore Water Pressure ◽  
Numerical Models ◽  
Water Pressure ◽  
Shear Bands ◽  
Triaxial Tests ◽  
Water Saturated

AbstractWhile Terzaghi justified his principle of effective stress for water-saturated soil empirically, it can be derived by means of the neutrality of the mineral with respect to changes of the pore water pressure $$p_w$$ p w . This principle works also with dilating shear bands arising beyond critical points of saturated grain fabrics, and with patterns of shear bands as relics of critical phenomena. The shear strength of over-consolidated clay is explained without effective cohesion, which results also from swelling up to decay, while rapid shearing of water-saturated clay can lead to a cavitation of pore water. The $$p_w$$ p w -neutrality is also confirmed by triaxial tests with sandstone samples, while Biot’s relation with a reduction factor for $$p_w$$ p w is contestable. An effective stress tensor is heuristically legitimate also for soil and rock with relics of critical phenomena, particularly for critical points with a Mohr–Coulomb condition. Therein, the $$p_w$$ p w -neutrality of the solid mineral determines the interaction of solid fabric and pore water, but numerical models are questionable due to fractal features.

First Adsorbed Water Layer and Its Wettability Transition under Compressive Lattice Strain

2019 ◽  
Vol 124 (7) ◽  
pp. 4057-4064
Author(s):  
Guobing Zhou ◽  
Bradley H. Schoen ◽  
Zhen Yang ◽  
Liangliang Huang
Keyword(s):  
Lattice Strain ◽  
Water Layer ◽  
Adsorbed Water
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