A new theoretical method to evaluate the internal stability of granular soils

2012 ◽  
Vol 49 (1) ◽  
pp. 45-58 ◽  
Author(s):  
Nicola Moraci ◽  
Maria Clorinda Mandaglio ◽  
Domenico Ielo
Keyword(s):  
Fine Particles ◽  
Filter Design ◽  
Critical Diameter ◽  
Theoretical Method ◽  
Rigid Wall ◽  
Spherical Particles ◽  
Granular Soils ◽  
Internal Stability ◽  
Granular Base ◽  
Geotextile Filter

The geotextile filter design is particularly complex when granular base soils are internally unstable. In these conditions, the design criteria available in literature are not always reliable. This paper deals with a new theoretical method developed to evaluate the internal stability of granular soils. To simulate, theoretically, the filtration process inside these soils, a set of spherical particles and different soil relative densities have been considered. The soil has been represented by means of a sequence of parallel layers, containing constrictions and particles, placed upon each other at a distance, in the direction of hydraulic flow, which is a function of the soil relative density. The movement of the fine particles through the different soil layers has been simulated by means of a mechanism that compares each particle contained in the i layer with the constrictions contained in the next i + 1 layer. The results of the numerical simulations were used to evaluate the internal stability of the analyzed granular soil and the corresponding critical diameter of suffusion, Dc. Finally, the reliability of the proposed theoretical method was evaluated by means of the results of experimental long-term filtration tests performed using a rigid-wall permeameter on different unstable granular soils.

Corrigendum: A new theoretical method to evaluate the internal stability of granular soils

2012 ◽  
Vol 49 (7) ◽  
pp. 875-875
Author(s):  
Nicola Moraci ◽  
Maria Clorinda Mandaglio ◽  
Domenico Ielo
Keyword(s):  
Theoretical Method ◽  
Granular Soils ◽  
Internal Stability

Similarity of internal stability criteria for granular soils

1992 ◽  
Vol 29 (4) ◽  
pp. 711-713 ◽  
Author(s):  
Robert P. Chapuis
Keyword(s):  
Grain Size ◽  
Groundwater Flow ◽  
Distribution Curve ◽  
Fine Particles ◽  
Frost Damage ◽  
Granular Soils ◽  
Internal Stability ◽  
Stability Criteria ◽  
Mathematical Expressions ◽  
Internal Instability

Internal instability produces segregation in fine particles, modifies drainage properties, and increases pore pressures, capillary retention, and possible frost damage. Three criteria are commonly used to assess the internal instability of granular soils. It is shown here that they can take similar mathematical expressions where the secant slope of the grain-size distribution curve indicates the risk of internal instability. Key words : suffossion, groundwater flow, gradation.

scholarly journals Effect of the Number of Constrictions on the Filtration Behaviour of a Soil-Geotextile System

2020 ◽  
Vol 28 (1(139)) ◽  
pp. 87-92
Author(s):  
Anna Miszkowska ◽  
Anna Miszkowska ◽  
Eugeniusz Koda ◽  
Zygmunt Krzywosz
Keyword(s):  
Selection Criteria ◽  
Fine Particles ◽  
Filter Design ◽  
Ratio Test ◽  
Flow Through ◽  
Gradient Ratio ◽  
Geotextile Filters ◽  
Nonwoven Geotextile ◽  
Geotextile Filter ◽  
Base Soil

Nonwoven geotextile filters have been used in geo-environmental engineering for decades to prevent the movement of base soil fine particles, allowing adequate seepage to flow through the geotextile plane. Most of the design criteria developed for nonwoven geotextiles are based only on the comparison between their characteristic opening size and the indicative diameter of the soil to be filtered. In the meantime, the nonwoven geotextile fibrous structure has an influence on the filtration of the soil-geotextile system. In this paper the numbers of constrictions of nonwoven geotextile samples were determined to verify the existence of a correlation between the geotextile structure and the filtration behaviour of soil-geotextile systems. The compatibility between an internally unstable soil and a nonwoven geotextile filter was evaluated using the gradient ratio test. The results obtained can also be the basis for modifying the geotextile filter design and selection criteria.

scholarly journals HYDRODYNAMIC FEATURES OF SUSPENSIONS AND EMULSIONS FLOWS.

2021 ◽  
Vol 2 (446) ◽  
pp. 99-104
Author(s):  
S.R. Rasulov ◽  
G.R. Mustafayeva
Keyword(s):  
Gas Flow ◽  
Fine Particles ◽  
Mutual Influence ◽  
Transport Coefficients ◽  
Spherical Particles ◽  
Scientific Article ◽  
Two Phase ◽  
Real Picture ◽  
Turbulent Gas Flow ◽  
Gas Pulsations

This scientific article is devoted to the problems associated with the flow of suspensions and emulsions and some simplifications of the real picture of the flow of a polydisperse medium are made. It is also stipulated that differential equations characterizing the motion of suspensions and emulsions should take into account the fundamental discontinuity of the medium and the physicochemical processes of heat and mass transfer occurring in it. Taking into account all these factors, a general equation for multiphase systems is proposed with certain simplifications that do not change. The behavior of particles in two-phase systems, their concentration, collision and coagulation are considered. As a result, it was concluded that there is a multifactorial interaction and mutual influence of both phases in a dispersed flow. A differential equation of motion of a single i-th spherical particle in suspension was proposed, and an equation describing the drag force of a solid spherical particles. Equations of conservation of mass and momentum are presented for one-dimensional laminar motion of two incompressible phases in a gravity field with the same pressure in the phases. Having studied the parameters of the flow of fine particles in a turbulent gas flow, some assumptions were made. It was found that the pulsating motion of particles, performed by them during one period of gas pulsations, can be represented as a change in the pulsating gas velocity in time. The parameter of entrainment of particles by a pulsating medium is an important characteristic in determining the transport coefficients in a turbulent flow. It is concluded that the presence of various kinds of particles in the liquid complicates the problem of solving hydromechanical problems in turbulent and laminar flow, and the assumptions given in the work facilitate the study of this problem.

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