Method for waterproofing a bed of water

Abstract

A method is disclosed for waterproofing a bed of water, comprising the following steps: prefabricating lining sheets each of which is made up of a single geocomposite with only two layers, i.e. a waterproof geomembrane layer and a protective geotextile layer; carrying out an excavation to create a berm in an upper part of a bank of the bed; arranging the lining sheets underwater to line the bed by joining together contiguous sheets with a watertight zip; preparing ballast materials and / or elements which are external, distinct, and independent of the lining sheets, reversibly depositing the ballast materials and / or elements on the lining sheets to ballast each sheet in one or more ballasting areas defined according to fluid dynamic features of the water and / or morphological features of the bed.

Description

Method for waterproofing a bed of waterBackground to the invention

[0001] The invention relates to a method for waterproofing a bed of water, with still water or with running water. In particular, the method in question installs a waterproof covering underwater, without emptying the bed and, in the case of running water, without interrupting the flow of water.

[0002] Specifically, but not exclusively, the method may be applied to the underwater installation of a waterproof covering in a canal for supplying drinking water, water for irrigation, for navigation, for land reclamation, for industrial purposes, or for still other purposes. The method may nevertheless be applied to installing a waterproof covering even in other types of water bed, like, for example, in collecting and / or containing basins of water and reservoirs.Prior art

[0003] A technique is widely known for dry installation of watertight sheets for lining water beds, in which the sheets are welded together to ensure a watertight seal. This solution is not however applicable underwater. There is on the other hand a greatly felt need for enabling waterproof lining to be installed underwater without emptying the bed and / or without stopping the flow of water, for example in canals, reservoirs, tanks or other types of water bed.

[0004] Large earth canals are an example of water beds that need to be waterproofed. According to the International Commission on Irrigation and Drainage (ICID), large unlined earth canals suffer water losses comprised between 25 and 35%, which corresponds to billions of cubic meters. It is understood how the watertight seal is fundamental for an earth canal. In order to reduce water leaks, it is known to line earth canals with concrete. The method of lining an earth canal with (cement or bituminous) concrete cannot however be carried out in the presence of water, but involves draining the canal. Further, owing to the settling of the terrain, the action of the water, the cycles of freezing and thawing, concrete linings develop cracks, fissures, sagging of the joints and general loss of watertightness, which make refurbishment works necessary that again require the canal to be drained. As a result, there are multiple interruptions to the supply of water, with a multiple impact on users and ecosystems, in addition to a significantincrease in costs.

[0005] There is thus a need to waterproof a bed of water without emptying the bed or without stopping the bed, i.e. allowing underwater installation rather than dry installation.

[0006] This invention refers to a method for waterproofing the bottom and the banks of a bed of water without emptying the bed of water or without interrupting the flow. The method in question comprises the steps of arranging underwater waterproof lining elements alongside one another to line the bed, of joining contiguous lining elements by a watertight zip to make a lining, and of ballasting the lining.

[0007] Such a method is known from patent publication WO 2016 / 016367 Al, of the same applicant, in which each impermeable lining element comprises a prefabricated tubular panel provided with a tubular chamber defined by a lower geomembrane - which is coupled with a geotextile layer intended for contact with the bottom to protect the geomembrane from possible perforations caused by the bottom underneath and to provide friction to immobilize the panel - and by an upper geomembrane with the function of confining and lining a permanent ballast (continuous over the entire surface) made of cement material that is injected into the tubular chamber after laying of the tubular panel to line the bed. Each waterproof tubular panel further comprises two sealing lateral wings that feature corresponding toothed bands of a watertight zip, so that two contiguous panels can be joined together by the zip. This waterproofing system is marketed by the applicant and is called SIBELONMAT®. This solution known from WO 2016 / 016367 Al has proved to be effective in waterproofing water beds, in particular canals with underwater installation with the water moving. Nevertheless, this known solution, owing to the presence of a layer of concrete enclosed between the two lower and upper geomembranes, reduces the cross section of the canal. Further, the visible presence of the upper geomembrane made of synthetic material creates an aesthetic appearance that is not natural and has a great environmental impact.

[0008] In certain situations it would be moreover desirable to be able to install underwater a lining with a more simplified and / or lighter structure, and which alters as little as possible the profile of the bed and / or guarantees a surface finish that is more integrated into the natural environment. It would also be desirable in certain cases to be able to do without ballasting the lining by pumping fluid cement material as this entailssignificant consumption of high-quality material with resulting problems of procurement and technological complication. Further, pumping cement material implies the risk that during pumping operations a part of the material exits, causing the bed of water to become polluted with grave environmental consequences for fauna, flora, water potability, etc. Other aspects that could be improved are the flexibility of the lining element, with resulting in better adaptability to the bottom of the bed, with the possibility of providing a lining with a reduced ecological and landscape impact on the natural environment.Summary of the invention

[0009] One object of the invention is to devise a method that is able to meet one or more of the aforesaid needs of the prior art.

[0010] One object of the invention is to install a waterproof lining without suspending normal operating conditions of the bed of water, for example, without interrupting navigation in a navigable canal, or without stopping crop-irrigation programs, etc.

[0011] One object of the invention is to provide a waterproofing method that can be executed underwater without emptying the bed of water.

[0012] One object of the invention is to propose a solution that is alternative to the prior art to waterproof a bed of water.

[0013] One object of the invention is to find a solution that enables a waterproof lining to be installed underwater consisting of watertight elements that are connected directly together during laying underwater, permitting thorough control of the quality of the intervention and a high degree of waterproofing.

[0014] One object of the invention is to suggest a method of underwater installation of a waterproof lining that is particularly suitable for an earth bed.

[0015] One advantage is to provide a method for laying and installing a waterproof lining in a bed, in which the structure of the lining is relatively simple and cheap and at the same time perform its functions - in particular, preventing soil erosion and water leaks caused by seepage - effectively and with great durability.

[0016] One advantage is succeeding in waterproofing a bed of water, in particular a canal, avoiding reducing the cross section thereof.

[0017] One advantage is leaving exposed, in the submerged part of the waterproof lining, a large geomembrane surface, owing to the fact that it is possible to perform onlypartial ballasting, in particular concentrated on the visible upper part of the sides and partially also on the bottom.

[0018] One advantage is ensuring a relatively high flowrate of the current of water in a channel, so that, in a channel waterproofed using the method in question, the friction resistance that the bottom and / or the banks of the channel exert on the flow of running water is anyway relatively reduced.

[0019] One advantage is ensuring effective and safe protection of the waterproof lining against aging and / or vandalism, in particular at the upper part of the banks of the bed.

[0020] One advantage is minimizing the environmental impact, owing to the possibility of hiding, or making less obvious, the artificial intervention caused by the presence of the waterproof lining, without significantly and excessively altering the state and natural and / or landscape appearance of the bed of water.

[0021] One advantage is creating a waterproof lining that enables the degree of permeability and / or an appropriate complete seal to be monitored continuously even in the joining zones between contiguous lining elements.

[0022] One advantage is avoiding a step of pumping ballast material in fluid state to achieve anchoring of the waterproof lining.

[0023] One advantage is making removal of a single lining element, and laying and installation of a new lining element in place of the removed one particularly easy.

[0024] One advantage is permitting the easy and stable installation of a waterproof lining also on a sandy surface of a bed, just as on any other type of bed surface.

[0025] One advantage is reducing execution time and / or costs compared with other methods used for waterproofing a bed underwater.

[0026] One advantage is permitting the installation, even in an earth bed, of a flexible waterproof lining of great quality, stability and durability.

[0027] One advantage is preserving water resources of an already existing bed, in particular when it is not possible to empty or arrest the flow.

[0028] One advantage is to make available a method for waterproofing a bed by using intensively the executing means available in situ.

[0029] It is observed that the method in question is particularly suitable for making awaterproof lining in an earth bed, but may be anyway applied to a bed lined with (cement or bitumen) concrete, or to yet another type of bed.

[0030] The method in question is used, in particular, to reduce the water losses of a bed and / or to ensure the complete water supply of a channel and, as said, may be implemented underwater without draining the bed.

[0031] The lining made eliminates the water leaks, protects the slopes of the bed, and withstands the action of ice, provides at least partially a smooth sliding surface that reduces losses by friction, promoting the flow of water in the channel.

[0032] The lining installed with the method in question, owing to its elasticity, in the event of subsidence and / or earthquakes, is able to fill cracks and openings, maintaining the bed in a safe condition, without the need for routine maintenance.

[0033] The lining made ensures durability (also more than a hundred years) and considerable respect for the environment as it has a very reduced carbon footprint (four times less that of concrete). Further, it takes significantly less time to build compared with concrete.

[0034] Such objects and advantages, and still others, are achieved by a method according to one or more of the claims set out below.

[0035] The method in question entails the underwater installation of a lining of the bed by impermeable flexible geomembrane (for example one of the plasticized polyvinyl chloride PVC-P -based geomembranes of the applicant named SIBELON®) without stopping the flow of moving water, without draining the bed, maintaining full operation and without affecting the users of the water downstream and without affecting the environment.

[0036] The method in question may comprise, in particular, a preliminary step of underwater inspection of the bed (for example, by sonar) in order to identify leaks, sections and areas of the bed that require the bottom, banks or profile to be refurbished or repaired.

[0037] The method in question may comprise, in particular, a possible further preliminary action in which accumulated sediment is removed and / or there is underwater evacuation of the bottom of the bed (generally by dragging).

[0038] It is further possible, after removal of the sediment, to perform a second inspection (for example by multibeam sonar) to check the condition of the surface of thebed and, if necessary, level any irregularities so as to make laying of the geomembrane more even, in particular by using a soft dragging tool based on vacuum technology.

[0039] The method may comprise, in particular, a step of excavating and compacting at least one portion of bank to make at least one berm.

[0040] The method may comprise, in particular, distributing rolls of sheets with geomembrane (for example, a SIBELON® geomembrane) on the bank of the bed (for example, rolls that are each 10 meters wide) and laying by unrolling (in the case of a canal, preferably in a direction perpendicular to the axis of the canal). The sheets are equipped with a waterproof zip that will easily join the adjacent sheets underwater, to construct a continuous waterproof lining.

[0041] The method may comprise, in particular, the step of restoring the upper part of the slope, which had been excavated to make the berm, using, for example, at least one part of the excavation material, in particular with a mixture of earth mixed with cement and / or stones and subsequently compacted. This enables the lining to be ballasted on the bank of the canal to allow normal use of the bank.

[0042] Possible ballasting of the lining on the bottom may be performed, in particular, by a dedicated pontoon with techniques adapted to specific local conditions. It is possible to perform ballasting with inert material and / or rocks and / or concrete and / or poles anchored in the terrain and / or with yet other materials.

[0043] When the geomembrane lining has been installed and ballasted, in subsequent years it will be possible to clean accumulated sediments with a soft dragging tool, without compromising the wholeness of the geomembrane.

[0044] The geomembrane lining has no impact on downstream water use and has no impact on the environment and ensures long durability without any need for maintenance. The geomembrane lining offers significant advantages over concrete. Whilst the impermeability of concrete is limited to just a few years (because of breaking of the concrete due to settling phenomena, to the presence of vacuums, to ice, to the dynamic action of water, etc), the geomembrane lining maintains the impermeable structure for long periods and unlike concrete does not require any maintenance. The geomembrane lining may be installed underwater, which is not possible with concrete. The geomembrane lining significantly increases the flow of water owing to the smoothness of its surface, withrespect to the concrete that has a higher surface friction coefficient and thus limits the speed of the water. Further, the carbon footprint of the geomembrane is four times less than that of concrete.

[0045] The method in question enables the use of executing means for executing the waterproofing method to be reduced (where executing means are materials, elements, instruments, tools, etc) that have to be conveyed to the place of operations and are normally heavy and bulky, in particular the means for ballasting the waterproof lining (in particular, the means and materials used to inject fluid cement material into a tubular panel).

[0046] The method in question enables a waterproof lining to be made that is installable underwater and without interrupting the operation of the bed of water, with a simple and cheap structure, which is nevertheless able to prevent the erosion of the bottom and the water losses caused by seepage, effectively and very durably, especially in the case of particularly sandy and thus highly permeable terrain.

[0047] Compared with other prior-art methods for the underwater installation of impermeable linings, the method in question also enables lining operations and equipment to be simplified so as to reduce the time and / or the costs of executing the waterproofing method.

[0048] It is further possible to ballast the waterproof lining elements by rationalizing and simplifying the various steps of in situ conveying, handling and application of the balance, in particular with respect to prior-art underwater installation procedures.

[0049] Further, owing to the method in question, each of the waterproof lining elements - elements that have been laid, joined together and anchored on the bottom of the bed next to one another - may be removable and replaceable singly, if necessary, in the simplest, most rapid and practical manner possible, without removing the neighboring elements, to enable only worn or damaged parts of the lining to be replaced and / or maintained.

[0050] According to the method in question, each lining element is a sheet consisting of a single geocomposite with only two layers coupled on one another, i.e. a waterproof layer (geomembrane) and an underlying (geotextile) protective layer, without setting up any tubular chamber and thus without any step of injecting ballast material in fluid stateinto a tubular chamber. The structure of the lining element, in the form of a single geomembrane sheet, is thus particularly simple and light and at the same time sufficiently robust in addition to being elastic and significantly adaptable to the bottom of the bed.

[0051] According to the method in question, each lining sheet is joined with a contiguous lining sheet by a watertight zip, so that the reciprocal coupling between the lining sheets - each of which is characterized, as has been seen, by a relatively simple and light structure - is significantly rapid, practical and easy, just like the possible uncoupling and removal of a single lining sheet in the event of necessity.

[0052] According to the method in question, the lining sheets arranged on the bottom of the bed are ballasted (also only partially), in order to increase by friction the action of anchoring in the bottom - an action already partially performed by the underlying layer of protection that is able to generate friction with the bottom - using ballast materials and / or elements which are external, distinct, and independent of lining sheets (in practice, as already said, without using ballast in fluid state injected inside the lining element, but with a ballast arranged outside the lining element).

[0053] Using a ballast that is external and is not incorporated in the lining, which is deposited reversibly on the lining and is thus removable from the lining, enables the ballast to be removed easily in the event of necessity, in particular in the event of the need to remove a single lining element. The external ballast arranged on the lining may be further removed without causing any damage to the single lining element to be removed.

[0054] At least one part of the external ballast may be deposited reversibly, in particular, above and in contact with an upper portion of the lining sheet that lines an upper zone of the bank of the bed (in particular, a zona where a berm had been formed previously), which enables both the deposition and the possible removal of this part of external ballast resting on an upper bank zone to be facilitated. Further, it has been found that this external ballast that is deposited reversibly on the upper portion of the lining sheet contributes considerably to anchoring of the lining, ensuring an effective seal also over the long term. It is further possible to ballast the upper bank zone so as to leave the natural landscape appearance apparently unaltered.

[0055] According to the method in question, each lining sheet is ballasted at one or more ballasting areas that are defined according to certain operating parameters of the bed,for example the dimensions and / or the configuration of the bed of water (in particular the features of the bottom and / or the state of a preceding lining) and / or the flow speed of the water in the bed and / or the lifting action of the wind. It has been seen that in general the speed of the water is the most significant parameter. For example, ballasting areas of greater size and / or number may be chosen if the flow speed of the water is particularly high (for example greater than 0.5 m / sec). It is observed that, in general, the flow of water in a channel may have a speed that is variable both over time and locally, for example a speed comprised between 0.1 and 2.5 m / sec.

[0056] The fact of selecting the number and / or the size of the ballasting area / s in function of one or more operating parameters enables the use of the ballast means to be so rationalized without compromising the anchoring effect that a possible subsequent local removal of the ballast means, for example to replace a single lining sheet, may be performed with an appropriate and not-excessive force.

[0057] Further, in the case of lining of a channel of water with still or running water, in which the features of the channel could vary along the course of the channel, ballasting area / s may be chosen that is / are of a size and / or number suitable to the channel depending on the specific portion of channel, so if in the laying and installation portion of the single lining sheet the flow speed of the water in that portion is greater, it is then possible to choose a ballasting area of greater size and which is particularly suitable for that portion.

[0058] It is possible for the ballasting areas to comprise, in particular, one or more ballasting areas (for example, at least one continuous ballasting area) each extending along an upper zone of the bank of the bed. It is possible for the ballasting areas to comprise, in particular, one or more ballasting areas (for example, at least one continuous ballasting area) each extending along a bottom zone of the bed. It is possible for the ballasting areas to comprise, in particular, at least two ballasting areas (for example, continuous ballasting areas) extending respectively along two opposite banks of the bed (channel), in particular each area may extend along an upper zone of the respective bank. It is possible for the ballasting areas to comprise, in particular, at least two ballasting areas (for example, continuous ballasting areas) parallel to one another, each extending along a respective lateral zone of the bottom (for example, an almost horizontal bottom) of the bed (channel) at an intermediate zone where the bottom of the bed ends and the declivity starts (i.e. thetilted or steep bank or wall) of a respective bank of the bed. It is possible for the ballasting areas to comprise, in particular, one or more ballasting areas each extending along an upper zone of the bank of the bed and one or more ballasting areas each extending along a bottom zone of the bed.

[0059] The protective layer of the single lining sheet, below the waterproof layer, consisting normally of a geotextile, may be chosen, in particular, with grammage greater than 200 g / m2, in particular, equal to about 500 ± 200 g / m2, as it has been seen that with these grammage values it is possible to obtain an effect of anchoring to the bottom by friction so as to enable the number and / or the size of the ballasting areas to be reduced.Brief description of the drawings

[0060] The invention can be better understood and implemented with reference to the attached drawings that illustrate some embodiments thereof by way of non-limiting example, in which:Figure 1, which shows schematically and partially a cross section of a bed of water to be waterproofed, shows a step of an embodiment of the method in question, during which, by excavation, an upper zone of a bank of the bed of water is prepared;Figure 2 shows the upper zone of the bank of the bed after the preparation step by excavation shown in Figure 1;Figure 3 shows a step of the method, subsequent to Figures 1 and 2, in which a roll of lining sheet is arranged in the upper zone of the bank;Figure 4 shows a step of the method, subsequent to Figure 3, in which the roll of lining sheet is unrolled on the bank of the bed;Figure 5 shows the roll of lining sheet of Figure 4 during laying by unrolling on the bottom of the bed;Figure 6 shows a detail of the lining sheet during the unrolling step of Figures 4 and 5, in which the joint zone is visible between the lining sheet that is in the unrolling zone and the contiguous lining sheet that had been laid previously;Figure 7 is a schematic section of the joining zone between the two contiguous lining sheets of Figure 6 laid on the bottom of the bed;Figure 8 shows a step of the method, subsequent to Figures 4 and 5, in which the lining sheet laid on the bottom of the bed is anchored by ballasting on the upper partof the bank;Figure 9 shows a step of the method, subsequent to Figure 8, in which the lining sheet is anchored by ballasting on the bottom of the bed;Figure 10 shows another embodiment of a waterproof coating of a bed of water with ballasting on the sides and on the bottom of the bed;Figure 11 is a top plan view of a distribution of concrete blocks used to perform ballasting on the bottom of the bed in order to obtain appropriate anchoring of a waterproof lining, made with the method illustrated in the preceding figures, in function of a speed of a flow of water that flows in the bed.Detailed description

[0061] With reference to the aforementioned figures, a bed of water comprising a bottom and two opposite banks has been indicated by 1.

[0062] The bed 1 may comprise, in particular, a canal (for example a canal for irrigation, for navigation, for reclamation, for industrial purposes, etc) with a central bottom and two substantially lateral banks parallel to one another. In the specific embodiment, the bed 1 comprises an earth canal.

[0063] The method for waterproofing the bottom and the banks of the bed 1 comprises the step of prefabricating a plurality of lining sheets 2 each of which consists of a single geocomposite with only two layers coupled with one another. The two layers of the geocomposite are a waterproof layer 3 and a protective layer 4.

[0064] The waterproof layer 3 may have, in particular, a thickness comprised between 1 and 5 mm. The waterproof layer 3 may consist, in particular, of a geomembrane, in particular a geomembrane with a permeability coefficient K comprised between IO-9m / sec and ICT15m / sec.

[0065] The protective layer 4 may be, in particular, a layer of nonwoven geotextile fabric. A grammage of the protective layer 4 may be, in particular, greater than 200 g / m2. Embodiments are possible in which the grammage of the protective layer 4 is greater than 250 g / m2. Other embodiments are possible in which a grammage of the protective layer 4 is greater than 300 g / m2. A grammage of the protective layer 4 may be, in particular, even greater, for example greater than 350 g / m2, or greater than 400 g / m2. In this specific embodiment, the grammage of the protective layer 4 is equal to about 500 g / m2. It isnevertheless possible for the grammage of the protective layer 4 to be comprised in a 500 ± 300 g / m2range, or in a 500 ± 200 g / m2range. These grammage values enable the protective layer 4 to perform, in addition to the protective action, also an effective action of anchoring by friction.

[0066] A component of the protective layer 4 may be, in particular, a geotextile in polypropylene PP. A component of the waterproof layer 3 may be, in particular, a plasticized polyvinyl chloride PVC-P -based geomembrane. The waterproof layer 3 may be made, in particular, not only of polyvinyl chloride PVC, but also of other materials, for example, of polyethylene or other polyolefins of varying density (HDPE, LDPE, VLDPE, EPDM, TPO, EVA, etc).

[0067] It is possible for the protective layer 4 to comprise polypropylene PP, the waterproof layer 3 to comprise polyvinyl chloride PVC (or polyethylene, or other polymer materials) and the protective layer 4 and the waterproof layer 3 to be coupled together by thermofusion during manufacturing.

[0068] The method for waterproofing comprises the step of depositing the lining sheets 2 contiguously alongside one another to line the bed 1 such that, for each lining sheet 2, the protective layer 4 is below the waterproof layer 3 and in contact with a bottom 5 of the bed 1. Each lining sheet 2 may have, in particular, a rectangular shape that extends longitudinally over the entire length of the bed 1 or over at least one part of the width.

[0069] Each lining sheet 2 may be supplied in the form of a roll 6 that is positioned (see Figure 3) on a hydraulically driven carriage 7 (for example, a carriage 7 of known type) and is then unrolled by the carriage 7 and installed to line the sides and the bottom of the bed 1 (see Figures 4 and 5).

[0070] The lining sheets 2 are so deposited alongside one another that each lining sheet 2 comprises at least one lower sheet portion 2’ that lines the bottom of the bed 1 and at least one upper sheet portion 2” that lines an upper zone of a bank of the bed 1. In particular, each lining sheet 2 may comprise two upper sheet portions 2”, which are opposite one another, each of which lines an upper zone of each of the two opposite banks of the bed 1 (in this case, an earth canal). Each lining sheet 2 may comprise, in particular, an intermediate leaf portion 2”’ that is interposed between the lower sheet portion 2’ and the upper sheet portion 2” and lines a slope (generally tilted) of a bank of the bed 1. In thisembodiment, each lining sheet 2 comprises two intermediate sheet portions 2”’ interposed between the lower sheet portion 2’ and the two upper sheet portions 2”.

[0071] Each lining sheet 2 may be provided, in particular, with two side zones 8 and with two sealing lateral wings 9. Each sealing lateral wing 9 is connected watertight to a respective lateral zone 8. A part of a zip 10 is connected watertight to each sealing lateral wing 9. Purely by way of non-limiting example, each sealing lateral wing 9 may be about 50 cm wide and each zip 10 (formed by two joined hinge parts) may be overall about 20- 30 cm wide.

[0072] The method for waterproofing comprises the step of joining together each pair of contiguous lining sheets 2 by a respective watertight zip 10. In particular, it is possible for the lining sheets 2 (for example wound in rolls 6) to be extended sequentially (for example by unwinding the rolls 6, laying the rolls 6 on the bottom 5 and simultaneously joining the sealing wings 9 of contiguous sheets by the zip 10. It is also possible for an end of the lining sheet 2 to be provisionally fixed to the bank from which the unrolling operation starts between the two opposite banks of the bed 1 (canal) by anchoring pickets, in particular to facilitate extending the lining sheet 2 during underwater laying by guiding the carriage 7.

[0073] The watertight zip 10 allows a watertight mechanical connection between longitudinal edges of adjacent lining sheets 2, maintaining the sheets together structurally and functionally independent, i.e. able to be easily removed if damaged and replaced with a new lining sheet 2, restoring the continuity and seal of the waterproof lining.

[0074] Each lateral zone 8, to which a respective sealing lateral wing 9 is connected watertight, may consist, in particular, of a lateral end portion of the two-layer geocomposite.

[0075] Each sealing lateral wing 9 is flexible and may consist, in particular, of just one waterproof layer, for example a layer equal to the waterproof layer 3 of the two-layer geocomposite. Each flexible sealing lateral wing 9 may be, in particular, welded to the upper waterproof layer 3 of the geocomposite, in particular at each longitudinal side of the lining sheet 2.

[0076] Each sealing lateral wing 9, to which the joining means is zipped watertight, has a width that is such as to protrude laterally from the respective longitudinal edge of thelining sheet 2, so as to form a slack zone when the sealing lateral wings 9 reciprocally facing two contiguous lining sheets 2 are zipped together watertight by the zip 10. This slack zone enables possible misalignments between adjacent lining sheets 2 during laying of a sheet to be compensated.

[0077] The watertight zip 10 may comprise, in particular, an interlocking mechanism with two toothed bands 11 and 12, i.e. a toothed band 11 welded along an edge of a sealing lateral wing 9 of a lining sheet 2 and another toothed band 12 welded to a sealing lateral wing 9 of a contiguous sheet. A cursor 13 is provided for engaging and disengaging the two toothed bands 11 and 12 of the zip. During the step of arranging the lining sheets 2 to line the bed 1, the cursor 13 is connected to the carriage 7, for example by a (flexible) traction element 14.

[0078] Each zip 10 may comprise, in particular, two seals for sealing the zip. Each seal is welded (during the prefabrication step) to an end side edge of a respective sealing lateral wing. Each seal may comprise, in particular, a longitudinal element (for example, with a full cross section or with a hollow cross section) made of elastomer material, for example made of silicone or EPDM synthetic rubber.

[0079] When the zip 10 is closed, the two seals are arranged facing in contact with pressure against one another and remain trapped inside the interlocking mechanism, interposed and closed between the two toothed bands 11 and 12, to ensure the watertight seal.

[0080] The zip 10 enables two contiguous lining sheets 2 to be joined together directly during laying (dry or underwater), maintaining the structural and functional independence of the sheets. Further, the use of disengageable zip fasteners enables a single damaged lining sheet to be removed and replaced easily with a new waterproof sheet rapidly and without interrupting the flow of water or emptying the bed.

[0081] The method for waterproofing comprises the step of setting up appropriate ballast materials and / or elements 15 which are external, distinct, and independent of the lining sheets 2. The method for waterproofing comprises the step of depositing reversibly the ballast materials and / or elements 15 above and in contact with the upper sheet portion 2” of each lining sheet 2 so as to ballast each lining sheet 2 in one or more ballasting areas.

[0082] These ballasting areas may be in particular identified according to at least onemorphological feature of the bed 1 and / or according to at least one fluid dynamic feature of the water of the bed 1.

[0083] The aforesaid morphological feature may comprise, in particular, a depth of the bed 1. The aforesaid morphological feature may comprise, in particular, a width of the bed 1. The aforesaid morphological feature may comprise, in particular, a slope of a bank of the bed 1. The aforesaid morphological feature may comprise, in particular, a geometric conformation of a cross section of the bed 1. The aforesaid morphological feature may comprise, in particular, a geotechnical parameter of the bottom of the bed 1.

[0084] The aforesaid fluid dynamic feature may comprise, in particular, a flow speed of the water of the bed 1. The aforesaid fluid dynamic feature may comprise, in particular, the viscosity of the water of the bed 1. The aforesaid fluid dynamic feature may comprise, in particular, the turbidity of the water of the bed 1.

[0085] An example is disclosed below of a calculation of the ballast according to the speed of the flow of water, in which the ballast is provided by way of non-limiting example by using concrete blocks 16. Each block 16 is parallel epipedon-shaped with a square base, with thickness equal to 0.35 m (35 cm) and with a base side measuring “a” (see Figure 11). In particular, the ballast consists of a square mesh lattice of concrete blocks 16 distributed at the same distance “d” from one another. The space “d” between the blocks 16 is measured between the centers of the various blocks 16.

[0086] It is considered that in these examples of ballast calculations, the weight of the concrete underwater is about 15 kN / m3, calculated as the difference between the weight of the concrete (25 kN / m3) and the floating thrust (10 kN / m3).

[0087] A table of the dimension “a” of the side of a single block 16 is shown below, belonging to the lattice of blocks 16 that forms the ballast, which is suitable for correct ballasting according to the speed of the flow of water, considering a distance “d” to be equal to 5 meters of lattice:Distance “d” between the blocks = 5 m

[0088] A table is shown below of dimension “a” of the side of a single block 16, belonging to the lattice of blocks 16 that forms the ballast, which is suitable for correctballasting according to the speed of the flow of water, considering a distance “d” to be equal to 10 meters of lattice:Distance “d” between the blocks = 10 m

[0089] The aforesaid calculation of the ballast comprises a system of non-linear equations with a plurality of variables, including the volume of the ballast, the density of the ballast, the distance between the discrete elements of ballast and the gap between the discrete elements of ballast. The calculation of the ballast (in particular, of the weight of ballast per surface unit to be ballasted) depends on the square of the speed of the flow of water.

[0090] The method for waterproofing may comprise, in particular, before the step of depositing the lining sheets 2 to line the bed 1, the step of performing at least an excavation (see Figure 1) to make at least one berm 17 on an upper part of at least one of the banks of the bed 1. The berm 17 may be, in particular, horizontal or at least partially horizontal.

[0091] It is in particular possible that for each lining sheet 2 the upper sheet portion 2” lines at least partially the aforesaid berm 17. It is further possible, in particular that for each lining sheet 2 the ballast materials and / or elements 15 are deposited above the upper sheet portion that lines the berm 17 above and in contact with this upper sheet portion 2”.

[0092] In this case it is possible that the ballast materials and / or elements 15 that are deposited above and in contact with the upper sheet portion 2” that lines the berm 17 comprise possibly at least partially the materials of the aforesaid excavation performed to make the berm 17.

[0093] It is possible, in particular, that the ballast materials and / or elements 15 used to ballast the lining comprise, in addition to or in replacement of the excavation materials of the berm 17, gabions (made of iron or a synthetic material or another material) filled with stones and / or earth that may be mixed with cement or bentonite and / or prefabricated concrete elements like, in particular, concrete slabs and / or beams. Each of the aforesaid gabions may comprise a flexible gabion (rock bag) made, in particular, with a net of synthetic material, for example a net with a double layer of polyester yam.

[0094] It is possible, in particular, for each intermediate leaf portion 2”’ lining a slopeof a respective bank of the bed 1 not to have any overlap of ballast materials and / or elements. In practice, the intermediate leaf portion 2”’ is in direct contact with the water of the bed 1, so that the upper layer 3 in geomembrane may facilitate the running of the water and promote the flow thereof.

[0095] As said, it is possible for the lining sheets 2 to be supplied in rolls 6 and for the step of depositing the lining sheets 2 to line the bed 1 to comprise the step of unrolling the aforesaid rolls 6. The step of joining a pair of contiguous lining sheets 2 may be performed, in particular, by the aforesaid zip 10 at the same time as unrolling the roll of one of the two contiguous lining sheets 2 that are joined together.

[0096] The method for waterproofing may comprise, in particular, the step of depositing further ballast materials and / or elements 18 above the lower sheet portion 2’ of each lining sheet 2. These further ballast materials and / or elements 18 may comprise, in particular, at least one part of the excavation materials for making the berm 17 and / or other earth and / or earth mixed with cement or bentonite and / or concrete and / or prefabricated concrete elements (in particular concrete slabs and / or beams) and / or gabions (made of iron or a synthetic material or another material) filled with stone.

[0097] The method for waterproofing may comprise, in particular, the step of laying a geotextile above the waterproof lining, after joining the lining sheets 2 by the watertight zip 10 and before depositing ballast, to protect the waterproof layer 3 from the ballast.

[0098] The aforesaid further ballast materials and / or elements 18 may be deposited to cover in a discrete manner the lower sheet portions 2’ of the lining sheets 2 that line the bottom of the bed. It is possible for the aforesaid ballast materials and / or elements 15 to be deposited to cover continuously the upper sheet portions 2” of the lining sheets 2 that line the berms 17.

[0099] As has been seen, a waterproof lining for a bed of water has been disclosed, which waterproof lining may be used in particular to implement the method for waterproofing disclosed above. The waterproof lining comprises a plurality of lining sheets 2 each of which consists of a single geocomposite of just two layers coupled with one another. The aforesaid two layers are a waterproof layer 3 and a protective layer 4. The waterproof layer 3 consists of a geomembrane with a permeability coefficient K comprised between IO-9m / sec and ICT15m / sec. A grammage of the protective layer 4 is greater than200 g / m2. A component of the protective layer 4 is polypropylene PP and a component of the waterproof layer 3 is plasticized polyvinyl chloride PVC-P (or polyethylene or other polyolefins of varying density, for example HDPE, LDPE, VLDPE, EPDM, TPO, EVA, etc). The protective layer 4 is a nonwoven geotextile layer. Each lining sheet 2 is provided on two opposite sides with elements of a watertight zip 10 that is so configured as to be able to join together contiguous lining sheets.

[0100] The aforementioned objects and advantages are achieved by the method in question, in particular: as the waterproof lining is formed by sheets joined by a zip 10, in which each lining sheet 2 consists of a single geomembrane with just two layers, both laying and installation of the lining are made easier without compromising sealing efficacy and the possible removal of a single damaged lining sheet 2 is made easier; the use of external and easily removable ballasting means independently of the lining sheets, together with the simplicity and constructional lightness of the waterproof lining and the removability of the watertight coupling between the lining sheets 2, makes the removal of a single lining sheet 2 even more convenient and easier; selecting ballasting areas on the basis of one or more operating parameters enables a desired lining anchoring action to be achieved rationally and without wasting resources, further facilitating possible subsequent local removal of the ballast materials and / or elements in one or more of the aforesaid ballasting areas, at the single lining sheet 2 that it is desired to remove.

Claims

CLAIMS1. Method for waterproofing the bottom and banks of a bed (1) of water, said method comprising the steps of: prefabricating lining sheets (2) each of which is made up of a single geocomposite with only two layers coupled on top of each other, said two layers being a waterproof layer (3) and a protective layer (4); joining, to each of said lining sheets (2), two sealing lateral wings (9) to which two toothed bands (11; 12) suitable to form a watertight zip (10) are connected; carrying out an excavation, dry and / or in water, to create at least one berm (17) on an upper part of each of said banks; arranging, at least partly under water, said lining sheets (2) contiguously next to each other to line said bed (1) so that said protective layer (4) is under said waterproof layer (3) and in contact with a soil of said bed (1) and so that each lining sheet (2) comprises a lower sheet portion (2’) and two upper sheet portions (2”), wherein said lower sheet portion (2’) at least partially lines said bottom and each of said two upper sheet portions (2”) at least partially lines said at least one berm (17) created on an upper part of a respective bank; joining contiguous lining sheets (2) to each other by means of said watertight zip (10); preparing ballast materials and / or elements (15) which are external, distinct, and independent from said lining sheets (2); and reversibly depositing said ballast materials and / or elements (15) on top and in contact with said upper sheet portions (2”) each of which at least partially lines a respective berm (17).

2. Method according to claim 1, wherein said step of reversibly depositing is made for creating one or more ballasting areas identified according to at least one fluid dynamic characteristic of the water of said bed (1).

3. Method according to claim 2, wherein said at least one fluid dynamic characteristic includes a flow speed of the water of said bed (1) and / or a viscosity of the water of said bed (1) and / or a turbidity of the water of said bed (1).

4. Method according to any one of the preceding claims, wherein said step of reversiblydepositing is made for creating one or more ballasting areas identified according to at least one morphological characteristic of said bed (1).

5. Method according to claim 4, wherein said at least one morphological characteristic includes a depth of said bed (1) and / or a width of said bed (1) and / or a slope of a bank of said bed (1) and / or a conformation of a section of said bed (1) and / or a geotechnical parameter of said soil of said bed (1).

6. Method according to any one of the preceding claims, wherein said ballast materials and / or elements (15), which are deposited on top and in contact with said upper sheet portions (2”), comprise excavated materials.

7. Method according to any one of the preceding claims, wherein said ballast materials and / or elements (15) comprise gabions filled with stones, in particular gabions made of iron or synthetic material, and / or wherein said ballast materials and / or elements (15) comprise earth and / or a mixture comprising earth and cement and / or bentonite.

8. Method according to any one of the preceding claims, wherein said ballast materials and / or elements (15) comprise prefabricated concrete elements, in particular concrete slabs and / or beams.

9. Method according to any one of the preceding claims, wherein a basic weight of said protective layer (4) is greater than 200 g / m2.

10. Method according to any one of the preceding claims, wherein a basic weight of said protective layer (4) is greater than 250 g / m2, or greater than 300 g / m2, or greater than 350 g / m2, or greater than 400 g / m2, or within a range of 500 ± 300 g / m2, or within a range of 500 ± 200 g / m2.

11. Method according to any one of the preceding claims, wherein a component of said protective layer (4) is polypropylene PP and a component of said waterproof layer(3) is plasticized polyvinyl chloride PVC-P.

12. Method according to any one of the preceding claims, wherein said protective layer(4) is a nonwoven geotextile layer and / or wherein said waterproof layer (3) has a thickness between 1 and 5 mm and / or wherein said waterproof layer consists of a geomembrane, in particular a geomembrane with a permeability coefficient K between IO-9m / sec and ICT15m / sec.

13. Method according to any one of the preceding claims, wherein said lining sheets (2)are supplied in rolls (6) and said step of arranging said lining sheets (2) to line said bed (1) comprises the step of unrolling said rolls (6), and wherein the step of joining contiguous lining sheets (2) is carried out by means of said zip (10) simultaneously with an unrolling of a roll (6) of one of said contiguous lining sheets.

14. Method according to any one of the preceding claims, comprising the step of depositing further ballast materials and / or elements (18) on top of said lower sheet portion (2’) of each of said lining sheets (2).

15. Method according to claim 14, wherein said further ballast materials and / or elements (18) comprise earth and / or earth mixed with cement or bentonite and / or concrete and / or prefabricated concrete elements, in particular concrete slabs and / or beams, and / or gabions filled with stones, in particular gabions made of iron or synthetic material.

16. Method according to claim 14 or 15, wherein said further ballast materials and / or elements (18) are deposited to discretely line said lower sheet portions (2’) of said lining sheets (2).

17. Method according to any one of the preceding claims, wherein said ballast materials and / or elements (15) are deposited to continuously line said upper sheet portions (2”) of said lining sheets (2).

18. Method according to any one of the preceding claims, wherein each lining sheet (2) comprises two intermediate sheet portions (2”’) which are interposed between said lower sheet portion (2’) and said upper sheet portions (2”) and which are left free in direct contact with the bed water without overlapping any ballast materials and / or elements.

19. Method according to any one of the preceding claims, wherein said at least one berm (17) is horizontal or at least partly horizontal.

20. Waterproof lining for a water bed, usable in particular to implement a method according to any one of the preceding claims, said waterproof lining comprising a plurality of lining sheets (2) each of which is constituted by a single geocomposite with only two layers coupled on top of each other, said two layers being a waterproof layer (3) and a protective layer (4), said protective layer (4) being a nonwoven geotextile layer, each of said lining sheets (2) being provided on two opposite sideswith toothed bands (11; 12) of a watertight zip (10) configured so as to be able to join adjacent lining sheets (2) to each other using said zip (10).

21. Waterproof lining according to claim 20, wherein said waterproof layer (3) is made up of a geomembrane with a permeability coefficient K between 10-9m / sec and 10-15m / sec, and / or wherein a basic weight of said protective layer (4) is greater than 200 g / m2, and / or wherein a component of said protective layer (4) is polypropylene PP, and / or wherein a component of said waterproof layer (3) is plasticized polyvinyl chloride PVC-P.

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