After focusing on aggregates in this workshop turned its attention in to embankments and natural hazards Such a topic could

Jean Pierre Magnan

Description

Niveau: Supérieur, Doctorat, Bac+8
contents S p e c i a l I s s u e - M a r c h 2 0 0 9 S p e c i a l I s s u e G e o t e c h n i c a l E n g i n e e r i n g After focusing on aggregates in 2007, this workshop turned its attention in 2008 to embankments and natural hazards. Such a topic could not be of more current interest given the recent events causing damage in the south of France. Embankments and dykes represent for many regional laboratories a field of longstanding expertise, particularly the Blois Laboratory, which I would like to congratulate here for their flawless organisation of these plenary sessions and for the very insightful assessment shared concerning the unique Middle Loire context. Both the maintenance and monitoring approaches towards these facilities adhere to strict risk prevention guidelines. These annual sessions have once again provided the ideal occasion to highlight the noteworthy studies and actual projects, along with recent methodological achievements involving Ponts et Chaussées network contributions and the research leading to such innovative approaches.

• hydraulic risks


• geotechnical engineering


• infiltration monitoring


• monitoring


• saar river


• lcpc


• methods employed


• identifying higher-risk embankment


• regional laboratory

Sujets

• Aix-en-Provence
• Loire (département)
• Maillet
• Ledoux
• Maurin
• Magnan
• Design
• Labrousse
• Mathon

Informations

• Publié par: mijec
• Nombre de lectures: 34
• Langue: English

Extrait

Spotlight on
embankments at the
editorial LCPC's Plenary Session
Jean-Pierre Magnan
LCPC T echnical Director, devoted to Geotechnical
Geotechnical Engineering
Engineering
After focusing on
aggregates in 2007,
this workshop turned its
attention in 2008 to
embankments and natural
hazards. Such a topic could
not be of more current interest given the recent
events causing damage in the south of France.
Embankments and dykes represent for many
regional laboratories a field of longstanding
expertise, particularly the Blois Laboratory,
which I would like to congratulate here for their
flawless organisation of these plenary sessions
and for the very insightful assessment shared
concerning the unique Middle Loire context.
Both the maintenance and monitoring
approaches towards these facilities adhere to
strict risk prevention guidelines. These annual
sessions have once again provided the ideal
occasion to highlight the noteworthy studies
and actual projects, along with recent Middle Loire embankments: A key to protecting people and property.
methodological achievements involving Ponts
et Chaussées network contributions and the days concentrated on rockfall risks, landslide risks andThe entire geotechnical engineering
research leading to such innovative several site visits. The incidents of major floodingcommunity within the Ministry'sapproaches. regularly reported in the news stress the importance
The workshop programme also underscored scientific and technical network of this category of infrastructure, whose maintenance
the close collaboration enjoyed with gathered during the three days of remains crucial to efficiently preventing risks and
organisations like the local offices of Public
protecting facilities that in some cases date back toNovember 18 through 20, 2008 inWorks and Agriculture Ministries and the
the Middle Ages. These considerations become evenCemagref and Cetmef institutes. Moreover, Seillac (south-western France) for
more pressing in a zone like the Middle Loire, wherethe event set the stage for formal and informal the year's Plenary Session on
the State owns approximately 1,200 km ofexchanges, which are both necessary and Geotechnical Engineering topics.critical to generating a cooperative spirit and embankments. The geotechnical-related activities
advancing the state of knowledge. I would like The central topic of this session's undertaken by the Blois Regional Laboratory focus
to personally thank all participants for their heavily on these aspects, by way of performing stabilityagenda was embankments and natural
presence and ask that they mark in their assessments, providing consulting services and technicalhazards.calendars the next edition of this plenary assistance to the local Public Works authorities and
gathering, to be held in Nice from September Organised jointly by LCPC and the Regional Laboratory actors, and establishing expert evaluations within thest29 to October 1 , 2009. in Blois, the event was open to all members of the framework of a technical support group dedicated to
The topic addressed during the upcoming Public Works Ministry's Scientific and Technical network hydraulic facilities. The wide array of presentationssession's opening day will tie into a current (including LCPC, CETE, the regional laboratories, as throughout the day dealt specifically with one of fiveconcern voiced during the 2007 Grenelle well as the Setra, CETU and CERTU research units) overall themes: the perspective of a facility managerEnvironmental Roundtable: seismic risks. working in the geotechnical field. In his welcoming and the Middle Loire context, regulatory changes,
remarks, Michel Labrousse, Director of the Normandy- breakthroughs in the area of diagnostics, monitoring
Centre regional CETE Office, emphasised the massive and measurement methods, and actual field examples.
participation of the network's regional laboratories:
among the 135 attendees, 17 of these labs werecontents represented. Mr. Labrousse also acknowledged the
initiative to have opened this session to external
Regulatory environment: Embankments partners, like Cemagref and Cetmef, in addition to
to receive greater scrutiny p. 2 representatives from local administrative agencies,
including DDE (Public Works), DDAF (Agriculture),
The unique context DIREN (Environment), DRDe) and
of the Middle Loire zone p. 2 DGPR (Risk Prevention).
Diagnostic capabilities: Risk prevention and historical
Making the most of shared experiences p. 3 preservation
Embankments topped the agenda on this first day ofResearch: Improving understanding of the
the workshop programme, while the two subsequentmechanisms that compromise structures p. 4 Capturing the attention of a large audience.




9
0
0
2

g
h
c
n
ra
i
M
r
-

e
e
u
e
ss
I
n
la
i
ic
g
ep
n
SE
lac
inhcetoeG
eu
ss
I la
ic
e
pSSpecial Issue Geotechnical Engineering March 2009
■ focus
The unique
context of the
Middle Loire zone
Six hundred kilometres
of levees contain the Loire
between Nevers and
Angers, delimiting a total
of 100,000 hectares ofNicolas Monié presented the series of new regulatory measures.
floodplain.
Regulatory environment: Loire River embankments are responsible for
protecting several large cities, chief among themEmbankments to receive greater
Tours, Orleans and Blois, accounting for a
scrutiny population served of some 300,000, including
120,000 housing units, 14,000 companies andRedefining rolesThe new set of regulations regarding 72,000 jobs. Given these magnitudes, the directThese updated regulations provide a clear distinctionhydraulic structures, which took cost of a major flood occurring on the Loire hasbetween obligations incumbent upon the facilityeffect on January 1, 2008, have been estimated at 10 billion euros.manager and the set of missions assigned to water
served to strengthen embankment supply services. The embankment owner is responsible
Built in some cases during Medieval times, thefor maintaining, overseeing and verifying facility condition.monitoring activities.
majority of Middle Loire levees date back to theThese obligations include conducting in-depth technicalMr. Nicolas Monié, Deputy Head of a unit with technical
16th century. These are highly fragile systemsinspections and submitting evaluation reports, butoversight of electricity supply, large dams and hydraulic
above all assessing the structural hazards. For their that require regular monitoring. Many types offacilities*, presented the newly-adopted regulatory
part, water supply inspectors periodically supervise phenomena are capable of causing levees tomeasures. According to Mr. Monié, "the key to this
the owner's actions, in ensuring compliance withadministrative reform is to generate a sufficient level break: internal erosion, leaks due to the
regulatory obligations and verifying structural safety.of embankment supervision and maintenance in order presence of pits or roots, levee base
to avoid, to the greatest extent possible, their failure Adoption of a new structural destabilisation (resulting from depression of the
prior to overflowing and internal erosion. classification riverbed and in some areas reaching two
The recent decree has classified structures accordingUntil the present time, it had never been requested metres), or perhaps the presence of significant
to their level of hazard, given the introduction offor embankments to undergo the same type of monitoring karst formations (natural underground passagesgraduated obligations. Four structural categories haveas for dams, which often serve as a means of energy
whose appearance would be due to thethereby been defined (A, B, C and D) based onproduction. The December 11, 2007 decree officially
dissolution of rocks carbonated by circulatingembankment height and population within thestandardises regulatory requirements for both
protection zone. The timetable for conducting the groundwater containing carbonic acid), while notembankments and dams; moreover, the revised
hazard study depends on the designated classification:framework imposes that embankment owners submit overlooking the risk of overflow in the event of
2012 for class A, and 2014 for the other three. Instudies and diagnostic evaluations to the competent large-scale flooding.
addition, the new regulations foresee instituting aauthorities.
cooperative agreement among the corresponding An embankment reinforcement programme for
Beyond safety-related improvements, this modification
monitoring agencies to intervene on behalf of facility the Middle Loire was launched in 1960 and, tohas also been intended to enhance knowledge in the
managers. this day, is still far from completion. Severalarea of structural strength and stability.
*This unit is a component of the Natural and Hydraulic Risks techniques are being employed, namely:
Department within the Ministry's Risk Prevention Directorate. reinforcement by means of a grout curtain,■ testimonial consolidation of levee bases, elimination of low
points, and the installation of weirs.