Niclas, Pettersson
Sten-�ke
Niclas, Pettersson
Sten-�ke
| 1. | A method of providing a substantially leakproof shielding layer (8, 9) in ground consisting of porous rock and/or soil, characterized by the following steps: a) making a plurality of substantially parallel holes (H) in the ground by means of a guided drill head (4) which ejects grounddecomposing liquid mainly in the advance direction of the head, and b) passing through each hole an injection head (6) which ejects injection liquid therein essentially trans¬ versely to the advance direction thereof, so that the injec¬ tion liquid will penetrate into the ground material and will mix therewith and after transition to a solid state, together with injection liquid in an adjacent hole, which has also penetrated into and mixed with the ground material and has been transformed into a solid state, will form part of the shielding layer. A method according to claim 1 , wherein the drill head (4) and the injection head (6) form one head, charac¬ terized in that the head ejects grounddecomposing liquid when being passed in the hole making direction and injection liquid when being retracted in the opposite direction thereof. 3 A method according to claim 1 , wherein the hole making is initiated at a location (S1) and completed at a location (S2) on the ground surface spaced therefrom, characterized in that the drill head (4) connected to a drill string (3) is exchanged for or connected to the injec tion head (6) when the drill head has made the hole and is located at the ground surface at the second location and that the injection head is retracted by means of the drill string thereby ejecting injection liquid. 4 A method according to claim 1 , wherein the hole making is initiated at a location (S1) and completed at a location (S2) on the ground surface spaced therefrom, characterized in that on completion of the hole making and round their longitudinal axis. 9 A method according to any of the preceding claims, characterized in that the injection head (6) ejects liquid essentially only in two opposite directions perpendicular to the direction of advance. 10 A device for performing the method according to any of the preceding claims, characterized by a single machine (1) for moving the drill head (4) as well as the injection head (6) through the hole (H) . 11 A device for performing the method according to any of claims 1 9, characterized in that the injection head (6) is provided with means for the orientation thereof round its longitudinal axis. 12 A device for performing the method according to any of claims 1 9, characterized in that the injection head (6) is provided with nozzles, which are oriented in such a way as to eject injection liquid essentially only in two opposite directions substantially perpendicular to the direction of advance of the head. 13 A device for performing the method according to any of claims 1 9, characterized in that the drill head (4) and the injection head (6) are combined into one head including blockable drilling and injection nozzles. |
Technical field The present invention relates to a method of pro¬ viding a substantially lea proof shielding layer in the ground and a device for performing the method. A shielding layer of this kind is necessary to delimit a ground area from the surrounding ground, such that material accumulated in said area will not spread thereby causing contamination or damage. Examples of such ground areas are refuse dumps and bodies of water.
Prior art It is previously known to make long holes in the ground the extension of which may be horizontal, for example under a road. Examples of a device capable of making such holes are given in EP 0 195 559. Said device includes a head connected to a drill string and having nozzles which under high pressure and at high speed eject liquid that carries out the making of the holes. The head is provided with means to orientate it round its longitudinal axis thereby to guide the head in a desired course.
It is also previously known to insert into a drill hole an injection head provided with nozzles which under high pressure eject a liquid injection medium which will mix with the ground material surrounding the hole and, on removal of the head, will solidify and form a leakproof layer.
Summary of the invention
It is an object of the present invention to provide a method and a device by which a shielding layer can be provided in a simple and economical way by the use of simple means.
This object is achieved in that the invention has been given the features stated in the characterizing por-
tions of the independent claims.
Description of the figures
Fig. 1 is a schematic side view, in section, showing a ground area with a partially made hole and a device for performing the method according to the invention,
Fig. 2 is a schematic side view, in section, showing the ground area and the device of Fig. 1, wherein the hole is completely made and partly injected, Fig. 3 is a section along the line A-A of Fig. 2 according to a first type of extension of the injection,
Fig. 4 is a section along the same line A-A of Fig. 2 according to a second type of extension of the injection, and Fig. 5 is a view of a portion of Fig. 4, on an enlarged scale.
Preferred embodiments
A ground area consisting of porous rock and/or soil, in which a shielding layer is to be provided, is indicated at M1. In and/or on this area there is an area M2 with, for example, refuse matter, to be screened off from the surrounding ground area in order to prevent, for example, contamination thereof. In Figures 1 and 2 there is shown a machine 1 and a plant 2 placed on the ground surface on either side of the area M2. The machine 1 is a drilling machine, for instance of the kind marketed by Atlas Copco AB, Stockholm, Sweden, under the registered trademark of TERRABOR, while the plant 2 is a jet injection plant, for example of the kind made by Colla CCP International, Parma, Italy, and referred to as Jet Grouting. The drilling machine 1 is designed so as to be able to feed a tubular, flexible drill string 3 backwards and forwards and also rotate it round the longitudinal axis of the drill string. One end of the drill string 3 is detachably connected to a drill head 4 which is known per se, such as a drill head shown in SE-B 464 146. Said drill
head is provided with an oblique leading guide surface 5 and one or more nozzles (not shown) in the front portion of the head, through which fluid can be ejected under high pressure and at high speed. The fluid is fed through the drill string 3 from a source (not shown) placed at the machine. The drill head 4 is provided with means (not shown) which are known per se and which provide the operator of the machine 1 with information on the orientation of the head round its longi¬ tudinal axis as well as on the distance of the head from the ground surface.
During the advance of the drill head 4 achieved by the machine 1, beginning at a location S1 and ending at a location S2 on the ground surface, the head makes an elongated, substantially horizontal hole H in the ground under the area M2.
When the drill head 4 has penetrated the ground surface at the location S2 and the supply of fluid has been interrupted, the head is released from the end of the drill string 3. The plant 2 includes an essentially cylindrical injection head 6, which is provided with one or more nozzles (not shown) round its periphery and which is then mounted to said end of the drill string 3. The head 6 is connected to a hose 7 which is wound at the plant 2 and iε connected via a pump (not shown) to a source of injection medium in the form of a fluid, usually consisting of a mixture of water, con¬ crete and bentonite.
The drill string 3 is retracted through the hole H by the machine until the head 6 is accessible at the loca¬ tion S1 when it is disconnected from the drill string. The head 6 is then drawn back into the hole H by means of the hose 7 towards the location S2 while the injection medium is ejected under high pressure and at high speed (= jet injec¬ tion 200 - 800 bars) from the nozzles of the head substan¬ tially transversely to the longitudinal axis of the head. During ejection, the medium enters into the walls of the hole and into the adjacent ground material and mixes there¬ with. When the head 6 has been returned to the location S2,
injection is completed. After a certain length of time, the injection medium will solidify, making the hole and the surrounding parts of the ground substantially leakproof.
Instead of removing the drill head 4 from the drill string 3 first and thereafter connecting the injection head 6 to the free end of the drill string, as described in the preceding paragraphs, the drill head can stay mounted to the drill string and the injection head can be connected thereto at the location S2. When the injection head has reached the location S1, the head is disconnected from the drill head and the injection head is retracted.
After making several holes, corresponding to the hole H, which are substantially parallel to and equally spaced from each other, and after injection into these in the above described way, the injected holes together will form a leakproof shielding layer under the entire area M2.
As is evident from Figs. 3 and 4, showing a portion 8 and 9 respectively of said shielding layer, seen in a cross-sectional view transversely to the longitudinal axis of the hole H of Fig. 1, the distances between the holes H are spanned by the injection medium I present in the holes and the surrounding ground. In Fig. 3 injection has been carried out by means of an injection head which has several nozzles round its periphery and which has not been oriented round its longitudinal axis, while in Fig. 4 injection has been carried out using a head which has several nozzles placed in such a way as for injection medium to be ejected essentially in two opposite directions only and which has been oriented round its longitudinal axis, so that the injection medium will mainly spread horizontally in the ground surrounding the drill hole.
Fig. 5 shows one of the holes H of Fig. 4 and the injection head 6 therein during ejection of injection medium I. According to an alternative arrangement of the above described method shown in Fig. 2, the drill head 4 (or the end of the drill string 3 from which the drill head is
disconnected) after the drilling of the hole H is immediately connected to a long wire cable 10 and is drawn through the hole when the drill string is retracted there¬ through by the machine 1. On removal of the entire drill string from the hole H, the wire cable is disconnected from the drill string at the location S1 , and the injection head 6 is connected to the wire cable at the location S2, where¬ upon the wire cable is drawn through the hole by a hoist 11, disposed adjacent the machine 1, at an even speed while the injection medium is ejected through the injection head 6. On disconnection of the wire cable from the injection head, the injection hose 7 is retracted through the hole towards the location S2 with or without the injection head. As may be seen from Fig. 2, the injection head 6 has been drawn to the right by the wire cable 10 about one third of the length of the hole H and during this distance has injected the hole and the area around it.
According to a further alternative arrangement, the machine 1 and the plant 2 may both be placed at the location S1. After the hole H has been drilled by the head 4 and the drill string 3 has been retracted by the machine 1 , the head 4 is removed from the drill string 3 at the location S1 and the head is then attached thereto. The machine 1 will then press the head 6, via the drill string 3, through the hole H to the location S2 and will thereafter retract the head to the location S1. Injection medium is fed via the drill string 3 through the head 6 in one feed direction or in both. Owing to the head 6 being connected to the drill string, which is substantially rigid in the circumferential direction, the head 6 may be oriented round its longitudinal axis and is able to provide the injection pattern shown in Figs. 4 and 5.
Alternatively to the latter described arrangement in which the machine 1 and the plant 2 are placed at the location S1 , a wire armed hose may be drawn through the hole, after or in connection with the making of the hole H in the above described way, whereupon the injection head 6
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