P1 – Guides and recommendations
Operations of the rockfall protections are intended to secure people and property. In the absence of regulations on results to be achieved, the implementation of the operations of the rockfall protection is framed by respect “rules of art”, fruit of the experience feedback on operations already carried out.
Operations of this type grow and are carried out by masters of works very various, sometimes little experienced and in the inability to identify their needs as well as the General Organization of these operations.
So, following the approach chosen by the contracting authority and / or the driver operation, and depending on their level of expertise, the practices are very different and can lead to considerable extra costs, even in dangerous situations.
Today, it appears important to supervise the uses and to define common principles, the result of the confrontation of the experiences of the main actors who are all grouped in the national project C2ROP.
The conduct of operation recommendations should address the following points:
- Definition of a glossary
- The process of operation
- Assistance to the maîtrise d’ouvrage
- Project management
- Other benefits
- General requirements on the basis of issues and phenomena
- External constraints
- Organization and general planning of operations
- Alternative funding
- Definition and management of natural risks
- Definition of acceptable residual natural hazards
- General principles of parades
- Definition of the specific needs
- Exploitation of issues, exploitation of parades
- Information and consultation with external stakeholders
- Design of parades
- Procurement of works
- Follow-up work
- Completion of the work
- Maintenance of structures
- Inspection of books
The establishment of nets deflectors is framed by the respect “rules of art”, fruit of the return of experience on similar articles already. Following the approach chosen by the master of work and depending on his level of expertise, practices are very different and may drift towards questionable purposes see dangerous.
However, this kind of work develops as it allows to limit the random part linked to the spread of the landslide covering the whole of the area of potential and can reduce the operating cost. The operating options offered by this type of book (diverter, diverter, thru, output… Control) strengthens the value of these products to meet the various configurations encountered best.
Today, it appears important to oversee their use and to define common principles, the result of the confrontation of the experiences of the main actors who are all grouped in the national project C2²OP. Recommendations should address the following points:
- Definition of the various types of books in this category
- Definition of a glossary
- Determination of cases of employment and limits
- Principle of dimensioning of structures and their berth in various types of terrain
- Technical specification on the constituent elements and rules of implementation and control
The design of works of protection against type merlon rockfall is framed by the respect “rules of art”, fruit of the experience feedback on operations already carried out.
Today, it appears important to supervise the uses and to define common principles, the result of the confrontation of the experiences of the main actors who are all grouped in the national project C2ROP.
Recommendations should address the following points:
- Definition of a glossary
- Natural phenomena and solicitations, definition, qualification, quantification
- Definition of the expected result, limits of use
- Geological, hydrogeological, geotechnical and hydrological context
- Morphological and environmental context
- Principles of works
- Geometric design
- Structural design
- Internal stability under static and dynamic stresses
- External stability under static and dynamic stresses
- Materials, equipment and specifications
- Methods of work
- Monitoring, testing and phase controls work
- Maintenance of structures
- Inspection of books
Protection against rockfall by auscultation-type devices or instrumental monitoring is and will be used more and more. Numerous publications and scientific work has been made.
It appears necessary to refresh and synthesize operational recommendations, destined for the infrastructure managers, owners and contractors.
Production of a guide on the maintenance and rehabilitation of the former block-screens, established on the basis of feedback from the different MOa (SNCF, different CG, etc) who need to federate for the collection of information which may be confidential. The drafting will begin only after production of certain works programmed in the risk group.
Guide to the use of the MOa for the management of the maintenance of their screens block-Park. Presence of parades experts and managers of parks of works block-MOa.
P2 – Experimentation
Any modelling must be confronted with the reality to validate its robustness. It is therefore essential to perform instrumented tests so that the national project to succeed to a numerical simulation know-how that is sufficiently reliable to be used in design by companies and study of actual behavior by owners / contractors.
We propose to establish a testing program in order to address the following points:
- Influence of the type of net on the dissemination of internal stresses
- Influence of the mode of distribution of the brakes on the effectiveness of the work
- Influence of geometry on the residual heights
In addition, owners and contractors arise legitimate questions about the behavior of the stone-guard screens in real job configurations that go far beyond the stereotypical and very reductive of ETAG test protocol conditions. Similarly, in a context of ageing of Park screens french, infrastructure managers wonder about evolution in time of the effectiveness of their works with the consequences on rehabilitation resulting. In this context, tests in real size with offset impact tests on former work will be conducted Montagnole station.
Expected results
Design support: influence of technology options
Helps the recommendation: behaviour off fields ETAG
Experiments on the deflectors works are very rare. It is even more damaging these yet routine works are designed empirically. The absence of quantified data leads to designs that change at the discretion of diseases encountered without that there is logic optimization.
In the context of drafting of a recommendation on the subject, it is essential to instrument types works to determine the sustained internal constraints, but also the influence of this work on the rockslide channeled and then diverted into another work of interception located downstream.
Expected results
- Understanding the mechanisms of functioning
- Assistance in the design of structures
- Helps the recommendation of books
This action has for objectives:
- to enable the use of earthworks double (low footprint) stiffened siding to high-energy impacts.
- optimize repair techniques after event
- identify techniques for improvement of nominal capacity of an existing structure
Expected results
- Better understanding of the response of different types of siding of earthworks, notably in terms of deformation, effort, energy dissipation.
- Provision of data calibration and validation of numerical models (this context-specific data)
- Optimization of energy dissipation of merlons siding capacity
1. Tests on the behaviour of cables used as weak ground anchors
This program will be launched after the results of the research program on the anchorages by bars B500 and S670 (see corresponding). The work programme offers tensile bending tests and accelerated corrosion tests in order to highlight modes of corrosion and the effects of oxidation on the sustainability of the cables used as anchors in soft ground.
Expected results: validation or invalidation of the use of cables for the mooring of barrier blocks (or snow sheds) works in soft ground.
2. Comparative testing full-scale on anchorages S670 and B500 working bending
First expertise showed failure of the S670 anchors when they are used for mooring of works in soft ground by virtue of the bending of steel and the absence of protection against corrosion. The work programme offers complete expertise of steels S670 and carry out comparative tests with bars B500. Different laminated bars will be subjected to corrosion accelerated and analyzed in order to highlight modes of corrosion and the effects of oxidation on the sustainability of different shades.
Results can be scaled up bars used for reinforcement at Rock anchors.
Expected results: specific validation or invalidation of the use of steel grades, for mooring of books barrier blocks in soft ground and the confortements at the rock.
3. Tests of dynamic pressure on the Rock anchors
Objective: measure of solicitation of an anchorage sealed at the rock subjected to dynamic loading to optimize sizing. The tests will be performed in a test station arranged for the release of rock masses who seek the anchor in pure tension. Anchors will be equipped with force-strain sensors distributed along their length to investigate solicitation of steel at the time of the dynamic load.
In parallel, study of the behavior of anchor head at the level of the anchor of the work and the contact plate distribution / anchor. Dynamic load testing non-axial will also be conducted for this purpose. The durability of a solicited anchoring aspect will be discussed also in the programme of behavioural study of S670 and B500 (see corresponding) steels.
Expected results: the anchors subjected to dynamic load optimization. Adaptation / optimization methods of binding book / anchor to improve sustainability.
4. Validation of the protective by galvanizing on anchors subjected to bending
Following the expert assessment carried out on the failure of anchorages S670 for anchors in soft ground, conducting tests on galvanized anchor bars to quantify the contribution of galvanizing for protection of bars plasticized. If necessary, similar tests will be conducted in parallel on bars B500.
Expected results: validation or invalidation of the use of rods galvanized for mooring of books barrier blocks in soft ground. Extrapolating the functioning and durability of the reinforcement at rock anchorages.
Objective
The objective of this action is to evaluate the effectiveness and sustainability of different types of protection works type biological engineering (works wood, nets anchored on trees…) using tests of laboratory, field and modelling.
This type of works can be an alternative or a complement to the ‘classics’ of civil engineering structures and are little expensive, especially in the context of temporary protection (emergency situations, protection of work…).
Expected results
- Synthesis of the results of research: descriptive report of the effectiveness of different types of biological engineering according to their terms of use.
- Recommendations or guide to sizing of implementation and design of biological engineering.
P3 – modeling
Book of judgment (form ETAG)
The modelling of the behaviour of structures under solicitation dynamic appears as an essential tool for the development of future screens. It is ambitious to consider the development of a robust predictive tool both these works in very large deformation behavior is difficult to grasp. But the use of modelling to perform a parametric analysis of the different phenomena involved would be helpful to guide enterprises in their technological choices and to focus the developments of the constituent materials.
Book diverters/deflectors
In the context of the recommendation provided for flexible control of propagation (diverters and deflectors) works, it is important to study the effectiveness of the various existing principles and to quantify the energy change during the passage of the boulders in the book. Taking into account the costs of experimentation on these large-scale works, their modeling is essential to study the behaviors.
This work must respond to the following questions:
- What is the influence of the device on the spread of the landslide (dissipation of energy, distribution between translation and rotation, trajectory of output… energy)?
- What is the influence of the terrain on the functioning of the work (nature, irregularity, incline, vegetation cover…)?
- What is the solicitation of the constituents of the work during its operation (mooring, rigging, post NET, control output…)?
The work will be structured in 3 parts:
1. Advanced and improved tools and methods of dimensioning of the merlons.
Points of improvement will need to take into account the mechanics of the various phases of behaviour of the components of the siding, integrate into the modelling of phenomena not supported currently relating to enhanced account domestic, implement a probabilistic approach to the sizing of the earthworks in connection with trajectographiques simulations.
2. Benchmark: comparison of modelling with the results of tests carried out under action 2.4 theme Parades and previous trials (Rempare).
3. Packing of models and research of convergence.
Expected results
- Better understanding of the response of different types of siding of earthworks, notably in terms of deformation, effort, energy dissipation, so optimization of structures.
- Calibration and validation of numerical models.
Objective
The objective of this action is to evaluate the effectiveness and sustainability of different types of protection works type biological engineering (works wood, nets anchored on trees…) using tests of laboratory, field and modelling.
This type of works can be an alternative or a complement to the ‘classics’ of civil engineering structures and are little expensive, especially in the context of temporary protection (emergency situations, protection of work…).
Expected results
- Synthesis of the results of research: descriptive report of the effectiveness of different types of biological engineering according to their terms of use.
- Recommendations or guide to sizing of implementation and design of biological engineering.
P4 – new concept
Events affecting infrastructure with important strategic issues, and in order to restore a partial traffic within a very short time or to allow teams to work in acceptable security conditions, it is often temporary works of all kinds.
Interventions and reinstatements of circulations were then operated in degraded security conditions which are often very uncertain.
Currently, these situations are managed in the emergency, both for the phases of engineering for the phases of production, generating uncertain, little optimized, and even dangerous situations for the users or stakeholders.
It is appropriate to provide a ready-made tool and can be pre-positioned, allowing a partial re-circulation in very short periods of time, on the other hand these devices could be used as interim protection when carrying out work under conditions of enhanced security for users.
