METHOD AND DEVICE FOR DRILLING A PIT OR PASSAGE, AND FLEXIBLE TUBE THEREFOR

The invention relates to a method for drilling a pit or passage extending substantially vertically under the ground. Such a pit or passage is for instance used for placing a foundation element such as a foundation pile. It is also possible to use such pits or passages for instance for a heat/cold storage. Other applications are also possible.

Arranging an elongate hole in the form of a pipe in the ground is generally carried out via drilling with a soil drill or in similar manner with for instance water injection. The agitated soil in the form of clay, loam, sand, peat etc. is herein transported to the surface and discharged. A hole can also be realized via displacement of the soil, as takes place in pile-driving.

The arranging of such holes requires in practice the use of relatively complex and heavy installations, for instance a pile-driving installation. This is a relatively expensive process. In addition, these processes cause considerable nuisance for the immediate vicinity, and the process is difficult to control, for instance in respect of the forces applied.

The object of the invention is to obviate or at least reduce the above stated problems and to provide a method for arranging an elongate hole in the ground.

This object is achieved with the method according to the invention for drilling a pit or passage extending per se substantially vertically under the ground, the method comprising of:

- providing a frame with a pressure chamber;
- arranging a first outer end of a flexible tube on the pressure chamber using connecting means;
- applying a pressure in the pressure chamber with a pressure medium by means of pressure means; and
- carrying the flexible tube into the ground.

A flexible pipe is provided according to the invention. A first outer end hereof is connected to a pressure chamber which can be brought to pressure by means of a pressure medium. This pressure medium is a fluid, for instance water or air. The flexible tube is then pressed into the ground by the pressure in the pressure chamber while the first outer end is held fixedly on the pressure chamber. This is achieved by providing this pressure chamber in substantially airtight manner such that there is only one possible way out for the pressure medium. This exit is formed by the flexible tube or hose. The second outer end of the flexible tube is preferably sealed airtightly here.

By positioning the flexible tube toward the ground this flexible tube will be pressed into the ground by applying the pressure and here move in the ground in a substantially vertical direction. The soil is pressed or displaced here to the side. This relates therefore to displacement of the soil by the flexible tube. After a desired diameter and depth are realized for the pit or passage, the flexible tube is preferably removed therefrom and the pressure chamber is brought once again to atmospheric pressure.

The flexible tube used is preferably sufficiently flexible to be fixed and held with a first outer end in the pressure chamber on one side and to be pressed into the ground on the other. The flexible tube is preferably provided on a reel to thereby enable a considerable length to be provided effectively in compact manner. It has been found that the use of a PVC film material or a type of fire hose as flexible tube is highly advantageous. Depending on the ground and the thickness of the PVC film, use can be made here of a double or triple-walled tube. On the one hand sufficient stability is hereby obtained and the chance of leakage simultaneously avoided, and on the other sufficient flexibility is obtained such that the flexible tube can be pressed into the ground from the pressure chamber.

The pressure medium preferably comprises air. Air can be brought to the desired pressure in relatively simple manner. Depending on the ground, this pressure amounts for instance to 20-26 bar. The use of a different fluid, such as water or drilling fluid, is however also possible.

In an advantageous preferred embodiment according to the present invention the flexible tube is provided from the pressure chamber.

By feeding the flexible tube into the ground from the pressure chamber, the pressure medium has a way out of the pressure chamber via the flexible tube and presses the flexible tube into the ground. In a possible embodiment the flexible tube is stored in the pressure chamber. The pressure chamber can hereby be substantially airtight, with the exception of the outgoing flexible tube and the feed of the pressure medium. The flexible tube is preferably provided here on a reel in this pressure chamber, which is unrolled during use.

In an alternative embodiment the flexible hose is carried during use into the pressure chamber using sealing means. This has the advantage that a relatively small pressure chamber can be provided. This increases the manageability of the device in which the method is performed. An additional advantage is that the flexible hose can for instance be provided on a reel which is provided some distance from the pressure chamber. This is particularly advantageous when for instance a pit has to be made in a terrain which is relatively difficult to access and wherein a reel can remain placed some distance away, for instance on a paved road. This clearly enhances the flexibility of the method.

In an advantageous preferred embodiment according to the present invention the flexible hose is carried with a bend into the ground using bend means.

Providing additional bend means achieves that the flexible hose or tube can be placed in the ground using a bend. The hose is deflected to some extent here from a straight, for instance vertical line. Use is preferably made for this purpose of a number of annular elements which are mounted round the hose.

In a currently preferred embodiment the annular elements are mounted around the hose or tube on the basis of slippage and are carried therewith into the ground. It should be taken into consideration here that the speed of the tube is twice as high as the drilling speed. Rotation is then possible by for instance a rotation of the annular elements, wherein these are provided with heights which are not wholly equal, in order to thereby realize a bend. Alternatively, the annular elements can be pushed away from each other on one side using a cylinder such that a bend is also realized. Such cylinders are for instance embodied as hydraulic cylinders and thereby form sliding means for mutually displacing the bend means, preferably in the form of the annular elements.

In a further advantageous preferred embodiment according to the present invention the method further comprises of repeating one or more of the above stated steps for the purpose of a second drilling in order to thereby enlarge the diameter of the pit or passage.

An effective method is realized with stepwise forming of relatively large drilled holes, i.e. gradually increasing the diameter with separate drillings. A diameter of 10 cm can for instance be used in a first drilling, can be increased to 30 cm in a second drilling and then be increased still further to a diameter of 60 cm in an optional third drilling. Other dimensions are of course also possible. This also depends on the relevant soil composition.

The invention further relates to a device for drilling a pit or passage for a structural element, comprising:

- a frame;
- a pressure chamber connected in or on the frame;
- connecting means operatively connected to the pressure chamber for connecting a flexible tube to the pressure chamber; and
- pressure means for bringing the pressure chamber and the flexible tube operatively connected thereto during use under pressure using a pressure medium, such that a pit or passage extending in substantially vertical direction is realized in the ground.

Such a device provides the same effects and advantages as described for the method. The device is particularly suitable for performing one or more of the above-mentioned method steps.

The device according to the invention preferably makes use of a flexible tube which is provided at a first outer end on the connecting means and is pressed into the ground by the pressure medium. For this purpose a pressure chamber is provided in substantially airtight manner such that the pressure seeks to escape via the flexible tube and thereby presses it into the ground. As discussed above, the pressure medium is a fluid, for instance water or air.

Use is made in a currently preferred embodiment of air wherein, also depending on the ground, air pressures of 20-26 bar are employed. Other pressures are however also possible. The flexible tube is preferably a PVC film which can take a single, double or triple-walled form. Other embodiments are likewise possible.

In a possible embodiment the pressure chamber is provided with sealing means for throughfeed of flexible tube to the pressure chamber during use. It is hereby possible to suffice with a smaller pressure chamber, as stated above. Use can also be made of bend means which optionally make use of extendable cylinders.

The invention further also relates to a flexible tube comprising a PVC film and/or other optionally fibre-reinforced plastic material suitable for applications in a device and/or method as described above.

Such a flexible tube has the same effects and advantages as described for the method and device.

Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings, in which:

FIGS. 1 to 53 show diverse views of the method and device according to the invention.

Device 10 (FIG. 1) is used in the shown embodiment to perform a film drilling technique, wherein a hole or pit 12 is arranged in ground 14. Hose 2 is pressurized here by pump 1 using a pressure medium.

In order to utilize this technique strips of plastic film 16 are applied which, when under strain of tension, can absorb sufficiently great forces such as will occur when this technique is applied, and which will most likely, though not necessarily, be a type of fibre-reinforced plastic film. Longitudinal sides 18 of such a strip are welded or adhered to each other in longitudinal direction with sufficient overlap, whereby this strip will take on the form of a hose 2. This hose, having for instance a length of 50 metres and a diameter of 10 cm in the exemplary embodiment elucidated below, is sealed airtightly at the one outer end and provided with a connection option for arranging a rope (belt, cord, cable) or an (air) hose. First the rope and then the hose are then rolled onto a reel 3 (FIG. 1), the other outer end of the hose is arranged airtightly on the housing airtightly on clamping provision 6 at the position of manifold 7, and the reel can be placed in housing 4 that is to be sealed airtightly. The film hose is carried to the centre of the manifold via a guide provision, for instance in the form of a guide roller 5.

The film hose can possibly also be manufactured integrally by means of for instance extrusion.

By subsequently sealing the housing airtightly and positioning it at the location where the hole must be arranged, for instance by placing the manifold in the hole arranged therefor and optionally weighting the housing sufficiently or fixing it to the ground, an overpressure can be arranged in the housing by allowing inflow of compressed air or other fluid suitable for this purpose. The direct result hereof is that the part of the hose which is unrolled in this situation is pressed against the ground with the pressure value of the compressed air. As soon as this pressure value becomes sufficiently higher than the permissible pressure value of the ground, the ground will be pushed aside by the expanding of the hose during the further unrolling and the hose will begin to form the wall of the drilled hole, and herein take on its maximum diameter. This unrolling process is continued for as long as the overpressure continues to sufficiently exceed the permissible pressure value of the type of soil to be displaced. At a pressure value of for instance 12 bar or higher it would seem likely that all types of soil occurring in the Netherlands can be displaced in this manner. The permissible pressure of very compact sand at great depth under the ground surface thus amounts to a maximum of 6 kgf/cm², and it is expected that the pressure exerted on this ground by the compressed air of 12 bar or higher may be deemed sufficiently high to allow the displacement process to be effected. Higher pressures can optionally also be utilized for this purpose.

FIGS. 2 and 3 show the situation in which the hose is about a quarter unrolled and the hole is formed to a depth of about 13 metres.

FIG. 4 shows the situation in which both the hose and the rope are fully unrolled and the hole has reached a depth of in this case 50 metres.

FIG. 5 then shows the situation of the rope and the hose where they are rolled up again, wherein the formed hole, optionally filled with compressed air or with for instance water, has retained its shape. After the position of FIG. 4 a support construction, for instance in the form of a perforated tube structure, can optionally then be arranged in the hose for the purpose of form-retention of the hose.

For the purpose of rolling the hose up again by firstly retracting and rolling up the rope, it will be necessary in order to leave the formed drilled hole as intact as possible for the drilled hole to be filled with (compressed) air or another fluid, for instance water, while the hose is pulled up. The supply of this air or fluid can for instance be ensured by providing the hose with a dual weld arranged at some mutual distance, and by providing the outer part of the film material situated between these welds with a perforation 20, whereby an air-permeable air hose profile can form (FIGS. 6 and 7). By replacing the rope with an air hose and connecting it to this air hose profile, the injection of air or other fluid under the film hose can be provided for during retraction.

For multiple applications it may be found desirable or even necessary to leave the film hose in the drilled hole. It is not then absolutely necessary here to attach a rope to the hose. Not sealing or lightly sealing the hose at the outer end situated in the drilled hole can achieve that the hose will be opened or can be opened from below. This may for instance be desirable for arranging a water drainage provision in areas with poorly permeable ground layers because an open hose connection through such ground layers can hereby be achieved.

For instance for drainage applications this film hose can, after a drilled hole is formed, be provided with a perforation optionally arranged later locally or over the whole length. Lowered for this purpose into the hose is a perforation mechanism from which a number of pins is forced through the film material. When it becomes apparent after a time that the arranged perforation has become clogged, which occurs regularly in drainage arranged in tips, the perforation operation can be repeated and the draining function will once again be restored.

In the case that it becomes apparent that it will not be possible to achieve penetration of hard soil layers with the above described drilling procedure, the unrolling part of the hose can be provided with a penetration tube 22 (FIG. 8). It will be possible to ensure the unrolling action of the film hose by arranging a smooth inner lining in this penetration tube. Such a penetration tube can be provided on the underside with a tip shape or cutting line.

The tip of this penetrating tube can also consist of for instance three parts 24 which are slidable relative to each other (FIG. 9). One of these parts can be made to protrude relative to the other parts by actuating an internal mechanism (FIG. 10), whereby the direction of the movement of the film hose is influenced. The film hose can be made to follow a desired path with this form of control.

FIG. 11 shows an alternative embodiment for controlling outer end 26 of the film hose in the form of a control pin 28 by changing the position of conical attachment 30 relative to the pin and therefore the central axis of the film hose.

Arranging a throughfeed provision 32 in housing 34 of the pressure chamber (FIGS. 12 and 13) makes it possible to carry the film hose into and out of the pressure chamber, for instance from a reel 36 situated outside the housing. A solution can be found for performing this operation in arranging in the housing an externally driven triple roller system 38 through which the hose is fed in flat form and clamped sufficiently to realize the forces necessary for this purpose, particularly the forces necessary for pulling the drilling hose upward again after a drilling operation has been performed.

Owing to the hose supply being moved outside the pressure chamber the length of the film hose to be arranged no longer determines the dimensioning of the pressure chamber, whereby the necessary dimensioning of the pressure chamber is greatly limited, a lighter construction is possible and the drive need not be isolated when water is used as pressing medium therefor. Giving this pressure chamber the flattest possible construction will enable maximum limitation of the necessary working height and maximize operating options in for instance a crawl space.

Once a drilling operation is completed and the hose has to be removed from the drilled hole, without precautionary measures there will be a possible danger during retracting of the film hose of the drilled hole being closed by an underpressure thus created in the drilled hole during this operation. In order to prevent this there is arranged in plug 40 arranged in the outer end of the film hose a tap 42 which is in the closed position during the drilling operation (FIG. 14) and is opened for the retracting operation, whereby the fluid present in the hose can flow out of the hose and into the drilled hole during this operation, see FIG. 15.

An alternative method herefor when drilling larger diameters can be found in inserting a pipe or hose 44 in the then formed shaft (FIGS. 16 to 19) to enable supply of air or a fluid under the film hose while the film hose is being pulled upward.

When a drilled hole of 10 cm diameter is for instance arranged in a relatively firm ground and the film hose used for this purpose is removed from the drilled hole (FIG. 16), but the desired diameter of this drilled hole must be not 10 cm but 30 cm, the drilling operation with the means for arranging this drilled hole of 30 cm diameter can be performed in similar manner to the previously performed drilling operation, see FIGS. 16, 17, 18 and 19. So that this operation can be performed in this way, the hole of 10 cm diameter must be enlarged to a hole of 30 cm diameter and a depth of for instance 25 cm, as shown in FIG. 16. When the ground has a relatively quite loose top layer of for instance 40 cm with a firmer ground layer of for instance clay lying thereunder, an alternative method is to use a hose of 10 cm diameter 46 with a length in this example of 50 cm (FIG. 20). When an overpressure is then applied in the pressure vessel found to be sufficient to allow the hose to penetrate out of the casing into the existing drilled hole over a length of for instance 80 cm, see FIG. 21, the pressure can be increased further by fixing the hose feed such that the hose part which has moved out of the casing is inflated to a diameter of 300, see FIG. 22. At this moment the hose has acquired sufficient anchoring in the drilled hole to continue the drilling operation, see FIGS. 23 and 24, without further operations for fixing or anchoring the housing. By then retracting the film hose again, for instance to the position of FIG. 21, and in this case hoisting the pressure chamber for instance 70 cm upward, see FIG. 25, the upper part of the shaft can be enlarged to the diameter of 30 cm, see FIG. 26.

This procedure for further increasing the diameter of the shaft will result in further increasing the drill diameter sizes, whereby tunnel shafts for vehicles and trains can also be realized using this film drilling technique.

For the purpose of performing a drilling along a straight line, it is necessary that each movement of the head of the hose deviating therefrom can be corrected and, to enable control of the drilling operation in respect of forming bends, in the exemplary embodiment of FIGS. 27 to 31 a control mechanism is arranged which is constructed in this embodiment from five annular elements 48 which in this example are positioned and fixed in horizontal direction relative to each other via a fitting. Also arranging per coupling in this exemplary embodiment three pressure cylinders 50 as shown, or actuators or other means for achieving a desired change in position, for the purpose of mutual coupling of these rings makes it possible to change the position of for instance the two lower rings, see FIG. 28, relative to each other such that the lowest ring undergoes an angular displacement of for instance 3° relative to in this case the vertical line. This angular displacement is applied during the drilling over a length of the rings. When the four other rings successively undergo the same angular displacement relative to each other in the same manner, see FIGS. 29 to 31, the control mechanism will ensure that a bend of for instance 45° is arranged at this location in the drilled hole. Once this bend has been realized and the drilling must once again follow a linear path, the above described operations must take place in the same sequence, but now in reverse direction.

In order to hold the control mechanism in position in the positioning of FIGS. 27 to 31 in the outer end of the film hose, there is arranged in the final link of the control mechanism a clamping provision which clamps the part of the film hose moving downward through this drive mechanism while allowing sufficient slip. This is possible because the hose part moves downward at double speed relative to the speed of movement of the control mechanism.

An alternative for controlling the drilling operation can be found in arranging a system of two rings 54 mutually coupled by three pressure elements 52 in the outer end of the hose, as shown in FIGS. 32 and 33. The supply of the hose takes place through the innermost ring. By actuating the pressure elements it becomes possible to change the positioning of the inner ring relative to that of the outer ring, whereby the symmetrical, annular contact surface between the hose end and the bottom, which is present in FIG. 32, is changed into an asymmetrical annular form, see FIG. 33, whereby the direction in which the subsequent drilling runs will deviate from the, in this example vertical, line until the moment at which there will once again be a symmetrical annular contact surface between the hose end and the bottom.

The embodiment of FIGS. 34 to 39 shows a method which in desert-like and dry regions greatly increases the chance of for instance newly planted trees being able to survive the first vulnerable period following planting and develop into saplings rooted properly in the ground and finding sufficient groundwater. According to the method of the invention a tube film of for instance 20 cm diameter is for this purpose driven into the ground to a depth of 50 cm, see FIG. 34, after which the tube film is sealed via for instance welding or binding and, as shown in FIG. 35, severed beyond the arranged weld. The drilling operation is then continued until the position of for instance about 1 m¹deep shown in FIG. 35 is reached. The pressure chamber can then be removed and, as FIG. 36 shows, the tube film in the form of a plastic bag sealed watertightly on the underside is left behind in the hole thus given a nicely round form. By pressing the ball of the young plant to a diameter of for instance 16 cm and a length of 1 m¹it then becomes possible to lower the ball of a young plant 58 into plastic bag 56, see FIG. 37. By then tamping the ball down well, the ball will completely fill the plastic bag and the young plant can be provided with the necessary water (see FIG. 38). As shown in FIGS. 36 and 37, the plastic bag protrudes a little above ground level. It hereby becomes possible to seal the whole ball from the ambient air, see FIGS. 38 and 39, such that as little as possible of the supplied water will evaporate, whereby practically all this water will be effectively utilized for growth of the young plant. The interval between the moments of watering can hereby also be increased. FIG. 39 shows the situation in which the young plant has developed into a young tree firmly rooted in the ground wherein, at a certain moment at which this young tree was ready, it has caused its roots to penetrate the plastic bag.

The film drilling technique can be applied for diverse forms of sinking wells 60. The exemplary embodiment shown here in FIGS. 40 to 47 is intended to enable the fire service to have access in a very short time to sufficient extinguishing water by means of pumping up groundwater at locations from which too little or no extinguishing water at all is currently available to effectively combat a fire which has broken out.

For this application the film hose situated on a reel at the fire station and having a diameter of for instance 12 cm is provided at its outer end with a prearranged airtight air balloon and has a breaking diameter in this example of about 1 m¹. On the basis of an inventory of the region in question it is known, for all locations suitable for application of this system, at which depths sufficiently voluminous water reservoirs 62 are located to enable effective fire fighting in the case a fire breaks out. In this case the layer providing sufficient water supply is found to be located 2 m¹below ground level, and this depth dimension is passed on to the relevant fire crew immediately after the fire is reported. A film hose with a length of 2.20 m¹is then cut off the roll and, as described above, clamped onto the casing of the pressure chamber and accommodated in the pressure chamber.

A standard fire hose attachment with arranged provisions and with a length, for this fire, of for instance 2 m¹is moreover loaded. This fire hose, of about 10 cm diameter, is provided at the one outer end with a hose coupling, see FIG. 43, and at the other outer end with a perforated tube part, see FIG. 44. A swelling material in an inflatable sleeve with a breaking diameter of for instance 70 cm is in this example fixed around this tube part. As a result of contact with optionally pressurized water or with water having an additive soluble therein this swelling material will begin to swell such that this swelling material acquires sufficient volume and shape-retention here to give the hollow space created for this purpose a filling remaining sufficiently stable in the situation of FIG. 48, which will guarantee that a sufficient supply of extinguishing water will remain available during extinguishing of the fire in question.

Instead of the above arranged swelling agent, it is also possible to place around the inflatable sleeve a stretchable mesh cage which will take on substantially the shape of the realized cavity as a result of the enlarging of the inflatable sleeve. The inflatable sleeve will in that case have to be given a greater breaking diameter, which will however have to be smaller than that of the balloon.

Immediately upon arrival at the location a hole of for instance 30 cm deep is drilled using a soil drill with a diameter of 10 cm and the pressure chamber is placed in this hole, immediately after which the required pressure value is applied in the pressure chamber, in this case preferably using compressed air, so that the film hose forms the desired drilled hole until it has reached the water-bearing ground layer (see FIG. 40). The film hose can then penetrate this water-bearing layer, for instance over a length of 20 cm, (see FIG. 41) such that the film hose will be fully expanded. When a measured quantity of compressed air is then also supplied, the balloon mounted on the fire hose will begin to displace the ground mass present at that position until this balloon acquires a diameter of for instance 80 cm. When the pressure is then relieved in the pressure chamber, the cover of the pressure chamber can be removed and, as shown in FIG. 43, the fire hose attachment can be lowered into the formed shaft. Through addition of a certain quantity of water in this attachment 64 (FIG. 44) the swelling material will begin to swell, see FIG. 45, such that the formed hollow space will begin to fill as shown in FIG. 46. During this swelling (situation from FIG. 45 to FIG. 46) a moment will be reached at which the sleeve arranged around this swelling material will burst. This moment can be traced, for instance in that there is a sudden great decrease in the water level in the attachment. At this moment the cover is arranged on the pressure chamber, after which the compressed air can once again be supplied and the air balloon can expand further until it also reaches its breaking diameter, see FIG. 47, which can again be noted due to a sudden drop in pressure. The swelling material has followed the inflation of the air balloon here, whereby the situation of FIG. 48 will for instance be reached.

At this moment the pressure chamber can be removed and this attachment can be coupled via a fire hose 66 to the water pump of the fire truck which by this time will be present, after which pumping up of the ground water and subsequent extinguishing of the fire can begin.

Fires in waste heaps resulting from for instance overheating are found very difficult to extinguish. The position of the source of the fire in such a heap can be determined very precisely using detection means and then be penetrated and extinguished using the film drilling technique.

In the exemplary embodiment of extinguishing such a fire described below, a fire has broken out in a silo 68 filled to the brim with soy meal. In this case a hole 72 is arranged in the wall of the silo at the position of the top of the source of the fire 70 which has just broken out, see FIG. 49, through which hole the casing 74 of the pressure chamber can be inserted into the meal (see FIG. 50). In this embodiment the pressure chamber is provided with for instance electromagnets 76, with which the pressure chamber is fixed against the in this case steel wall of the silo. Suction cup attachment, screw or cotter bolt anchoring or support by an external structure can also be used for this purpose.

As soon as the pressure chamber is fixed to the silo wall, the pressure chamber is filled with water and the pressure of the water supply is further increased so that the hose expanding out of the pressure chamber begins to penetrate the meal heap, see FIG. 51, following which the hose will, after a time, reach and also penetrate the source of the fire, see FIG. 52. The intense heat of the fire source will then ensure that the part of the plastic hose which has penetrated into the fire source will melt, after which extinguishing water can be sprayed freely through this hose into the source of the fire until the fire is extinguished, see FIG. 53.

This fire extinguishing method makes it possible to fight such a fire very quickly and effectively using very limited means, and to limit as far as possible the damage to the meal and the silo not yet affected by the fire.

When it is found that melting of the film hose is too difficult or too minimal for effective fire extinguishing due to the presence of water present therein, the penetration operation could in the first instance be performed by applying compressed air. As soon as the hose is then burnt through to sufficient extent, the water supply can then be fully opened immediately and the fire extinguished in a short time with a large jet of extinguishing water.

The present invention is by no means limited to the present preferred embodiments thereof. The rights sought are defined by the following claims, within the scope of which many modifications can be envisaged. It is thus for instance possible to use the device as a structural element, for instance as a lifting beam or hoisting beam, for the purpose of a hoisting device. In this way it is for instance possible to extend the structural element, with a flexible tube brought to pressure by pressure medium, for instance 1 to 5 metres out of an upper window and thereby displace goods with a compact device.

Number	Date	Country	Kind
1038414	Dec 2010	NL	national
1039014	Aug 2011	NL	national

METHOD AND DEVICE FOR DRILLING A PIT OR PASSAGE, AND FLEXIBLE TUBE THEREFOR

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CPC

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