Method and device for inserting a drainage wick

Abstract

A method and device for inserting a drainage wick into the ground wherein the method includes the steps of: threading a drainage wick through an inserting tube;fixing a portion of a tie to the lower end of the drainage wick;fixing an anchorage component to another portion of said tie, where said tie is loose between the drainage wick lower end and the anchorage component when the anchorage component contacts the inserting tube lower end;driving a anchorage component, the drainage wick and the inserting tube downwardly into the ground;pulling up the inserting tube and the drainage wick, whereby said anchorage component is permitted to remain in the ground; andfurther pulling up the inserting tube whereby the anchorage component and the drainage wick are permitted to remain in the ground.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagrammatic perspective view of a device used for implementing the process of an embodiment according to the invention;

FIGS. 2A-2D are a series of diagrams of a longitudinal section of a portion of the device equipment depicting the different process steps;

FIG. 3 A is a diagrammatic longitudinal section of a portion of an embodiment of a device according to the invention;

FIG. 3 B is a diagrammatic transverse section along the lines III B-III B of FIG. 3 A; and

FIG. 4 is a diagrammatic longitudinal section of a portion of the equipment and of the ground according to one process feature of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

An embodiment of a device used to implement an example of a process according to the invention is shown in FIG. 1 and comprises: a frame formed by a hydraulic crane 1; a mast, column, shaft or guide 2; an inserting tube 3; supply means 4 for a drainage wick 5; and a drive member such as a cable 6. Guide 2 is arranged in a generally vertical position in operating conditions.

The guide 2 may typically comprise a hollow tube for example, which has been inserted or is insertable into the soil. Assuming that the guide 2 has been inserted into the soil, the wick inserting tube 3 may then be moved or directed through the guide or guide tube 2 to transfer the drainage wick 5 into the soil. That is, the inserting tube 3 is moved in a downward direction through the guide tube 2 by means of a loop of cable 6 having opposite ends attached to a fastening element attached to the tube 3. The closed loop of cable 6 fits over the reversing driven wheel 7 at the top end of crane 1 and an idler 7A at the lower end of guide 2. The inserting tube 3 may therefore be set into movement by rotating the cable 6 about the reversing wheel 7. Alternatively, the inserting tube 3 may be directed in a downward direction into the soil by vibration means in guide tube 2.

Further steps of the described process are shown sequentially in FIGS. 2A-2D.

FIG. 2 A shows the step before inserting the tube 3 into the ground: a drainage wick 5 is unwound from wick supply means 4, positioned or guided over a wheel 8 and threaded through inserting tube 3. When lower end 51 of drainage wick 5 is coming out or close to the lower end 15 of inserting tube 3, one can fix a portion of a loose tie or connector 10 at the lower end 51 of drainage wick 5 and another portion of said loose tie 10 to a fixation point 12, such as a ring, of anchorage component 11. (FIG. 2-C).

The anchorage component 11 shown in FIG. 2 A is a disc which diameter is slightly larger than the maximum size of the external part of the section of inserting tube 3.

The distance between the anchorage component 11 and the lower end 51 of drainage wick 5 is lower or less than the distance between the two portions of the tie 10 fixed to above mentioned parts, 51 and 12. Thus initially, the anchorage component 11 is laying on the ground level 40; the drainage wick lower end 51 is situated just above it, and the lower end 15 of inserting tube 3 contacts said anchorage component 11 so that the tie or connector 10 is loose or unextended.

FIG. 2 B illustrates the driving step of anchorage component 11 and drainage wick 5 downwardly into the ground with inserting tube 3. The tie 10 remains loose.

According to an embodiment of the present invention, loose tie 10 is kept loose thanks to a temporary bond. Drainage wick 5 and anchorage component 11 are driven downwardly into the ground by means of inserting tube 3. The strength of said temporary bond is designed as to be higher than tractive effort when driving inserting tube 3 downwardly and lower than anchorage resistance of anchorage component 11. The temporary bond breaks when pulling up inserting tube 3.

According to another embodiment of the present invention, means are included in the device for inserting the drainage wick so that the distance between wheel 8 and upper part 16 of inserting tube 3 remains constant when driving inserting tube 3 downwardly. No stress is applied on drainage wick 5 nor tie 10, so that tie 10 remains loose when driving downwardly into the ground inserting tube 3.

When the lowest desired position of the inserting tube 3 is reached, the inserting tube 3 is pulled up and the anchorage component 11 is permitted to remain into the ground. The lower end 51 of the drainage wick remains inside the inserting tube 3 up to the moment where the tie portion 10 between the lower end 51 of drainage wick 5 and fixation point 12 of anchorage component 11 is completely tightened as shown in FIG. 2 C. The distance between lower end 51 of drainage wick 5 and fixation point 12 of anchorage component 11 is then, for example, 1 meter.

The inserting tube 3 is subsequently pulled up further detaching the lower end 51 from tube 3 and the anchorage component 11 pulls on drainage wick 5 so that both anchorage component 11 and drainage wick 5 are permitted to remain into the ground.

After pulling out inserting tube 3, drainage wick 5 is cut near ground level 40 and another drainage wick can be installed.

Referring to FIG. 3A, gas, namely compressed air, may be introduced in inserting tube 3 when frictional means or retention means, such as a balloon 21, compresses drainage wick 5 into the internal wall of inserting tube 3. Thus, valve 23 may be opened to permit pressurized air from conduit 24 to flow through inlet conduit 22 to expand balloon 21 from its uninflated position (20 in FIG. 4) to its expanded position depicted in FIGS. 3 and 4. In the expanded position, wick 5 is fixed in tube 3 and will be pulled from storage drum 4 over pulley or wheel 8 as tube 8 moves into the soil. In this manner, strain on wick 5 is diminished and the bond at end 51 is maintained during placement of tube 3 into the soil.

Also, in the device of FIG. 3 A, a gas inlet 30 is located under balloon 21 to provide compressed air generated by compressor 33. A tube 32 connects compressor 33 to a valve 31. Valve 31 is opened when it is desired to introduce compressed gas into inserting tube 3 in order to push anchorage component 11 into the ground.

Referring to FIG. 3B there is further depicted the schematic view of the mechanism which may be used to retaining the drainage wick 5 in engagement with the interior wall of the inserting tube 3. Thus, there is depicted the external guide or guide tube 2 which receives the inserting tube 3. The wick 5 is positioned within the inserting tube 3. Inflatable balloon 21 may be expanded from a non-engaged position 20 to an engaged position, as depicted in FIG. 3B by providing compressed gas through the inlet 22. In this manner, the wick 5 will be held in a fixed position within the inserting tube 3 as the tube 3 is driven or positioned into the soil by movement within the guide 2. Thus, the wick 5 will be in position during removal of the insertion tube 3.

FIG. 4 shows an application of the process and apparatus disclosed. The ground in FIG. 4 consists of two soil layers: layer 41 is a soft soil layer and layer 42 is a hard soil layer.

Inserting tube 3, anchorage component 11 and the bottom of drainage wick 5 are driven downwardly into the hard soil layer 42, penetrating in said hard soil layer 42 to a distance less than the length between fixation points 12, 51 of tie 10 when tie 10 is tightened. Inserting tube 3 and drainage wick 5 are then pulled up and the bottom end 51 of drainage wick 5 is, as a result, located in the soft soil layer 41 above the hard soil layer 42. It is thus possible to take advantage of the hard soil layer 42 to fix anchorage component 11.

The soil around anchorage component 1 typically rearranges when pulling up inserting tube 3 and drainage wick 5. As bottom end 51 of drainage wick 5 is located in soft soil layer, no connection between hard soil 42 and drainage wick 5 can occur, since they are separated by a tie connection or connector, which is typically not water conductive. It is then possible to avoid water contamination when hard soil 42 contains aquifer table or to allow processing vacuum soil consolidation.

The invention is not restricted to the above described embodiments which can be varied in a number of ways within the scope of the claims.

Claims

1. A method for inserting a drainage wick into the ground comprising the steps of: threading said drainage wick through an inserting tube;fixing a portion of a tie to the lower end of said drainage wick;fixing an anchorage component to another portion of said tie, where said tie is loose between the drainage wick lower end and the anchorage component;driving said anchorage component, said drainage wick and said inserting tube downwardly into the ground;pulling up said inserting tube and said drainage wick, whereby said anchorage component is permitted to remain into said ground; andfurther pulling up said inserting tube whereby said anchorage component and said drainage wick are permitted to remain into said ground, said wick being separated from said anchorage component.

2. A method according to claim 1 comprising the steps of: jamming the drainage wick before the inserting tube is firstly pulled up;releasing the drainage wick before the inserting tube is further pulled up.

3. A method according to claim 2 comprising the step of introducing compressed air in said inserting tube after the drainage wick jamming step.

4. A method according to claim 1 comprising the steps of: closing the lower end of said inserting tube with a shutter before driving said anchorage component and said drainage wick downwardly into the soilreleasing said shutter before and/or when pulling up said inserting tube.

5. A method according to claim 1 comprising the step of filling the soil zone around the anchorage component with a sealing material before or when said inserting tube and said drainage wick are pulled up.

6. A method according to claim 1 where the distance between the position the anchorage component is permitted to remain in the soil and the position the drainage wick end is permitted to remain in the soil is at least 0.10 m, and preferably no more than 2 m.

7. A method according to claim 1 where said tie is selected from the group consisting of a rope, a cord, a cable.

8. A method according to claim 1 where said sealing material comprises water expandable material.

9. A method according to claim 5 where said anchorage component and said drainage wick are driven downwardly into a layer of soft soil and are permitted to remain in said layer of soft soil.

10. A method according to claim 1 where said anchorage component and said drainage wick are driven downwardly into a layer of hard soil situated underneath a layer of soft soil and said anchorage component is permitted to remain in said layer of hard soil where said drainage wick is permitted to remain in said layer of soft soil.

11. A device for inserting a drainage wick downwardly into the earth and which includes: a drainage wick;an inserting tube that is adapted to surround and protect said drainage wick as the inserting tube penetrates downwardly into the earth,a guide which is designed to initially position said inserting tube generally vertically above the earth,means to move said inserting tube from its initial generally vertical position downwardly with respect to said guide so that said inserting tube and the drainage wick it protects will penetrate into earth; andmeans for jamming said drainage wick into said inserting tube.

12. A device for inserting a drainage wick downwardly into the earth and which includes: a drainage wick;an inserting tube that is adapted to surround and protect said drainage wick as the inserting tube penetrates downwardly into the earth,a guide which is designed to initially position said inserting tube generally vertically above the earth,means to move said inserting tube from its initial generally vertical position downwardly with respect to said guide so that said inserting tube and the drainage wick it protects will penetrate into earth; anda blockage element arranged into said inserting tube able to operate to retain said drainage wick in said inserting tube.

13. A device according to claim 12 where said blockage element is a gas expandable balloon.

14. A device according to claim 12 where said blockage element is a movable plate, such as a folding plate or a plate sliding in a slot arranged in said inserting tube.

15. A device according to claim 12 comprising a compressed gas inlet arranged in said inserting tube below said blockage element

16. A device according to claim 15 where both blockage element and compressed gas inlet are arranged close to one another, near the upper end of said inserting tube.