Is the Conventional Pore Water Pressure Concept Adequate for Fine-Grained Soils in Geotechnical and Geoenvironmental Engineering?

Lu, Ning; Likos, William J.; Luo, Shengmin; Oh, Hyunjun

doi:10.1061/(asce)gt.1943-5606.0002612

Cited by 11 publications

(4 citation statements)

References 54 publications

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“…In addition to the spatially constant negative capillary pressure (tension), the nonlinearly decaying feature of SSP also determines the local variation in pore water pressure along the direction perpendicular to the soil particle surface (i.e., the distance x shown in Figure 10). The compressive water pressure in the first two adsorptive layers can be as high as ∼1.6 GPa (e.g., Lu et al., 2021). This abnormally high water pressure will decrease quickly and nonlinearly away from the soil particle surface to the tensile pressure in capillary water (Lu & Zhang, 2019), partially compensating the spatial difference in SSP and maintaining the same matric potential everywhere within the soil–water–air REV.…”

Section: Implications Of Soil Water Potentialsmentioning

confidence: 99%

Soil water potential: A historical perspective and recent breakthroughs

Luo

Zhang

et al. 2022

Vadose Zone Journal

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Soil water potential is a cornerstone in defining the thermodynamic state of soil water required to quantify phenomena such as water phase change, water movement, heat transfer, electric current, chemical transport, and mechanical stress and deformation in the earth's shallow subsurface environment. This potential has historically been conceptualized as free energy stored in a until volume of soil water. Though the concept of soil water potential has been evolving over the past 120 yr, a consensual definition is still lacking, and answers to some fundamental questions remain controversial and elusive. What are the origins and mechanisms for the free energy of soil water? Can the common mathematical expression of soil water potential as superposition of gravitational, osmotic, and matric potentials be used to define water phase transitions in soil? Are these major components of soil water potential independent or coupled? Is pore water pressure always tensile under unsaturated conditions? If so, how can soil water density be as high as 1.7 g cm −3 ? How do adsorptive soilwater interactions originating from the electromagnetic field around and within soil particles transfer to mechanical pore pressure? In this review, the authors (a) provide critical analysis of historical definitions of soil water potential to identify their strengths, limitations, and flaws; (b) synthesize the origins of electromagnetic energies in soil to clarify the fundamental differences between adsorptive and capillary soil water potential mechanisms; (c) introduce a recently emerging concept of soil matric potential that unifies contributions of adsorption and capillarity to soil water potential; and (d) illustrate the generality and promise of the unified definition of soil water potential for answering some of the fundamental questions that remain elusive to the hydrology, geoengineering, and geoscience communities.

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Section: Implications Of Soil Water Potentialsmentioning

confidence: 99%

Soil water potential: A historical perspective and recent breakthroughs

Luo

Zhang

et al. 2022

Vadose Zone Journal

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“…Care should be taken to not mistake the negative algebraic term with its real mechanism as it is the pore pressure in excess of a steady-state flow condition in soil in the vicinity of PVDs under vacuum preloading. (Lu, Likos et al 2021) has discussed in detail the inefficiency of common definition of pore pressure in soil mechanic and emphasized the necessity for developing better theories and seeking better engineering solutions for problems in geotechnical engineering.…”

Section: Introduction Bbbb Bbbsfsfmentioning

confidence: 99%

Coupling Effect and Superposition Law in Soil Treatment Systems Incorporating Vacuum Preloading

pardsouie¹

2022

Preprint

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In previous published literatures it was stated that superposition law might be valid for ground improvement techniques consisting of prefabricated vertical drains (PVDs) along with surcharge and vacuum preloading. Even some professional geotechnical engineers might think of this false idea that superposition law might be valid in such ground improvement techniques. It was shown that the superposition law is not valid because of the hydro-mechanical coupling interactions which exist between vacuum and surcharge preloading. A case history was presented and Finite element modeling (FEM) was used for verification and the demonstration of coupled consolidation interaction between vacuum and surcharge preloading. Three main parameters as settlement, lateral displacement, and excess pore pressure were evaluated for different scenarios. The results that are based on a macro-element approach can be used for better comprehension of the working mechanism of combined treatment systems. Considering the results of this literature, a complex combined vacuum and surcharge preloading can be broken in simpler cases that can be used for either deriving analytical or empirical solutions.

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“…The freezing of water to form ice is one of the most common phase transformations in the natural environment (Wettlaufer, 1999). Nearly one-third of the land surface of the Earth experiences freezing and thawing annually (Lu et al, 2021). In these permafrost and seasonally frozen regions, unfrozen water and pore ice coexist within a frozen soil, due to the complex soil-water interactions.…”

Section: Introductionmentioning

confidence: 99%

Use of an artificial neural network model for estimation of unfrozen water content in frozen soils

Ren

Fan

et al. 2022

Preprint

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A portion of pore water is typically in a state of unfrozen condition in frozen soils due to the complex soil-water interactions. The variation of the amount of unfrozen water and ice has a significant influence on the physical and mechanical behaviors of the frozen soils. Several empirical, semi-empirical, physical and theoretical models are available in the literature to estimate the unfrozen water content (UWC) in frozen soils. However, these models have limitations due to the complex interactions of various influencing factors that are not well understood or fully established. For this reason, in the present study, an artificial neural network (ANN) modeling framework is proposed and the PyTorch package is used for predicting the UWC in soils. For achieving this objective, extensive UWC data of various types of soils tested under various conditions were collected through an extensive search of the literature. The developed ANN model showed good performance for the test dataset. In addition, the model performance was compared with two traditional statistical models for UWC prediction on four additional types of soils and found to outperform these traditional models. Detailed discussions on the developed ANN model, and its strengths and limitations in comparison to different other models are provided. The study demonstrates that the proposed ANN model is simple yet reliable for estimating the UWC of various soils. In addition, the summarized UWC data and the proposed machine learning modeling framework are valuable for future studies related to frozen soils.

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Is the Conventional Pore Water Pressure Concept Adequate for Fine-Grained Soils in Geotechnical and Geoenvironmental Engineering?

Cited by 11 publications

References 54 publications

Soil water potential: A historical perspective and recent breakthroughs

Soil water potential: A historical perspective and recent breakthroughs

Coupling Effect and Superposition Law in Soil Treatment Systems Incorporating Vacuum Preloading

Use of an artificial neural network model for estimation of unfrozen water content in frozen soils

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