A theoretical model to predict suffusion‐induced particle movement in cohesionless soil under seepage flow

2020 ◽  
Vol 72 (3) ◽  
pp. 1395-1409
Author(s):  
Zhe Huang ◽  
Yuchuan Bai ◽  
Haijue Xu ◽  
Jian Sun
Keyword(s):  
Theoretical Model ◽  
Seepage Flow ◽  
Cohesionless Soil ◽  
Particle Movement

A hydromechanical relation governing internal stability of cohesionless soil

2011 ◽  
Vol 48 (3) ◽  
pp. 413-424 ◽  
Author(s):  
Ricardo Moffat ◽  
R. Jonathan Fannin
Keyword(s):  
Seepage Flow ◽  
Hydraulic Gradient ◽  
Cohesionless Soil ◽  
Cohesionless Soils ◽  
Critical Hydraulic Gradient ◽  
Internal Instability ◽  
Short Period ◽  
Flow Through ◽  
Permeameter Tests ◽  
Novel Concept

Results are presented from permeameter tests involving unidirectional seepage flow through reconstituted specimens of four widely graded cohesionless soils. The onset of instability is defined by a significant decrease in local hydraulic gradient over a relatively short period of time. The novel concept of a hydromechanical path in stress ([Formula: see text]) – gradient (ijk) space is proposed, which describes the response to seepage flow during testing and terminates at the value of critical hydraulic gradient. The path terminus establishes a hydromechanical boundary governing the onset of seepage-induced internal instability in one-dimensional flow. The boundary represents a failure envelope, which is different for each of the four soils tested. A ranking of seepage-induced instability for each soil, from most unstable to least unstable, is found similar, but not identical to, the susceptibility to internal instability determined from empirical analysis of the gradation shape.

Spatial and temporal progression of internal erosion in cohesionless soil

2011 ◽  
Vol 48 (3) ◽  
pp. 399-412 ◽  
Author(s):  
Ricardo Moffat ◽  
R. Jonathan Fannin ◽  
Stephen J. Garner
Keyword(s):  
Seepage Flow ◽  
Hydraulic Gradient ◽  
Internal Erosion ◽  
Cohesionless Soil ◽  
Cohesionless Soils ◽  
Multi Stage ◽  
Internal Instability ◽  
Post Test ◽  
Erosion Test ◽  
Permeameter Tests

Permeameter tests were performed on four widely graded cohesionless soils, to study their susceptibility to internal erosion. Test specimens were reconstituted as a saturated slurry, consolidated, and then subjected to multi-stage seepage flow under increasing hydraulic gradient. The occurrence of internal instability is described qualitatively, from visual observations through the wall of the permeameter during a test and from post-test observations; it is also described quantitatively, from change of hydraulic gradient within the specimen and from axial displacement during a test. The results provide a novel insight into the spatial and temporal progression of seepage-induced internal instability. This insight yields an improved characterization of suffusion and suffosion in cohesionless soils, the progression of which appears governed by a critical combination of hydraulic gradient and effective stress.

A Model for Analyzing Suicide Prevention

Crisis ◽  
2000 ◽  
Vol 21 (2) ◽  
pp. 80-89 ◽  
Author(s):  
Maila Upanne
Keyword(s):  
Risk Factors ◽  
Theoretical Model ◽  
Protective Factors ◽  
Suicide Prevention ◽  
Suicide Risk ◽  
Practical Work ◽  
Individual Risk ◽  
Self Assessment ◽  
Prevention Project ◽  
Individual Risk Factors

This study monitored the evolution of psychologists' (n = 31) conceptions of suicide prevention over the 9-year course of the National Suicide Prevention Project in Finland and assessed the feasibility of the theoretical model for analyzing suicide prevention developed in earlier studies [ Upanne, 1999a , b ]. The study was formulated as a retrospective self-assessment where participants compared their earlier descriptions of suicide prevention with their current views. The changes in conceptions were analyzed and interpreted using both the model and the explanations given by the subjects themselves. The analysis proved the model to be a useful framework for revealing the essential features of prevention. The results showed that the freely-formulated ideas on prevention were more comprehensive than those evolved in practical work. Compared to the earlier findings, the conceptions among the group had shifted toward emphasizing a curative approach and the significance of individual risk factors. In particular, greater priority was focused on the acute suicide risk phase as a preventive target. Nonetheless, the overall structure of prevention ideology remained comprehensive and multifactorial, stressing multistage influencing. Promotive aims (protective factors) also remained part of the prevention paradigm. Practical working experiences enhanced the psychologists' sense of the difficulties of suicide prevention as well as their criticism and feeling of powerlessness.

Do self-compassion and self-coldness distinctly relate to distress and well-being? A theoretical model of self-relating.

2018 ◽  
Vol 65 (3) ◽  
pp. 346-357 ◽  
Author(s):  
Rachel E. Brenner ◽  
David L. Vogel ◽  
Daniel G. Lannin ◽  
Kelsey E. Engel ◽  
Andrew J. Seidman ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Well Being ◽  
Self Compassion
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