ES2445575T3 - Method and set to build a continuous screen - Google Patents

Abstract

Method for molding a continuous screen comprising two primary sections (10, 11) joined by a secondary section (20), the method comprising a first stage of digging a primary molding volume for each primary section (10, 11), a second stage of molding the primary sections (10, 11) in the primary molding voltages, a third stage of digging a secondary molding volume to mold the secondary section (20), a fourth stage of removing a sacrificial junction region (16) of one or both adjacent primary sections (10,11), the method being characterized in that the second stage comprises arranging a prefabricated sacrificial displacement element (31) in the sacrificial junction region (16) of one or both of the primary molding volumes ( 16), positioned so that the molding material of the primary sections (10, 11) is displaced by the sacrificial displacement element (31) in the or each joining region (16) and so that The withdrawal of the or each region of sacrificial union (16) performed in the fourth stage includes the withdrawal of or of each element of sacrificial displacement (31).

Description

Method and set to build a continuous screen.

The present invention relates to the field of civil engineering and, in particular, to the excavation and construction of molded concrete structures, such as continuous swamps, below ground level.

Continuous screens, also known as screen walls, are built to form a barrier that blocks water and retains the earth surrounding underground structures such as tunnels, basements or roadway milling.

A continuous screen is essentially a waterproof vertical concrete wall that is molded in situ on the ground. To build such a continuous swamp, a ditch that defines the volume of molding for concrete is first excavated. The ditch remains full of grout until the concrete is poured, to prevent the sides of the ditch from falling inside. After the trench has been excavated, reinforcement steel is lowered into the trench, and the concrete is poured, displacing the grout and filling the volume around the reinforcement steel.

In prior art methods of constructing continuous screens such as WO 031006750 A 1, the screen is conventionally constructed in alternate sections. First, a series of separate primary wall panels are excavated, poured and allowed to harden. In the following description, the panels that are first molded are called primary panels or primary sections. The spaces between the hardened primary panels are then excavated and filled with concrete to form a set of secondary panels, also known as closure panels. In both cases, reinforcements are usually placed inside the trenches before the concrete is poured. When the secondary panels are excavated, using a hydro-press, for example, the side faces of the primary panels:> s can also be milled to remove any soil from the concrete, and to create a clean, textured surface against which the concrete of the concrete can be molded. secondary panel Milling removes concrete from the side face of the primary panels and creates a milled joint, or similar profile, that will ensure a ground-free joint with the concrete of the adjacent secondary panel when it is poured.

The excavation of the secondary panels is carried out conventionally using a hydrofoil, which is a large vertical excavation machine, which is lowered into the ditch with a crane. Hydrofores are typically 2.8 m wide and 60 cm to 1.5 m thick. At its lower end, a conventional hydrofoil has two sets of reverse rotation sprockets that remove material from the ditch. Hydrofore sprockets also remove some material from the sides of adjacent primary panels, creating the milled joint profiles mentioned above. The milled profile may be constituted, for example, by a series of vertical grooves grounded in depth (from 50 mm to 100 mm) in the concrete of the primary panels. The purpose of these gaps is to create a clean intertllocking joint between the primary and secondary panels when concrete is poured for the latter. The form of the milled profile can be a regular pattern of grooves or grooves, or simply a rough surface, depending on the type of milling wheel and arrangement of teeth used.

Once the milling and the "l: digging of the molding volume for the secondary panels is complete, the secondary reinforcement cage is lowered into the excavated secondary molding volume, and the concrete is poured around it and let cure.

After curing, the primary and secundslfios panels form a continuous concrete wall in the ground, each pair of neighboring panels being mechanically bonded in a resilient manner to each other by the strawberry joint profile described above.

In some constructions, such as a continuous curved screen, it may be necessary for some or all of the primary and secondary panels to be positioned at an angle to each other. However, conventional hydrofores or milling cutters generally have fixed-orientation milling heads with sprockets that are designed to cut a rectangular section, which means that, where said hydrofoil or milling cutter is used to excavate a secondary panel that is angled with its neighboring primary panel, milling will be done in an angle with the side face of the primary panel.

As a result of this angle milling, the amount of material to be removed during milling of the sides of the primary panel will vary significantly on the side face of:! primary panel Instead of milling all over the joint at an approximately equal depth in concrete of the primary pallet (generally 50 mm to 200 mm in the case of adjoining coptane panels), the angle of the hydrofore can be such that the milling depth can be up to 600 rrm at the inner edge of the milled joint, or even more, depending on the angle and thickness of the wall panels. Milling of such large amount of material outside the primary panel takes time,

wastes concrete of good quality, increases the amount of residual material to be removed and shortens the life of the cutting tools.

5 1 0 1 5 2 O

The invention proposes the use of sacrificial vacuum matrices, also referred to as displacement elements, which can be removed by milling to create a clean edge against which the adjacent section can be molded. The use of sacrificial elements in the molding of concrete structures is known. Document W02OO3I006750, for example, discloses the use of corrugated tubular elements that fill the width of a vada ditch, adding as temporary formwork for successive sections. The empty open end tube is fixed to the reinforcement cage and placed in the ditch. The tube is then filled with gravel or sand to give it sufficient strength to support the IX "sion of concrete during molding. During the excavation of the adjacent section, the tube is broken and removed, along with its contents. This method It has the disadvantage that the tube must be sealed and filled with gravel or sand after it is placed in the trench.!: This is a time-consuming process and can cause gravel and sand to fall inside the trench, compromising In this way the integrity of the molding in the lower region of the trench, Once the reinforcement cage and the tube have been lowered into the ditch, there is no longer any way to dig material that subsequently falls into the interior of the ditch. In addition, the bentonite slurry normally used to fill the trench before molding can begin to "clump" into the walls of the eyelet, and any delay in concrete pouring results in a greater agglutin I lie, with reduced concrete coverage accordingly. For this reason, it is important to minimize the amount of time between the placement of the reinforcement cage and the tube, and the pouring of the concrete. Having to fill the tube with sand and gravel significantly increases this time. In addition, the concave faces that remain once the tube and its contents have been excavated using the method of document W02003IOO6750 cannot be directly milled, so that a two-phase excavation process is used, in which half of the tube is removed using a conventional dredge or hydrofoil, and the other half is excavated using a specially shaped dredge with a semicircular profile.

2 5

The object of the present invention, therefore, is to provide a method of construction of a continuous screen that will allow the side faces of the primary panels to be milled more quickly, while providing a maximum clearance to install the weave, without the need for specially shaped excavation tools, without the risk of spilling exlratla material inside the trench, while reducing the waste of good concrete and with reduced wear of the cutting tools, even when the mill is oriented in a angle with respect to the primary panel.

3 0

In this application, the expressions primary panel and primary section are used interchangeably, as are the expressions secondary panel and secondary section. The term milling is used to indicate any process to remove material from the surface of the primary panels. Such processes may include mechanical abrasion for the cogwheels of a hydrofore, for example, or high pressure water Chofers or other suitable mechanical processes.

3 5 4 O

To overcome the above and other disadvantages of the prior art, the invention IX "avoided a method for molding a continuous screen comprising two primary sections joined by a secondary section, the method comprising a first stage of digging a dolding volume. for each primary section, a second stage of molding the primary sections in the primary rendering volumes, a third stage of digging a secondary molding volume to mold the secondary section, a fourth stage of forming a joint surface profile in each section primary milling an adjoining region (16) of each adjacent primary section, the second stage comprising molding a sacrificial detachment element in each of the adjoining regions, and the third and / or fourth comlX stages "enden to remove the sacrificial displacement elements.

According to a variant of the method of the invention, the third and fourth stages are performed simultaneously. Dig and mill in the same operation, for example, now time and equipment.

Four. Five

According to another variant of the method of the invention, the primary and secondary sections are substantially flat and vertical, and the secondary section is molded in a plane that is at an angle different from 180 · with respect to the plane of at least one of the prirnary sections. angled sections such as these are often used in the construction of containment tanks, for example, or deep wells,

5 o

According to another variant of the method of the invention, the second step includes constructing a molding preparation assembly comprising a reinforcing element to reinforce each primary section, fixing the sacrificial displacement element to the reinforcing element, and arranging the assembly of molding preparation in the respective primary molding volume. In this way, the reinforcing elements and the sacrificial displacement elements can all be lowered into the trench at once, and the molding can begin without any delay.

55

According to another variant of the method of the invention, the second stage includes arranging separating elements to keep each displacement element: ;; acrificial in position at a predetermined distance from the reinforcing element.

2 o

According to another variant of the method of the invention, each prefabricated sacrificial displacement element is made of a material that is more easily millable than the concrete used to mold the primary section into which each prefabricated sacrificial displacement element is molded.

The invention also provides a molding preparation set for placing inside a volume of primary molding excavated to mold a primary section of a continuous concrete screen, the primary section having at least one adjoining region, the or each one being adjacent region a region of the primary section to be milled to create a joint surface profile to join the primary section to an adjacent secondary section of the continuous screen, '1 at least one element of prefabricated sacrificial displacement, the or each being sacrificial displacement element made of a millable material more easily than the concrete used to mold the primary section, the or each sacrificial displacement element being positioned in the molding preparation assembly so that, when the molding preparation assembly is placed in the volume of primary molding and the primary section has been molded, the or each element or sacrificial displacement is in an adjacent region.

According to another variant of the Invention, the assembly comprises a reinforcement structure to provide reinforcement for the primary section when the primary section is molded, the or each sacrificial displacement element being fixed to the reinforcement structure.

According to another variant of the invention, the material of each prefabricated sacrificial displacement element is softer, or more brittle, or more 'friable, or less dense than the concrete used to mold the primary sections.

According to another variant of the invention, the profile of the joining surface comprises one or more grooves formed in the material of the primary section.

According to another variant of the invention, each prefabricated sacrificial displacement element comprises at least two or more prefabricated modules. By assembling the sacrificial displacement elements in a modular manner, the assembly process can be simplified and accelerated.

According to another variant of the invention, each prefabricated sacrificial displacement element is shaped

of a substantial cross section prism! triangular or trapezoidal. the shape of the displacement elements can be selected to suit an angle orientation between the primary and secondary sections, for example, thereby reducing the amount of molding concrete that must be milled to create the required angle joint.

According to another variant of the invention, the or each sacrificial displacement element comprises one or more vacuum forming members to exclude concrete from one or more regions of the primary molding volume.

According to another variant of the invention, unc. or more of the prefabricated sacrificial displacement elements or modules enclose a hollow void.

According to another variant of the invention, one or more of the prefabricated sacrificial displacement elements or modules comprises a solid block.

According to another variant of the invention, the volume of the secondary section is excavated using a hydrofoil.

According to another variant of the invention, one or both of the primary molding volumes are excavated using a hydrofoil.

According to another variant of the invention, the hydrofoil is slightly wider than the distance between the two primary molding volumes. the relative widths can be predetermined so that a single pass of the hydrofore can achieve the desired milling (at an angle, if appropriate) in both of the adjacent primary sections.

The invention will be described below with reference to the accompanying drawings, in which:

Figure 1 shows a schematic cross-sectional view of a typical prior art method of construction of the primary panels for a continuous screen.

Figure 2 shows, in cross-sectional schematic section, a view of the prior art method of construction of the secondary panels, and milling of the edges of the primary panels, to create a continuous screen.

Figures 3a and 3b show schematic elevational and plan views illustrating the regions to be milled when the primary and secondary panels are mutually angled.

Figures 4a and 4b show, in plan view and schematic perspective, an example of continuous screen sections constructed in accordance with the invention.

Figures 4c, 4d and 4e show, in schematic plan view, a sequence of construction of a (secondary) closing panel using a method according to the present invention.

Figures 5a, 5b and 5c show, in schematic view, an example of how a primary panel molding can be prepared according to the invention.

Figure 6 shows in more detail a schematic elevation view of the primary section molding assembly prepared in accordance with the invention.

The attached figures are intended to be an aid in understanding the invention, and are not intended to imply any limitation on the scope of the invention. Where the same reference signs are used in different drawings, these reference signs are intended to refer to the same or corresponding characteristics.

The prior art method of building a continuous screen will be described in more detail below with reference to Figures 1, 2, 3a and 3b. Figure 1 shows the process of digging, preparing and molding the primary panels. Regions 10, 11, 12, 13, and 14 are five primary section molding regions in soil 3 that show successive phases of digging and molding the primary panels. Region 10 shows a primary panel region before excavation, while region 11 shows a primary panel region being excavated using a crane dredge tool mounted on a crane (8), although a hydrofoil 9 can also be used for This stage of excavation. The excavated ditch is kept full of water or grout (not shown) to prevent the sides of the ditch from falling inwards. Region 12 is shown completely excavated, and having an armor cage (armor) of steel 4 descended inside. Region 13 shows the concrete 5 being poured into the primary molding region around the steel of the reinforcement cage 4, with the concrete being introduced using a pipe or hopper 6, and region 14 is shown after the molding is complete and the primary panel has been allowed to cure. Figure 1 also shows four regions 20, 21, 22 and 23 that must be excavated for the molding of secondary panels.

Figure 2 shows the arrangement of Figure 1, in which the molding of the primary panels has been completed, ready for the molding of four secondary panels 20 to 23 between the primary panels 10 to 14. Region 20 shows a region of Secondary panel molding before excavation. The region 21 is shown in the process of being excavated using a hydrofoil 9 that removes the soil ~ f mills the lateral faces of the neighboring primary panels, to facilitate a good bond between the two adjacent sections, and thus achieve a joint that It has good water blocking properties. The hydrofoam 9 is shown being lowered into the excavation zone 21 by the crane 8. The secondary panel 22 is shown in the process of being molded, with the reinforcement already in position, and the panel 23 is shown in its cured state and completed, forming a continuous screen with neighboring primary panels 13 and 14.

Figure 3a illustrates how, when the primary panels 10, 1 "12 are positioned at an angle with respect to their neighboring secondary panels, the amount of material 16 to be milled from the side faces of the primary panels is smaller towards the outer edge of the side and greater towards its internal borcle. "Internal", in this case, refers to the side of the panels in which the joining angle of two adjacent panels is less than 180 degrees S. "External · refers to the side of two adjacent panels in which the joint angle of two adjacent panels is greater than 180 degrees. Reference 15 in the figures indicates the profile of strawberry straw to be milled on the side face of each primary panel.

A plan view of the arrangement of Figure 3a is shown in Figure 3b, which also indicates where the material for secondary panels 20 and 21 should be excavated and milled. In the illustrated example, a large amount of material 16 must be removed from the primary panels 10, 11, 12 to achieve the desired milling joint profile 15 on all side faces of the primary panels 10, 1 "12. The concrete used For molding the primary panels, it is customary to have high specifications, very hard and impervious to water.The removal of cradles 16 from very hard concrete presents a great challenge to the hydrofoil 9, which must therefore be lowered much more slowly that when the neighboring panels are aligned with each other in a coplanar manner, the removal of such a hard concrete also means a significantly increased wear on the expensive machinery of the hydropower plant. Varying the depth of concrete to be milled also means that there is a risk increased that the hydrofoil detracts from the vertical plane as it moves down.

Figures 4a, 4b, 4c and 4d show the principle behind the present invention. Figures 4a and 4b show, in plan and perspective views respectively, a primary panel armature 30 having two sacrificial displacement elements 31 fixed thereto. The sacrificial displacement elements 31 are essentially means for excluding the concrete used to mold the primary panels from predetermined regions of the molding volume of the primary panel, and in particular from the regions that must be removed when the joint is to be milled. It is not necessary that the sacrificial displacement elements be hollow - their function is to create a region of the volume of molding from which the high specification concrete is excluded when it is poured. As such, the sacrificial displacement elements 31 may be prefabricated solid blocks of lightweight concrete, for example, or they may be prefabricated hollow shapes such as sections of hollow pipe previously sealed against the concrete inlet, and optionally prefilled with soft concrete or materials loose, soft such as sand_The sacrificial displacement elements 31 are fixed to the armature 30 for convenience, using sanding elements 32, so that the displacement elements

Prefabricated sacrificials 31 and armor 30 can be lowered together inside the ditch in a single operation, and concrete pouring can begin immediately. The fasteners 32 may be pieces of steel bars nailed to the frame 30, for example. Since it is probable that the fusing elements 32 are introduced into the area to be milled, they should be of a shape and material such that they do not significantly interfere with the milling of the milling joint 15.

The sacrificial displacement elements 31 are positioned so that, when the armature assembly 30 (complete with fixed sacrificial displacement elements 31) is lowered into its primary panel molding volume, and the high spec concrete is molds around the armature 30 and the saaificial displacement elements 31, the sacrificial displacement elements 31 will form regions 16 of the primary panel that will be removed when the neighboring secondary sections are excavated. Figure 4c shows, in plan view, where the joint profile 15 should be milled by removing the material from the sacrificial displacement elements 31 and milling inside the hard concrete di! the primary panels 10, 11. In Figure 4c, the primary panels 10 and 11 are in their complete state, ready to be milled, after the concrete 25 has been molded around the reinforcements 30 and the displacement elementsclS sacrificial 31 and after the molded concrete has been allowed to cure The molding volume for the secondary panel 20 is then excavated / milled as described above, removing the material from the sacrificial displacement elements 31 and creating the profile of joint 15 in the hard material of the primary panels 10, 11. A certain amount of high-specification dense concrete must be, in any case, removed to achieve a solid joint between adjacent panels, but the method of the invention minimizes the amount of this dense concrete of high specifications to be milled, especially when adjacent panels are angled together.

Figure 4d then shows the completed excavation of the secondary molding volume 20, with the milled joint faces 15 ready to mold the secondary panel. Figure 4e shows the secondary panel 20, including the reinforcement 26, molded and cured between primary panels 10 and 11. panels 10, 11 and 20 must then be mechanically joined by the Hi joints to form a continuous, more impermeable screen structure.

Figures Sa, 5b Y An example of how sacrificial displacement elements can be assembled before lowering the armature of the primary panel into the trench is illustrated. In these figures, the sacrificial displacement elements 31 are shown fixed to the armature 30 by means of fasteners 32, but kept away from the armature by separating elements 33. By keeping the sacrificial displacement elements 31 away from the 3D armor, it can be guaranteed that the subsequent milling of joints is carried out in a region that does not run the risk of entering the region of the reinforcement 30. If such intrusion occurs, this could damage the milling machinery and / or significantly compromise the strength and integrity of the primary panel that is being molded.

The separating elements 33 are preferably fixed to the reinforcement 30, and can be shaped not only to create a space between the sacrificial displacement elements 31 and the reinforcement 30, but also to support the sacrificial displacement elements 31 before and during molding. . Prior to molding, the separator elements are required to be able to support the weight of the sacrificial displacement elements 31. During molding, the separator elements 33 must also be able to hold the sacrificial displacement elements 31 in position against any forces. of hydraulic substitution upwards exerted on the sacrificial displacement elements 31 when they are immersed in the slurry and / or when the densest relative concrete is poured around the sacrificial displacement elements 31. the separator elements 33 can also be made of an easily millable, vacuum forming material such as lightweight concrete. As shown in the example of Figures 58 a se, the sacrificial displacement elements 31 can be fixed in a modular manner, with each successive set of modules being fixed as the armature descends into the excavated ditch 12. Note that The figure shows a particular exemplary situation, in which the sacificial displacement elements 31 are installed in the lower and middle sections of the panel, but not in the upper section. Many hydrofores only work effectively when the milling head is submerged in the grout. In the upper section of the panel, therefore, the joints between the primary panel and its neighboring secondary panels are formed using conventional temporary stop-steel joints that are then removed before starting the excavation of the secondary panels . This is only a variant of the invention, however, and the sacrificial displacement elements 31 can be positioned where required.

Although the present invention has been described in the context of grooves fabricated in the ground using reinforced concrete, the invention can be used to construct any structure where it is required to create a milled type joint between two adjacent molding elements, and in which at least one of the elements can be molded so that it has a joint-forming region that compresses a forming element of sacificial vacuum.

Claims (13)

1. Method for molding a continuous screen that c: includes two primary sections (10, 11) joined by a secondary section (20), the method comprising 5 a first stage of digging a primary molding volume for each primary section (10, 11), a second stage of molding the primary sections (· 10, 11) in the primary molding volumes, a third stage of digging a secondary molding volume to mold the secondary section (20), a fourth step of removing a sacrificifll junction region (16) from one or both adjacent primary sections (10, 11), 10 the method being characterized because the second stage comprises arranging a prefabricated sacmtcial displacement element (31) in the sacrificial joining region (16) of one or both of the primary molding volumes (16), positioned so that the molding material of the primary sections (10, 11) I! S displaced by the sacrificial displacement element (31) in the or each region of union (16) and so that the withdrawal of the or each region of sacrificial union (16) 15 carried out in the fourth stage includes the withdrawal of or of each element of sacrificial displacement (31) .

2.

Method according to claim 1, wherein the primary (10.11) and secondary (20) sections are substantially flat and vertical, and wherein the secondary section (20) is molded in a plane that is at an angle different from 1800 with respect to the plane of at least one of the adjacent primary sections (10, 11).

3.

Method according to claim 1 or claim 2, wherein the second stage includes constructing a molding preparation assembly comprising a reinforcing element (30) to reinforce each primary section (10, 11), fixing the elements of Prefabricated sacrificial displacement (31) to the reinforcing element (30), and arranging the molding preparation assembly in the respective primary molding volume.

4. Method according to claim 3, wherein the second stage includes arranging separating elements (33) to hold each sacrificial displacement element (31) in position at a predetermined distance from the reinforcing element (30). 3 OR 5. Molding preparation set for placing inside a volume of primary molding excavated to mold a primary section (10) of a continuous concrete screen, the primary section having at least one adjacent region (16), being the or each adjacent region (16) a region of the primary section (10) to be milled to create a joining surface profile (15) to join the primary section (10) to an adjacent secondary section (20) of the continuous screen, 35 the molding preparation assembly being faceted by at least one prefabricated sacrificial displacement element (31), the or each sacrificial displacement element (31) being made of a millable material more easily than the concrete used to mold the primary section (10), the or each sacrificial displacement element (31) being positioned in the molding preparation assembly 4 Or so that when the molding preparation assembly is placed in the primary molding volume and the primary section (10) has been molded, the or each sacrificial displacement element (31) is in a joint region (16) to be removed during milling of the adjacent secondary section (20). 6. Assembly according to claim 5, comprising a reinforcing structure (30) for 4 5 provide reinforcement for the primary section (10) when the primary section (10) is molded, the or each sacrificial displacement element (31) being fixed to the "reinforcement ludge (30). 7. A method according to one of claims 1 to 4, or a set of aJerdo one of claims 5 6 6, wherein the material of each prefabricated sacrificial displacement element (31) is softer, or more brittle, or more friable, or less dense than the material used to mold the primary sections (10, 11). 6. Method according to one of claims 1 to 4, or assembly according to one of claims 5 or 6, wherein the joint surface profile (15) comprises one or more grooves formed in the material of the primary section (10). A method according to one of the claims, actions 1 to 4, or cofoint of aaJerdo with one of claims 5 6 6, wherein each prefabricated sacrificial displacement element (31) comprises at least two prefabricated modules . 10. Method according to one of the claims 1 to 4, or set according to one of the 15 claims 5 or 6, wherein each prefabricated structural shift element (31) is in the form of a substantially triangular or trapezoidal cross-sectional prism. 11. Method according to one of claims 1 to 4, or set according to one of the claims 5 6 6, wherein one or more of the prefabricated sacrificial displacement elements (31) or 20 modules encloses a hollow ford. Method according to one of claims 1 to 4, or set of aQJerdo with one of claims 566, wherein one or more of the prefabricated sacrificial displacement elements (31) or modules comprises a solid block.

13.

Method according to one of claims 1 to 4, or assembly according to one of claims 5 6 6, wherein the volume of the secondary section is excavated using a hydroffesa (9).

14.

Method according to one of claims 1 to 4, or set according to one of the

Claims 5 or 6, wherein one or both of the primary molding volumes are excavated using a hydrofoil (9). 15. Method or assembly according to GOn of claim 13 or 14, wherein the hydrofoil (9) is slightly wider than the distance between the two primary molding volumes.