IE57077B1

IE57077B1 - A method of and apparatus for grouting

Info

Publication number: IE57077B1
Application number: IE174588A
Authority: IE
Original assignee: Joseph Edwards
Priority date: 1985-07-11
Filing date: 1985-07-11
Publication date: 1992-04-22
Also published as: GB8616943D0; GB2178092A; 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.

Description

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 are inserted. The lance tube is usually between 50 and 75 millimeters in diameter and is driven into a previously drilled borehole 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a « casing, usually approximately of 75 millimeters in diameter and to inject grout into the borehole as the casino is withdrawn gradually up through the borehole as each level of -3the hole is grouted to refusal.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 constraints 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 lo the invention there ia provided a method of grouting cavities and/or fissures in a num-nu^de structure, land-filled, natural strata or the like, the method comprising the steps ofsΪ* drilling & borehole, lining the borehole with a casing as the borehole is being drilled, inserting a duct into the casing lining the 5 borehole, the duct having an inlet opening and a plurality of valveless outlet openings, th© outlet openings being axially and peripherally spaced-apart » along a side wall of duct to provide outlet openings at a plurality of locations in the borehole, withdrawing the casing from the borehole, injecting grout into the duct, the grout exiting directly through the valveless outlet openings in the duct to directly fill th© cavities and/or fissures.

In one embodiment 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 also provides an apparatus for carrying out the method of the invention, the apparatus including a duct and an injection pipe or lance inserted into the duct inlet opening.

• % 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.

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:5 Figs. 1 to 3 are schematic side views illustrating the method of grouting according to the invention, and « F1g. 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 dri11ed it is lined with a cylindrical casing 5 having an internal diameter in the range 1Ί5 to 137 millimeters. The drilling step with the casing 5 in place is illustrated in Fig. 1.

When the borehole 2 has 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 fhe inventlon9 is inserted -7into the casing 5 as illustrated in Fig. 2. The duct 6 comprises a cylindrical pipe having 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 spaced-apart 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 Ί1.

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 -8into 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 resulting in con15 siderable time and cost savings over conventional grouting methods 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. -9It will be appreciated that the shape, configuration, size and spacing of the outlet openings in the duct is goverened by the particular application for example, in the case of quay walls the diameter and spacing of the openings is goverened 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 further be appreciated that the duct may b© of any suitable material. For example th© duct may be of a steel or other metal rather than of a plastics material.

Claims

1. A method of grouting cavities and/or fissures in a manmade structure, land-filled, natural strata or fhe like, fhe method comprising the steps of?5 drilling a borehole, lining the borehole with a casing as fhe borehole is being drilled, inserting a duct into fhe casing lining fhe borehole, the duct having an inlet opening and a

2. A method as claimed in claim 1 including the step of sealing the space between the duct and an injection pipe or lance inserted Into the duct inlet opening.

3. A method as claimed in claim 1 or 2 wherein the duct

4. A method as claimed in claim 3 wherein the pipe is approximately 100 millimetres in diameter. 5. Claim, fhe apparatus including a duct for insertion in a borehole, the duct having an inlet opening and a plurality of outlet openings axially and peripherally spaced-aparf along the duct, grout injected into the duct exiting through the outlet openings at various levels in

5. A method as claimed in any of claims 1 to 4 wherein each of the outlet openings is of substantially circular 5 comprises a cylindrical pipe.

6. A method as claimed in claim 5 wherein the openings are between 10 and 40 millimetres in diameter.

7. A method as claimed in claim 6 wherein the openings are approximately 25 millimetres in diameter. 15

8. A method as claimed in any of claims 1 to 7 wherein the duct is of plastics material.

9. A method as claimed in claim 8 wherein the duct is of polyvinylchloride. 10. Casing for insertion in a borehole to line the borehole during drilling. 21. Apparatus as claimed in any preceding claim including means for sealing the space between the duct and an injection pipe for lance inserted into the inlet opening. 10 a borehole to fill the cracks and/or fissures.

10. A method of grouting cavities and/or fissures substantially as hereinbefore described with reference to fhe drawings. 10 shape. 10 plurality of valveless outlet openings, fhe outlet openings being axially and peripherally spaced-e.p©rt along a side wall of duct to provide outlet openings at a plurality of locations in fhe borehole, withdrawing the casing from fhe borehole, 15 injecting grout into fhe duct, fhe grout exiting directly through the valveless outlet openings in the duct to directly fill the cavities and/or fissures.

11. Apparatus for carrying out fhe method of any preceding

12. Apparatus as claimed in claim 11 wherein the duct comprises a cylindrical pipe.

13. Apparatus as claimed in claim 11 or 12 wherein fhe outlet openings comprises a plurality of holes extending through 15 the duct side wall.

14. Apparatus as claimed in claim 12 or 13 wherein fhe pipe is approximately 100 millimetres in diameter. 15. Apparatus as claimed in any of claims 11 to 14 wherein each of the outlet openings is. of substantially circular 20 shape. 't, 16. Apparatus as claimed in claim 15 wherein the openings are between 10 and 40 millimetrefii in diameter. 17. Apparatus as claimed in claim 15 or IS wherein the openings are approximately 25 millimetres in diameter. 5 18. Apparatus as claimed in any preceding claim wherein the duct is of plastics material. 19. Apparatus as claimed in claim 18 wherein the duct is of polyvinylchloride. 20. Apparatus as claimed in any preceding claim including a

15. 22. Apparatus as claimed in claim 21 wherein the sealing means comprises a sealing ring which is interposed between the duct and an injection pipe or lance.