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VisCon - Visualisering av tvådimensionell konsolidering i undervisningssammanhang

Forsman, Karin LU (2017) In TVSM-5000 VSM820 20171
Structural Mechanics
Department of Construction Sciences
Abstract
When a ground surface is subjected to a load an increased level of stress will occur in the soil underneath. As soil material has a limited permeability, an increased stress will initially result in an excess pore water pressure. However, as time passes the water will flow and the pore water pressure will even out. The relation between the total stress, the excess pore water pressure and the effective stress is given by the effective stress equation. It states that the total change in stress will always equal the sum of the excess pore water pressure and the effective stress. Consequently, when the excess pore water pressure diminishes the effective stress increases accordingly. This process is referred to as consolidation. It results in a... (More)
When a ground surface is subjected to a load an increased level of stress will occur in the soil underneath. As soil material has a limited permeability, an increased stress will initially result in an excess pore water pressure. However, as time passes the water will flow and the pore water pressure will even out. The relation between the total stress, the excess pore water pressure and the effective stress is given by the effective stress equation. It states that the total change in stress will always equal the sum of the excess pore water pressure and the effective stress. Consequently, when the excess pore water pressure diminishes the effective stress increases accordingly. This process is referred to as consolidation. It results in a greater load within the soil skeleton followed by settlements. The permeability and water content of the soil are determining characteristics of how long the consolidation process will take. In a soil with low permeability, such as clay, it can take a long time for the settlements to fully develop.

For educational purposes it is common to idealise the problem of consolidation and simply study one dimensional groundwater flow. The main reason behind this simplification is that many students struggle to picture the two dimensional case. Furthermore, a two dimensional model requires more complex calculations and often assumes knowledge within numerical solution methods such as the finite element method. The aim of this master’s dissertation has been to enhance students understanding
of two dimensional consolidation. In order to do so a program, VisCon,
has been developed to visualise how the excess pore water pressure varies with time and space. The program is based on a two dimensional model solved by applying the finite element method. Besides the two dimensional visualisation of the results the program produces one dimensional graphs. These illustrate the excess pore water pressure as well as the effective stress for any defined section of the model. By assisting students with a numerical solution of the excess pore water pressure a second aim with VisCon has been to switch focus within education from numerical calculations to actual geotechnical aspects of consolidation.

When developing a program for educational purposes it is important to consider its usability. The usability can be determined by studying how well the program is adjusted to its area of application, considered target group, previous knowledge of users and whether it is user-friendly or not. Furthermore, for a program to function as pedagogic software is has to be integrated within the education in a deliberate way. To facilitate the use of VisCon a user’s manual as well as exercises has been developed.
The exercises are intended to guide students in using VisCon for calculating settlements in two dimensions as well as analysing restrictions of the implemented model. (Less)
Popular Abstract (Swedish)
Datorer används allt oftare i undervisningssammanhang. En stor styrka ligger i möjligheten att på ett enkelt sätt kunna genomföra avancerade beräkningar och visualisera komplexa fenomen. VisCon är ett program som har utvecklats för att underlätta förståelsen av vad som händer i en jord när man belastar den med en byggnad eller en anläggning. Det här är en viktig kunskap för att undvika skador på byggnader.
Please use this url to cite or link to this publication:
author
Forsman, Karin LU
supervisor
organization
course
VSM820 20171
year
type
H3 - Professional qualifications (4 Years - )
subject
publication/series
TVSM-5000
report number
TVSM-5225
ISSN
0281-6679
language
Swedish
id
8919692
alternative location
http://www.byggmek.lth.se/english/publications/tvsm-5000-masters-dissertations/
date added to LUP
2017-06-30 11:38:38
date last changed
2017-09-07 15:03:21
@misc{8919692,
  abstract     = {When a ground surface is subjected to a load an increased level of stress will occur in the soil underneath. As soil material has a limited permeability, an increased stress will initially result in an excess pore water pressure. However, as time passes the water will flow and the pore water pressure will even out. The relation between the total stress, the excess pore water pressure and the effective stress is given by the effective stress equation. It states that the total change in stress will always equal the sum of the excess pore water pressure and the effective stress. Consequently, when the excess pore water pressure diminishes the effective stress increases accordingly. This process is referred to as consolidation. It results in a greater load within the soil skeleton followed by settlements. The permeability and water content of the soil are determining characteristics of how long the consolidation process will take. In a soil with low permeability, such as clay, it can take a long time for the settlements to fully develop.

For educational purposes it is common to idealise the problem of consolidation and simply study one dimensional groundwater flow. The main reason behind this simplification is that many students struggle to picture the two dimensional case. Furthermore, a two dimensional model requires more complex calculations and often assumes knowledge within numerical solution methods such as the finite element method. The aim of this master’s dissertation has been to enhance students understanding
of two dimensional consolidation. In order to do so a program, VisCon,
has been developed to visualise how the excess pore water pressure varies with time and space. The program is based on a two dimensional model solved by applying the finite element method. Besides the two dimensional visualisation of the results the program produces one dimensional graphs. These illustrate the excess pore water pressure as well as the effective stress for any defined section of the model. By assisting students with a numerical solution of the excess pore water pressure a second aim with VisCon has been to switch focus within education from numerical calculations to actual geotechnical aspects of consolidation.

When developing a program for educational purposes it is important to consider its usability. The usability can be determined by studying how well the program is adjusted to its area of application, considered target group, previous knowledge of users and whether it is user-friendly or not. Furthermore, for a program to function as pedagogic software is has to be integrated within the education in a deliberate way. To facilitate the use of VisCon a user’s manual as well as exercises has been developed.
The exercises are intended to guide students in using VisCon for calculating settlements in two dimensions as well as analysing restrictions of the implemented model.},
  author       = {Forsman, Karin},
  issn         = {0281-6679},
  language     = {swe},
  note         = {Student Paper},
  series       = {TVSM-5000},
  title        = {VisCon - Visualisering av tvådimensionell konsolidering i undervisningssammanhang},
  year         = {2017},
}