CA1337893C - Injection apparatus for foundation piles - Google Patents
Injection apparatus for foundation pilesInfo
- Publication number
- CA1337893C CA1337893C CA 589240 CA589240A CA1337893C CA 1337893 C CA1337893 C CA 1337893C CA 589240 CA589240 CA 589240 CA 589240 A CA589240 A CA 589240A CA 1337893 C CA1337893 C CA 1337893C
- Authority
- CA
- Canada
- Prior art keywords
- grout
- stage
- tube
- orifices
- pod
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
- E02D5/38—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
- E02D5/38—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds
- E02D5/44—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds with enlarged footing or enlargements at the bottom of the pile
Landscapes
- Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Paleontology (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
Abstract
The invention concerns an apparatus and a method for forming underground piles. Apparatus is provided comprising a tube having holes at least near its lower end for introducing first stage grout into a borehole, and means for injecting second stage grout under pressure to infiltrate the first stage grout and enhance and reinforce its action. Second stage grout is injected through an inner coaxial tube having, at its lower end, a reservoir pad which splits open longitudinally along lines of weakness or partial slits to release second stage grout suddenly. The force of second stage grout may expand the bottom of the tube for first stage grout thus further improving the anchor. The tube for injection of second stage grout may be withdrawn when the process is complete.
Description
This invention relates to apparatus for the production of underground structures, especially piles.
While the invention is particularly concerned with the production of piles, the principles may also be applied to the production of ground anchors or other underground structures. An important difference between piles and ground anchors is that piles are usually load bearing generally vertical structures set into the ground, whereas ground anchors are generally anchoring stays in the ground by means of masses which are stable against stresses and strains on the stay with various lateral and vertical components.
Many of the considerations in producing ground anchors and piles and other underground structures are somewhat similar. For example, when injecting grout for such structures into the ground, control of the amount, the direction and the spread of the grout is of especial importance.
Examplary U.S. patents which disclose means in which especial attention is given to the control of the amount of a fluid for underground injection are U.S. Patent No.
4,378,997 to Kasama et al, issued April 15th 1983, U.S.
Patent No. 3,698,196 to Janowski issued October 15th 1972 and U.S. Patent No. 3,699,687 to Bourland issued October 24th 1972 These patents all disclose capsules which may be ruptured to release their contents into their immediate surroundings for, respectively, breaking up the surroundings, filling cracks with swellable foam or anchoring purposes.
The use of such rupturable capsules may be suitable when a generally multi-directional unconfined splash of *
- 1 3378~3 material is required or for generally providing pressure to force fluid into existing cracks or crevices.
However, for the provision of generally vertical piles, which may be provided with thickened bulbous base S portions, considerably more control is required.
Where the use of conventional mechanical pile drivers is contra-indicated, or as an alternative from such use, it is known to form a bore into the ground, insert an injection tube into the bore and inject grout to form a pile through the tube.
One problem with this type of method involves the provision of non return injection valves for the injection tubes so that the grout can be flushed non-returnably from the tube into the ground whereafter the tube may be withdrawn and reused.
A number of U.S. patents such as No. 3,984,988 to Portier issued October 12th 1976, No. 4,545,702 to Sano et al issued October 8th 1985 and No. 4,710,063 to Faktus et al issued December 1st 1987 concern structures of non return valves for such injection tubes.
U.S. Patent No. 4,426,175 to Lin issued January 17th 1984, French patent No. 2,552,462 to Acaplast, Societe Anonyme and Russian patent No. 600,245 all disclose apparatus in which grout is not released into the surroundings from the injection tube when pressure is built up sufficiently to burst rupturable valves in the injection openings. Means is provided to seal the bore above the valved part of the tube so that pressure will not escape up the bore. No provision is made to stabilise the surroundings of the bore into which grout is to be injected to control the spread of grout.
U.S. patent No. 3,494,134 to Jorge issued February 10th 1970 discloses means for setting a stay or rod into the ground as a ground anchor in which precautions are taken to first proved establishment of grout around the stay or rod and thereafter fill the bore with grout which may penetate to into the walls of the bore where they are, by chance, of a nature to allow such penetration.
No stabilisation of the environment of the walls of the bore is attempted.
U.S. patent No. 1,386,876 to Dupeuble issued June 7th 1981 discloses an apparatus using an injection tube with non-return valves for anchoring the rods. This apparatus again involves sealing the bore to prevent back flow of grout and then injecting grout into the lower part of the bore and to fill the tube which surrounds the tie rods.
The whole of the tube remains in the ground.
Some of the previous techniques of providing underground structures by injection of grout have been "one shot" processes. This involves the establishment of a plug in the borehole above the injection region and then simply injecting grout into the lower part of the borehole, allowing any natural seepage into its walls.
An improved "two-shot" process may also be used in which, after a structure formed by a one shot process has been allowed to set, a second injection through the same injection tube is performed, cracking open the first structure at least at its base and injecting grout therethrough to form a bulb on root system. When the second grouting sets, second stage grout bonds with the broken first grout. Efficient non-return valves have been very important in such processes. Even so it has been difficult to achieve consistent results. Moreover, the more sophisticated non-return valves add expense to the apparatus. Such a two-stage process is described in an article entitled "Pieux-Aiguilles" published by Soletanche, 7, Rue de Logelbach, Paris 17.
An attempt has now been made to provide apparatus and a method for grout injection into bore holes, especially for the production of piles. Important considerations were the desirability of stabilising the environment in the immediate vicinity of grout injection, and the provision of relatively inexpensive apparatus without the need for sophisticated non-return valves.
Thus according to the invention we provide apparatus for use in the production of a structure anchored in the ground comprising a first stage grout injection sheathing tube having first orifices therethrough adapted for the passage of fluid grout therethrough, the first orifices being distributed over at least a lower part of the tube;
a second stage grout injection tube adapted for the introduction of pressurised grout locatable substantially coaxially within said first stage sheathing tube and having second orifices therethrough distributed over a lower part;
an elongate pod of resiliently deformable material releasably enclosing the lower part of the second stage tube, the pod having longitudinal lines of weakness in a sidewall rupturable to form corresponding longitudinal slits, and adapted to, under pressure of grout from the second orifices, rupture to allow the passage of pressurised fluid grout into the lower part of first stage injection tube and through the first orifices thereof.
According to the invention we also provide a process for the production of a structure anchored in the ground comprising:
introducing into a borehold, a first stage grout injection sheathing tube having first orifices therethrough adapted for the passage of fluid grout, the first orifices being distributed over at least a lower part of the tube;
introducing co-axially said first stage tube, a second stage grout injection tube adapted for the introduction of pressurised grout said second stage tube having second orifices therethrough distributed over a lower part thereof, the lower part of the second stage tube being releasably enclosed by an elongate pod of resiliently deformable material, the pod having longitudinal lines of weakness in the sidewall rupturable to burst open to form corresponding longitudinal slits under pressure of grout from the orifices of the second stage injection tube, to allow the further passage of pressurised grout at least into the lower part of first stage injection tube;
introducing into the first stage injection sheathing tube, fluid first stage grout at a pressure to fill the tube and inject it through the first orifices into surrounding environment;
allowing said grout to set;
introducing into the second stage injection tube, second stage fluid grout and injecting it under pressure through the second orifice to rupture the lines of weakness in the pod and crack the first stage grout, and flow through the first orifices; and B~ ~
i allowing the second stage grout to set releasing the second stage tube from the pod and withdrawing it therefrom.
The apparatus used in the process of the inventions may have the advantage that only first stage injection tube and the pod are left in the ground. The first stage injection tube makes a useful reinforcement for the resulting pile and the pod may be relatively inexpensive.
An embodiment of the invention will now be described with reference to the drawings in which:
Figure 1 is a sectional diagramatic sketch of one form of apparatus according to the invention located in a borehole;
Figure 2 is a view similar to Figure 1 after a first stage introduction of grout;
Figure 3 is a section of Figure 2 on the line III-III of Figure 2;
Figure 4 is a view similar to Figure 2 after a second stage injection of grout;
Figure 5 is a section of Figure 4 on the line V - V
of Figure 4; and Figure 6 is a view similar to Figure 1 of the resulting pile.
The drawings show a borehole 10 in which a pile is to be located. A first stage injection tube 12 having a cap ~_ 29 above ground level 23 is inserted into the borehole 10. Grout to be dispensed into the borehole 10 through tube 10 may be under low pressure, for example, it may be introduced by pouring. However, conveniently it is introduced through primary grout injection tube 21. The tube 10 has means for dispensing grout into the borehole 12 at least at the lower end and preferably over, its length. The means for dispensing grout may be first orifices 14, as shown, or may be rupturable diaphragms or orifices provided with non-return valves. However, simple orifices 14 are sufficient and any rupturable diaphragms or non-return valves should be suitable to dispense grout unto the borehole 10 under quite low pressures.
lS A second stage injection tube 20 has second orifices 22 for the injection of pressurised grout only at its lower end portion 24.
A pod 26 comprising a tubular portion 28 of greater diameter and coextensive with the lower end portion 24 of the second stage injection tube 20 has a closed lower end 30 and means for releasable connection to the injection tube 20 at its upper end. The means for connection with the injection tube 20 may be a conventional pipe reducer 32, its smaller end being adapted for screw threaded engagement with a screw-threaded portion 34 of injection tube 20 above the lower portion 24. Figures 1 to 3 of the drawings show the pod 26 with the smaller end of the pipe reducer 32 engaged with screw-threaded portion 34 of tube 20. The wider end of the pipe reducer 32 is connected to the tubular portion 28 of the pod 26 by any convenient means, for example, by a solvent joint.
The pod 26 may conveniently comprise an outer sheath _ 25 of flexible plastic having longitudinal lines 6 weakness or slits 36 at least partially therethrough.
The outer sheath 25 of pod 26 may be made of flexible deformable plastics material such as polyvinyl chloride and the longitudinal slits 36 may be only in the outer surface of its side wall. Thus, the slits 36 need not extend completely through the side wall but form weakened portions adapted to rupture under the influence of pressurised grout. For supporting the flexible sheath 25, an inner support pod 27 may be provided comprising a cylinder of longitudinally corrugated, perforated metal, for example, steel.
In operation first stage injection tube 12 is lowered down borehole 10 and second stage injection tube 20 is, with pod 26 engaged thereon, lowered down tube 12.
Primary grout 38 is injected under low presure through or even poured into first stage tube 12. The grout 38 flows down the tube and is injected into the borehole 10 through orifices 14. There may be seepage 39 of grout 38 beyond the walls of borehole 10. This will depend upon the structure of the soil, the compaction of the borehole walls and the pressure of grout 38.
Grout 38 also acts to exert pressure to compress pod 26 so that it tends to assume the somewhat flattered oval form shown in Figure 3. Since the slits 36 are in the sheath 25 surface of tubular portion 28, this flattening action tends to close the slits firmly guarding against any tendency of grout 38 to burst inwardly into the pod 26 through slits 36. The longitudinal corrugations of support pad 27 are an aid against undue deformation of pad 27 during application of primary grout 38.
Grout 38, 39 is allowed to set to form a pile structure. The pile structure within the borehole 10 will tend toward constant cross section of which corresponds to the diameter of the borehole 10. The structure is reinforced by the embedment of first stage injection tube 12 therein. Seepage 39 extends outwardly of the borehole 10 where the soil structure allows it and may provide some additional anchoring force. Except where particular crevices or soil weakness or mud areas exist, the cross section of the whole pile structure including seapage 39 will probably be generally constant from the bottom of tube 12 to ground level.
The process, thus far, is not totally dissimilar to previous one step processes with a notable exception that, no attempt is necessarily made to provide non-return valves for orifices 14 and first stage injection tube 12 is embedded into the structure as reinforcement.
When grout 38 has been given the opportunity to set grout 40 is injected under pressure through second stage injection tube 20. The resultant action at the bottom of borehole 10 is that pressurized grout 40 re-expands pod 26 to expand the support pad 27 and burst open the slits 36 of flexible outer sheath 25 as shown in Figures 4 and 5.
The surrounding set grout 38 in tube 12, borehole 10 and seepage 39 may crack and break under the strain opening crevices to orifices 14. The bottom part of tube 12 may splay out as shown in Figure 4 to form a strong anchor in the ground. At a preset pressure of grout 40, which is determined by the size, and depth of slits 36, the material of tubular portion 28 and the strength of set grout 38, the slits 36 rupture. Thus pod 26 bursts open to release second stage grout 40 into the bottom part of tube 12 and through orifices 14 in the bottom part of tube 12 to spread outwardly to extend beyond the limits of seepage 39. The spread of grout 40 may be as a root system 42 as shown in Figure 4 or it may form a bulb surrounding the bottom of tube 11.
In any case the presence of seepage 39 and set grout 38 in tube 12 and borehole 10 tends to direct the spread of grout 40 downwardly as well as outwardly to form a root system 42 for the resulting pile.
As grout 40 sets, it bonds with previously set grout 38 to form a cohesive structure.
Burst point of pod 26 may be consistent, resulting in a root system 42 of consistent size and shape for each configuration of tube 12. The grout 40 may be applied in consistent amount by using water pressure or other pressure to force a set amount of grout 40 through injection tube 20. Either while grout 40 is still wet or if water is used to force the grout through the tube 20.
The pressure in tube 20 may be relieved after injection of an appropriate amount of grout 40. The tubular portion 28 will then be compressed against lower portion 24 of tube 20 thus having some tendency to seal orifices 22 against return of grout 40. At this stage, either while grout 40 is still wet or if water is used to force the grout through the tube 20, ~he tube 20 may be unscrewed from the pipe reducer 32 and withdrawn for reuse leaving tube 12 and ruptured pod 26 in place in a substantial rooted pile structure.
While the invention is particularly concerned with the production of piles, the principles may also be applied to the production of ground anchors or other underground structures. An important difference between piles and ground anchors is that piles are usually load bearing generally vertical structures set into the ground, whereas ground anchors are generally anchoring stays in the ground by means of masses which are stable against stresses and strains on the stay with various lateral and vertical components.
Many of the considerations in producing ground anchors and piles and other underground structures are somewhat similar. For example, when injecting grout for such structures into the ground, control of the amount, the direction and the spread of the grout is of especial importance.
Examplary U.S. patents which disclose means in which especial attention is given to the control of the amount of a fluid for underground injection are U.S. Patent No.
4,378,997 to Kasama et al, issued April 15th 1983, U.S.
Patent No. 3,698,196 to Janowski issued October 15th 1972 and U.S. Patent No. 3,699,687 to Bourland issued October 24th 1972 These patents all disclose capsules which may be ruptured to release their contents into their immediate surroundings for, respectively, breaking up the surroundings, filling cracks with swellable foam or anchoring purposes.
The use of such rupturable capsules may be suitable when a generally multi-directional unconfined splash of *
- 1 3378~3 material is required or for generally providing pressure to force fluid into existing cracks or crevices.
However, for the provision of generally vertical piles, which may be provided with thickened bulbous base S portions, considerably more control is required.
Where the use of conventional mechanical pile drivers is contra-indicated, or as an alternative from such use, it is known to form a bore into the ground, insert an injection tube into the bore and inject grout to form a pile through the tube.
One problem with this type of method involves the provision of non return injection valves for the injection tubes so that the grout can be flushed non-returnably from the tube into the ground whereafter the tube may be withdrawn and reused.
A number of U.S. patents such as No. 3,984,988 to Portier issued October 12th 1976, No. 4,545,702 to Sano et al issued October 8th 1985 and No. 4,710,063 to Faktus et al issued December 1st 1987 concern structures of non return valves for such injection tubes.
U.S. Patent No. 4,426,175 to Lin issued January 17th 1984, French patent No. 2,552,462 to Acaplast, Societe Anonyme and Russian patent No. 600,245 all disclose apparatus in which grout is not released into the surroundings from the injection tube when pressure is built up sufficiently to burst rupturable valves in the injection openings. Means is provided to seal the bore above the valved part of the tube so that pressure will not escape up the bore. No provision is made to stabilise the surroundings of the bore into which grout is to be injected to control the spread of grout.
U.S. patent No. 3,494,134 to Jorge issued February 10th 1970 discloses means for setting a stay or rod into the ground as a ground anchor in which precautions are taken to first proved establishment of grout around the stay or rod and thereafter fill the bore with grout which may penetate to into the walls of the bore where they are, by chance, of a nature to allow such penetration.
No stabilisation of the environment of the walls of the bore is attempted.
U.S. patent No. 1,386,876 to Dupeuble issued June 7th 1981 discloses an apparatus using an injection tube with non-return valves for anchoring the rods. This apparatus again involves sealing the bore to prevent back flow of grout and then injecting grout into the lower part of the bore and to fill the tube which surrounds the tie rods.
The whole of the tube remains in the ground.
Some of the previous techniques of providing underground structures by injection of grout have been "one shot" processes. This involves the establishment of a plug in the borehole above the injection region and then simply injecting grout into the lower part of the borehole, allowing any natural seepage into its walls.
An improved "two-shot" process may also be used in which, after a structure formed by a one shot process has been allowed to set, a second injection through the same injection tube is performed, cracking open the first structure at least at its base and injecting grout therethrough to form a bulb on root system. When the second grouting sets, second stage grout bonds with the broken first grout. Efficient non-return valves have been very important in such processes. Even so it has been difficult to achieve consistent results. Moreover, the more sophisticated non-return valves add expense to the apparatus. Such a two-stage process is described in an article entitled "Pieux-Aiguilles" published by Soletanche, 7, Rue de Logelbach, Paris 17.
An attempt has now been made to provide apparatus and a method for grout injection into bore holes, especially for the production of piles. Important considerations were the desirability of stabilising the environment in the immediate vicinity of grout injection, and the provision of relatively inexpensive apparatus without the need for sophisticated non-return valves.
Thus according to the invention we provide apparatus for use in the production of a structure anchored in the ground comprising a first stage grout injection sheathing tube having first orifices therethrough adapted for the passage of fluid grout therethrough, the first orifices being distributed over at least a lower part of the tube;
a second stage grout injection tube adapted for the introduction of pressurised grout locatable substantially coaxially within said first stage sheathing tube and having second orifices therethrough distributed over a lower part;
an elongate pod of resiliently deformable material releasably enclosing the lower part of the second stage tube, the pod having longitudinal lines of weakness in a sidewall rupturable to form corresponding longitudinal slits, and adapted to, under pressure of grout from the second orifices, rupture to allow the passage of pressurised fluid grout into the lower part of first stage injection tube and through the first orifices thereof.
According to the invention we also provide a process for the production of a structure anchored in the ground comprising:
introducing into a borehold, a first stage grout injection sheathing tube having first orifices therethrough adapted for the passage of fluid grout, the first orifices being distributed over at least a lower part of the tube;
introducing co-axially said first stage tube, a second stage grout injection tube adapted for the introduction of pressurised grout said second stage tube having second orifices therethrough distributed over a lower part thereof, the lower part of the second stage tube being releasably enclosed by an elongate pod of resiliently deformable material, the pod having longitudinal lines of weakness in the sidewall rupturable to burst open to form corresponding longitudinal slits under pressure of grout from the orifices of the second stage injection tube, to allow the further passage of pressurised grout at least into the lower part of first stage injection tube;
introducing into the first stage injection sheathing tube, fluid first stage grout at a pressure to fill the tube and inject it through the first orifices into surrounding environment;
allowing said grout to set;
introducing into the second stage injection tube, second stage fluid grout and injecting it under pressure through the second orifice to rupture the lines of weakness in the pod and crack the first stage grout, and flow through the first orifices; and B~ ~
i allowing the second stage grout to set releasing the second stage tube from the pod and withdrawing it therefrom.
The apparatus used in the process of the inventions may have the advantage that only first stage injection tube and the pod are left in the ground. The first stage injection tube makes a useful reinforcement for the resulting pile and the pod may be relatively inexpensive.
An embodiment of the invention will now be described with reference to the drawings in which:
Figure 1 is a sectional diagramatic sketch of one form of apparatus according to the invention located in a borehole;
Figure 2 is a view similar to Figure 1 after a first stage introduction of grout;
Figure 3 is a section of Figure 2 on the line III-III of Figure 2;
Figure 4 is a view similar to Figure 2 after a second stage injection of grout;
Figure 5 is a section of Figure 4 on the line V - V
of Figure 4; and Figure 6 is a view similar to Figure 1 of the resulting pile.
The drawings show a borehole 10 in which a pile is to be located. A first stage injection tube 12 having a cap ~_ 29 above ground level 23 is inserted into the borehole 10. Grout to be dispensed into the borehole 10 through tube 10 may be under low pressure, for example, it may be introduced by pouring. However, conveniently it is introduced through primary grout injection tube 21. The tube 10 has means for dispensing grout into the borehole 12 at least at the lower end and preferably over, its length. The means for dispensing grout may be first orifices 14, as shown, or may be rupturable diaphragms or orifices provided with non-return valves. However, simple orifices 14 are sufficient and any rupturable diaphragms or non-return valves should be suitable to dispense grout unto the borehole 10 under quite low pressures.
lS A second stage injection tube 20 has second orifices 22 for the injection of pressurised grout only at its lower end portion 24.
A pod 26 comprising a tubular portion 28 of greater diameter and coextensive with the lower end portion 24 of the second stage injection tube 20 has a closed lower end 30 and means for releasable connection to the injection tube 20 at its upper end. The means for connection with the injection tube 20 may be a conventional pipe reducer 32, its smaller end being adapted for screw threaded engagement with a screw-threaded portion 34 of injection tube 20 above the lower portion 24. Figures 1 to 3 of the drawings show the pod 26 with the smaller end of the pipe reducer 32 engaged with screw-threaded portion 34 of tube 20. The wider end of the pipe reducer 32 is connected to the tubular portion 28 of the pod 26 by any convenient means, for example, by a solvent joint.
The pod 26 may conveniently comprise an outer sheath _ 25 of flexible plastic having longitudinal lines 6 weakness or slits 36 at least partially therethrough.
The outer sheath 25 of pod 26 may be made of flexible deformable plastics material such as polyvinyl chloride and the longitudinal slits 36 may be only in the outer surface of its side wall. Thus, the slits 36 need not extend completely through the side wall but form weakened portions adapted to rupture under the influence of pressurised grout. For supporting the flexible sheath 25, an inner support pod 27 may be provided comprising a cylinder of longitudinally corrugated, perforated metal, for example, steel.
In operation first stage injection tube 12 is lowered down borehole 10 and second stage injection tube 20 is, with pod 26 engaged thereon, lowered down tube 12.
Primary grout 38 is injected under low presure through or even poured into first stage tube 12. The grout 38 flows down the tube and is injected into the borehole 10 through orifices 14. There may be seepage 39 of grout 38 beyond the walls of borehole 10. This will depend upon the structure of the soil, the compaction of the borehole walls and the pressure of grout 38.
Grout 38 also acts to exert pressure to compress pod 26 so that it tends to assume the somewhat flattered oval form shown in Figure 3. Since the slits 36 are in the sheath 25 surface of tubular portion 28, this flattening action tends to close the slits firmly guarding against any tendency of grout 38 to burst inwardly into the pod 26 through slits 36. The longitudinal corrugations of support pad 27 are an aid against undue deformation of pad 27 during application of primary grout 38.
Grout 38, 39 is allowed to set to form a pile structure. The pile structure within the borehole 10 will tend toward constant cross section of which corresponds to the diameter of the borehole 10. The structure is reinforced by the embedment of first stage injection tube 12 therein. Seepage 39 extends outwardly of the borehole 10 where the soil structure allows it and may provide some additional anchoring force. Except where particular crevices or soil weakness or mud areas exist, the cross section of the whole pile structure including seapage 39 will probably be generally constant from the bottom of tube 12 to ground level.
The process, thus far, is not totally dissimilar to previous one step processes with a notable exception that, no attempt is necessarily made to provide non-return valves for orifices 14 and first stage injection tube 12 is embedded into the structure as reinforcement.
When grout 38 has been given the opportunity to set grout 40 is injected under pressure through second stage injection tube 20. The resultant action at the bottom of borehole 10 is that pressurized grout 40 re-expands pod 26 to expand the support pad 27 and burst open the slits 36 of flexible outer sheath 25 as shown in Figures 4 and 5.
The surrounding set grout 38 in tube 12, borehole 10 and seepage 39 may crack and break under the strain opening crevices to orifices 14. The bottom part of tube 12 may splay out as shown in Figure 4 to form a strong anchor in the ground. At a preset pressure of grout 40, which is determined by the size, and depth of slits 36, the material of tubular portion 28 and the strength of set grout 38, the slits 36 rupture. Thus pod 26 bursts open to release second stage grout 40 into the bottom part of tube 12 and through orifices 14 in the bottom part of tube 12 to spread outwardly to extend beyond the limits of seepage 39. The spread of grout 40 may be as a root system 42 as shown in Figure 4 or it may form a bulb surrounding the bottom of tube 11.
In any case the presence of seepage 39 and set grout 38 in tube 12 and borehole 10 tends to direct the spread of grout 40 downwardly as well as outwardly to form a root system 42 for the resulting pile.
As grout 40 sets, it bonds with previously set grout 38 to form a cohesive structure.
Burst point of pod 26 may be consistent, resulting in a root system 42 of consistent size and shape for each configuration of tube 12. The grout 40 may be applied in consistent amount by using water pressure or other pressure to force a set amount of grout 40 through injection tube 20. Either while grout 40 is still wet or if water is used to force the grout through the tube 20.
The pressure in tube 20 may be relieved after injection of an appropriate amount of grout 40. The tubular portion 28 will then be compressed against lower portion 24 of tube 20 thus having some tendency to seal orifices 22 against return of grout 40. At this stage, either while grout 40 is still wet or if water is used to force the grout through the tube 20, ~he tube 20 may be unscrewed from the pipe reducer 32 and withdrawn for reuse leaving tube 12 and ruptured pod 26 in place in a substantial rooted pile structure.
Claims (6)
1. Apparatus for use in the production of a structure anchored in the ground comprising a first stage grout injection sheathing tube having first orifices therethrough adapted for the passages of fluid grout therethrough, the first orifices being distributed over at least a lower part of the tube;
a second stage grout injection tube adapted for hte introduction of pressurised grout locatable substantially coaxially within said first stage sheathing tube and having second orifices therethrough distributed over a lower part;
an elongate pod of resiliently deformable material releasably enclosing the lower part of the second stage tube, the pod having longitudinal lines of weakness in a sidewall rupturable to form corresponding longitudinal slits, and adapted to, under pressure of grout from the second orifices, rupture to allow the passage of pressurised fluid grout into the lower part of first stage injection tube and through the first orifices thereof.
a second stage grout injection tube adapted for hte introduction of pressurised grout locatable substantially coaxially within said first stage sheathing tube and having second orifices therethrough distributed over a lower part;
an elongate pod of resiliently deformable material releasably enclosing the lower part of the second stage tube, the pod having longitudinal lines of weakness in a sidewall rupturable to form corresponding longitudinal slits, and adapted to, under pressure of grout from the second orifices, rupture to allow the passage of pressurised fluid grout into the lower part of first stage injection tube and through the first orifices thereof.
2. Apparatus as claimed in claim 1 in which the pod of resiliently deformable material comprises a tubular portion capped at a lower end and having at an upper end, a pipe reducer engaged, on the one hand, with said tubular portion and, on the other hand, releasably with the second stage injection tube above its lower part.
3. Apparatus as claimed in claim 1, which the pod comprises an outer sheath of flexible plastic having the longitudinal lines of weakness and an inner support pod having perforated walls.
4. Apparatus as claimed in claim 3 in which the inner support pod is formed of perforated metal and is longitudinally corrugated whereby it is expansible under pressure of grout.
5. A process for the production of structure anchored in the ground comprising:
introducing into a borehole, a first stage grout injection sheathing tube having first orifices therethrough adapted for the passage of fluid grout, the first orifices being distributed over at least a lower part of the tube;
introducing co-axially said first stage tube, a second stage grout injection tube adapted for the introduction of pressurised grout said second stage tube having second orifices therethrough distributed over a lower part thereof, the lower part of the second stage tube being releasably enclosed by an elongate pod of resiliently deformable material, the pod having longitudinal lines of weakness in sidewall rupturable to burst open to form corresponding longitudinal slits under pressure of grout from the orifices of the second stage injection tube, to allow the further passage of pressurised grout at least into the lower part of first stage injection tube;
introducing into the first stage injection sheathing tube, fluid first stage grout at a pressure to fill the tube and inject it through the first orifices into surrounding environment;
allowing said grout to set;
introducing into the second stage injection tube, second stage fluid grout and injecting it under pressure through the second orifices to rupture the lines of weakness in the pod an crack the first stage grout, and flow through the first orifices; and allowing the second stage grout to set releasing the second stage tube from the pod and withdrawing it therefrom.
introducing into a borehole, a first stage grout injection sheathing tube having first orifices therethrough adapted for the passage of fluid grout, the first orifices being distributed over at least a lower part of the tube;
introducing co-axially said first stage tube, a second stage grout injection tube adapted for the introduction of pressurised grout said second stage tube having second orifices therethrough distributed over a lower part thereof, the lower part of the second stage tube being releasably enclosed by an elongate pod of resiliently deformable material, the pod having longitudinal lines of weakness in sidewall rupturable to burst open to form corresponding longitudinal slits under pressure of grout from the orifices of the second stage injection tube, to allow the further passage of pressurised grout at least into the lower part of first stage injection tube;
introducing into the first stage injection sheathing tube, fluid first stage grout at a pressure to fill the tube and inject it through the first orifices into surrounding environment;
allowing said grout to set;
introducing into the second stage injection tube, second stage fluid grout and injecting it under pressure through the second orifices to rupture the lines of weakness in the pod an crack the first stage grout, and flow through the first orifices; and allowing the second stage grout to set releasing the second stage tube from the pod and withdrawing it therefrom.
6. A process as claimed in claim 5 in which the pod comprises a resiliently deformable tubular portion capped at a lower end, and having at an upper end, a pipe reducer engaged, on the one hand, with said tubular portion and, on the other hand, releasably with the second stage injection tube above its lower part.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 589240 CA1337893C (en) | 1989-01-26 | 1989-01-26 | Injection apparatus for foundation piles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 589240 CA1337893C (en) | 1989-01-26 | 1989-01-26 | Injection apparatus for foundation piles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1337893C true CA1337893C (en) | 1996-01-09 |
Family
ID=4139520
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 589240 Expired - Fee Related CA1337893C (en) | 1989-01-26 | 1989-01-26 | Injection apparatus for foundation piles |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1337893C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101845819A (en) * | 2010-05-25 | 2010-09-29 | 武汉大学 | Method for solidifying support of deep and thick soil side slope |
| CN109519151A (en) * | 2019-01-07 | 2019-03-26 | 兰州理工大学 | A kind of fracture grouting hole sealing device and method suitable for Site of Collapsible Loess |
-
1989
- 1989-01-26 CA CA 589240 patent/CA1337893C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101845819A (en) * | 2010-05-25 | 2010-09-29 | 武汉大学 | Method for solidifying support of deep and thick soil side slope |
| CN109519151A (en) * | 2019-01-07 | 2019-03-26 | 兰州理工大学 | A kind of fracture grouting hole sealing device and method suitable for Site of Collapsible Loess |
| CN109519151B (en) * | 2019-01-07 | 2024-03-01 | 兰州理工大学 | Splitting grouting hole sealing device and method suitable for collapsible loess field |
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