How to place ACCROPODE ™ II or X-bloc ®

Placement of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks

 

1 The placing drawings

Placement drawings are established by CLI for ACCROPODE ™, ACCROPODE ™ II, CORELOC ™ and ECODPODE ™ blocks and by DMC for Xbloc®.

Placement drawing for CORELOC ™

 

Companies and project managers can establish them themselves as soon as they know the vertical and horizontal distances that must be respected between the centers of gravity of the blocks. This is true for all ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks.

This requires a designer who masters the Autocad® software and this has the advantage of saving time compared to the usual production times which can sometimes be long.

The placement plan is generally established theoretically, using standard sections and plans of the structure to be built.

It is sometimes established by using a multibeam sonar survey in order to correspond as closely as possible to reality. From experience we have found that this does not have any advantages over the theoretical plans, because generally the slopes if they were built long time before the installation of the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc blocks ® are removed by the swell and must be reconstructed or repaired just before installing ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or Xbloc®.

There are also differences between the multibeam survey and reality due in particular to the tolerances applied and the possible smoothing of the results.

The placing drawing is not the tool to know where to place the blocks. It may come as a surprise, but it is a fact. In the past, CLI TID did not specify this. This is due to the fact that for a long time, engineers believed that the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks interlocked naturally and definitively as soon as the theoretical position was respected. In reality it does not work. This error comes from the fact that the engineers who established these rules do not actually install ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks on real projects underwater, they work in the laboratory, with small, waterless models.

Construction of a 2D model for ACCROPODE ™ II: the blocks are placed without water

IDMer and then CLAS have understood long time ago the differences between the installation of waterless models and the actual installation of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks in water. Reason why there are no works built with the assistance of IDMer or CLAS which knew damage. This reality finally forced CLI to add a new paragraph 6-5-3 in its TID which says:

This new article introduced late in the CLI TID confirms that finally, above the first line of ACCROPODE ™ II, the placing drawing is not so important, whether it is based on a plan established by multibeam or on a theoretical level, because it is the interlocking that counts, without tolerance in relation to the placing drawing.

 

2 The underlayer

The underlay is a key point that will determine whether the placement of the blocks is easy or whether it will be long and difficult.

The underlayer must be built with tolerances which, if they are not respected, will make the placement more difficult and may jeopardize the stability of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks.

The construction of the underlayer requires operator know-how that not all companies have. It is also very common for the riprap available in quarries to be of the wrong size, or to be too fragile or too far away and very expensive. The underlayer is the most difficult part to achieve and yet it is the key point which will determine if the company will gain or lose money, because a non compliant underlayer makes the installation of ACCROPODE ™ blocks. , ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® very difficult, sometimes impossible or unstable.

Inspection of the underlayer just before placing ACCROPODE ™ II blocks

To provide a simple and effective solution to this problem, the CLAS company has developed an artificial underlayer, placed by connected block panels, which perfectly reproduces the hardness of the concrete sought, the roughness of the surface and the longevity of the materials.

Example of concrete panels for artificial underlayer

This artificial underlayer is automatically within the tolerances required for the underlayer, does not require new tests because it reproduces the natural underlayer identically with the advantage of controlling production on site and apply easily and faster than a natural underlayer.

Artificial underlayer link.

 

The approval of the underlayer is generally made on the control of profiles every 5 meters or every 10 meters.

However, the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks are placed over the entire surface of the slope. This is why it is recommended to check the entire installation surface. Companies are doing it with multibeam sonar.

From experience, we have found on all sites that it is essential to control the underlayer just before installing the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks because often the slope has been approved. several days or even several weeks, before installing the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks. There are differences between the approved slope and the slope modified by falling rocks or swell, after sampling or multibeam sonar checks. Finally, multibeam sonar is generally not effective near the surface, due to air bubbles and sea foam which cause interference and make multibeam sonar ineffective in this very sensitive area of ​​the structure. Finally, the multibeam sonar will give a state of the laying surface, not the nature of the riprap used, which can sometimes hold surprises:

Underlayer approved with multibeam sonar yet built with materials intended for the core of the dike. Incompatible with ACCROPODE ™ II placement

A systematic inspection of the entire placement surface is compulsory, rapid, it eliminates the last localized problems which could cause ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks placed out of profile or poorly iterlocked and susceptible to move and break.

The CLAS inspector removes a stone before placing CORELOC ™

 

3 Placement rules

CLI and DMC have established placement rules and recommendations in their TID which are sometimes difficult to understand and can be interpreted differently depending on the person. It should be understood that these TID are a guide and are not a golden rule. The principle that prevails and that these guides try to highlight is the good interlocking of the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc® blocks which must not be able to move, otherwise they may break or be extracted by swell.

 

4 The importance of interlocking ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and Xbloc®

 

In all the technical references it can be read that the correct interlocking of the blocks, ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc®, is very important, it even has priority over the theoretical position defined by the placing drawing.

We will explain why from our point of view, this criterion is the most important of all to guarantee the stability and durability of your armour protection.

What is the interlocking of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks?

An ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® block must be placed between two other blocks, whose position on the first line is defined with the greatest possible precision.

 

Example with the ACCROPODE ™ II block

 

H is the size of the block

The precision for placing the first line is H / 12

The first line guides the installation of all the other blocks. A block must come between two already placed:

 

This is the reason why construction always starts with a triangle.

 

Starting triangle with CORELOC ™ on the training slope

In theory, the correct interlocking is acquired when it is impossible to take out a block without first moving those placed on it.

We know from experience that this is not enough. Avoid preserving contact faults between the blocks during construction and make sure that the block cannot go down further after installation. We know that the weight of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and X-bloc® blocks will cause adjustments, small natural movements over time. If the placement has not left any contact faults and if visually the block does not seem to be able to go down any more, these movements will be light and without incidence. If the builder has neglected the interlocking and the block can still go down after placement, these movements will cause holes, extraction of blocks, breakages and ultimately a risk for the armour protection and the breakwater.

 

ACCROPODE ™ II correctly interlocked

X-bloc® correctly interlocked

 

From experience and after having assessed, installed and repaired over a million ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and X-bloc® blocks, we know and teach that the placement density is always good or too high when the interlocking is good. In our opinion, a placing density that drops locally below 100% is not desirable. On the other hand, the placemen must be visually homogeneous. One can have a correct placing density with a zone of strong interlcing and a zone of weak interocng in the surface used for the calculation. In this case, the weak interlocking area will not be solid and will cause visible damage by settlements and breakages. The placing density is therefore not a criterion which guarantees the solidity of the construction.

CORELOC ™ perfectly interlocked but too high density due to similar installation

ACCROPODE ™ broken due to movement underwater with correct density but poor interlocking

 

Consequences after a few years of an unrepaired interlocking fault on ACCROPODE ™

Contact faults always exist after placement of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and X-bloc®, even when we avoid leaving them. But when they are rare, it has no consequence. This is why during construction CLAS inspectors report and have contact faults repaired. So the problem remains too marginal after construction to cause disorders.

The strength of the shell and its durability strongly depend on the quality of the interlocking. CLAS used and tested all inspection and construction assistance tools available on the market including ECHOSCOPE®, POSIBLOC ™ and the DIDSON and ARIS acoustic cameras. Until now, only a specially trained human can avoid the accumulation of contact faults detrimental to an ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and X-bloc® construction.

 

The position of the first row is very important because it guides the placement of the following rows. An ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® block must be placed between two blocks of the lower row, without really taking into account the theoretical position indicated on the placing drawings, taking care to retract enough so that it does not go down further after installation and making sure to prepare a hole open enough above to facilitate the interlocking of the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and X-bloc blocks ® higher rank later. It is the work of specialists.

 

5 The placing tools

5-1 ECHOSCOPE®

The ECHOSCOPE is an acoustic tool developed by CODA OCTOPUS, of the sonar type which gives a real-time image of the installation area. The image produced makes it possible to see the position of the blocks placed and to determine the position of the block which must come to interrlock therein.

Once the block is placed, the image is no longer clear enough to determine whether the block is well interlocked or not, whether it is broken or not and whether it touches the underlayer or not. It is therefore necessary to associate a control by diver with the ECHOSCOPE®. When you can't use divers to control, you have to accept the risk of having badly interlocked blocks. This is what happened on the DAS ISLAND project where the company that installed and validated the installation on the basis of the ECHOSCOPE® images was confronted with settlement and breakage of X-bloc® and had to rebuild 5,500 meters of Xbloc® armour.

Another boundary of the ECHOSCOPE® is the area near the surface. Because of the air bubbles and the foam produced by the sea in contact with the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks, the image is not good and no longer allows to work.

Using the ECHOSCOPE to check the interlocking of X-bloc ® does not allow you to be sure of the result

 

We have used the ECHOSCOPE® successfully on several projects by associating it with divers. When visibility becomes reduced, the ECHOSCOPE® saves time and therefore money, compared to using divers alone and above all increases the safety of operations underwater. Divers are no longer used only to check the interlocking of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks, and to make any repairs if blocks are badly interlocked, broken or out of profile.

When you know the limits of the ECHOSCOPE® and know how to use it, combined with control by diver, it increases production and improves safety.

Average production underwater, including dismantling of possible non-conformities, is 6 to 8 ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks per hour.

 

5-2 POSIBLOC ™

The POSIBLOC® is a tool based on measurement, developed by SOGREAH which has become ARTELIA and marketed by its subsidiary CLI. Being based on the principle of measurement and compliance with the placing drtawings, its operating principle contradicts the principle of interlocking which takes precedence over the theoretical position. There is another limit which is related to precision. Differences between screen representation and reality may appear from the second line of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks, but more frequently from the third line and above. The main cause of these problems comes from the fact that the POSIBLOC® system considers that an ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® block is well placed when the target is reached, when in reality an ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-block is well placed when it is well interlocked and has no freedom of movement. The POSIBLOC® system does not allow to see if a block is broken during installation, it does not always identify the blocks out of the profiles, it does not identify the holes, it does not identify all the interlocking problems and does not allow to identify with certainty if a block is in contact with the underlay or not because it is a theoretical plan or a survey sometimes old which entered the system, this is is not a picture of reality at the time of the placement.

The POSIBLOC ™ screen image shows a CORELOC ™ that appears to float above others, which is impossible

This is the reason why CLI, which markets it, prohibits in its TID from validating the placement of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™ and ECOPODE ™ based on the information produced by POSIBLOC®.

Comment contained in the CLI TID for the installation of CORELOC ™ and ACCROPODE ™ II:

Average production underwater, before dismantling any non-conformities, is 3 to 4 ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks per hour.

 

5-3 Divers

Divers are the traditional tool for placing, checking or repairing ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® armours. The use of divers is associated with increasingly heavy and restrictive regulations. On the other hand, there is no specific training in the handling of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks, except at CLAS, which only trains company divers within the framework installation assistance contracts entrusted to us. CLI and DMC which market the licenses ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ and X-bloc® are not companies of maritime works or diving and do not have skills in matters of security. Only CLAS today provides inspectors who are trained in pedagogy and are trained in handling ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks.

 

Properly trained divers can safely place ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks with production unmatched by other setting tools. This training is done in several stages:

1 Theoretical and security training

Inspector CLAS provides theoretical training to divers responsible for placing ACCROPODE ™ II in Romania

 

2 Practical training and safety above water

Inspector CLAS provides practical training out of water to divers responsible for placing X-bloc ® in Costa Rica

3 Practical training and safety in water

Inspector CLAS provides practical training in water to divers responsible for installing CORELOC ™ in Kuwait

Average production underwater, including dismantling of possible non-conformities, is 10 to 12 ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks per hour.

Divers cannot be used when visibility is zero or the swell is too strong.

In this case it is the use of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks that is questioned because it will not be possible to be sure that they are interlocked and well placed and in case of disorders requiring repairs, it will be impossible to achieve them with quality and precision. This is a problem that the designers do not address because in the laboratory it is always possible to build a model.

CLAS trains and evaluates divers in terms of safety, quality of installation and production capacity and issues a training certificate with an assessment of the capacities of each diver in these three areas.

 

6 Placement control

6-1 Divers

Divers can control the underlay and interlocking of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks as long as visibility and swell allow. This inspection can be implemented quickly and does not penalize the progress of the work. A CLAS inspector can dive several times a day because the structures using the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks are generally shallow.

Inspector CLAS controls a CORELOC™ placement

The inspection when it detects a non-conformity gives rise to a report supplemented by photos and videos. Usually the video is shown immediately after the inspection dive, to explain the non-compliance to the installation team. This procedure has several advantages:

1 The non-compliance is not questionable when it is shown on video.

2 The non-compliance is understood by the installation team and this contributes to its training.

3 There is no accumulation of non-conformities which would require the dismantling of a large quantity of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks because the frequency of controls avoided this problem.

 

Inspector CLAS explains a non-conformity to the ACCROPODE ™ II installation team immediately after leaving the water. There is no loss of time and only the non-conforming block must be replaced without any other disassembly

Divers are in our opinion the only reliable means and do not penalize the progress of the project.

 

6-2 Sonar

Sonar is the method recommended by CLI in particular or by companies wishing to use the ECHOSCOPE to install and to control and approve the installation. An acoustic tool is not used to control a single block or a single line of blocks. Sonar is used after several lines have been placed. If a non-conformity is detected, it will then be necessary to dismantle several blocks or several tens of blocks to repair the area, with the risk of reproducing another non-conformity which will only be detected after the new passage of the sonar. In addition the sonar does not give an immediate result, it takes several hours for the processing and analysis of the images. We have found that the sonar used as a means of finding non-conformities on ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® armours is a delay factor in the progress of the project. On the other hand the sonar does not detect all the non-conformities and above all does not correctly detect the interlocking faults. It does not correctly detect the holes and not always the out of profiles. Near the surface the sonar cannot be used because of air bubbles and foam caused by contact between the sea and the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks . The use of acoustic tools to control and approve the laying of the blocks was the main cause of the settlements and the breakages observed on the DAS ISLAND project among others.

Example of picture produced by a multibeam on ACCROPODE™II. Its impossible to check if the inerlocking is good.

Sonar and acoustic tools in general are, in our opinion, well suited to controlling the outer armour of the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® breakwaters, but because of the complexity of the shapes of these blocks, the acoustic beams are reflected and give inadequate responses. The technology evolves but it is necessary all the time to calibrate and validate the inspection tool, by comparing the result it produces with reality, before validating its use as an approval tool.

 

Whatever installation tools you choose, CLAS can provide training in the installation of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc ® blocks, optimize production, carry out inspections and deliver certificates of compliance.

 

7 The classification of armour breakwaters according to the care taken in construction

CLAS HAS ESTABLISHED A A CLASSIFICATION

With our experience in both expertise on old works and in full-time site monitoring, we have been the privileged witnesses of destruction movements that the quality of installation allows or does not allow depending on whether it has been more or less rigorous. We include in our analysis the risks linked to breakage of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks, which is never taken into account in studies on a 3D model because on models the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks never break, contrary to reality.

We have established three levels of quality defined by classes A, B and C. This classification stems from the experience of 20 years, exclusive to CLAS inspectors and its use without the affixing of the trademark CLAS TECHNOLOGY COMPLIANT ™ exposes the client at an incorrectly assessed risk. As the inventor of this classification, CLAS recommends that companies and clients not to accept copies or counterfeits produced by third parties, of the classification principle that we deliver in association with the registered trademark CLAS TECHNOLOGY COMPLIANT ™ :

Class A

ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® armours with a lifespan that meets design objectives or more. These are the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® works presenting zero risk, built within the framework of the certification that we apply either at the request of Concrete Layer Innovation or Delta Marine Consultants in as part of an additional guarantee granted to the construction, either at the request of the Contracting Authority or the contractor.

This requires complete monitoring of the construction of the underlayer and the toe mount, by a diving inspector accredited by CLAS and complete monitoring of the placement of the ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc®.

ACCROPODE™ CLASS A breakwater Dung Quat Vietnam

As part of a more complete inspection procedure, CLASS A can be extended to the entire construction of the structure and includes the control of compliance with the design.

 

 

Class B

Carapace whose durability cannot be guaranteed due to an unknown part of the quality of construction or the presence of non-conformities identified on ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X shells -bloc® and which have not been rectified.

This also concerns the approval given on the basis of surveys provided by the contractor, the use of POSIBLOC ™ and ECHOSCOPE® placing tools and validation with multibeams without CLAS accredited diving inspectors to assess the reality underwater.

 

ACCROPODE™ armour with major disorders and premature obsolescence.

 

Class C

ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® armours of which the durability cannot be guaranteed because serious non-conformities have been identified in the implementation of ACCROPODE ™, ACCROPODE ™ II blocks , CORELOC ™, ECOPODE ™ or X-bloc®.

This also concerns the approval given on the basis of surveys which do not correspond to reality and a monitoring of the installation of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks without diving inspectors by accredited CLAS.

X-bloc® completely out of profile not detected by installation and inspection tools.

CLASS C corresponds to works which are known to be poorly constructed and will suffer damage.

ACCROPODE ™ II placed on very fine materials. Non-compliance with design and non-compliance with TID.

 

8 Possible production

The productions that a contractor can achieve in the implementation of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks depend on the means implemented and on the conditions of work and on-site inspection.

 

The following table gives the productions observed on several projects, for an approved installation of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks.

 

Approved average production in water with visibility

Tools

Wire crane

Excavator

Divers

6

12

POSIBLOC™

3

3

ECHOSCOPE®

4

6

ECHOSCOPE®

+

Divers

6

8

 

Approved average production in water with poor visibility

Tools

Wire crane

Excavator

Divers

4

6

POSIBLOC™

3

3

ECHOSCOPE®

4

6

ECHOSCOPE®

+

Divers

6

8

 

If the good nesting and the good respect of the design cannot be formally confirmed by diving inspectors during the implementation of ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks, we have solutions to force nesting and improve the stability and sustainability of the structures. These inspectors must be properly trained by dyke construction professionals using ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks, who know how to teach specific safety rules and technical rules for inspection of these blocks.These inspectors must be properly trained by professionals in construction using ACCROPODE ™, ACCROPODE ™ II, CORELOC ™, ECOPODE ™ or X-bloc® blocks, who know how to teach specific safety rules and technical rules for inspection of these blocks.

 

 

Trained diver places ACCROPODE™II communicating directely with the crane operator to rotate the ACCROPODE™II without touching it, the dive ris always in a safe position 

 

 

 

 

 

 

 

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