Method and apparatus for stabilising a dike

Abstract

A method of stabilizing a dike using a ground anchor assembly, includes: connecting a ground anchor to a first end of a tensile member; introducing the ground anchor through the earth body and into a stable layer beneath the dike; providing a pressure distributing member on or around the tensile member at a position within the dike where stabilization against lateral earth movement is required; and connecting a second end of the tensile member to a counter member at an outer surface of the dike.

Claims

1. A ground anchor assembly for stabilizing a dike, comprising a ground anchor, a counter member and an elongate tensile member, connecting the ground anchor and the counter member, wherein said tensile member is provided between the ground anchor and the counter member with one or more pressure distributing members centered around the tensile member and arranged to prevent earth flow in a direction perpendicular to a length direction of the tensile member, wherein the one or more pressure distributing members comprise three solid blades extending from the tensile member.

2. The assembly according to claim 1, wherein the one or more pressure distributing members are elongated and extend along the tensile member.

3. The assembly according to claim 1, wherein the one or more pressure distributing members are slideably mounted around the tensile member.

4. The assembly according to claim 1, wherein the one or more pressure distributing members are integral with the tensile member.

5. The assembly according to claim 1, wherein the one or more pressure distributing members comprise a composite material.

6. The assembly according to claim 1, wherein the one or more pressure distributing members are a plastic or a metal strip.

7. The assembly according to claim 1, wherein the ground anchor is a pivotable ground anchor that can be inserted into the dike by an insertion rod and pivoted into position by applying tension to the tensile member.

8. The assembly according to claim 1, wherein the tensile member is a flexible composite rod, secured to the ground anchor and to the counter member.

9. The assembly according to claim 1, wherein the counter member is a perforated plate.

10. The assembly according to claim 1, wherein the counter member comprises a net.

11. A dike comprising a number of adjacently arranged ground anchor assemblies according to claim 1, arranged to prevent earth flow in a direction (a) perpendicular to the length direction of the tensile member.

12. The dike according to claim 11, wherein the counter member is provided near an outer surface of the dike.

13. The assembly according to claim 1, wherein the one or more pressure distributing members are elongated and extend along at least 10% of the length of the tensile member.

14. The assembly according to claim 1, wherein the one or more pressure distributing members are elongated and extend along at least 30% of the length of the tensile member.

15. The assembly according to claim 1, wherein the one or more pressure distributing members comprise a basalt epoxy composite.

16. The assembly according to claim 1, wherein the tensile member is a flexible basalt fibre composite rod, secured to the ground anchor and to the counter member.

17. The assembly according to claim 1, wherein the counter member is a perforated plate of basalt composite.

18. A method for stabilizing a dike using a ground anchor assembly, the method comprising: connecting a ground anchor to a first end of a tensile member; introducing the ground anchor through the dike and into a stable layer beneath the dike; providing a pressure distributing member on or around the tensile member at a position within the dike where stabilisation against lateral earth movement is required, wherein the pressure distributing member comprises three solid blades centered around and extending from the tensile member; and connecting a second end of the tensile member to a counter member at an outer surface of the dike.

19. A method according to claim 18, wherein the pressure distributing member is introduced together with the ground anchor and tensile member.

20. A method according to claim 18, wherein introducing the ground anchor comprises pivoting the ground anchor relative to the tensile member to engage with the stable layer.

21. A method according to claim 18, wherein the counter member is connected to the tensile member with a pretension.

22. A method according to claim 18, further comprising performing a geotechnical survey of the dike and positioning the pressure distributing member at a position corresponding to a slip zone within the dike.

23. A method for stabilizing an earth body, comprising the steps: providing a plurality of mechanical ground anchor assemblies, each assembly comprising a ground anchor and a flexible tension member for coupling the ground anchor to an object to be anchored, as well as a coupling member which fixedly couples the anchor to the tension member, and one or more pressure distributing members centered around the tension member, the one or more pressure members each comprising two or more solid blades extending around the tension member, installing a ground anchor of the plurality of mechanical ground anchor assemblies through the earth body in a respective anchor location at least 0.5 meter below the earth body surface for stabilizing the earth body, applying a geonet, to the earth body for ground stabilization, coupling the flexible tension member, associated with said one ground anchor of the plurality of mechanical ground anchor assemblies, with the geonet for maintaining the earth body.

24. The method according to claim 23, comprising repeating the steps: installing one ground anchor of the plurality of mechanical ground anchor assemblies through the earth body in a respective anchor location at least 0.5 meter below the earth body surface for stabilizing the earth body, coupling the flexible tension member, associated with said one ground anchor of the plurality of mechanical ground anchor assemblies, with the geonet for maintaining the earth body, for each respective ground anchor of the plurality of mechanical ground anchor assemblies.

25. The method according to claim 23, wherein the ground anchor of the plurality of mechanical ground anchor assemblies is a pivoting ground anchor and the method comprises the step: setting the pivoting ground anchor in an anchor position upon taking in of the flexible tension member.

26. The method according to claim 24, wherein adjacent tension members are coupled with the geonet at a mutual tension member spacing in the range of 0.1 meter to 10 meter.

27. The method according to claim 24, wherein a tension member spacing is about 1 meter.

28. The method according to claim 26, wherein the tension members are coupled with the geonet along a pattern.

29. The method according to claim 23, wherein the tension member is a flexible strip made of woven or non-woven fabric suitable for coupling with the geonet.

30. The method according to claim 23, wherein the tension member is a plastic or a metal strip.

31. The method according to claim 23, wherein the coupling of the tension member with the geonet comprises at least one of weaving of the tension member with the geonet, clamping of the tension member with the geonet, and hooking of the tension member into the geonet.

32. The method according to claim 23, comprising the step: installing each of the mechanical ground anchors of the plurality of mechanical ground anchor assemblies through the earth body from opposite sides of the earth body for stabilizing the earth body.

33. The method according to claim 23, wherein installing each ground anchor comprises driving of the ground anchor with a driving rod coupled with the ground anchor by a driving rod coupling member for temporary coupling the anchor with the driving rod to drive the anchor to the anchor location, wherein the method comprises the step filling of the space left by the driving rod with a filler like grout, bentonite or any other suitable filling material, upon retracting the driving rod after the ground anchor has been installed in a respective anchor location.

34. The method according to claim 23, wherein the driving rod comprises a conduit which extends in the longitudinal direction of the driving rod, and wherein the conduit is provided with a discharge at is leading end, and the filling of the space left by the driving rod comprises supplying of the filler through the conduit.

35. The method according to claim 23, wherein the length (1) of the tension member exceeds 0.5 meter.

36. The method according to claim 23, wherein the length (1) of the tension member is such that the anchor location below the earth body surface is at a separate earth layer distinct from the earth body.

37. The method according to claim 23, wherein the tension member is of one piece.

38. The method according to claim 23, wherein the tension member is continuous.

39. The method according to claim 23, wherein the geonet is a geotextile.

40. The method according to claim 28, wherein the pattern is a line pattern or a check pattern.

41. The method according to claim 35, wherein the length (1) of the tension member exceeds 3 meter.

Description

(1) The invention will be further elucidated referring to preferred embodiments shown in the drawing in which:

(2) FIG. 1 shows schematically a ground anchor assembly according to the invention;

(3) FIG. 1a is a detail of FIG. 1;

(4) FIG. 2 is partial cross section through a dike according to the invention;

(5) FIG. 3 is an arrangement of a number of ground anchor assemblies according to the invention;

(6) FIG. 4-6 show cross sectional views of several embodiments of the pressure distributing member; and

(7) FIG. 7 shows a schematic view of a reel of tensile member attached to a ground anchor.

(8) In FIG. 1 a ground anchor assembly according to the invention is generally shown at 1. It comprises a ground anchor 4 having a pivot 15 for connection to a tensile rod 3. A substantial part of tensile rod 3 is provided with a pressure distributing member 2. Remote from the ground anchor 4 a counter plate 5 is provided. In FIG. 1a connection of the counter plate 5 and the tensile rod 3 is shown. A clamping sleeve 7 is provided over tensile rod 3 and crimped thereto. Thereafter an epoxy sealing material 6 is introduced in the cavity in which clamping sleeve 7 is arranged to make the assembly vandal proof. It will be understood that alternative fixations may be provided instead of the clamping sleeve, including screw fixation and adhesives, depending on the material of the tensile member. Other materials may be used for encasing the fixation member. Such clamping action can be effected after inserting the ground anchor 4 to the desired position and tensioning the tensile rod 3 to the desired value.

(9) In FIG. 2 an example is given wherein the final condition after mounting a ground anchor assembly is shown. FIG. 2 shows that the counter member 5 is embodied as a plate having perforations. It should be understood that counter member 5 can have any configuration according to the related requirements. It is also clear from FIG. 2 that counter plate 5 is at the surface of the dike 8. It should be understood that it can also be provided below the surface thereof. Dike 8 is arranged above the original soil layer 10 and comprises an earth core 9. One side of the dike 8 is subjected to pressure from water 11 whilst the other side thereof should remain dry. By placing a number of ground anchor assemblies 1 as shown in FIG. 2 adjacent to each other in length direction and having the ground anchor 4 extending into the original soil the position of the earth core 9 is fixed in normal conditions.

(10) However due to rain or other particular circumstances it might be possible that the moisture content in the dike becomes so high that flow of earth material is possible resulting in removal of earth material between ground anchor 4 and counter plate 5. This results in lowering of the stabilization force from counter plate 5 on the body of earth such that the effectiveness of such an anchor assembly is greatly reduced. According to the invention by using pressure distributing member 2 movement of earth is substantially prevented. By placing a number of ground anchor assemblies adjacent to each other occurrence of a flow of earth material is blocked.

(11) In FIG. 2, arrow a shows a flow direction perpendicular to the tensile rod 3. It should be understood that other flows, for example horizontal flows, are also prevented.

(12) In FIG. 2 the pressure distributing member 2 is shown as having a cross shape in cross-section. This is further shown in FIG. 5. FIG. 4 shows the pressure distributing member 2 embodied in the form of a strip. FIG. 6 shows the pressure distributing member 2 in the form of a three bladed shape. It will be understood that these shapes are merely exemplary and that any other suitable cross-section may be provided that increases the surface area for the prevention of lateral flow. The pressure distributing member 2 may also be spiralled along the length of the tensile member and that other shapes are possible. It is also possible that the shape thereof is not the same over the length thereof but might vary according to the requirements set which depend from the constitution of the several ground layers and the probability of lateral movement.

(13) FIG. 3 shows a further example of a dike 8 having a top surface 13 and earth core 9. In this embodiment 14 shows possible slip lines. Portions of the dike can slide with respect to each other under unfavourable circumstances in the direction of arrows d along these slip lines 14. The location of these slip lines 14 or planes can be determined through geotechnical surveying of the dike. Through the presence of the ground anchor assemblies 1 according to the invention and more particular the pressure distributing members 2 such migration can be effectively prevented. In the FIG. 3 embodiment the ground anchor assemblies 1 are placed at numerous elevations within the dike 8 and each tensile member 3 carries two pressure distribution members 2 located such as to span a respective slip line 14.

(14) FIG. 7 shows a reel 16 on which a length of material is provided comprising a flexible tensile member 3 formed of basalt based material. In use, the tensile member 3 can be threaded through the pressure distributing member 2 and connected by a crimped connecting sleeve (not shown) to a ground anchor 4. The ground anchor 4 is then inserted into the dike to the required depth using a conventional push rod and vibratory driver which drive both the ground anchor 4 and the pressure distributing member 2 into the dike. Once the required depth is reached, the ground anchor 4 is pivoted to its anchoring position by applying a pulling force on the tensile member 3. This can then be cut to the required length after which counter member 5 can be connected using the clamping sleeve 7 shown in FIG. 1a.

(15) In an alternative embodiment it is possible to first insert the ground anchor together with the tensile member and subsequently slide flow restrictor 2 over the tensile member 3 to the required depth. It is also possible to introduce a hardening or non-hardening stabilizing material into the body of earth before, during or after introduction of tensile member 3, in particular to fill any voids created during insertion and prevent channel forming along the tensile member.

(16) It should be realized that the above are only examples of the invention. Furthermore it should be clear that combinations can be made with other techniques resulting in further effectiveness of stabilization. For example it is possible that the counter plate is embodied as geonet, such as a geotextile.

(17) Starting from this disclosure, many more embodiments will be evident to a skilled person, which are within the scope of protection and the essence of this invention and which are obvious combinations of prior art techniques and disclosure of this invention.