Fakultät Umweltwissenschaften, Fachrichtung Hydrowissenschaften.
Hydrological Regime Simulation in Earth y g gDams and Dikes using the Program
PCSiWaPro® as a Basis for Stability AnalysisPCSiWaPro as a Basis for Stability Analysis
Kassel, 16.05.2014 Jinxing Guo
Table of contentsTable of contents
Introduction Introduction
Hydrological regime analysis
Description of simulation Program PCSiWaPro®
Simulation results
Further application of the simulation results (in general)
Literature
2
1. Introduction
• Dikes as an effective flood protection systems
1. Introduction
• Dikes as an effective flood protection systems • about 630 km of dike length in Saxony alone • Simulation is necessary, especially in forecasting floods for dams and dikes.
[Source: André Künzelmann / UFZ, flooding of the Elbe, August 2002] [Source: Website of TU Dresden]
3
Introduction
Dam stability is influenced by
Introduction
• Dam stability is influenced by
various factors, such as
construction soil materials andconstruction, soil materials and
geometry, atmospheric conditions
(e g precipitation) vegetation and(e.g. precipitation), vegetation and
so on.
Example for the instability of the dam
The effect of precipitation
• Direct influence on the water
content change in the unsaturated
slope and seepage line (in an
extreme rainfall event)
4
IntroductionIntroduction
The importance of vegetation on slope stability
• Influence on the water content in
the upper layer of dams via the
p g p y
the upper layer of dams via the
soil-plant-atmosphere continuum
(COPPIN ET AL 1990 ) (COPPIN ET AL., 1990.)
• Soil reinforcement from the root
system (Gray 1995) main effectsystem (Gray, 1995)—main effect
5
2. Hydrological regime analysis2. Hydrological regime analysis
Model analysis:
• Calculation of seepage in a dam model (numerical modeling)
Water balance (especially in an extrem rainfall event)
How fast is the unsaturated area moistened in order to lead t d i t bilit (l d lid )?to dam instability (landslide)?
unsaturated
saturated
Water balance in the saturated and partially saturated zone (I. Hasan et al., 2012)
6
2. Hydrological regime analysis
Laboratory analysis:
2. Hydrological regime analysis
Result from a physical model experiment in IWD of TU Dresden
[S Ai 2004][Source: Aigner, 2004]
Landslide in the partially saturated region Clear hydrological process
p y g
7
3. Description of Program PCSiWaPro®
Advantages:
3. Description of Program PCSiWaPro
Based on Richard‘s equation and van Genuchten-Luckner modelE t l l ti f li i
Advantages:
Exact calculation of seepage line in dams
Consideration of atmospheric boundary conditions root water boundary conditions, root water uptake and soil evaporation
Consideration of hysteresis in unsaturated zoneunsaturated zone
integrated weather generator for arbitrary time series in high resolutionimplemented parameter identification implemented parameter identification algorithm
Soil databases according to DIN 4022 and DIN 4220 plus pedotransferand DIN 4220 plus pedotransferfunctions
8
Description of Program PCSiWaPro®
Model setup
Description of Program PCSiWaPro
p
Transient flooding level, rainfall (an example)
Boundary conditions
Analysis of function of rubber wall (an example)
9
Description of Program PCSiWaPro®
Material parameters
Description of Program PCSiWaPro
10
4. Simulation results
1) Simulation for the laboratory experiment
4. Simulation results
Simulation of the physical dam model with atmospheric BC also a test of rubber wall efficiencyy
cm Pressure head
Water content
11
Simulation resultsSimulation results
2) Simulation for a dam in Germany
73 0Water Levels in the Dam
Comparison of the caculated and measured data
72,5
73,0
evel
) [m
]
71,5
72,0
ove
sea
le
70,5
71,0
rlev
el (a
b Pegel6398/ measured
computed by PCSiW P
70,0
0 30 60 90 120
150
180
210
240
270
300
330
360W
ater
PCSiWaPro
Time [d] (I. Hasan et al., 2012)
• showing a very good agreement between measured and computed values
12
g y g g
3) Simulation for an earth dam in China)
0,220,24
)
0,120,140,160,180,2
tion
(m
/d
)
0,020,040,060,080,1
Pre
cip
itat Precipitation
0,
Jan Feb Mrz Apr Mai Jun Jul Aug Sep Okt Nov Dez
Time
300301
a
294295296297298299300
ove
th
e se
am
)
289290291292293294
lev
el a
bo
leve
l (m
water level above the sea level
286287288289
Jan Feb Mrz Apr Mai Jun Jul Aug Sep Okt Nov Dez
wat
er
Time
13
Time
Precipitation and water level change of an earth dam in China in 2006
Simulation results
Change in the degree of pressure g g phead during the simulation time
(08.02.2006 – 30.06.2006)
Clear movement of the seepage line
14
Simulation results
Ch i th d f Change in the degree of water content during the
simulation time (08 02 2006 30 06 2006)(08.02.2006 – 30.06.2006)
15
Simulation results
Water content in the dam on 25.06.2006 Water content in the dam on 25.06.2006
smaller degeneration rate of soil water in the core when the water core when the water level falls clear sensitivity of the
model parameters (hydraulic conductivity, pore space diameter...)
2% 8%19% 40%
285 m
∆
16
Simulation results
280Water level in the dam slope
283 0
284,0
285,0
vel)
Water level in the clay core
276277278279280
a le
vel)
280,0
281,0
282,0
283,0
he
sea
lev
272273274275276
ve t
he
sem
)
measured by pore water pressure
276 0
277,0
278,0
279,0
(ab
ove
t(m
) measured by pore water pressure measurer (PE26)
l t d b PCSiW P269270271272
evel
(ab
ov (m
measured by pore water pressure measurer (PE15)
caculated by PCSiWAPro
273,0
274,0
275,0
276,0
ater
leve
l caculated by PCSiWaPro
265266267268
J F b M A M i J J l A S Okt N D
wat
er le
272,0
,
Jan Feb Mrz Apr Mai Jun Jul Aug Sep Okt Nov Dez
Wa
Time (2006)
Jan Feb Mrz Apr Mai Jun Jul Aug Sep Okt Nov Dez
Time (2006)
• The agreement between the measured values and the computed ones usingthe program PCSiWaPro® was good for both cases.
• Deviations could be caused by poorly estimated hydraulic soil parameterswhich are based on the given DIN 4220 values and not on actual measurementsfrom China.
17
Simulation results
Conclusion:
The agreement between measured and computed values was very
d i G
Conclusion:
good in Germany;
The deviation for Chinese dams was credited to the uncertainties of
i lmaterials parameters;
More local investigations of the soil parameters in China are necessary
in order to get better application results of PCSiWaPro.
The computation of various variants indicates clearly the sensitivity of
the Model parameters (geometry, soil parameters und geohydraulic
boundary conditions).
18
What’s it for?
leeyankun.blogspot.com
Too much water causes instability!
20
6. Application of the simulation results --- Stability analysis--- Stability analysis
Method for the stability analysis:Method for the stability analysis:
Basic definition --- factor of safty
• The "infinite slope" – Model
• Bishops simplified method
• Mohr Columb Model
To be improved
• Mohr-Columb Model
• Bacelona Basic Model
• Cambridge model
21
Stability analysis model
--- Mohr–Coulomb failure criterionMohr Coulomb failure criterion
--- Improvement of the Mohr-Coulomb Model by D.G.Fredlund (1993)
Reference: Pierre Delage, 2013
22
Stability analysis model
Fs (factor of safety) analysis within the root layer :Fs (factor of safety) analysis within the root layer :
• Significant reinforcement from the roots has been considered;• Weight of vegatation is neglected;• For Fs analysis under the root layer there is no C in the equation• For Fs analysis under the root layer, there is no Cr in the equation.
23
Stability analysis model
1) Cohesion (C') VS water content:
C0 - - initial soil cohesion with θr
(Guo, 2013)
C0 initial soil cohesion with θrC0 - - soil cohesion with θs
(B k B lli h 2009)(B.k.Bellingham, 2009)
2) Matric suction (Ua – Uw) VS water content
(by VAN GENUCHTEN-LUCKNER)
24
Stability analysis model
3) Friction (tanØ’) VS water content3) Friction (tanØ ) VS water content
(Bian Jiamin and Wang Baotian, 2011; Guo, 2013)
(Bian Jiamin and Wang Baotian, 2011)
4) tanØb VS water content
(S.K. Vanapalli et al., 1996)
25
Stability analysis model
Relationships between water content and those four Relationships between water content and those four parameters:
W
negative Cohesion (C' )Water
Content negative
negativeSoil internal friction (tanØ’)
θnegative
positive
Matric suction (Ua – Uw)
tan Øbtan Ø
26
Stability analysis results
Factor of safety analysis on different lays in the slope on one day (29.06.2006)
Depth inthe slope* Water Fs value
from the Fs value withoutthe slope*
(air side, m)
contentθ
from the new
model
withoutinfluence of
water content
Water content simulation from PCSiWaPro®
0.3 0.15 13.1 18.6
0.3' 0.15 4.6 14.4
1 0 15 2 6 5 5 Clear positive effect of root on the stability
1 0.15 2.6 5.5
10 0.19 1.7 5.4
20 0 1 1 8 1 9Necessity of protective structure on the bottom layer of the slope
20 0.1 1.8 1.9
50 0.05 0.9 1.8
*vegetation root depth = 0.5m‘ no vegetation layer
Failure Mode Foundation Type F.S.Shear Earthwork for Dams Fills etc 1 2 1 6
layer of the slope
Shear Earthwork for Dams, Fills, etc. 1.2 - 1.6(Bowels J. E, 1988)
27
Stability analysis results
Conclusion and outlook
Based on the simulation results of water content from PCSiWaPro®,
t bilit l i d l b t k f l t l t
Conclusion and outlook
new stability analysis model can be taken as a powerful tool to
forcast the possible landslides.
N d l i l h l f l f h d i i f h i d New model is also helpful for the determination of the size and
the structure (e.g. the core) of the dam.
Programing work of those relationship models into the program
PCSiWaPro® is in planning to get the distribution of the Fs value
ith th t t t hwith the water content change.
28
6. Literature
Bian Jiamin and Wang Baotian 2011; Research on Influence of Water Contents on the Shear StrengthBian Jiamin and Wang Baotian, 2011; Research on Influence of Water Contents on the Shear StrengthBehavior of Unsaturated Soils; Chinese Journal o fUnderground Space and Eng ineering;
Bowles, J. E. 1988. Foundation Analysis and Design, 4th Edition, McGraw-Hill.
D.Gfredlund, et al, 1993; Effect of pore air and negative pore water pressures on stability at the end-of-construction;
Francisco Sandro Rodrigues Holanda1 and Igor Pinheiro da Rocha, 2011; Streambank Soil Bioengineeringg g , ; g gApproach to Erosion Control;
Pierre Delage, 2013; Testing and modeling of unsaturated soil.
S. K. Vanapalli, D. G. Fredlund, D. E. Pufahl and A. W. Clifton 1996; Model for the prediction of shearstrength with respect to soil suction; Canada, Geotech. J. 33: 379-392 (1996).
Tien H. Wu ,2013; Root reinforcement of soil: Review of analytical models, test results, and applicationsto design; NRC Research Press;
USDA National Agroforestry Center; Vegetation for Bank Erosion Control.
Y ng X eming 1989 Cl ifi tion of oil tem nd oil te nd the m l ondition Soil 02 1989Yang Xueming, 1989 ;Classification of soil system and soil water and thermal conditions; Soil, 02.1989.
29
Thank you for your attention!
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