Center Detudes Techniques Of Lequipement Of Lyon

Autun, France

Center Detudes Techniques Of Lequipement Of Lyon

Autun, France
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Kasperski J.,Center Detudes Techniques Of Lequipement Of Lyon | Delacourt C.,IUEM UBO | Allemand P.,University Claude Bernard Lyon 1 | Potherat P.,Center Detudes Techniques Of Lequipement Of Lyon | And 2 more authors.
Remote Sensing | Year: 2010

The active Séchilienne landslide (Isère, France) has been continuously monitored by tacheometry, radar and extensometry devices for 25 years. Indeed, if the 3 mil. m3 of rocks in the active zone named "Ruines" fell down, the debris would dam the Romanche valley. The breaking of the dam by overtopping and rapid erosion would bring a catastrophic flood and other dramatic consequences throughout the valley. Given the rockfall hazard in the most active zone, it is impossible to use targets in this area: Only reflectorless remote sensing techniques can provide information. A time-series of seven Terrestrial Laser Scanner (TLS) point clouds acquired between 2004 and 2007 enable us to monitor the 3D displacements of the whole scanned area, although point coverage is not homogeneous. From this sequential monitoring, the volume of registered collapses can be deduced and the landslide movement along the main geological structures can be inferred. From monitoring associated subsidence and toppling observed on TLS data, it can be deduced that blocks rearrangements are linked to structural settings and that the Séchilienne landslide is complex. To conclude, TLS point clouds enable an accurate monitoring of the evolution of the inaccessible "Ruines" area and, therefore, this device has proven its ability to provide reliable kinematic information, even in areas where on-site instrumentation is infeasible. © 2010 by the authors.


Bievre G.,Joseph Fourier University | Bievre G.,Center Detudes Techniques Of Lequipement Of Lyon | Kniess U.,Joseph Fourier University | Jongmans D.,Joseph Fourier University | And 5 more authors.
Geomorphology | Year: 2011

Paleotopography in Quaternary sedimentary environments can be an important factor that controls landslide movement. This study investigates the relation between paleotopography and landslide activity in two adjacent landslides in glaciolacustrine sediments located in the Trièves area (French western Alps). Although both are in slopes underlain by the same lacustrine deposits, the Avignonet and Harmalière landslides exhibit major differences in morphology and displacement rates. Through a combination of geological mapping, airborne light detection and ranging (LiDAR) data, aerial photographs, global positioning system (GPS), and seismic noise measurements, a three-dimensional impression was made of both landslides. The analysis reveals that the difference in kinematics between the two mass movements can be traced back to at least 50. years ago. The results show that the Harmalière slide, which failed catastrophically in 1981, is still much more active than the Avignonet landslide. The fear was that the Avignonet landslide might develop in a similar catastrophic manner, threatening a number of houses constructed on the landslide. A geophysical survey based on ambient noise measurements allowed us to map the base of the lacustrine clays, and the results indicate the presence of a N-S ridge of hard sediments (Jurassic bedrock and/or compact alluvial layers) on the eastern side of the Avignonet landslide. This ridge disappears when approaching the Harmalière landslide and makes a place to what can be interpreted as a NW-SE oriented paleovalley of the river Drac. We proposed that the ridge acts as a buttress that could mechanically prevent the Avignonet landslide from evolving as fast as the Harmalière. Furthermore, the NW-SE paleovalley located under the Harmalière landslide corresponds to the motion direction of the slide. Therefore, the different behaviour of the two landslides is partly controlled by the paleotopographic setting of Lake Trièves during the last Glacial Maximum extension. These results suggest a major influence of the bedrock paleotopography on the kinematics of the landslides. © 2010 Elsevier B.V.


Jorry S.J.,French Research Institute for Exploitation of the Sea | Bievre G.,Center Detudes Techniques Of Lequipement Of Lyon | Bievre G.,Joseph Fourier University
Sedimentology | Year: 2011

Ground-penetrating radar has not been applied widely to the recognition of ancient carbonate platform geometries. This article reports the results of an integrated study performed on an Upper Jurassic outcrop from the south-east Paris basin, where coral bioherms laterally change into prograding depositional sequences. Ground-penetrating radar profiles illustrate the different bedding planes and major erosional unconformities visible at outcrop. A ground-penetrating radar profile conducted at the base of the cliff displays a palaeotopographic surface on which the outcropping bioherms settled. The excellent penetration depths of the ground-penetrating radar (20m with a monostatic 200MHz antenna) images the carbonate platform geometries, ranging between outcrop workscale (a few metres) and seismic scale (several hundreds of metres). This study supports recent evidence of icehouse conditions and induced sea-level fluctuations controlling the Upper Jurassic carbonate production. © 2010 The Authors. Journal compilation.


Bievre G.,Joseph Fourier University | Bievre G.,Center Detudes Techniques Of Lequipement Of Lyon | Jongmans D.,Joseph Fourier University | Winiarski T.,National School of Public Civil Engineering | Zumbo V.,Center Detudes Techniques Of Lequipement Of Lyon
Hydrological Processes | Year: 2012

Rainfall and its consequences are usually considered as the major factor triggering slope instabilities within clay deposits. The link between rainfall, water infiltration and landslide activity may be complex, and comprehensive sets of data are still necessary to understand how water infiltrates in cohesive material. On unstable slopes made of fine-grained sediments, gravitational deformation generates superficial shear ruptures and tension fissures whose continuous opening could be amplified by shrinkage during dry periods. This fissure network at the surface can be very dense and strongly controls the water infiltration process. However, it remains difficult to assess the fissure evolution at depth and its eventual relationship with shallow slip surfaces. This work presents the results of a geophysical study which aimed to characterize the fissures that are observed along the unstable clay slopes of the Trièves area (French Alps). The site was first investigated combining geomorphological analysis, drilling, borehole logging, geotechnical tests and geophysical experiments. This investigation evidenced the presence of at least three rupture surfaces (at 5, 10-15 and 42 m) with a water flow at the second one. In a second step, permanent instruments were installed (piezometers and soil water content probes). Results indicate high water infiltration velocities, down to the water table located at 2·5 m depth, that are likely to be linked with sub-vertical preferential paths, such as fissures. Geophysical parameters (electrical resistivity, S-wave velocities and Rayleigh waves attenuation) were monitored. Geophysical results suggest that fissures are permanently open, that they serve as preferential infiltration paths, and that they can reach, at least, a depth of 2 m. The methods employed in this research put forward that the system of imbricated fissures drains water from the surface down to the shallow slip surfaces at 5 and 10-15 m. This work highlights the role of fissures network in water infiltration in the numerous clay landslides of the Trièves area. © 2011 John Wiley & Sons, Ltd.


Charrier S.,Center Detudes Techniques Of Lequipement Of Lyon | Ponthieux J.,Center Detudes Techniques Of Lequipement Of Lyon | Huet A.,Center Detudes Techniques Of Lequipement Of Lyon
International Journal of Ventilation | Year: 2014

Envelope airtightness is incorporated in the French Energy Performance (EP) Regulation (named "RT") and is a key factor in the reduction of energy consumption. From 2006 until 2012, the French 2005 Energy Performance Regulation (RT, 2005) did not require justification of envelope airtightness. However, constructors could get certification for airtightness through a quality management (QM) approach, in order to build better-than-regulatory buildings. Since 2012, French 2012 EP regulation (RT 2012) requires building airtightness to be justified for residential buildings, with two ways of justification. One is by the application of a certified quality management approach on envelope airtightness and the second is by direct measurement. In order to evaluate the airtightness quality management approach, the French State has created a specific national committee which aims at authorizing constructors to justify the airtightness of their buildings This paper presents the French airtightness QM approach for building envelope airtightness and analyzes the evolution of the committee processes and statistics, concurrently with the French EP regulation. The first part focuses on an assessment of the committee validation process. It also presents the evolution of the number of requests and certifications since 2006. Results show, that compared to each previous year (2006-2011), the number of RT 2012 requests in 2012, has increased by a factor of 4. Moreover, the number of RT 2012 certifications was, by September 2013, higher than the whole RT 2005 certifications delivered over 6 years. The second part presents the control processes that are implemented on certified constructors. First, this presents the self-declared airtightness values that are presented by constructors in their yearly renewal files. Then, it focuses on results of a 'control' campaign. Results show that the majority of measured dwellings meet the required airtightness level. Nevertheless, results of the control campaign show that approved constructors do not entirely implement the required quality management approach. The paper concludes with a discussion on further improvements to the process. These must meet the increasing number of requests, without losing quality and reputation. Moreover, control of certified constructors will continue in two ways i.e. yearly renewals and control campaigns, with some evolution to improve efficiency. There is now also a need to externalize this quality management approach because of the number of requests. In addition QM approaches are now expected on the airtightness of ventilation ducts.

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