CA2438634C

CA2438634C - Method and apparatus for excavating soil material

Info

Publication number: CA2438634C
Application number: CA002438634A
Authority: CA
Inventors: Stefan Konrad Schwank
Original assignee: Bauer Maschinen GmbH
Current assignee: Bauer Maschinen GmbH
Priority date: 2002-09-20
Filing date: 2003-08-29
Publication date: 2008-06-03
Anticipated expiration: 2023-08-29
Also published as: ZA200307140B; DE10243747B4; DE10243747A1; CA2438634A1; AU2003244520A1; AU2003244520B2

Abstract

The invention relates to a method for excavating ground or soil material under a water surface, in which a flat soil layer is crushed by the planned lowering of a working appliance a number of times from a floating body and the crushed soil material is delivered to the water surface. In a first excavation step primary zones are excavated and between the primary zones soil material is left behind in secondary zones. The secondary zones are removed in a second excavation step. For performing the method an apparatus is provided for excavating soil material below a water surface, which comprises a floating body, a working appliance for crushing the soil material, a lifting mechanism and at least one delivery line.

Description

METHOD AND APPARATUS FOR EXCAVATING SOIL MATERIAL
FIELD OF THE INVENTION

The invention relates to a method for excavating soil material below a water surface by means of a working appliance, which is installed on a floating body, in which a flat soil layer is crushed by lowering several times said working appliance and the crushed soil material is delivered to the water surface, during each lowering of the working appliance a zone is excavated from the soil layer which is approximately perpendicular to the water surface, in a first excavation step primary zones are excavated in an offset manner with respect to one another and between the primary zones soil material remains in secondary zones, and in a second excavation step the secondary zones are removed. The invention also relates to an apparatus for excavating soil material below a water surface for performing the method according to the invention and having a working appliance for crushing soil material, a floating body, a lifting mechanism with which the working appliance can be lowered from the floating body onto the bed and at least one delivery line for delivering the crushed soil material to the water surface.
BACKGROUND OF THE INVENTION

German published Patent Application No. DE 1 812 879 A discloses a method for working the bed of watercourses, in which in an area of the watercourse bed to be worked, boreholes are made with a mutual spacing down to a predetermined depth and the parts left standing between these boreholes are also worked to a predetermined depth by means of a rotary tool. Boring devices with a rotating boring rod are used for making the boreholes.

It is also known to excavate underwater soil layers using excavating buckets on a conveying chain. However, this method is relatively imprecise and is not particularly efficient in the case of hard soil layers. Moreover, excavating with excavating buckets introduces much turbid matter into the water.

2 DE 2 310 769 A describes an apparatus for producing boreholes in the bed of watercourses. This known apparatus has an excavating tool with shovels and prospecting cutters which is rotated about a rotation axis substantially parallel to the direction of advance. The apparatus also has a suction pipe for sucking off broken loose soil material.

EP 0 819 819 Al discloses a method and an apparatus for removing rock samples from the ocean bed. A milling head with a roughly circular boring cross-section bores in the ocean bed from a ship and as a result punctiform sampling can take place.

SUMMARY OF THE INVENTION
The object of the invention is to provide a method and an apparatus permitting a planned and particularly economic excavation of even hard soil layers under water.

In an aspect of the present invention, there is provided a method for the excavation of soil material below a water surface by means of a working appliance, which is installed on a floating body, in which a flat soil layer is crushed by lowering the working appliance several times and the crushed soil material is delivered to the water surface, one zone is excavated from the soil layer roughly perpendicular to the water surface during each lowering of the working appliance, in a first excavation step primary zones are excavated in an offset manner with respect to one another and between the primary zones soil material is left behind in secondary zones, and in a second excavation step the secondary zones are removed, whereby the working appliance is constituted by a milling device with a rectangular excavation cross-section, and the primary zones and secondary zones are arranged in an alternating sequence, having an overhead appearance similar to that of a chessboard.

In a further aspect of the present invention, there is provided an apparatus for the excavation of soil material below a water surface, for performing the method according to any one of claims 1 to 9, having a working appliance for crushing soil material, a

3 floating body, a lifting mechanism with which the working appliance can be lowered to the bed from the floating body and at least one delivery line for delivering the crushed soil material to the water surface, wherein the working appliance is a milling device with a rectangular excavation cross-section incorporating at least one milling cutter.

From the method standpoint the object is achieved according to the invention in that the working appliance is constituted by a milling device having a rectangular excavating cross-section and in that the primary zones and secondary zones are arranged in chessboard-like manner or in a checkered formation.

A fundamental idea of the invention is that by lowering a soil-breaking and crushing device from a floating body the soil within an excavation zone can be removed and the removed material delivered to the floating body. As a result of repeated, planned lowering of the soil-removing and crushing device the soil is removed within further excavation zones. The desired soil layer can be efficiently excavated in that in planned manner a plurality of specific excavation zones are removed. This permits a complete, layerwise removal of a soil layer, even in the presence of hard rock. The roughly vertical lowering and direct conveying away of the crushed soil material ensure that the environment of the excavation site suffers to a greatly reduced extent.

In principle, numerous excavation sequences are possible when excavating a flat soil layer as a result of lowering the working appliance several times. Thus, in a linear excavation sequence e.g. the individual zones can directly follow on to one another.
However, according to the invention, from the soil layer during each lowering of the working appliance one zone is excavated roughly perpendicular to the water surface, in a first excavation step initially primary zones are excavated offset with respect to one another and between the primary zones soil material is left behind in secondary zones, and the secondary zones are removed during the second excavation step. With this procedure, following the first excavation step soil walls or columns are left behind in the soil layer and can be used for guiding the working appliance. Thus, it is possible to

4 largely eliminate the risk of running off centre of the working appliance and the intended vertical excavation direction can be maintained, which allows a particularly rapid and thorough excavation.

According to the invention the primary and secondary zones are arranged in a chessboard-like manner, or from an overhead view, appear similar to that of a chessboard. Such an arrangement can be easily produced. It is particularly preferred for the secondary zones to be smaller than the primary zones, because this allows a particularly reliable guidance of the working appliance. The cross-sectional area of the secondary zones is in particular dimensioned in such a way as to be smaller than the excavation area of the working appliance.

In principle, the primary zones and the secondary zones can be sunk to the same depth.
However, preferably, the primary zones and secondary zones are sunk to a different depth. Should it prove necessary to subsequently excavate the soil layer to a greater depth in further excavation steps and following on to the second excavation step, the soil walls or columns left behind after said second excavation step can be used for guiding the working appliance in the following excavation steps.

During the excavation of the zones, the working appliance can be retained solely by gravity and its own mass moment of inertia in the working direction. However, the working appliance is preferably guided on a guide device, which is preferably fixed in the soil layer. If the guide device is provided during the excavation of the secondary zones, it can advantageously be fixed to the side walls of the columns left behind following the first excavation step.

According to the invention, the working appliance is guided by a leading tool.
The leading tool can in particular be a milling cutter. A guidance with a guide device or a leading tool permits a particularly precise positioning of the working appliance and therefore a thorough excavation of the soil layer.

The inventive method can be used for the excavation of soil layers below any natural water surface such as lakes, rivers and oceans. A method according to the invention involves the water surface being artificially created by flooding an open-cast mining boiler. Such normally circular or oval pits are used in open-cast mining for diamonds

5 along extinct volcanic vents. The conically downwardly narrowing pits must have a specific minimum diameter, so that the truck necessary for transporting the excavated material can be driven spirally along the pit edge. Thus, the starting diameter of such boilers establishes the attainable final depth. If excavatable material is found below the maximum reachable final depth, the boiler diameter must be increased in order to reach a greater final depth, which involves a very considerable material excavation.
As a result of the inventive flooding of the bottom of the open-cast mining pit by a height of a few metres, it is possible to use the inventive method for the further excavation of the pit bottom. Thus, without changing the boiler wall, it is possible to significantly increase the final depth by up to 200 m or more.
Fundamentally the crushed soil material can be delivered to the water surface by means of a suction device, which can have a pump. However, in a preferred embodiment soil material delivery takes place by the feeding in of compressed air to the crushed soil material over a first line, the soil material being removed with the compressed air by means of a second line.

It is advantageous when performing the method according to the invention to precisely fix the position of the floating body on the water surface. This can e.g. take place by an active control of drives of the floating body through a position determination system.

However, with particular preference the position of the floating body is set by adjusting the length of at least two cables, which link the floating body with the bank or with anchor points. This makes it possible to precisely fix the position, whilst involving a very limited energy expenditure. The anchor points can in particular be fitted to the bed below the water surface.

6 A further inventive method performance is characterized in that the crushed soil material is supplied to a separating or dressing plant for extracting mineral resources.
The mineral resources can e.g. be diamonds or precious metals. In principle, the separating or dressing plant can be located on the floating body, on the bank or on another floating body. After passing through the separating or dressing plant the worthless part of the soil material can be delivered to a waste dump or returned to the excavation zones.

The crushed soil material can be delivered continuously from the floating body to the separating or dressing plant by means of a pump line, which can be constructed in floating manner in the water area. Alternatively there can be a transfer station on the bank, to which the crushed soil material is supplied by means of a pump line and which transfers said soil material to trucks, which transport it to the separating or dressing plant.

From the apparatus standpoint the object is achieved in that the working appliance is a milling device with a rectangular excavation cross-section and which incorporates at least one milling cutter.

The floating body of the apparatus according to the invention is preferably a pontoon, ship or boat and the floating body preferably has a drive, such as e.g. a propeller.
Preferably the floating body incorporates at least two controllable cable winches with cables, which are fixed to the bank or to anchor points. This permits an energy-favourable, very precise positioning of the floating body.

According to the invention the working appliance is a milling device incorporating at least one milling cutter. A milling device permits a particularly efficient excavation and crushing of even very hard soil or ground material. The excavation cross-section of the milling device is, according to the invention, rectangular, because this allows a complete excavation of the soil layer. The milling cutter can be in the form of so-called

7 trench wall cutters, in which the drive is located in a frame or support between the milling or cutting wheels and the crane suspension.

In a particularly preferred embodiment, at least one milling cutter has a milling wheel pair, which permits particularly efficient milling.

In order to increase the boring cross-section attainable during a single lowering of the working appliance, it is particularly preferable for there to be two parallel milling cutters. In principle, it is also possible to have three or more milling cutters. It is particularly preferred for the two milling cutters to be arranged in such a way that the milling wheel pairs are axially parallel. This permits a particularly simple design and construction of the milling device. The drive for the milling wheels is preferably hydraulic, but it is also possible to use other drives, e.g. of an electrical or mechanical nature.

The two milling cutters are preferably mounted so as to be displaceable relative to one another. In the case of transverse displaceability, this makes possible a sliding apart, thereby giving access to the inner milling wheels, which is advantageous from the maintenance standpoint. Access for changing the inner milling wheels can also be made possible in that the two milling cutters are constructed so as to be at least partly separable from one another. In the case of vertical displaceability it is possible with displaceably mounted milling cutters to use in a mutual movement of the two cutters one leading cutter for guiding the entire milling device.

A particularly precise guidance of the working appliance during sinking can be achieved in a particularly preferred embodiment in that the working appliance has a guide frame, which can be fitted to one or more sides of the working appliance. It is particularly preferred to provide on the floating body a boring rig for fixing the guide frame on the milling base. Fixing can take place by means of a soil auger or other fixing means.

8 An apparatus according to the invention is further developed in that the working appliance can be moved by a lifting mechanism in a plane parallel to the water surface relative to the floating body. This permits a particularly precise positioning of the working appliance.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in exemplified manner hereinafter relative to the attached drawings, wherein show:

Fig. 1 A side view of an apparatus according to the invention for the excavation of soil material.

Fig. 2 A plan view of an apparatus according to the invention for excavating soil material.

Fig. 3 A plan view of an apparatus according to the invention for the excavation of soil material whilst also showing the watercourse bed for illustrating the method according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Figs. 1 and 2 show a pontoon as the floating body 10 floating on a water surface 7. To the pontoon is fitted a working appliance 20, which comprises a frame 21 and a bottom positioned milling cutter 22. By means of a lifting mechanism the working appliance 20 can be lowered and then raised again through an opening 11, known as a moon pool.

The lifting mechanism comprises supporting cables 45, 45', which are connected by means of guide pulleys 38, 38' to supporting cable winches 46, 46'. The guide pulleys 38, 38' are mounted on a crane frame 30, which has ajib 32. The crane frame 30 also has a hydraulic cylinder 31 permitting an adjustment of the position of the working appliance 20.

9 To the working appliance 20 are supplied supply hoses or lines 41, 41' and 43 through which crushed soil material is delivered and compressed air and hydraulic fluid supplied and removed. The supply hoses 41 and 41' run over guide pulleys 36 from working appliance 20 to drums 42, 42'. The supply hose 43 passes over guide pulleys 37, 37' to drum 44. On lowering or raising the working appliance 20, a corresponding length of the supply hoses 41, 41' and 43 is unwound or wound onto the drums 42, 42' and 44.

Cable winches 16, 16', 16" and 16"' are marginally fitted to the four corners on the pontoon. Said cable winches are used for the planned shortening or lengthening of the cables, which are connected to the bank and/or anchor points, so that the pontoon position can be precisely moved and fixed. The pontoon also carries diesel hydraulic units 13, 13' and a cabin 14 for the operating personnel.

A method according to the invention for the excavation of a soil or ground layer is illustrated in Fig. 3, which diagrammatically shows an apparatus according to the invention and the watercourse bed 6 below it during the excavation of primary zones in a first excavation step. The pontoon is moved in one direction and by repeated lowering of the working appliance 20 the soil within the primary zones 1 is worked to a depth of approximately 15 metres. Soil material in the form of columns is left between the primary zones 1 in secondary zones 2. The primary zones e.g. have a length (lp) of 3.2 metres and the secondary zones a length (15) of 2 metres, both zones having a width (b) of 3 metres.

The excavation sequence during one pass of the pontoon in the X-direction is illustrated by the broken line arrows. In order to bring about this excavation sequence the working appliance 20 can be alternately moved in the Y-direction by the crane frame 30. As a result of the excavation sequence shown, at the end of the first excavation step, there is a chessboard-like arrangement of the primary zones 1 and between them smaller, secondary zones 2. These secondary zones 2 are removed in a following operation, during which the pontoon can move in the X or Y-direction, by the lowering of the working appliance 20. In the case of use under extreme weather conditions, the entire pontoon or only the crane with the supply means and the moon pool can be protectively housed, particularly being covered by a dome or a casing.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for the excavation of soil material below a water surface by means of a working appliance, which is installed on a floating body, in which - a flat soil layer is crushed by lowering the working appliance several times and the crushed soil material is delivered to the water surface, - one zone is excavated from the soil layer roughly perpendicular to the water surface during each lowering of the working appliance, - in a first excavation step primary zones are excavated in an offset manner with respect to one another and between the primary zones soil material is left behind in secondary zones, and - in a second excavation step the secondary zones are removed, whereby - the working appliance is constituted by a milling device with a rectangular excavation cross-section, and - the primary zones and secondary zones are arranged in an alternating sequence, having an overhead appearance similar to that of a chessboard.

2. A method according to claim 1, whereby the primary zones and secondary zones are sunk to the same or a different depth.

3. A method according to claim 1 or 2, whereby the working appliance is guided along a guide device during the excavation of at least the secondary zones.

4. A method according to claim 3, whereby the guide device is fixed in the soil layer.

5. A method according to any one of claims 1 to 4, whereby the working appliance is guided by a leading tool.

6. A method according to any one of claims 1 to 5, whereby the water surface is artificially created by flooding the bottom of an open-cast mining boiler.

7. A method according to any one of claims 1 to 6, whereby soil material is delivered by supplying compressed air by means of a line to the crushed soil material, which is removed with the compressed air by means of a second line.

8. A method according to any one of claims 1 to 7, whereby the position of the floating body is adjusted by setting the length of at least two cables, which connect the floating body to the bank or to anchor points.

9. A method according to any one of claims 1 to 8, whereby the crushed soil material is supplied to a separating or dressing plant for extracting mineral resources.

10. Apparatus for the excavation of soil material below a water surface, for performing the method according to any one of claims 1 to 9, having - a working appliance for crushing soil material, - a floating body, - a lifting mechanism with which the working appliance can be lowered to the bed from the floating body and at least one delivery line for delivering the crushed soil material to the water surface, wherein, - the working appliance is a milling device with a rectangular excavation cross-section incorporating at least one milling cutter.

11. Apparatus according to claim 10, wherein the floating body is a pontoon, ship or boat.

12. Apparatus according to claim 10 or 11, wherein the floating body incorporates at least two controllable cable winches with cables, which are fixed to the bank or to anchor points.

13. Apparatus according to claim 10, 11 or 12, wherein the floating body has its own drive.

14. Apparatus according to any one of claims 10 to 13, wherein the at least one milling cutter has a milling wheel pair.

15. Apparatus according to any one of claims 10 to 14, wherein there are two milling cutters, which are parallel and positioned so that the milling wheel pairs are axially parallel.

16. Apparatus according to claim 15, wherein the two milling cutters are mounted so as to be displaceable against one another.

17. Apparatus according to any one of claims 10 to 16, wherein the working appliance has a guide frame.

18. Apparatus according to claim 17, wherein on the floating body is provided a boring rig for fixing the guide frame to a milling base.

19. Apparatus according to any one of claims 10 to 18, wherein the working appliance can be moved by means of the lifting mechanism in a plane parallel to the water surface relative to the floating body.

20. Apparatus according to any one of claims 10 to 19, wherein at least part of the floating body with the lifting mechanism is housed.