METHOD AND INSTALLATION FOR POURING CONCRETE UNDER WATER

Abstract: A method for pouring a fluid, settable mass, such as concrete, on the bed (4) of a body of water, comprises the steps of introducing the mass (7) onto the bed (4) by means of a delivery pipe (3) in such a way that the bottom end (8) of the delivery pipe (3) penetrates into the poured mass (7), and smoothing off the poured mass (7) at a level higher than the bottom end (8) of the delivery pipe. The poured mass (7) is smoothed off by means of a smoothing element (12) brought into vibration.

Description: Method and installation for pouring concrete under water The invention relates to pouring a fluid, settable mass under a water surface, in particular to pouring underwater concrete. With a pouring process of this type various phenomena occur which do not arise or arise to a lesser extent when pouring above water. First of all, there is a risk that demixing of the concrete occurs at the location of the contact surface with the water. As a result problems can arise with regard to the durability of the concrete. Moreover, it is not simple to make the poured layer of concrete sufficiently flat. As a consequence of this, a separate finishing screed also has to be applied later. NL-A 8 200 533 discloses an installation for pouring underwater concrete, wherein a floating body is used which floats on the freshly poured layer of concrete. The delivery pipe has a float which is pushed up through the freshly poured concrete, as a result of which the thickness increases. The disadvantage of this known installation is that the layers of concrete produced therewith are of poorer quality. Consequently a finishing screed is necessary in order to be able to comply with the requisite flatness for the floor of the subsequent facility and in order to prevent water leakages as a consequence of groundwater forced upwards through channels present. NL-A 9 301 089 discloses an installation for pouring underwater concrete, wherein the delivery pipe has a foot which rests on the bed of the body of water. The concrete floor poured using this installation therefore has to follow the contours of the bed. Said installation is therefore less suitable for the production of a flat concrete floor. The aim of the invention is, therefore, to provide a method which does not have these disadvantages and with which a high quality, flat concrete floor can be poured. Said aim is achieved by means of a method for pouring a fluid, settable mass, such as concrete, on the bed of a body of water, comprising the steps of introducing the mass onto the bed by means of a delivery pipe in such a way that the bottom end of the delivery pipe penetrates into the poured mass, and smoothing off the poured mass at a level higher than the bottom end of the delivery pipe. With the method according to the invention no demixing of the concrete can occur because the concrete mass issuing from the bottom end of the delivery pipe is always protected from the water by the previously poured concrete, which is at a higher level. Only the surface of the concrete at the higher level is in contact with the water, where, however, hardly any more demixing takes place. This means that the various components, such as gravel or aggregate, sand, cement, additives, plasticisers and the like, hardly demix, as a result of which the quality of the concrete is assured. Smoothing off the freshly poured concrete has a beneficial effect on the quality of the final finished concrete floor. A further advantage of this is that the floor can remain relatively thin, so that a cost advantage is obtained with respect to the material used. With such good concrete quality it is also possible to make use of reinforcement. This is because the latter is encapsulated so well in such concrete that it is well protected against corrosion. For this reason as well it is then superfluous to apply a finishing screed. As a consequence of the reinforcement, the thickness of the concrete layer can be even further reduced. Finally, with a relatively thin concrete layer the depth of the excavation in the bed of the body of water can remain restricted, which likewise results in a cost advantage. Preferably, the poured mass is smoothed off by means of a smoothing element brought into vibration. In particular, the smoothing element can be brought into vertical vibration at a frequency of between 5 Hz and 40 Hz. For the horizontal vibrations of the smoothing element, the preference is for horizontally oriented vibrations which have a frequency which is between 0.1 Hz and 3 Hz, the amplitude of the vibration being between 2 and 200 millimetre. As a consequence of the vibrations transmitted to the freshly poured concrete mass, the quality of the concrete layer can be even further improved. The delivery pipe and the smoothing element can be moved over the bed of the body of water during pouring. As a result, work can be carried out in a continually progressive manner. Various measurements can be carried out in order to obtain the required height location of a floor to be produced. For the horizontal position of the delivery pipe use can be made of the known Global Positioning System, GPS, or preferably the Differential Global Positioning System, DGPS. For the vertical position one or more reference points on the delivery pipe are measured, for example above water, by means of which the height and slope of the delivery pipe and thus the position of the bottom of the delivery pipe are known. For correction of the height position of the bottom of the delivery pipe, for example, the height of the poured mass around the delivery pipe is measured with the aid of sonar. The height of the fluid, settable mass in the delivery pipe and the flow rate of the mass in the delivery pipe can also be measured. It is also possible to determine other properties of the mass to be poured, such as temperature and fiowability. All these measurements can be fed to a processing unit, such as a computer with the software and hardware required for the application. With the aid of the processing unit it is possible to place the bottom of the delivery pipe in the correct position, for which purpose a lifting unit can be activated. Using the said processing unit it is also possible to correct the distance between the bottom of the delivery pipe and the bottom of the smoothing element with the aid of a lifting unit. The vibration pattern of the smoothing element can also be adjusted to ensure that the finish and the quality of the floor to be produced meet the specified requirements as well as possible. To enable the feed of the settable mass to be poured to be controlled under water it is possible to fit a shut-off element in the form of a flexible valve in the delivery pipe at the bottom, as is shown in the patents NL-A 7 803 176 and FR-A 2 125 916. The invention also relates to an installation for carrying out the method, comprising a floating body having a delivery pipe which, at the top end of which, has a feed for a fluid, settable mass, such as concrete, and a bottom end for discharging the mass onto a bed of a body of water, as well as a smoothing element for smoothing off the poured mass, which smoothing element has a downward-facing smoothing surface which is at a higher level than the bottom end of the delivery pipe. The smoothing element can be annular or torus-shaped and surrounds the delivery pipe some distance above its bottom end. Preferably, at least part of the bottom surface of the smoothing element slopes upwards from the delivery pipe. Even if the delivery pipe, and thus the smoothing element, are at somewhat of an angle, the smoothing element is still able to produce a level surface without "biting" into the concrete mass. The smoothing element is connected to means for generating vibrations. It can comprise at least one watertight chamber in which the means for generating vibrations are located. Preferably, the smoothing element has two concentric cylindrical walls at the bottom of which a baseplate is fixed, part of which slopes upwards from the delivery pipe. The smoothing element can also be rotatable about the delivery pipe. In another embodiment, the smoothing element can be connected by lifting means to a lifting unit which can differ from that for the delivery pipe, by means of which unit the distance between the bottom of the delivery pipe and the base of the smoothing element can be changed. The said distance can be adjusted on the basis of measurements of material characteristics, the pressure, flow rate out of the delivery pipe, flow, temperature of the settable mass and height of the top of the poured mass and/or smoothed-off mass around the delivery pipe. Said adjustment can take place automatically if the measurements are fed to a processing unit equipped for this purpose, such as a computer, which processes the measurements and activates the various control elements to move delivery pipe and/or smoothing element. The invention will be explained in more detail below with reference to an example of an installation for carrying out the method according to the invention which is shown in the figures. Figure 1 shows a side view of the installation, in operation during pouring a floor on the bed of a body of water. Figure 2 shows a top view of the smoothing element. Figure 3 shows an enlarged side view of the smoothing element. The installation shown in Figure 1 for carrying out the method according to the invention firstly comprises a floating body, such as a pontoon 1 , from which a delivery pipe 3 is suspended by means of supporting construction 2. The delivery pipe 3 extends downwards in the direction of the bed 4 of the body of water; the water level is indicated by 5. In the position shown in Figure 1 , the installation is close to a sheet pile wall 6 which has been driven into the bed 4 and against which a freshly poured concrete mass 7 has just been applied. At the start of work the delivery pipe 3 is placed with its bottom end virtually on the bed 4 of the body of water, as is shown by the position 8 indicated by broken lines. The delivery pipe 3 is then pulled higher and higher during pouring, in which context, however, care must be taken that the bottom end 9 of the delivery pipe 3 is always below the level 10 of the freshly poured concrete. In the position shown in Figure 1 the level 10 also indicates the nominal level of the floor to be produced on the bed 4 of the body of water, only an initial small portion of which has been poured in Figure 1. Anchors or piles 11 can also have been driven into the bed 4 of the body of water in order to hold the subsequent finished floor in place against the water pressure of the groundwater. A smoothing element 12, which will be described in more detail with reference to Figures 2 and 3, is located slightly above the bottom end 9 of the delivery pipe 3. As work progresses, the pontoon 1 will be towed along such that the delivery pipe 3 with the smoothing element 12 is continually moved over the bed 4 of the body of water in order to lay a track of concrete. The pontoon 1 is then brought back to its original position and shifted a little to the side, after which the next track can be laid, and so on until the floor is complete. In order to keep the height of the top of the freshly poured concrete floor constant, one or more reference points on the top of the delivery pipe above water are continually measured with respect to a reference surface on the shore with the aid of, for example, a laser spirit level. Depending on the slope of the delivery pipe 3, and taking account of a possibly sloping surface of base 13 of the underwater smoothing element, the top of the delivery pipe 3 is continually adjusted to the required height with a lifting unit, while pouring concrete. As shown in the views in Figures 2 and 3, the smoothing element 12 has a base 13 which slopes slightly upwards from the delivery pipe 3. A cylindrical wall 14 is welded to the periphery of said base 13; a second cylindrical wall 15, located further towards -the inside, is also welded on the base 13. Six brackets 16 are welded to the inner wall 15 and six brackets 17 are also welded to the delivery pipe 3, in corresponding locations. The brackets 16, 17 are joined to one another by elastic and/or resilient elements 18, which, for example, are made of rubber or comprise steel springs or suspension cables, such that a link is obtained between smoothing element 12 and delivery pipe 3 which allows a certain degree of displacement. Base 13 is joined to a flexible, for example rubber, collar 21, which is fixed to the bottom of delivery pipe 3. Collar 21 is fixed close to the bottom end 9 of delivery pipe 3, using, for example, a clip binding 22. With this construction it is possible to move base 13 relative to delivery pipe 3 in such a way that no concrete rises above base 13. It is also possible for openings to be made in the base 13, through which concrete is able to rise above base 13. The walls 14, 15 enclose three watertight chambers 19, in each of which a vibrating element 20 is located. Said vibrating elements can consist, for example, of an electric, hydraulic or pneumatic motor with an imbalance and/or of hydraulic or pneumatic cylinder elements which slide into and out of one another. By means of said vibration elements 19, the smoothing element 12 can be brought into vertical and horizontal vibration, such that the concrete in concrete mass 7 can be spread well and compacted to a level, the floor reaching level 10. When pouring the concrete, the bottom end 9 of the delivery pipe 3 is continually below the surface 10 of the freshly poured concrete, with the consequence that demixing because of the water present above the floor 10 is effectively counteracted. By virtue of the slightly sloping shape of the base 13, a properly finished floor 10 can still be obtained even should the delivery pipe 3, and consequently also the smoothing body 12, be at a slight angle.

Claims: Claims 1.Method for pouring a fluid, settable mass, such as concrete, on a bed of a body of water, comprising the steps of introducing the mass onto the bed by means of a delivery pipe in such a way that the bottom end of the delivery pipe penetrates into the poured mass, and smoothing off the poured mass at a level higher than the bottom end of the delivery pipe. 2. Method according to Claim 1, wherein the poured mass is smoothed by means of a smoothing element brought into vibration. 3. Method according to Claim 2, wherein the smoothing element is brought into vertical vibration at a frequency of between 5 Hz and 40 Hz. 4.Method according to Claim 2 or 3, wherein the smoothing element is brought into horizontally oriented vibration at a frequency of between 0.1 Hz and 3 Hz. 5. Method according to one of the preceding claims, wherein the delivery pipe and the smoothing element are moved over the bed of the body of water during pouring. 6. Method according to one of the preceding claims, wherein the smoothing element is brought into rotation about the delivery pipe. 7. Method according to one of the preceding claims, wherein reference points at the top of delivery pipe 3 are continually measured by a measuring instrument located on the shore, after which the measurements, by means of a processing unit, such as a computer, activate a lifting unit, which lifting unit adjusts the top of delivery pipe 3 to the required height such that account is taken of the sloping position of delivery pipe 3 and the sloping surface or surfaces of the base 13 of the smoothing element 12, in order to obtain a top surface of the freshly poured concrete at the level 10 of a floor to be produced. 8. Method according to one of the preceding claims, wherein the level of the top of the floor which has been freshly poured and treated with the smoothing element and/or is to be treated with the smoothing element is measured by means of a depth measuring instrument, such as a sonar, in such a way that the measurements of the heights of said floor, by means of a processing unit, such as a computer, activate a lifting unit, as a result of which the delivery pipe (3) is brought to the required height in order to obtain a top surface at the level (10) of a floor to be produced. 9. Method according to one of the preceding claims, wherein the smoothing element is connected via lifting means to a lifting unit and wherein the lifting unit is activated by means of a processing unit, such as a computer, which processing unit processes process measurements for the floor to be produced in order to adjust the distance between the bottom of delivery pipe (3) and base (13) of smoothing element (12) to a distance such that a floor is obtained at the level (10). 10. Installation for carrying out the method according to one of the preceding claims, comprising a floating element, such as a pontoon (1) or a movable bridge construction located above the water level (5), having a delivery pipe (3) which at the top end has a feed for a fluid, settable mass, such as concrete, and a bottom end (9) for discharging the mass onto the bed (4) of a body of water, as well as a smoothing element (12) for smoothing the poured mass, which smoothing element (12) has a downward-facing smoothing surface (13) which is at a higher level than the bottom end (9) of the delivery pipe (3). 11. Installation according to Claim 10, wherein the smoothing element (12) is annular or torus-shaped and surrounds the delivery pipe (3) some distance above its bottom end (9). 12. Installation according to Claim 10, wherein at least part of the bottom surface (13) of the smoothing element (12) slopes upward from delivery pipe (3). 13.Installation according to Claim 10, 11 or 12, wherein the smoothing element (12) is connected to means for generating vibrations (20). 14.Installation according to Claim 13, wherein the means for generating vibrations (20) are on the one side connected to the smoothing element (12) and on the other side are connected to the delivery pipe (3). 15. Installation according to Claim 13, wherein the smoothing element (12) has at least one watertight chamber (19) in which the means (20) for generating vibrations are located. lό.lnstallation according to Claim 12, 13, 14 or 15, wherein the smoothing element (12) has two concentric cylindrical walls (14, 15) at the bottom of which a baseplate (13) is fixed, part of which slopes upwards from the delivery pipe (3). 17.Installation according to Claim 16, wherein at least one chamber (19) is located between the two concentric walls (14, 15). 18. Installation according to Claim 17, wherein each chamber (19) is delimited by two partitions (21) running radially with respect to the delivery pipe between the concentric walls. 19.Installation according to one of Claims 10 - 18, wherein the smoothing element (12) is connected to the delivery pipe (3) by elastic and/or resilient elements. 20.1nstallation according to one of Claims 10 - 18, wherein the smoothing element (12) is rotatable about the delivery pipe (3). 21. Installation according to Claim 20, wherein the smoothing element (12) has a flexible seal (21) which by means of a sealing lip interacts with the outer surface of the deliver}' pipe (3). 22. Installation according to one of Claims 10 - 21, wherein the smoothing element is linked by lifting means to a lifting unit, by means of which the desired distance between the bottom of delivery pipe (3) and base (13) of smoothing element (12) can be set. 23. Installation according to Claim 22, wherein the lifting unit is activated by a processing unit, such as a computer, which processing unit processes process measurements for the floor to be produced in order to adjust the distance between the bottom of delivery pipe (3) and base (13) of smoothing element (12) to a distance such that a floor is obtained at the level (10).

Inventors: DIRKS RONNY, DIRKS, RONNY
Applicants: DIRKS RONNY, HOLLANDSCHE BETONGROEP NV, DIRKS, RONNY, HOLLANDSCHE BETON GROEP N.V.
Application year: 1998
Main classification: E02D15
IPC codes: E02D15