Estructuras flotantes

7/28/2019 Estructuras flotantes

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CAUSEWAY PROJECT

TECHNICAL PROCEDURES

WORK PROCEDURE

FABRICATION OF CONCRETE STRUCTURES


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Document N R01-WP-CP FABRICATION OF CONCRETE STRUCTURES

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INDEX

1.- OBJECT

2.- SCOPE

3.- RELATED DOCUMENTS

4.- MANAGEMENT RESPONSABILITIES

5.- DESCRIPTION OF THE INSTALLATIONS FOR CAISSONS FABRICATION

5.1 .- Facilities and Equipments.

5.2.- Work Procedure for Fabrication of Caissons.

6.- PLACEMENT OF CAISSONS

7.- POSITIONING ON SITE THE CONCRETE CAISSONS

8.- EXECUTION CONTROL

8.1 .- Records

9.- ANNEXES


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1. OBJECT.The present document describes the different equipment required for the execution of concretefloating caissons in Coln to be sinking in Punta Rincn by means of the floating dockAlcntara Rocha, as well as the different methodologies involved.

This procedure has as objective the description and control of the work methodology used oncaisson execution and positioning in order to have a correct work execution and consequently ahigh quality product.

The floating dock Alcntara Rocha is composed ofa metallic pontoon over which four towersare installed - a structure that allows its immersion and emersion through the ballasting andde-ballasting of the tanks in which the pontoon is divided. This system allows the caisson to be

launched in order to continue the execution while the caisson is floating.

Floating Dock Alcntara Rocha

This execution method presents several advantages:

The possibility to begin the construction of a caisson before finishing the previous one. Independence from the area below the pontoon as this solution does not require the use

of spuds, which differs from other equipment used for the execution of caissons.

It is not necessary to adjust the area below the dock (dredging, gravel mark...): during thecaisson construction there is no contact between the dock and the land.

Generates less pressure in caisson-dock contact, as the final stage of the caisson slideoccurs while floating.

Requires less draught in comparison with other types of conventional docks.

The floating dock Alcntara Rocha is able to execute caissons with a length of up to 21.00mand a width of 14,75m, with no height limitation.


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2. SCOPE.

It applies to all operations necessary for the construction of the drawers with the specifiedcontractual quality requirements.

3. RELATED DOCUMENTS.

.- Drawings NOT INCLUDED

.- ITP-FC. Fabrication of Caissons

.- Contractual / Legal Documentation

.- Employers Requirements

.- Applicable legislation

.- Environmental Management Plan

.- Health and Safety Management Plan

4. MANAGEMENT RESPONSABILITIES.

Site Manager:

- Includes in the contract specifications for the procurement of necessary materials and

services necessary for the construction of this unit of work.

Quality Control Supervisor

- Documents and implements this procedure

- Oversees that perform and document the ITP under this procedure.

Supervisor/ Survey/ Quality Inspector

- Monitor the proper execution of the work and inspect and approve, where appropriate,implementing the different activities included in the corresponding ITP.

5. DESCRIPTION OF THE INSTALLATIONS FOR CAISSONS FABRICATION5.1.- Facilities and Equipments.


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In order to build the caissons, 80 linear meters of quay and an area of approx. 2,000m2 fordifferent facilities will be required.

Floating Dock Alcntara Rocha and auxiliary equipment

The facilities for the manufacture of caissons comprise the following elements:

Floating dock

Concrete Plant (local or external)

Sliding Formwork

Mobile Crane

Tower Crane

Concrete Pumps

Workshops and facilities

5.1.1.- Floating Dock

The following summarizes the main features of the dock ALCNTARA ROCHA:


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5.1.2.- Slipform

The elements that define the set of formwork system are:

1. Planking: consists of several cross modules, each of which has climbing equipmentas defined below and consist of sheet steel panels in the shape of the horizontalsection of the shaft of the box, with 1,12 meter high and attached on top of thedrawer slide system. Moreover, each of the modules has four shuttering supports for

resting on a horizontal surface or on finished drawer.2. Climbing equipment:

a. Yokes: elements connecting different parts of the formwork and transmit the

vertical force required for the sliding thereof, through the subject beams to hang theupper main structure (umbrella).

b. Climbing bars: vertical bars, which with the surface of the hearth slid support thedrawer.c. Cats climbing: hydraulic driven, centralized control house, doing the strength thatenables vertical formwork slipped supported climbing bars.


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5.1.3.- Mobile Crane

The main tasks for mobile crane are:

a. hoisting and subsequent placement in the dam ironwork grills for theassembly of the hearth,

b. moving formwork modules from the drawer to the pontoon over the hearthwith concreted.

5.1.4.- Tower Crane

Tower crane main functions are:

a. Supply of rebar during stem slide.b. Removing climbing rods once the slide and positioned posterior of the same

for the start of the new drawer.


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5.1.5.- Stationary Concrete Pump

For concrete slab and the wall are provided two stationary pumping equipments, plus areserve.

5.1.6.- Personnel, auxiliary Workshop and facilities

As personnel assigned to the construction of the concrete caissons, we can point out the

following relation (2 shifts of 12 hours each):

1. Concrete Pump: 5 carpenter-mason / shift. 5 unskilled workers / shift

2. Rebar 20 rebar fitter / shift 1 welder / shift

3. Others: 2 crane operator / shift 2 Captains 17 salilors 1 welder / shift 1 electrician / shift


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4 machine operators / shift 2 Team leader / shift 5 unskilled workers / shift

Besides all the facilities mentioned above, we can point out the following facilities and

auxiliary workshops:

Material storage area. Workshop rebar Welding Workshop Slab rebar. Booths, locker rooms and bathrooms.

5.2.- Work Procedure for Fabrication of Caissons.

Throughout this section will describe the steps and guidelines necessary for the properperformance and execution phases of reinforced concrete caissons with ALCANTARA ROCHAplatform.

The execution of this activity is made with a work team trained and specialized on thatkind of work.

The caissons will be executed in Puerto Cristobal, as follows:

1.- Execution of the bottom slab:

The reinforcement of bottom slab is prefabricated on steel near quay and moved to

dock with crane. This reinforcement is prefabricated and placed on bottom dock bysections (to avoid deformations of the shape) being after is executed the anchorage of

the several sections.

Pouring of the bottom slab is started. The concrete transport between the batchingplant and the concreting area will be executed by auto concrete truck mixer, being the

placement executed by a pump with hydraulic arm installed near quay.

2.- Caisson walls execution:


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The formwork used is slippery and constituted by wooden and metallic panels, with1,12 m high, linked to double T stringers of corner, with screwed splicing for an easydismantling.

Hydraulic jacks are used to lift formwork. Conical claws are used to climb the steel

bars by means of the hydraulic jacks, thus lifting the formwork as concretingprogresses.

The steel bars are supported on bottom caisson above this climbing the jacks

provoking formwork ascension.

The caisson walls are armed and concreted with an auto concrete truck mixer and

pump.

The caisson walls are executed, inside dock, in continuous pouring with slipperyformwork until a compatible height with its stability that will permit its floating.

When its finished the 1st phase of slippery, the floating dock is submersed and the

caisson already floating, one tug will taking out of the dock, for dock side, where itswalls will be concluded in floating.

3.- Caissons transport and positioning

After its fabrication, as above description, the caissons will be transported for thesettlement bottom, previously prepared or holding them quay anchored, floating.

The positioning will be executed with tugs and one culvert with winches, supported bytopography and controlled by divers.

After its positioning the caissons will be submerged by increase of weigh getting

through the water pumping water inside through opening valves that are placed on

caisson wall after its prefabrication.

The caisson will be set down above a bed previously regularized and leveled, being the

operations of submersion controlled by divers teams.

Follows filling operations of the caissons cells, with quarry fragments and concrete incase of frontal cells of the caissons, in order to get stability.

Caisson positioning should be monitored by divers and by the topography, in a waythat the caisson stays properly positioned.


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5.2.1.-Slab

The first step involves the preparation of the reinforcement in the concrete slab adjacent to

the dock, and executed for this purpose. To do so, will be staking out the slab reinforcementand mounting assembly.

In parallel with the preparation of the slab assembly, proceed the preparation of the

pontoon and the shuttering of the slab.

Process execution begins with the placement in the surface of the platform of a cardboard

sheet to prevent adhesion of concrete to the platform and facilitate the removal detach thedrawer before launching.

After placing armed grills drawer sill inside the formwork, proceeds the overlap between thetwo armed grills. Once formed entire grill assembly and after overseeing the Client

representative, you can start the concreting starting at one end and advanced to the opposite

extreme and not produce concrete joints.

Staking out the slab reinforcement

Placement of a cardboard sheet.

Lifting and location of the reinforcement.


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5.2.2.- Walls

Once the floor is finished and has elapsed concrete curing period, proceed to thepositioning of the sliding formwork modules.

The slipform filling is one delicate part of operation during concreting the shaft. Begins by

pouring in the bottom of the formwork rich cement slurry. Filling is performed continuously byshuttering tiers of concrete thickness of 20 cm.

Slipped system comprises a series of hydraulic jacks distributed throughout the formwork,connected to two oil pressure pumps. Hydraulic jacks are integral with the casing andtransmitted, simultaneously, the required strain to each of the corresponding rods which slide

climbs between them in order to obtain raise the formwork. The circuit is controlled from thecontrol unit this ensures that jacks are operated simultaneously and move vertically

throughout the structure.

Then is the continuous concreting of the shaft walls of the caisson, in sliding, at an averagespeed of 20cm/hour until the establish height to proceed to the launching of the drawer.

After reaching the floating height of the caisson, proceed to dip the platform to make thelaunch of it and proceed with the removal of the floating dock, continuing the pouring of

concrete of the shaft on floating caisson phase.


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When construction of caisson is completed, continues the sliding formwork undervacuum until remove completely, proceeding after that to cleaning, removing and cleaning theclimbing bars and other equipment. At this point the next slab of the caisson is already

concreted and ready to put on it the sliding formwork and thus proceed to the next caisson.

After the launching of the caisson, proceed to refloat the dock by opening the valves onthe tanks that facilitate the flow of water inside. Then proceed to clean the surface of the

pontoon and the assembly of the formwork of the floor construction in preparation for the nextcaisson.

The floating dock is fixed by quayside subject to moorings and other subject to mooringswith dead weight allowing the platform to bring the dock when required. To access staff have a

bridge between the dock and the drawer.

The pump of the concrete to caisson from the quay effected by one mobile pump and asecond backup, ensuring proper placement of the concrete, allowing proper drawer slide stem

continuously without interference or interruption, thereby avoid cold joints.


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During manufacture of the drawer will be a feedthrough tube insertion cell communicationin order to ensure communication groups independent of each other, to ensure stability andeasy control of anchoring operations. Moreover, the mark of the final tier is embedded leave

shot hook for anchoring tractels and necessary for towing and mooring the rear of the drawer.

6. PLACEMENT OF CAISSONS.

Placement of Caissons

Preliminary actions are made in order to reduce the risk of the project:

Weather proof and structural resistance to towage pull.

These particularities are fundamental for the project.

All measures are taken, during construction, in order to prevent the sea water to enter the

caisson, during each trip, due the combined effect of a small freeboard and high seas.

In what concerns the installation of the towage points, many aspects are considered:

- Type of tug boat, bollard pull, and speed during the sea passage,

- Type of the towage device, namely length and composition,

- Accordingly with the estimated final draft, the positions of the towage points are calculated inorder to guarantee that the caisson is always towed in the safest condition.

Seaworthiness and stability during voyage;

Before starting the arrangements for the voyage, special care is made in determining theseaworthiness condition, namely draft versus freeboard versus stability range.


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Depending of the type of the caisson, sometimes its necessary to introduce in the tanks,liquid or solid ballast, to achieve the voyage condition.

The final figures are presented to the insurance surveyor in order to be subject to approval,

before departure inspection.

Towage device and towage points.

The towage device and the towage points are specifically built in order to sustain thebollard pull of the tugboat combined with the effect of the sea.

Special attention is given to:

- Movement resistance

- Reynolds number,

- Friction coefficient,

- Antifouling factor,

- Wet area,

- Aerodynamic and hydrodynamic resistance,

- Expected cruise speed;- Bollard pull of the tugboat;

These are among others, the factors considered when calculating the towage points and the

towage device.

Normally for these operations the principal and the emergency towage devices are equaland constituted by:

- Four wire bridle, that are connected to four towage points

- Founder plate / shackle

- Intermediate pendant

- Tow line

7. POSITIONING ON SITE THE CONCRETE CAISSONS

The positioning on site of caissons is a well-known operation performed for more than 30

years by Somague.


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Basically everything is made by filling the different internal spaces of one caisson with seawater, after mooring it on site, in the specific position that has been previously prepared on thesea bed.

Mooring of concrete caissons.

The first action that are made before running around one caisson is placing it in correctforeseen position, this task is accomplished by different means, such as:

Tugboat / multicat,

Auxiliary crew boat,

Winches,

Anchors or concrete blocks.

After the sea bed is ready to receive the caisson, and depending of the geographical

situation of the site, the first task to be perform is to place anchors or concrete blocks inpredefined places to be used as mooring points for the lines that come from de winches

installed on the top of the caisson.

For this purpose is normally used a multicast and a small boat, as the first one tows thecaisson into positioning the small boat is used to establish mooring lines. When the positioning

is close to the shore, the bits / bollards placed on the quayside are used as mooring points.

The quantity of these mooring lines depend of the weather conditions at the moment, tide

current, wind, etc.

Ballast Plan


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Running around a concrete caisson is a task that must be evaluated with the outmost care,and for this reason long before this operation is performed, all the steps necessary to completethis activity are studied.

All begins with the stability analysis of the entire operation, to verify that the stability isgranted at all times. To achieve this goal, usually the internal spaces of the caisson are divided

in sections, and a sequence of ballast introducing is defined.

This ballast sequence guaranties that the operation is correctly performed and that noexcessive trim or heel is achieved.

In case that a caisson runs around in incorrect position, its always possible to put it afloat

by means of submersible pumps that remove the necessary quantity of water needed to floatthe caisson.

Placing in positioning (running around)

As the caisson is well secured in positioning the ballast operation takes place, this can beperformed in two ways:

Using bottom valves previously installed in side walls of the caisson close to the bottom.These are operated from the top of the caisson, and as they are open the different sections of

the internal spaces of the caisson are successively flooded.

Using pumps and hoses, positioned on deck of an auxiliary pontoon, as a way to flood thedifferent ballast sections in the correct sequence.

Once the caissons touch the sea bed, all internal spaces are flooded and the mooring linesare removed.


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8. EXECUTION CONTROL.

The execution of the work is subject to rigorous monitoring and self-control that will ensure

the high quality of the all process and the final product, according to standards established bythe contract specs.

From the beginning with the preparatory works, note that preventive measures areidentified in the Health and Safety Plan, and they are implemented, so collective and

individual protections are correctly located and it is compliance with RIPA - InternationalRegulations for Preventing Collisions at Sea- for restricted maneuverability for boats and other

craft in the area of work.

In the same way, necessary environmental licenses and specifications are assumed in theEnvironmental Management Plan.

Finally, before start working, the floor and slab design of the caisson must be checked andthe stakeout is performed, agrees with project plans and is authorized, if required, by ClientsRepresentative.

Slab

Once the works are going to start, supervisor has to assure the correct stakeout, cleaning,

sealing and floor caisson geometry of the conventional formwork. He must be sure the stakeoutis sufficient for the planned implementation. It is marked on the formwork the dimension of thefinal surface of the concrete situation when the caisson is getting the final dimension.

Furthermore, the surfaces of the formwork are clean and smooth and uniform, as sufficientlytight to prevent substantial loss of grout. The fixings and fasteners devices are placed with

effective step panels, not allowing substantial loss of grout.

Inequalities and separation of elements or tables do not exceed those specified in the

Technical Specifications.

Formwork


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In the same way for slipping formwork, supervisor must verify the correct positioning of thesheet metal of the stem of the caisson, the stiffening of joining yokes. He must approval thatstakeout is sufficient for the planned implementation and the correct functioning of sliding

(hydraulic jacks, metal bars, grips and formwork). The release agents for the formwork arecorrectly applied.

Also the form surfaces are clean and smooth and uniform. The formworks are sufficientlytight to prevent substantial loss of grout. Checking placed formwork geometry corresponds to

that shown in the drawings for element at concreting. The release agents for the formwork arecorrectly applied.

Inequalities and separation of elements or tables do not exceed those specified in the

Specifications and control the correct distribution of the concrete, so that the piping is clean,the correct operation of pumps and the cleaning of the flexible sections and correct operation of

the nibs.

Reinforcement

Although the supervisor is responsible of the correct bending, cleaning and placement of

the reinforcement of the caisson, Quality Inspector on site can review and document that thebars are clean and free of dirt, that they have been bended correctly and also according to the

figures in the steel type, number, diameter and geometry.

Quality staff will verify that the reinforcements are placed appropriately to provide and

ensure sufficient coatings although spacers are not used as could drag the fresh concretecausing the ruin of the walls. Furthermore, sufficient rigidity of reinforcement during concretingmust be ensured. Do not forget to check level location of trailer hitches.

Cleaning

Before start pouring concrete, Supervisor must verify the surfaces are clean and lightlymoist, not soggy and no puddles. The same way, the formworks are clean, no trace of binding

wire or rubbish. No necessary to impregnate the walls with release agent.

Pouring

Once Engineers representative approval is delivered, Supervisor can authorize pouring andplacement of concrete for the fabrication of the caisson.

After verify that received concrete corresponds to the requested, Supervisor and Qualityinspectors has to ensure that no more than two hours from manufacturing until work, or not

exceeding the time limit for use indicated on the delivery note. Furthermore, pouring will besuspended if the ambient temperature is above 40 C.

The download of the material will be made close to its final location trying to discharge notmore than 2m height. In the trunk, the concrete will be poured to avoid segregation of concrete,

and vigorously stirring the dough so that no air is trapped and go seating evenly.


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The Supervisor should observe that equipment for vibrating concrete works correctly andtechnical revision are conducted regularly so they can remove voids and obtain a completemass closed without producing segregation. In general, be performed by vibration, introducing

vertically in the tier, and keeping them immersed to appreciate that the slurry flows up to thesurface.

Test and checking

The control of the concrete is done by determining the consistency and resistance of twobatches per slab, and one batch per day or portion according to American Concrete Institute.

Visual check of the tightness of the large pitchers.

The estimated resistance will be greater than the required nominal strength at 28 days fck= 5000psi-.

If fest < 0.9 fck studies will be performed or new test information for final decision, according

to the Engineer and Designer analysis.

Tolerance limits for consistency established by Designer should be controlled into the

concrete plant, the value of consistency at the time of pouring is not significant to the qualityand suitability of the material, but its ability to be pumped to the caisson.

Anyway, consistency can be determined if required by Quality Inspectors when specimens

suspected abnormalities or deviation from a visual inspection.

The final control during fabrication must watch over the surfaces have no voids,honeycombs or cracking and are in good condition. Tolerances on walls should be specified likemaximum deflection as a rule about two meters long applied in any direction is lower than20mm.

Standard Operation Procedures for cracks or voids repair will be submitted along with theprocedure for application if necessary.

Curing

Curing in caisson is procured with sea water, as the element is immersed within a few

hours of manufacture. Thus, curing occurs in a saturated environment so they will generallynot cause shrinkage and cracking phenomena, even on surface.