Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D19/00—Keeping dry foundation sites or other areas in the ground
  • E02D19/06—Restraining of underground water
  • E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
  • E02D19/16—Restraining of underground water by damming or interrupting the passage of underground water by placing or applying sealing substances
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D19/00—Keeping dry foundation sites or other areas in the ground
  • E02D19/06—Restraining of underground water
  • E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
  • E02D19/18—Restraining of underground water by damming or interrupting the passage of underground water by making use of sealing aprons, e.g. diaphragms made from bituminous or clay material

Definitions

• the present invention relates to a method for introducing a moisture-impermeable layer into the ground, wherein the moisture-impermeable layer is placed into the ground in a trench, as well as a trench obtained by such a method.
• German Offenlegungsschrift no. 37 17 885 discloses a method for producing a sealing course of mineral sealing materials, such as, for example, bentonite, using a trench method, wherein the dry material is introduced into a trench.
• One drawback of said method is the fact that the dry mixture comes into direct contact with possibly contaminated water from the environment upon being introduced into the trench, which interferes with the swelling capacity of the bentonite, which is still dry at that stage, as a result of which the durability thereof is affected in comparison with bentonite that has been hydrated in advance. No further details with regard to the composition are provided.
• US patent no. 3,986,365 relates to a method for forming a moisture-impermeable layer, wherein a composition of sand and bentonite is mixed with a water-soluble polymer.
• the mixture thus obtained is only suitable for horizontal use under water basins, and owing to the properties of bentonite and sand, which are not specified in detail, this mixture is not suitable for use in vertical sealing systems.
• Such methods based on liquid slurries are characterized by a very low density in dry condition and a large specific surface area, however, as a result of which cracks are easily formed due to contraction.
• the slurry only provides limited resistance against penetration of the adjacent soil, so that local failure of the wall may occur. Since the impermeability of the slurries is relatively high in comparison with the density of the materials having a higher dry mass that are used in conventional horizontal seals, a relatively thick wall is necessary in order to provide sufficient certainty.
• the object of the present invention is to provide a method for introducing a moisture-impermeable layer into the ground, wherein the aforesaid problems of the prior art are eliminated to a significant degree.
• Another object of the present invention is to provide a method for introducing a moisture-impermeable layer into the ground, which method comprises a sealing system that corresponds to the horizontal sealing systems or the surface sealing systems that have been usual so far.
• the method as referred to in the introduction is according to the present invention characterized in that the trench is supported by one or more casing members, which trench is subsequently filled with a clay-containing mixture of dry solids, which mixture can form a moisture-resistant gel, comprising powdery or pulverized smectite and/or smectite-containing natural rock and a water-soluble polymer.
• Such a clay-containing mixture of dry solids is known per se from European patent no. 0 682 684 in the name of the present applicants. From said European patent the special application in accordance with the present invention, viz. the forming of a trench in the ground, which trench is subsequently filled with the clay-containing mixture of dry solids, is not known, however, which application must be considered to be novel and inventive, therefore.
• a clay-containing mixture capable of forming a moisture-resistant gel is known from European patent no. 0 335 653, but the application that is known therefrom is essentially different from the present application.
• the trench in the ground by using one or more casing members, wherein one or more hollow elements are installed in the ground, said elements consisting of at least two plates which are interconnected by means of spacers, which plates may include a disconnectable closure part on their bottom sides.
• a tight seal on the sides of the elements may also function as a spacer, which seal can also serve as a guide for the adjacent elements.
• the hollow element is filled with the clay-containing mixture of dry solids first before being installed in the ground, after which the element thus filled is installed in the ground.
• the hollow element is lined with a material on the inside before the element is filled with the clay-containing mixture of dry solids, which material prevents the clay-containing mixture of dry solids from adhering to the hollow element.
• Such a material facilitates sliding of the hollow element upon being removed from the trench, and it also functions as a barrier layer between the clay-containing mixture of dry solids and the adjacent soil.
• An example of such a material is geofabric.
• one or more hollow elements comprising a number of compartments.
• a different composition for example one compartment containing the clay-containing mixture of dry solids and one compartment containing sand.
• Such an embodiment is in particular advantageous if it is not necessary to fill the trench with the same clay-containing mixture of dry solids along its entire length, depth and width, so that generally a cost saving is achieved.
• the trench that has been formed in the ground is lined on both longitudinal sides thereof with one or more casing members consisting of one or more panels, after which the space thus enclosed by the panels is filled with the clay-containing mixture of dry solids.
• the clay-containing mixture of dry solids in the trench is densified by removing the panels from the trench in such a manner that this leads to densification of the clay-containing mixture of dry solids that is present in the trench.
• Such densification is obtained in particular if the panels are vibrated upon being removed from the trench.
• the panels In a special embodiment it is preferable to line the panels with a material on the side facing away from the soil before the panels are filled with the clay-containing mixture of dry solids, which material prevents the clay-containing mixture of dry solids from adhering to the panel.
• a material makes it easier for the panel to slide upon being removed from the trench, and it furthermore functions as a barrier layer between the clay-containing mixture of dry solids and the adjacent soil.
• the densification of the clay-containing mixture in the trench has resulted in a certain drop in the level of said mixture in the trench, it is preferable to fill the space that has thus formed, preferably with the same clay-containing mixture of dry solids. It is not inconceivable, however, to use a filling material other than the present clay-containing mixture of dry solids, for example sand. Thus the trench is filled in stages.
• a supporting fluid when forming the trench in the ground, in order to prevent the side walls of the trench from caving in. Furthermore it is preferred that the supporting fluid be forced out of the trench upon installation of the hollow elements and/or the mat in the trench.
• the smectite is preferably in an inactive state, that is, the lattice sodium and lithium ions that may be present do not make up more than 30% of the sum of the exchangeable lattice cations.
• the smectite may be one of the following: montmorillonite, beidellite, hectorite, montronite, saponite, illite, allevardite, mixtures thereof, natural rock containing one or more of the above (such as bentonite), or artificial mixtures of smectite-type silicate compounds (for example Laponite (trademark), Laporte Co., Great Britain).
• the moisture content of the present clay-containing mixture of dry solids is preferably ⁇ 20%, whereby the desired moisture content is determined to a significant degree by the manner in which said mixture is processed, as well as by the dimensions of the trench.
• a moisture content of ⁇ 10% will be preferred when a narrow trench is to be filled, in connection with the required flow characteristics of the clay-containing mixture; it will also be possible, however, to fill a hollow element outside the trench with a mixture having a moisture content of maximally 20%.
• the clay-containing mixture of dry solids additionally comprises a powdery solid activating agent in an amount of 0.8 - 6.0 wt. %, based on the weight of the smectite.
• the clay-containing mixture preferably comprises more than 0.5 wt. % of one or more solid inert fillers having an average particle size of more than 0.05 mm, based on the weight of the smectite.
• the clay-containing mixture of dry solids contains in particular 1 - 95 wt. % of a solid inert filler, based on the weight of the overall mixture. It is in particular preferred for the solid inert filler to have a particle size of 0.1 - 8.0 mm.
• Each water-soluble polymer which is capable of reacting with smectite can be used as the polymer component in the present clay-containing mixture of dry solids.
• polymers to be used are polyacrylamide having a degree of hydrolysis of less than 40%, polymethacrylamide, acrylamide-acrylic acid-copolymers, vinyl alcohol-acrylic acid copolymers, polyethylene oxides and mixtures thereof. It is also possible to use graft polymers, such as acrylamide grafted onto a cellulose backbone.
• the molecular weight of the polymer is generally less than 15,000,000, with the preferred molecular weight ranging between 400,000 and 10,000,000.
• the clay-containing mixture of dry solids may also comprise one or more solid inert fillers, for example sand, silica compounds, pulverized rock or minerals, a pulverized ceramic material or a mixture thereof.
• solid inert fillers for example sand, silica compounds, pulverized rock or minerals, a pulverized ceramic material or a mixture thereof.

Landscapes

• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Hydrology & Water Resources (AREA)
• Paleontology (AREA)
• Mining & Mineral Resources (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Civil Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Revetment (AREA)
• Bulkheads Adapted To Foundation Construction (AREA)
• Building Environments (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

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• 2000
  • 2000-01-26 NL NL1014185A patent/NL1014185C2/nl not_active IP Right Cessation
• 2001
  • 2001-01-25 WO PCT/NL2001/000049 patent/WO2001055514A1/en active IP Right Grant
  • 2001-01-25 JP JP2001554536A patent/JP2003520916A/ja active Pending
  • 2001-01-25 AT AT01906414T patent/ATE254699T1/de not_active IP Right Cessation
  • 2001-01-25 US US10/181,920 patent/US20030111425A1/en not_active Abandoned
  • 2001-01-25 DE DE60101258T patent/DE60101258T2/de not_active Expired - Lifetime
  • 2001-01-25 AU AU34242/01A patent/AU779942B2/en not_active Ceased
  • 2001-01-25 EP EP01906414A patent/EP1250494B1/en not_active Expired - Lifetime
  • 2001-01-25 CN CNB018042201A patent/CN1177977C/zh not_active Expired - Fee Related

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