GB2106849A

GB2106849A - An embedment anchor

Info

Publication number: GB2106849A
Application number: GB08129800A
Authority: GB
Inventors: Honma Koichi
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-09-29
Filing date: 1981-10-02
Publication date: 1983-04-20
Also published as: FR2513588B1; GB2106849B; FR2513588A1

Abstract

A ship 1 carries a high pressure water pump 2 connected by high- pressure hose 3 to a hollow vertical cylindrical member 4 to the lower end of which is detachably engaged the hollow stem of an embedment anchor 5 to which are hinged anchor blades curved in cross-section so as to be foldable upwards against the stem. The blades are equispaced along, and around the circumference of the stem. Attachment eye 5a secures cable 6. When water is pumped down cylindrical member 4 it excavates a pit into which the anchor 5 sinks. The anchor is drawn upwards slightly before the pump is stopped. This opens are hinged blades. Then cylidrical member 4 is disengaged from the anchor 5. <IMAGE>

Description

SPECIFICATION An underwater driving anchor This invention relates to an underwater driving anchor, to a method of immobilising equipment using such an anchor, and to an installation for carrying out the said method.

Japanese Patent Application 54 (1979)105192, (published under the number 56 (1981)-28929) of the same inventor as this application discloses a driving anchor which is caused to sink into an underwater examination created by high-pressure pumped water.

Such a prior art anchor, however, has the disadvantage that the hingerd anchor blades, and thus the anchor, can distort and move under strong forces. It now appears that this may be due to the positioning of such blades relative to each other and the stem. The present invention sets out to improve the resistance of such an anchor to dislodgement by changing these relative positions.

In one aspect therefore the invention provides an underwater driving anchor comprising a hollow cylindrical stem with an attachment eye for a rope or cable to which stem are hinged a plurality of anchor blades of curved transverse cross-section such that the blades can readily approach the cylindrical stem when folded upwards; the blades being hinged at positions which are generally equispaced along the stem, and extending in directions which are generally eqmarginlarly spaced around the stem.

Preferably, there are three of four such blades. Moreover, they preferably possess guide plates each defining an outer hinged blade position.

In another aspect the invention provides an installation comprising such an anchor, a cylindrical member adapted to receive at its lower end the hollow cylindrical anchor stem, a pressure hose connected to an upper end of the cylindrical member, and a high-pressure water pump in operative connection with the hose.

In yet another aspect these is provided a method of utilising such an installation which comprises the steps of: (i) positioning the assembled anchor and cylindrical member above a desired region of the sea bed, (ii) pumping water at high pressure through the hose, cylindrical member and anchor stem to excavate a depression into which the assembled anchor and cylindrical member sink, (iii) raising the cylindrical member and anchor, while continuing the flow of water, to cause the anchor blades to pivot outwards, (iv) discontinuing the flow of water, and (v) disengaging the cylindrical member from the anchor.

The invention will be further described with reference to the accompanying drawings, in which Figures 1A and 1B show an installation for operating an underwater driving anchor, in two stages of its use; Figures 2C and 2D show the anchor itself in two of its configurations; Figure 3 shows a prior art driving anchor and Figure 4 shows a net installation secured by such anchors.

As shown in Fig. 1, a ship 1 carries a high pressure pump 2 connected by high pressure hose 3 to a removable vertical cylindrical member 4. An anchor 5 is located at the bottom end of cylindrical member 4 and is attached by attachment eye 5a to a rope or cable itself securable to a marker or equipment such as a net (see also Fig. 4).

The anchor 5 comprises a hollow cylindrical stem carrying the attachment eye 5a for a rope or cable, etc, and a plurality of blades 7, three being shown in the embodiment of Fig.

2.

Each blade 7 is hinged to the stem and is curved in transverse cross-section so that it can readily fold back against the stem. It possesses guide plates 8 to support the fully opened blades 7.

The blads project in directions which are generally equiangularly spaced (viewed from one end of the stem) and their of hinged attachment are generally equispaced along the stem.

Three such blades are shown in the drawings. Two, four, or more can also be used, but three or four are preferred.

To use the invention, the cylinder 4 and anchor 5 are first manouvred into place by a diver. He gives a starting signal, and water is pumped down hose 3, and through the cylinder 4 and hollow stem of the anchor 5. This displaces sand, shingle or mud and the cylinder 4 and anchor 5 progressively sink into the hole thereby excavated. Blades 7 are folded back towards the stem while this takes place.

When the diver observes that the anchor is deep enough the cylinder 4 and pipe 5 are drawn out slightly while water still passes down the tube. This causes the blades 7 to open, until they meet guide plates 8. At this stage pumping is stopped and the cylinder 4 is disengaged from the anchor 5 and pulled out by the diver. Anchor 5 is securely held by its blades 7 within the material which falls back into the hole, and rope or cable 6 secures the market or net, etc, in the desired position.

Because the blades are spaced along and around the stem the structure is stronger than that prior art structure shown in Fig. 3 where all the blades are at the bottom and originate at one level.

The anchor is simple to contruct and to use, since no elaborate installation is required such as for example needed for underwater pile driving.

Claims

1. An underwater driving anchor comprising a hollow cylindrical stem with an attachment eye for a rope or cable to which stem are hinged a plurality of anchor blades of curved transverse cross-section such that the blades can readily approach the cylindrical stem when folded upwards; the blades being hinged at positions which are generally equispaced along the stem, and extending in directions which are generally equiangularly spaced around the stem.

2. An underwater driving anchor as claimed in claim 1 comprising three anchor blades.

3. An underwater driving anchor as claimed in claim 1 comprising four anchor blades.

4. An underwater driving anchor as claimed in claim 1, 2 or 3 further comprising guide plates each defining an outer anchor blade position.

5. An underwater driving anchor substantially as shown in Fig. 2C or 2D.

6. All installation comprising an underwater driving anchor as claimed in any one preceding claim, a cylindrical member adapted to receive at its lower end the hollow cylindrical anchor stem, a pressure hose connected to an upper end of the cylindrical member, and a high-pressure water pump in operative connection with the hose.

7. A method of utilising the installation as claimed in claim 6 comprising the steps of: (i) positioning the assembled anchor and cylindrical member above a desired region of the sea bed, (ii) pumping water at high pressure through the hose, cylindrical member and anchor stem to excavate a depression into which the assembled anchor and cylindrical member sink, (iii) raising the cylindrical member and anchor, while continuing the flow of water, to cause the anchor blades to pivot outwards, (iv) discontinuing the flow of water, and (v) disengaging the cylindrical member from the anchor.