Experimental Analysis of Shrinkage-swelling Phenomenon of Clays -Application to an Individual House Affected by Drought Under Climate Change Effects

Abstract

The shrinkage-swelling of clays (SSC) phenomenon, also known as a geotechnical drought, causes important movements of soils affecting the foundations of structures on the surface. Indeed, the volume of these clayey soils varies according to their water content; this leads to differential settlement phenomena that are particularly harmful for buildings such as: individual houses, buildings and road infrastructures (ARGIC, 2009; ARGIC 2, 2015).
In France, the SSC hazard is ranking second as the natural risk in terms of financial impact and disorders, with an average of 20,000 individual houses affected per year (BRGM, 2019). The impulse of climate change will not stop growing the SSC phenomenon and will bring the cost of average annual losses generated up to +23% by 2050 (CCR, 2018).
In this context, Cerema has invested heavily in the search for innovative techniques through national and international projects to overcome this major problem. For this case, Cerema has tested an innovative and environmental solution on one damaged-house localized at center region in France. The objective is to control the SSC phenomenon by injecting the rainwater, recovered and stored, directly in the ground of foundation. It is based on stocking rainwater into two tanks of 800 liters volume capacity of each one and the principle is to humidify the foundation soil during drought periods.
The foundation soil suction was monitored with connected probes, which is essential to the injection process. This operation allows recording the soil suction related to water content conditions, and can reach a maximum suction of 239 kPa. A monitoring system of cracking was also installed and consists to measure the open/close of cracks appeared in the house by the disorders observed during drought of 2015.
After three years of monitoring since the end of 2016, this solution highlights satisfying results in terms of closing cracks. Note that there is a real effect of rainwater injection on crack stabilization under drought conditions.

Full text

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Experimental Analysis of Shrinkage-swelling Phenomenon of Clays –Application to an
Individual House Affected by Drought Under Climate Change Effects
Lamine IGHIL AMEUR

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OUTLINE
ASCE EMI/PMC 2021 | Virtual event
Introduction: shrinkage-swelling phenomenon and climate change effects
The MACH solution: description and initial investigations
Why shrinkage-swelling phenomenon is problematic for the individual houses ?
Rainwater storage and humidification process
Conclusions and perspectives
Main experimental results since 2017
House monitoring summary
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21/04/2021
L. IGHIL AMEUR

1. Introduction: shrinkage-swelling
phenomenon and climate change
effects
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1. INTRODUCTION: SHRINKAGE-SWELLING PHENOMENON AND CLIMATE CHANGE EFFECTS
ASCE EMI/PMC 2021 | Virtual event21/04/2021
L. IGHIL AMEUR
Desiccation cracking phenomenon
in clay soils
Individual houses
Environment
Roads Radioactive waste storage
Climate change
Influence of the local
conditions

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1. INTRODUCTION: SHRINKAGE-SWELLING PHENOMENON AND CLIMATE CHANGE EFFECTS
ASCE EMI/PMC 2021 | Virtual event21/04/2021
L. IGHIL AMEUR
2017
2018
2019
2020
Temperature and precipitation mean values during summer from
1959 to 2020 in France
Photo credit: © Météo France 2020
To learn more: click here
Cumulated precipitation from June 21 to September 20 in
France from 1959 to 2020
Photo credit: © Météo France 2020
To learn more: click here
2020
Summer 2020 is
the driest since
1959
Summer weather report (June-July-August) in terms of temperature and precipitation by Météo France
Cumulated precipitation (mm)
Precipitation compared to normal (mm)
Mean temperature compared to normal (°C)

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1. INTRODUCTION: SHRINKAGE-SWELLING PHENOMENON AND CLIMATE CHANGE EFFECTS
ASCE EMI/PMC 2021 | Virtual event21/04/2021
L. IGHIL AMEUR
How climate change affects the shrinkage-swelling phenomenon of clay soils and how to remediate ?
Swelling
Suction ↑
Water content ↓
Suction ↓
Water content ↑
How to limit the shrinkage-swelling phenomenon effects
on the damage and cracking of roads and buildings ?
Clay soils
Shrinkage
Drying and wetting cycles under
climate change conditions

2. Why shrinkage-swelling
phenomenon is problematic for the
individual houses ?
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2. WHY SHRINKAGE-SWELLING PHENOMENON IS PROBLEMATIC FOR THE INDIVIDUAL HOUSES ?
ASCE EMI/PMC 2021 | Virtual event21/04/2021
L. IGHIL AMEUR
Béchade (2014)
Influence of the vegetation
The drainage around the
construction must be up to
standards and reliable to avoid
unwanted infiltration that could
cause the foundations to collapse
Influence of the water cycle
Photo credit: Luis Furushio ©️LF Design Photo credit: Luis Furushio ©️LF Design
House
Clay soils
Environment
Vegetation is not a problem
when planted at an
adequate distance to avoid
increasing soil suction by the
roots

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2. WHY SHRINKAGE-SWELLING PHENOMENON IS PROBLEMATIC FOR THE INDIVIDUAL HOUSES ?
ASCE EMI/PMC 2021 | Virtual event21/04/2021
L. IGHIL AMEUR
Origins of structural damage due to the drought and example of consequences on individual houses
Inadequate rainwater evacuation system Influence of the vegetation Construction defects
Cracking mechanisms
Deformation mode caused by
peripheral shrinkage of the soil under the house Deformation mode caused by localized shrinkage
of the soil due to influence of trees Deformation mode caused by
settlement of a facade wall
Photo credit: © Ifsttar 2017 To learn more: click here
Large cracks
Large
cracks
Large
cracks
Pavement

3. The MACH solution: description
and initial investigations
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3. THE MACH SOLUTION: DESCRIPTION AND INITIAL INVESTIGATIONS
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L. IGHIL AMEUR
Principle and experimental program
Droughts and
climate change Cracking and
structural damages
Photo credit: © Ifsttar 2017
Phase II
Rainwater humidification during drought periods
Follow-up: atmosphere parameters, suction and cracks
Phase I
Initial investigations
and house monitoring
Phase III
Follow-up and
project defense
2020End of 2016 2017 2018 2019
Start of the experimentation
08/11/2016 End of the experimentation
07/11/2020
The MACH solution
MAison Confortée par Humidification
House stabilized by humidification

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3. THE MACH SOLUTION: DESCRIPTION AND INITIAL INVESTIGATIONS
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L. IGHIL AMEUR
Localisation et description de l’environnement du site
Street facade
Gable facade
Garden facade
House description and presence of the vegetation (2016)
House location and geotechnical initial investigations
Soil
identification
Location
Particle size distribution Plasticity
Sieve passing (%) Dmax
(mm)
VBS
(g/100 g of
dry soil)
Plasticity
index (%)
2µm
80 µm
2mm
Decalcified clay
Excavator
drilling 57 97 99 10 /37
SP1 (1.5 m) /98 99 55,5 39
SP2 (1 m) /98 100 56,4 /
SP2 (2 m) /89 98 10 6,0 /
Beauce
limestone SP1 (5 m) /58 84 20 1,4 /
Laboratory test results

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3. THE MACH SOLUTION: DESCRIPTION AND INITIAL INVESTIGATIONS
ASCE EMI/PMC 2021 | Virtual event21/04/2021
L. IGHIL AMEUR
Structural damage and cracking state since drought of 2015
Gable facade
Street facade
Crack 1 Crack 2 Crack 3
Garden facade

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3. THE MACH SOLUTION: DESCRIPTION AND INITIAL INVESTIGATIONS
ASCE EMI/PMC 2021 | Virtual event21/04/2021
L. IGHIL AMEUR
Inside damage and cracking state since drought of 2015
Cracks
Crack
Differential settlement
effect

4. Rainwater storage and humidification
process
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4. RAINWATER STORAGE AND HUMIDIFICATION PROCESS
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L. IGHIL AMEUR
Rainwater collection and storage system
Humidification device and monitoring

5. House monitoring summary
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5. HOUSE MONITORING SUMMARY
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L. IGHIL AMEUR
Crack monitoring system
Identification and monitoring of existing cracks on the damaged facades

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5. HOUSE MONITORING SUMMARY
ASCE EMI/PMC 2021 | Virtual event21/04/2021
L. IGHIL AMEUR

6. Main experimental results since 2017
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6. MAIN EXPERIMENTAL RESULTS SINCE 2017
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L. IGHIL AMEUR
050 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500
Time (days)
0
50
100
150
200
250
300
Suction (kPa)
-1.4
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
Opening and closing of the crack in the street facade (mm)
Jan-2017 Jan-2018
01/06 31/10
9 humidifications
2660 liters
30/06
15 humidifications
4010 liters Jan-2019
15/12 20/1022/06
9 humidifications
2700 liters Jan-2020
30/06 24/10
7 humidifications
2100 liters
Drought period
Drought period Drought period Drought period
1 2 3 4 5 6 7 8 9 10 11 12
Months
0
5
10
15
20
25
30
35
Average maximum temperature (°C)
2017
2018
2019
2020
Drought period
1 2 3 4 5 6 7 8 9 10 11 12
Months
0
20
40
60
80
100
120
Cumulated precepitation (mm)
2017
2018
2019
2020
Drought period
Temperature Precipitation
Soil suction
Crack evolution
Meteorological
parameters evolution
during these 4 last
years at the MACH site
in terms of temperature
and precipitation
Soil suction and crack
opening/closing
evolution during these
4 last years and
rainwater volume used
for humidification
during drought periods
Crack closure

7. Conclusions and perspectives
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7. CONCLUSIONS AND PERSPECTIVES
ASCE EMI/PMC 2021 | Virtual event21/04/2021
L. IGHIL AMEUR
Thanks to these results, an additional objective is to work on the identification of the relationship between the local soil suction and
the imposed climatic conditions
New investigations are now performed to extend the MACH solution to many damaged houses in several configurations
Climate change and successive extreme droughts over the past 5 years have mainly contributed to the damage of buildings
This presentation summarizes the MACH monitoring operations and the experimental results since 2017
The humidification using rainwater carried out through the MACH solution induces the drop in soil suction and stabilizes the opening
of cracks during drought periods
In this context of climate change, conventional remedial solutions are not suitable in terms of the recurrence and intensity of extreme
weather events

Thank you for your attention
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Lamine IGHIL AMEUR
Researcher in Soil Mechanics, PhD
Head of the Soil Mechanics Laboratory
Contact 👉lamine.ighil-ameur@cerema.fr
Photo credit: Ighil Ameur © Cerema 2021
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