GB2178092A

GB2178092A - A method of and apparatus for grouting

Info

Publication number: GB2178092A
Application number: GB08616943A
Authority: GB
Inventors: Joseph Edwards
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-07-11
Filing date: 1986-07-11
Publication date: 1987-02-04
Also published as: IE57077B1; GB8616943D0; IE851745L

Abstract

The grouting by cement of cavities and/or fissures in structures is effected by apparatus consisting of a cylindrical duct 6 having a series of holes around its outer surface to allow liquid cement to be delivered through the holes at various levels to fill the fissures. A suitable bore-hole has to be drilled in the structure to receive the duct. <IMAGE>

Description

SPECIFICATION A method of and apparatus for grouting The invention relates to a method of and apparatus for grouting cavities and/or fissures in man-made structures such as foundations or walls, particularly quay walls, land fill, natural strata or the like, hereinafter referred to as "structures".

The term "grout" as used in this specification refers to any material which is suitable for sealing cavities and/or fissures in masonry.

The grout may comprise a cementitious slurry such as a fluid mixture of Portland or other cement and water to which sand or the like may be added.

One conventional method of filling cavities and fissures with grout is to first drill boreholes, usually approximately spaced-apart by about two meters into which lances through which grout is injected and inserted. The lance tube is usually between 50 and 75 millimeters in diameter and is driven into a previously drilled bore hole using a percussive action.

One variation on this method is to line the borehole with a casing, usually approximately of 75 millimeters in diameter and to inject grout into the borehole as the casing is withdrawn gradually up through the borehole as each level of the hole is grouted to refusal.

A further variation is to use flush jointed tubes, typically of 50 millimeter diameter, which are used not only as part of the drill string but also as injection lances in which the grout is extruded through the flushing holes in the drill bit.

Each borehole usually requires several stages of grout injection at different levels to fill cavities and fissures because of leakages, ground heave and time contraints on both drilling and grouting. When it is necessary to break off grouting the grout sets in the hole so that the hole must be re-drilled before grouting can be re-started. This re-drilling has an adverse effect on both the cost and the time taken to grout a particular area.

There is therefore a need for an improved method and apparatus for grouting cavities and fissures to overcome at least some of these disadvantages.

According to one aspect the invention provides an apparatus for grouting cavities and/or fissures in a man-made structure, land-fill, natural strata or the like, the apparatus comprising a duct for insertion in a borehole, the duct having an inlet opening and a plurality of outlet openings axially peripherally spacedapart along the duct, grout injected into the duct exiting through the outlet openings at various levels in a borehole to fill the cracks and/or fissures.

In a preferred embodiment of the invention the duct comprises a cylindrical pipe.

Preferably the outlet openings comprise a plurality of holes extending through the duct side wall.

Advantageously the pipe is approximately 100 millimeters in diameter.

Typically each of the outlet openings is of substantially circular shape. The openings may be between 10 and 40 millimeters in diameter. Preferably the openings are approximately 25 millimeters in diameter.

In a preferred embodiment of the invention the duct is of plastics material, for example polyvinylchloride.

In one embodiment of the invention the apparatus includes a casing for insertion in a borehole to line the borehole during drilling.

In a further embodiment of the invention the apparatus includes means for sealing the space between the duct and an injection pipe or lance inserted into the inlet opening. The sealing means may comprise a sealing ring which is interposed between the duct and an injection pipe or lance.

In another aspect the invention provides a method of grouting cavities and/or fissures in a man-made structure, land-fill, natural strata or the like, the method comprising the steps of drilling a borehole, inserting a duct into the borehole, the duct having an inlet opening and a plurality of outlet openings, the outlet openings being axially and peripherally spaced-apart along the duct to provide outlet openings at various locations in the borehole, and injecting grout into the duct, the grout exiting the duct through the outlet openings to fill the cavities and/or fissures.

In another embodiment of this aspect of the invention the method includes the step of lining the borehole with a casing as the borehole is being drilled, the duct being inserted into the casing when the borehole drilling is complete and the casing being removed from the borehole prior to injection of the grout.

In another embodiment of this aspect of the invention the method includes the step of sealing the space between the duct and an injection pipe or lance inserted into the duct inlet opening.

The invention will be more clearly understood from the following description thereof given by way of example only with reference to the accompanying drawings in which: Figure 1 to 3 are schematic side views illustrating the method of grouting according to the invention, and Figure 4 is a schematic side view of a modified step in the grouting method.

Referring to the drawings and initially to Figs. 1 to 3 thereof there is illustrated a method of grouting cavities and fissures in this case in a quay wall 1 comprising the steps of drilling a borehole 2 in the quay wall 1 using a conventional drill having an undereaming bit 3 which in this case is driven by rotary-percussive equipment 4. As the borehole is drilled it is lined with a cylindrical casing 5 having an internal diameter in the range 115 to 137 millimeters. The drilling step with the casing 5 in place is illustrated in Fig. 1.

When the borehole 2 had been drilled to the desired depth the drill bit 3 and equipment 4 is withdrawn from the hole and a duct 6, also according to the invention, is inserted into the casing 5 as illustrated in Fig. 2. The duct 6 comprises a cylindrical pipe haveing a top opening 7 defining an inlet through which grout is introduced into the pipe. The pipe 6 is formed with a plurality of outlet openings 8 which are axially and circumferentially spacedapart along the length of the pipe 6. Each of the outlet openings 8 is in this case approximately of 25 millimeters in diameter and the openings 8 are axially and radially spacedapart by about approximately 300 millimeters.

When the pipe 6 is inserted into the borehole 2 the casing 5 is then withdrawn and a grout injection pipe or lance 10 typically of approximately 37 millimeters internal diameter is inserted into the pipe 6 as illustrated in Fig. 3.

Grout is discharged from the injection pipe 10 through a lower outlet opening 11.

To fill cracks or fissures in the quay wall 1 grout is injected into the pipe 6 through the grout injection line 10 using a pressure pump (not shown). In this case the grout is discharged under gravity feed into the pipe 6 and passes into any cracks or fissures in the quay wall through the outlet openings 8 in the pipe 6. The grout exiting through the outlet openings 8 finds its own level and when it is desired to break off grout injection due to excessive consumption, ground heave, or time constraints, the grout injection pipe 10 is simply withdrawn from the perforated pipe 6 to another location. When the grout is set the grout injection pipe 10 is then inserted again into the duct 6 to the level where the grout is set and the procedure is repeated until adequate grout has been injected along the length of the borehole.

In the event of a leakage or excessive consumption of grout at a given level the injection pipe is removed from the perforated pipe and moved to the next available borehole while the grout is setting in the initial borehole. Similarly, when grouting has to be broken off because of time constraints it can simply be resumed at the next available time without any re-drilling requirement.

Thus, the method and apparatus according to the invention allows both drilling and grouting operations to be carried out on a continuous uninterrupted basis and substantially eliminates any re-drilling requirement resuiting in considerable time and cost savings over conventional grouting method and apparatus.

If necessary, grout can be injected into the perforated pipe 6 under pressure. One such arrangement is illustrated in Fig. 4. In this case the spacing between the injection line 10 and the perforated pipe 6 is sealed with any suitable sealing means such as a sealing ring 20. Using a suitable arrangement this sealing can be effected at any desired level.

It will be appreciated that the shape, configuration, size and spacing of the outlet openings in the duct is governed by the particular application for example, in the case of quay walls the diameter and spacing of the openings is governed by soil conditions. In some cases the diameter and spacing of the openings may vary along the length of the duct, depending on the soil conditions.

It will also be appreciated that the principle of the invention may be applied irrespective of the size of the borehole drill. However from experiments we have found that a 100 millimeter diameter PVC pipe appears to be the smallest diameter pipe possible compatible with the requirement for drilling sufficiently large outlet openings. It will of course also be appreciated that the size of the ducting used dictates the size of the drilling equipment and the figures given are by way of example only.

It will also be appreciated that in some cases it may not be necessary to insert a casing into the borehole as it is being drilled.

Depending on the condition of the material being drilled in some cases it may be possible to simply drill a borehole and insert a perforated duct into the borehole after the drill string has been removed.

It will further be appreciated that the duct may be of any suitable material. For example the duct may be of a steel or other metal rather than of a plastics material.

Claims

1. Apparatus for grouting cavities and/or fissures in a man-made structure, land-fill, natural strata or the like, the apparatus comprising a duct for insertion in a borehole, the duct having an inlet opening and a plurality of outlet openings axially and peripherally spacedapart along the duct, grout injected into the duct exiting through the outlet openings at various levels in a borehole to fill the cracks and/or fissures.

2. Apparatus as claimed in claim 1 wherein the duct comprises a cylindrical pipe.

3. Apparatus as claimed in claim 1 or 2 wherein the outlet openings comprise a plurality of holes extending through the duct side wall.

4. Apparatus as claimed in claim 2 or 3 wherein the pipe is approximately 100 millimeters in diameter.

5. Apparatus as claimed in any of claims 1 to 4 wherein each of the outlet openings is of substantially circular shape.

6. Apparatus as claimed in claim 5 wherein the openings are between 10 and 40 millimeters in diameter.

7. Apparatus as claimed in claim 5 or 6 wherein the openings are approximately 25 millimeters in diameter.

8. Apparatus as claimed in any preceding claim wherein the duct is of plastics material.

9. Apparatus as claimed in claim 8 wherein the duct is of polyvinylchloride.

10. Apparatus as claimed in any preceding claim including a casing for insertion in a borehole to line the borehole during drilling.

11. Apparatus as claimed in any preceding claim including means for sealing the space between the duct and an injection pipe or lance inserted into the inlet opening.

12. Apparatus as claimed in claim 11 wherein the sealing means comprises a sealing ring which is interposed between the duct and an injection pipe or lance.

13. A method of grouting cavities and/or fissures in a man-made structure, land-fill, natural strata or the like, the method comprising the steps of drilling a borehole, inserting a duct into the borehole, the duct having an inlet opening and a plurality of outlet openings, the outlet openings being axially and peripherally spaced-apart along the duct to provide outlet openings at various locations in the borehole, and injecting grout into the duct, the grout exiting the duct through the outlet openings to fill the cavities and/or fissures.

14. A method as claimed in claim 13 in which the method includes the step of lining the borehole with a casing as the borehole is being drilled, the duct being inserted into the casing when borehole drilling is complete and the casing being removed from the borehole prior to injection of the grout.

15. A method as claimed in claim 13 or 14 including the step of sealing the space between the duct and an injection pipe or lance inserted into the duct inlet opening.

16. A method as claimed in any of claims 13 to 15 wherein the duct comprises a cylindrical pipe.

17. A method as claimed in any of the claims 13 to 16 wherein the outlet openings comprise a plurality of holes extending through the duct side wall.

18. A method as claimed in claim 16 or 17 wherein the pipe is approximately 100 millimeters in diameter.

19. A method as claimed in any of claims 13 to 18 wherein each of the outlet openings is of substantially circular shape.

20. A method as claimed in claim 9 wherein the openings are between 10 and 40 millimeters in diameter.

21. A method as claimed in claim 20 wherein the openings are approximately 25 millimeters in diameter.

22. A method as claimed in any of claims 13 to 21 wherein the duct is of plastics material.

23. A method as claimed in claim 22 wherein the duct is of polyvinylchloride.

24. Apparatus for grouting cavities and/or fissures substantially as hereinbefore described with reference to the drawings.

25. A method of grouting cavities and/or fissures substantially as hereinbefore described with reference to the drawings.