WO2021064620A1

WO2021064620A1 - An injection lance

Info

Publication number: WO2021064620A1
Application number: PCT/IB2020/059187
Authority: WO
Inventors: Simon Paul COLLIS
Original assignee: Geoinnovationsltd
Priority date: 2019-10-02
Filing date: 2020-10-01
Publication date: 2021-04-08
Also published as: GB201914188D0; GB2587631A; GB2587631B

Abstract

An injection lance for permeation grouting. The injection lance (100) comprises one or more stages (150). Each stage comprises a tube (160) defining a longitudinal conduit and a resiliently deformable sleeve (170) fitted onto the exterior of the tube. Each stage further comprises a plurality of first apertures (165) through the tube between the conduit and the exterior of the tube and a plurality of second apertures (175) through the sleeve.

Description

An Injection Lance

Field of the Invention

The present invention relates to an injection lance for permeation grouting. Background to the Invention Permeation grouting is a process in which setting fluid, known as a grout, is injected into ground material such as soil, gravel or loose rock such that the grout spreads into gaps in the ground material before setting therein to bind the ground material together. Permeation grouting is commonly used to solidify, strengthen and reduce the permeability of loose soil or rock material during construction, excavation, or underpinning operations.

Grouts used in permeation grouting may be resins or cements which set after being injected into ground material. Grouts are typically low viscosity fluids before setting and are preferably colloids or Newtonian fluids. Such grouts are effectively free from particulates, allowing them to permeate more easily ground material and fill the gaps therein. Grouts may react with water, which may cause them to set and/or to expand to further permeate ground material. Hydro-reactive polyurethanes and colloidal silicates are particularly effective grouts.

Grouts should typically be injected into ground material at low pressures to avoid fissuring ground material such as soil, which could lead to the disposition of grout within veins, leaving layers of unbound soil between layers of pure set grout. Such an arrangement would not enhance the load bearing capacity of the soil.

The aforementioned grouts are typically injected into the ground using an injection lance. Injection lances are elongate pipes that are inserted into the ground so that fluid grout can be pumped therethrough and emerging from the pipes or lances and dispersing into surround soil and rock material. Grout is typically pumped into (the proximal) an end of the injection lance protruding out of the ground and typically exits the lance through one or more lateral openings intermediate the two ends along the length of the lance.

In open-end-tube grouting, or open case grouting, the injection lance is an elongate tube with openings only at its ends. The injection lance is inserted into the ground to be stabilised and grout is pumped into a first end of the lance protruding from the ground and enters the ground via an open distal second end of the lance embedded therein. In such grouting methods, separate volumes of grout may be injected into the ground at different depths, with the lance being lifted or otherwise displaced to different depths between the injection of each volume.

In some instances, a drill string is used as an open-end-tube grouting injection lance to deliver grouting down a hole drilled using the drill rig.

Open-end-tube grouting works well in open ground at depths of around 2 to 3 metres and is primarily used for compaction grouting deeper than around 4 metres below ground level or to infill deep solution ground features. This method is of limited use in small scale operations, wherein lifting and withdrawing the lance may cause loosening of soil within the ground. This in turn may cause injected grout to leak to the surface through gaps created between the lance and a border of the hole, through which the lance is inserted and thereby inadvertently cause a decrease in the pressure of the grout which can prevent the grout from adequately permeating the ground. In some instances a packer may be inflated between the injection lance and the bored hole into which it has been inserted, in order to prevent grout escaping.

Additionally, some effective grout types based on hydro-reactive polyurethane resin react quickly and may bind the lance into the soil where such vertical permeation back along the outside of the lance has occurred. This prevents the lance from being lifted and the grouting operation from being completed.

Multiple tube grouting is a method of inserting multiple injection lances into the ground to different depths so as to avoid the abovementioned problems. However, this method is only effective over limited ranges of depths as clusters of multiple lances can become very bulky.

Fully perforated injection lances comprise a plurality of regularly spaced lateral openings along their lengths, through which grout can escape into the ground when pumped into the lance. However, such systems offer a user no control of the volumes of grout displaced into the soil at different depths. This is disadvantageous because ground permeation may vary with depth and soil permeability and fully perforated injection lances will typically only deliver grout to the depths where the ground offers the least resistance, frequently close to the surface. Injecting grout in this way lacks the required degree of control and is therefore unreliable.

A tube-a-manchette, or sleeve port pipe, is an injection lance in the form of an elongate tube with sets of lateral openings at different points along its length, each set of lateral openings being covered by a short rubber sleeve. In use a chamber is defined within the tube by inflating two annular packers above and below a set of lateral openings located at a given point along the length of the tube. An inner grout carrying tube then delivers grout to the chamber under pressure causing grout to escape through the lateral openings and to force the rubber sleeve surrounding them to expand. This allows the grout to enter the ground surrounding the lance. After a volume of grout has been injected in this way, the pressure is removed and the sleeves contract, preventing grout from re-entering the tube. The packers are then deflated, the inner tube and packers are displaced within the injection lance to a different position along the length of the lance with another set of lateral openings, and the process is repeated.

In some types of injection lances the rubber sleeves are protected from damage by rings formed on the outside of the injection lance above and below the rubber sleeves, or by arranging the rubber sleeves in recessed portions of the tube where the sets of lateral openings are located.

In use, tube-a-manchette injections lances are typically inserted into drilled holes and sealed therein, such as with a bentonite clay fill.

Tube-a-manchette injection lances are effective and widely used especially for compensation grouting in clay. However, in loose soils, it can be difficult, cumbersome and expensive to maintain a drilled open hole for insertion of the injection lance.

Prior Art

International patent application WO-A-2014013215 (GEOINNOVATIONS LTD) discloses an injection lance in the form of an elongate tube with lateral openings along its length. The interior of the tube is separated into a plurality of chambers separated by bulkheads with valves therethrough. In use an inner grout carrying tube is inserted through one or more of the bulkhead valves to reach and deliver grout to one of the chambers at a time. A measured quantity of grout is then delivered through the inner tube and is only able to escape through the lateral openings of the chamber to which it is delivered, entering the ground at a desired depth. The injection lance is advantageously able to be driven into loose soil allowing it to be used to inject grout into weak, collapsing or saturated soil.

However, leakage of injected grout between the exterior of this injection lance and the ground into which it is driven may still occur in some circumstances. Additionally, when multiple such lances are used simultaneously to permeate a large area of ground (for example, when forming a curtain wall of bound soil), grout injected by one lance may permeate to, surround, and set around a neighbouring lance, causing the neighbouring lance to become clogged or bound within the ground so preventing its effective function. This also prevents additional lances being driven into the ground due to the presence of solidified masses of grout and soil.

Australian patent application AU 2415767 (Kiss) discloses a grouting system for use underground to fill voids and cracks.

Japanese patent application JP 2013241812 (Nittoc Construction) discloses a grouting device which can inject a grouting material uniformly with respect to a horizontal direction in a region subjected to injection. The device continuously injects the grouting material in a vertical direction by forming a crack in a seal material in a vertically continuous manner.

Japanese patent application JP 2016156142 (Kyokado Eng Co) provides a ground injection method and a ground injection device which evenly injects a material in the ground around a porous wall.

Japanese patent application JP 2017040079 (Kyokado Eng Co) provides a ground injection device and method suitable for increasing strength of heterogeneous ground around soil particles.

Japanese patent application JP 2018012987 (Kyokado Eng Co) discloses a ground injection device and a ground injection method. The injection material discharges via a port defined in a rubber tube with a plurality of material injection slits.

In some circumstances soil may be variable in composition which made even dispersion of grout difficult to achieve. This is in part due to the systems only being limited to be used once with resinous grouts. An aim of the present invention is to provide an improved injection lance and system for permeation grouting which overcomes the problems described above.

Another aim is to provide an injection lance that is able to be driven and so is better suited for use in ground that is sandy or has voids or is immersed and is therefore subject to collapse after a hole has been drilled.

Statement of the Invention

According to a first aspect of the present invention, there is provided a driven injection lance for permeation grouting, the injection lance includes: a driving tip; one or more stages, each of the one or more stages comprises a tube defining a longitudinal conduit; a plurality of first apertures are formed in the tube between the conduit and an exterior of the tube; a resiliently deformable sleeve is fitted tightly around the exterior of the tube and expands when pressure is applied from within the conduit; and a plurality of second apertures are formed through the resiliently deformable sleeve, the second apertures are closed when the injection lance is driven and are opened when the resiliently deformable sleeve expands when an internal pressure in the conduit exceeds a user defined threshold.

The second apertures are closed when not exposed to internal pressure. The resilient sleeve is such that only under high pressure can the ports be forced open. When pressure is reduced the ports self close. Ideally ports or apertures have a characteristic dimension of less than 0.5 mm.

Ideally the characteristic dimension of the ports or apertures is less than 0.3 mm, preferably less than 0.2 mm and most preferably less than 0.1 mm.

In use, the injection lance, which may comprise a single stage, or a plurality of stages connected end to end, is inserted or driven into ground material, such as non-cohesive soil. Fluid grout is then pumped into and along the lance through the one or more conduits defined by the one or more tubes and may exit the conduits through the first apertures. The grout escaping through the first apertures forces the resiliently deformable sleeve to expand and inflate around the tubes and then escapes from the resiliently deformable sleeve into the ground material through the second apertures. An advantage of the invention is that because the resiliently deformable sleeve is formed from a rigid plastics material or a synthetic plastics or polymer material, it is protected from damage by debris in the ground which might scuff or rub against its outer surface. Optionally the injection lance according to any preceding claim wherein the resiliently deformable sleeve is formed from a rubber or synthetic plastics material. In some embodiments the rubber or synthetic plastics material from which the resiliently deformable sleeve is formed, has an internal mesh or webbing in order to further enhance its strength. As grouting is performed in situ, the invention enables faster and more reliable application of grout and so saves time.

Also, as there are less ancillary equipment and valves, and no mechanical moving parts, the system is less prone to failure and problems when deployed and is therefore more rugged. Requires less maintenance and so can be deployed in more hazardous conditions.

The, or each, of the resiliently deformable sleeves may advantageously act as one way valves in a manner similar to the rubber sleeves of a tube-a-manchette injection lance, ensuring grout is unable to return into the injection lance. Additionally, expansion of the deformable sleeve under pressure acts to form a seal by expanding to fill any gaps between the injection lance and the ground material into which it is inserted, thereby preventing grout from escaping lengthwise, up or down, the soil lance interface.

By driving a hollow tube with very small outlet ports into the ground an elegant solution has been found which dispenses the grouting material in a controllable manner and ensures that a continuous structure is formed without voids.

As the tube is driven into the ground and when filled under pressure with a non particulate grout, and pressure is applied, an impedance to the pressurised fluid is produced by an equalisation of flow delivery through the small apertures against what are relatively minor variations in resistance offered by the surrounding soil. The result is that relatively speaking, the impedance to the flow of the liquid grout offered by the second apertures (or ports) formed in the resiliently deformable sleeve, is significantly higher than any resistive force offered by the surrounding soil or earth into which the lance is driven.

Controlled delivery of grout through the plurality of second apertures (or ports) therefore results in an approximation to a cylindrical consolidated mass as there is a continuous and even dispersal of liquid grout along substantially the entire length of the lance, thereby achieving a uniform structure when the grout cures or sets. This provides greater stability and strength as a foundation post, pillar or pile.

Mechanical impedance is a measure of how much a structure resists motion when subjected to a harmonic force. It relates forces with velocities acting on a mechanical system. The mechanical impedance of a point on a structure is the ratio of the force applied at a point to the resulting velocity at that point.

The impedance to flow is the ratio of a potential difference arising from application of a force, to a flow (e.g. velocity) where the arguments of the real (or imaginary) parts of both increase linearly with time. Impedance may therefore be seen as the reciprocal of mobility. If the potential and flow quantities are measured at the same point, then impedance is referred to as driving point impedance; otherwise it is referred to as transfer impedance.

Mechanical impedance is the inverse of mechanical admittance or mobility. The mechanical impedance is a function of the frequency and the magnitude of an applied force and can vary greatly over frequency. At resonant frequencies, the mechanical impedance is lower, meaning less force is needed to cause a structure to move at a given velocity. A simple example of this is pushing a child on a swing. For the greatest swing amplitude, the frequency of the pushes must be near the resonant frequency of the system. The use of the resiliently deformable sleeve resists the transfer of grout from inside the lance to its outside until sufficient pressure is obtained to inflate the deformable sleeve so as to form a seal against the surrounding ground. In addition the high resistance of the small pores creates a high pressure gradient, by offering high impedance to the flow, which ensures that an even flow of grout is achieved through the pores even when the surrounding sub-soil which may have different porosities or have voids. The very small holes (second apertures or ports) that are formed in the deformable sleeve therefore allow an even delivery of grout throughout the length of the lance. The closure of the second apertures or ports reduces the pressure and so hermetically seals the lance allowing for subsequent injections.

One, some, or all, of the stages may have any of the features described below.

In a particularly preferred embodiment, the ends of the resiliently deformable sleeve are secured around the tube without a gap between the resiliently deformable sleeve and the tube. The ends of the resiliently deformable sleeve are preferably secured tightly to the tube such that fluids (such as grout) are unable to pass between the tube and the resiliently deformable sleeve through the ends of the resiliently deformable sleeve and are preferably secured to the tube such that they cannot expand to provide a gap between the tube and the resiliently deformable sleeve through which material could exit the tube via its ends.

The ends of the resiliently deformable sleeve being secured snugly around the tube may advantageously ensure that fluids (such as grout) which have been pumped out of the tube through the first apertures, are only able to escape from the space between the tube and the resiliently deformable sleeve through the second apertures. This may also advantageously allow the resiliently deformable sleeve to expand around the tube, for example, when the rate at which fluid is passing through the first apertures exceeds the rate at which it is passing through the second apertures. This may enable the resiliently deformable sleeve to act as packer to fill space between the exterior of the injection lance and the ground into which it is inserted, thereby preventing injected grout from travelling along the length of the injection lance through a hole created by or for the insertion of the injection lance.

The ends of the resiliently deformable sleeve may be secured to the tube by collars or other annular connectors which preferably fit around the ends of the resiliently deformable sleeve and the portions of the tube which the ends surround and clamp together. The ends of the resiliently deformable sleeves may be crimped onto the tube by the collars or annular connectors.

The resiliently deformable sleeve preferably fits over the plurality of first apertures, which are preferably located intermediate the ends of the resiliently deformable sleeve (which are preferably secured around the tube as described above). The plurality of first apertures may be intermediate the collars or other annular connectors which secure the ends of the resiliently deformable sleeve to the tube. This arrangement advantageously ensures that all of any fluid (such as grout) which exits the tube through the first apertures, enters the space between the exterior of the tube and the interior of the resiliently deformable sleeve.

The resiliently deformable sleeve is preferably of generally equal length to the tube, substantially equal length to the tube, or of equal length to the tube. The ends of the resiliently deformable sleeve are preferably secured around the ends of the tube, the resiliently deformable sleeve in use is therefore maintained at a substantially equal length to the tube, even as it expands and inflates or retracts and deflates.

In preferred embodiments, the resiliently deformable sleeve is formed tightly around the tube with no gap between the interior of the resiliently deformable sleeve and the exterior of the tube when no internal pressure is applied. Similarly there is no gap when an internal pressure is applied and maintained below a threshold level to the resiliently deformable sleeve. For example, the resiliently deformable sleeve may have a radius less than the outer radius of the tube when it is fully relaxed. In preferred embodiments the second apertures through the resiliently deformable sleeve expand as the resiliently deformable sleeve expands and/or stretches and/or as pressure inside the resiliently deformable sleeve increases. For example, the second apertures may be holes pierced or otherwise formed in the resiliently deformable material forming the resiliently deformable sleeve such that they expand and stretch with the resiliently deformable sleeve and/or when the pressure of fluid within the resiliently deformable sleeve increases.

In such embodiments, when additional fluid is pumped into the injection lance, such that the rate at which fluid enters the lance exceeds the rate at which fluid exits the one or more resiliently deformable sleeves through the second apertures, the resiliently deformable sleeves inflate, and/or the pressure within the resiliently deformable sleeves may increase, thereby expanding and stretching the second apertures. This advantageously causes the rate at which fluid exits the resiliently deformable sleeves through the second apertures to increase until this rate equals the rate at which fluid is delivered to the lance. In further preferred embodiments, when the resiliently deformable sleeve is tight around the tube with no gap between the interior of the resiliently deformable sleeve and the exterior of the tube, the combined area of the second apertures is smaller than the combined area of the first apertures.

In such a configuration, if fluid is pumped into the tube at a given pressure, the rate at which fluid is able to exit the tube through the first apertures is greater than the rate at which fluid is able to exit the resiliently deformable sleeve through the second apertures, the resiliently deformable sleeve therefore expand as fluid exits the tube into the space between the exterior of the tube and the interior of the resiliently deformable sleeve.

In further preferred embodiments, when the resiliently deformable sleeve is tight around the tube with no gap between the interior of the resiliently deformable sleeve and the exterior of the tube, the second apertures are closed or substantially closed.

For example, the second apertures are piercings in, or formed through, the resiliently deformable material of the resiliently deformable sleeve without removing material such that when the resiliently deformable sleeve is substantially unexpanded, the edges of the second apertures are in contact with each other and the second apertures are substantially closed.

In further preferred embodiments, the second apertures are closed when the pressure within the resiliently deformable sleeve is below a threshold pressure. The threshold pressure is preferably greater than a pressure at which the resiliently deformable sleeve is expanded and/or inflated away from the tube.

In such embodiments, when the one or more resiliently deformable sleeves are formed tightly around the one or more tubes, with no gaps between the interior of the resiliently deformable sleeves and the exteriors of the tubes, and when fluid is pumped into the injection lance, the resiliently deformable sleeve is initially stretched and expanded as the fluid is unable to escape through the closed apertures. As the resiliently deformable sleeve expands and is stretched, the second apertures are opened, allowing the fluid to exit the injection lance. When fluid ceases to be pumped into the lance and the internal pressure is removed, the resiliently deformable sleeve may relax and retract back onto the exterior of the tube, removing any gap between the resiliently deformable sleeve and the tube and the second apertures may close, thereby sealing the injection lance. The threshold pressure for opening the second apertures is preferably sufficient to provide a significant fluid pressure gradient between the interior of the resiliently deformable sleeve and ground material into which the lance is inserted.

In particularly preferred embodiments, the second apertures are formed by piercing the sleeve with needles and/or the resiliently deformable material thereof without removing material.

In some embodiments, when the resiliently deformable sleeve is tight around the tube, with no gap between the interior of the resiliently deformable sleeve and the exterior of the tube, none of the first apertures overlap any of the second apertures. In such an arrangement, each of the first apertures opens onto an unpierced interior surface of the resiliently deformable sleeve and each of the second apertures open onto an unpierced exterior surface of the tube. Therefore, fluid is unable to pass from the conduit inside the tube out through one of the first apertures and then out of the resiliently deformable sleeve through one of the second apertures, without the resiliently deformable sleeve being expanded and/or stretched to define a gap between the exterior of the tube and the interior of the resiliently deformable sleeve, such that the fluid is able to travel from one of the first apertures to one of the second apertures.

The tube is preferably substantially straight, which allows the injection lance to be driven into ground material or may facilitate in driving the injection lance lengthwise into ground material. In preferred embodiments, the tube is substantially cylindrical and preferably defines a central cylindrical conduit along the full length of its longitudinal axis.

The tube is preferably formed from a metal such as steel or from some other rigid material strong enough to allow the injection lance to be driven into ground materials without bending or otherwise being damaged.

In some embodiments the lance comprises a plurality of sets of first apertures through the tube, each set comprising a plurality of first apertures at substantially the same distance along the length of the tube. The sets of first apertures are preferably regularly spaced along the length of the tube. The plurality of first apertures of each set may be distributed, preferably regularly, around the circumference or perimeter of the tube. A regular arrangement of first apertures may advantageously ensure fluid such as liquid grout is pumped into the tube and exits the tube in an even flow pattern and that the resiliently deformable sleeve is expanded and inflated in a controlled, continuous and even manner.

The resiliently deformable sleeve is preferably formed from an elastomer or synthetic rubber or from some other elastic or resiliently deformable material.

In some embodiments the stage comprises a plurality of sets of second apertures through the resiliently deformable sleeve, each set comprising a plurality of second apertures at substantially the same distance along the length of the resiliently deformable sleeve. The sets of second apertures are preferably regularly spaced along the length of the resiliently deformable sleeve. The plurality of second apertures of each set may be distributed, preferably regularly, around the circumference or perimeter of the resiliently deformable sleeve. For example, the resiliently deformable sleeve may comprise a plurality of sets of three second apertures, each of the apertures of each set being at approximately 120 degrees around the circumference of the resiliently deformable sleeve from the other two and the plurality of sets of second apertures being spaced apart along the length of the resiliently deformable sleeve with approximately 10 cm gaps between the sets of three second apertures.

Regularly spaced second apertures through the resiliently deformable sleeve thereby advantageously ensure that fluid, such as liquid grout, is released into ground material surrounding the injection lance in an even distribution pattern.

The elasticity of the resiliently deformable sleeve is preferably such that the resiliently deformable sleeve does not expand and/or inflate at internal pressures less than 15psi (0.1 mPa), preferably less than 45psi (3.1 mPa), preferably less than 75psi (0.52 mPa), preferably less than 10Opsi (6.9 mPa), preferably less than 125psi (8.5 mPa), preferably less than 150psi (1.03 mPa), and most preferably less than 185 psi (1.28 mPa).

The elasticity of the resiliently deformable sleeve and/or the size of the second apertures is/are preferably such that the second apertures remain substantially closed at internal pressures less than 10Opsi (6.9 mPa), less than 125psi (8.5 mPa), less than 150psi (1.03 mPa), less than 175psi (1.2 mPa), or less than 200psi (1.38 mPa). In preferred embodiments, when the resiliently deformable sleeve is held tightly around the tube with no gap between the interior of the resiliently deformable sleeve and the exterior of the tube, the resiliently deformable sleeve is flush with collars or other annular connectors which secure the ends of the resiliently deformable sleeve to the tube. The injection lance may therefore have a substantially constant radius when the resiliently deformable sleeve is not inflated or expanded. This may facilitate the driving of the injection lance into ground material.

In preferred embodiments, in addition to the one or more stages, the injection lance comprises an end seal for sealing an end of the conduit of one of the one or more stages. In use, the end of the conduit defined by the tube a single-stage injection lance, or by a plurality of interconnected tubes of a multi-stage injection lance may be sealed by the end seal, such that fluid (for example liquid grout) pumped into the conduit, through the proximal end of the injection lance, is only able to escape through the first apertures through the one or more tubes of the one or more stages.

The end seal may be in the form of, or may comprise a plug, which fits into an end of the conduit of one of the one or more tubes to seal it. In some embodiments, the end seal may be secured using adhesive.

In preferred embodiments, the end seal comprises or has fitted thereto a pointed tip and when sealing and end of the conduit of the tube of a stage defines a pointed tip for that stage. The end seal may therefore define a pointed tip for the injection lance, facilitating driving the injection lance into ground material and allowing it to be used as a ram injection lance, such as an injection lance which is driven into ground material without a hole being drilled or bored for it beforehand.

In preferred embodiments, the one or more stages are a plurality of stages. One, some, or each of the plurality of stages may comprise any of the optional features of the tube, resiliently deformable sleeve, and/or first and second apertures as described above. In preferred embodiments, each of the plurality of stages comprises the same features and may be substantially identical.

The plurality of stages are preferably connectable or connected to each other, preferably releasably. In preferred embodiments the plurality of stages are connected or connectable to each other end-to-end. In some embodiments where the plurality of stages are releasably connectable end-to-end, the length of the injection lance to be adjusted by attaching stages thereto and/or detaching stages therefrom. This allows the injection lance to be adjusted for permeation grouting to different depths.

In use, stages may be connected to the injection lance one by one as the injection lance is driven into the ground. For example, a single stage (preferably tipped with a pointed end seal) may be driven partially into the ground and an additional stage may then be attached to the end of the partially embedded stage which protrudes from the ground and the remainder of the partially embedded stage and a first part of the additional stage may then be driven into the ground. This may be repeated, with additional stages being added to the injection lance and driven into the ground until the injection lance has been driven to a desired depth.

In preferred embodiments the plurality of stages are connected or connectable to each other such that the conduit defined by the tube of each interconnected stage is interconnected with the conduits defined by the tube of each other stage to which its stage is connected.

In preferred embodiments the plurality of stages are connected or connectable to each other such that the conduits defined by their tubes are interconnected to define a combined conduit along the injection lance. This configuration of interconnected stages allows fluid, such as grout to be injected into the combined conduit so as to reach the first apertures of each of the plurality of stages. The combined conduit preferably extends along substantially the entire length of the injection lance and/or substantially between opposite ends of the injection lance (one of which may be sealed by an end seal and one of which may be fitted with a valve).

The plurality of stages and the conduits comprised by the tubes of the plurality of stages may be interconnected by connecting tubes which preferably fit into ends of the interconnected conduits of the tubes of the interconnected stages. The injection lance preferably comprises one or more such connecting tubes. In preferred such embodiments, the connecting tubes are fitted into and held within annular seals within the ends of the interconnected conduits of the tubes of the interconnected stages. Annular seals are preferably resiliently deformable material and preferably comprise a central aperture which is preferably smaller than the cross- sectional area of the connecting tubes. The friction between the connecting tube and the two annular seals preferably holds the two stages together.

In use a first end of a connecting tube may be forced into the annular seal in an end of the conduit defined by the tube of a first stage and a second end of the connecting tube may then be forced into the annular seal in an end of the conduit defined by the tube of a second stage. If necessary, the connecting tube may then be forced through the annular seals into which it is fitted until the ends of the first and second stages are in contact with each other.

In some embodiments, each of the stages comprises such an annular seal in and at or proximate to each of the ends of the conduit defined by its tube. In preferred embodiments, one stage comprises such an annular seal in and at or proximate to a first end of the conduit defined by its tube and the second distal end of the conduit defined by its tube is sealed by an end seal as described above, in such a preferred embodiment, each additional stage of the one or more stages comprises annular seals in and at, or proximate to, each of the ends of the conduit defined by its respective tube.

In some embodiments, the injection lance comprises an end valve. The end valve is preferably for fitting into an end of a conduit defined by the tube of one of the stages and may be for fitting into an annular seal as described above. The end valve is preferably a one-way valve. The end valve is preferably for connecting the injection lance to a pump or other means for delivering fluid into the injection lance.

In use, the end valve may be fitted into the end of the conduit defined by the tube of a stage at a first end of the injection lance preferably distal to an end seal at a second end of the injection lance. Fluid such as grout may be pumped into the injection lance through the end valve and the end valve or another optional valve preferably prevents fluid exiting the injection lance through the first end thereof. The end seal preferably prevents fluid exiting the injection lance through the second end thereof, such the fluid is only able to exit the injection lance through the first and second apertures.

The present invention advantageously provides an injection lance which can be driven into the ground, instead of only being inserted into pre-drilled or pre-bored holes, is well suited for use in weak or collapsing soils, running or loose gravel and in saturated ground. The lance is therefore capable of delivering grout evenly along the length of the lance irrespective of resistance created by the depth of insertion or differences in soil permeability. Therefore the lance may advantageously be reusable and unaffected by local impingement, allowing an embedded lance to be reused for additional injections of grout if required.

The lance may advantageously comprise inflating sleeves which prevent injected grout from spreading along the length of the lance between it and the ground material. The lance is ideally provided in a plurality of interconnectable stages facilitating its transport and storage and allowing it to be used in permeation grouting operations at a variety of different depths.

The invention will now be described by way of examples only and with reference to the Figures in which:

Brief Description of the Figures

Figure 1 shows a cross-sectional view of a first injection lance according to the present invention and a detailed exploded view of the driving stage thereof;

Figure 2a shows partially disassembled and fully assembled cross-sectional views of an injection lance according to the present invention;

Figure 2b shows a detailed cross-sectional view of the joint between two stages of the injection lance of Figure 2a; Figures 3a and 3b show cross-sectional views of the resiliently deformable sleeve expanded with grout passing through the first apertures but not the second apertures;

Figure 4 shows cross-sectional views left to right of an illustration of stages of installation and of gradual egression of grout from a lance into the ground during a placement; Figure 5 shows in cross-section an arrangement of lances which might typically be used to inject a solidifying grout into soil to form piles beneath a structure such as a house; and

Figure 6 shows in cross-section an arrangement of lances which might typically be used to inject a solidifying grout into soil to form a curtain wall where multiple injections may be required. Detailed Description of the Figures

Referring to the Figures generally, there are shown injection lances 100 according to the first aspect of the present invention. The injection lances 100 are each constructed from one or more stages 150 which are connectable end-to-end to define injection lances 100 of various lengths.

In addition to the one or more stages 150, each injection lance 100 further comprises a driving tip 110 with a plug 115 for sealing a lower end of the injection lance 100. The injection lances 100 optionally further comprise a one-way end valve 130 for fitting into an upper end of the injection lance 100. The driving tip 110 acts as a shield in order to protect the resiliently deformable sleeve 170.

Injection lances 100 comprising multiple stages 150 further comprise one or more connection tubes 120 for connecting multiple stages 150 and the conduits 162 thereof to each other.

Each stage 150 comprises an elongate cylindrical metal tube 160 which defines an elongate cylindrical conduit 162 along its length; an elastic resiliently deformable sleeve 170 fitted onto the exterior of the tube; a pair or annular collars 180 clamping the ends of the resiliently deformable sleeve 170 onto the tube 160; and at least one annular seal 190 in an end of the conduit 165.

Each tube 160 comprises a plurality of first apertures 165 formed through the wall between its interior conduit 162 and its exterior, around which the resiliently deformable sleeve 170 is fitted. The first apertures 165 are arranged in three sets, which are spaced apart along the length of the tube 160 with regular separations between them. The first apertures 165 of each set are regularly spaced around the circumference of the tube 160. Each resiliently deformable sleeve 170 is substantially cylindrical and is formed of an elastic resiliently deformable material such as an artificial elastomer or nitrile rubber. The resiliently deformable sleeves 170 are each dimensioned to fit tightly around the full length of one of the tubes 160 and as such have an internal radius substantially equal to or less than the external radius of the tubes 160 when fully relaxed. Therefore, unless a resiliently deformable sleeve 170 is stretched outwards by an internal pressure it fits tightly around the tube 160 without a gap between the exterior of the tube 160 and the interior of the resiliently deformable sleeve 170.

Each resiliently deformable sleeve 170 is of substantially equal length to the tube 160 around which it is fitted, such that it covers the entire outer surface of the tube 160. The ends of each resiliently deformable sleeve 170 are clamped onto and around the ends of the tube 160 around which it is fitted by a pair of annular collars 180. The collars 180 compress end portions of the resiliently deformable sleeve 170 against end portions of the tube 160 such that there is no gap therebetween and such that the exterior of the collars 180 are substantially flush with the outer surfaces of the resiliently deformable sleeve 170 when unexpanded.

Each resiliently deformable sleeve 170 comprises a plurality of second apertures 175 formed therethrough. The apertures are pores formed by piercing the resiliently deformable material of the resiliently deformable sleeve 170 without removing material. The second apertures 175 are therefore closed and do not permit the passage of fluid therethrough when the resiliently deformable sleeve 170 is unexpanded. The second apertures 175 open and expand as the resiliently deformable sleeve 170 is expanded and inflated.

In the illustrated embodiment, the resiliently deformable sleeve 170 is configured to inflate and expand at interior pressures between 15psi (1.03 mPa) and 180psi (1.24 mPa) and the second apertures 175 are configured to be opened at interior pressures greater than 10Opsi (0.69 mPa).

The number of second apertures 175 through the resiliently deformable sleeve 170 of each stage 150 is greater than the number of first apertures 165 through the tube 160. The second apertures 175 are arranged in sets, which are spaced apart along the length of the resiliently deformable sleeve 170 with regular separations between them. The second apertures 175 of each set are regularly spaced around the circumference of the resiliently deformable sleeve 170.

The second apertures 175 are offset from the first apertures 165 such that when the resiliently deformable sleeve 170 is unexpanded and uninflated, the first apertures 165 are covered by unpierced portions of the resiliently deformable sleeve 170. The resiliently deformable sleeve 170 is formed from a tough elastic material which is strong enough to resist damage from being driven into ground material which may contain brick or stone rubble, or fragments of metal, ceramics, slate or glass. For example, the resiliently deformable sleeve 170 may be a reinforced vulcanised rubber tube, a thick walled reinforced silicon tube or industrial unreinforced PVC tube.

Each injection lance 100 comprises an initial stage 150 to which the driving tip 110 of the lance 100 is fitted. The driving tip 110 comprises a point tapering from a wider circular end of the same radius as the annular collars 180 to a narrow end point. The driving tip further comprises a cylindrical tang of substantially the same radius as the conduit 162 defined by the inside of the tube 160. In use the tang is inserted into a first end of the conduit 162 of the lowermost stage 150 such that the wider end of the point abuts the end of the tube stage 150 and defines a pointed end for the lance 100. In the illustrated embodiment, the tang is secured within the first end of the conduit 162 using adhesive 182.

A plug 115 is also inserted into the open end of the conduit 162 before the tang of the driving tip 110. The plug 115 seals the end of the conduit and prevents fluid from escaping therethrough.

The initial stage 150 further comprises a single annular seal 190. The annular seal 190 is a cylindrical resiliently deformable body with a central cylindrical aperture extending therethrough. The exterior radius of the annular seal is substantially equal to the radius of the conduit 162 of the tube 160 and the annular seal is fitted into a second end of conduit distal from the first end and the driving tip 110. The annular seal 190 is secured within the conduit 162 by adhesive 192 proximate to the first end and intermediate the first end and the first apertures 165 closest to the first end.

In injection lances 100 comprising a plurality of stages 150 each additional stage 150 other than the initial stage 150 comprises two annular seals 190 as described above. The two annular seals are fitted into and secured within the two opposite open ends of the conduit 162 using adhesive 192 proximate to those ends and intermediate those two ends and the first apertures 165 closest thereto.

In use, the annular seals 190 may be used into interconnect adjacent stages 150 and the conduits 162 thereof using connecting tubes 120 so as to define joints 125 between the stages 150. In order to interconnect a pair of stages 150, a connecting tube 120 is inserted into the central cylindrical aperture of the annular seal 190 in the end of the conduit 162 of a first stage 150, such that the connecting tube extends out of the end of the conduit 162. The extending end of the connecting tube 120 is then inserted into the central cylindrical aperture of the annular seal 190 in the end of the conduit 162 of a second stage 150 and the first and second stages 150 are pressed together to define a joint 125 between the two stages 150. The connecting tubes 120 have central longitudinal conduits which interconnect the tube conduits 162 of the two stages which they form a joint 125 between. In some of the injection lances 150 a one-way valve 130 is inserted into the central cylindrical aperture of the annular seal 190 in the end of the conduit 162 at the end of the lance 100 distal (proximal to the injection) from the driving point 110. This is the end of the lance 100 which will protrude from the ground in use. The one-way valve 130 may be used to connect the injection lance 100 to a pump or other means for providing fluid (such as grout) to the injection lance 100 under pressure.

The one-way valve 130 prevents the pressure inside the injection lance 100 from falling below a minimum pressure (such as 150psi). When fluid ceases to be pumped into the lance, the second apertures 175 of the sleeve may seal as the pressure decreases, causing the pressure within the injection lance 100 to be maintained. Once the lance 100 is sealed, impingement from other grout sources will not have negative impacts on the lance 100. Additionally, this may allow multiple injections to be performed using the lance 100, allowing the treatment of variable ground using suitable grouts.

Figure 1 shows a cross-sectional view of an injection lance 100 comprising a pair of stages 150 interconnected by a single connection tube 120 with driving tip 110 at one end, as well an exploded view of one of the driving stage 150 of the lance, along with the driving tip 110 and the connection tube 120. The driving tip has a maximum diameter which is not less than the diameter of the unexpanded resiliently deformable sleeve. Figure 2A shows partially disassembled and fully assembled cross-sectional views of an injection lance 100 comprising a pair of stages 150, a driving tip 110, a single connecting tube 120 and a one-way valve. Figure 2b shows a detailed cross-sectional assembled view of the joint 125 between the two stages 150.

In use, after a lance 100 as described above is driven into the ground or inserted into a hole drilled or bored into the ground, pressurised fluid grout 200 is injected into the lance through the end of the lance distal from the driving tip 110, into the end of a conduit 162 of a stage 150 of the lance. This end may be open or may be fitted with a one-way valve 130 in an annular seal 190 thereof.

The fluid grout 200 fills the conduits 162 of each of the stages 150 of the injection lance and causes the sleeves 170 to inflate away from the tubes 160 as fluid passes through the first apertures 165. This allows the sleeves 170 to expand and press against the ground into which the lance 100 has inserted filling any gaps along the length of the exterior of the lance 100. The second apertures 175 initially remain closed during this expansion.

The internal pressure increases and is controlled by the volume of grout passing from the pump into the lances. The pump must be able to deliver sufficient volume of grout to ensure sufficient pressure is obtained to inflate resiliently deformable sleeve 170 given the number of secondary apertures 165.

The invention has been described by way of example only and it will be appreciated that variation may be to the invention and without departing from the scope of protection as defined by the claims appended hereto.

Claims

1. A driven injection lance for permeation grouting, the injection lance includes: a driving tip; one or more stages, each of the one or more stages comprises a tube defining a longitudinal conduit; a plurality of first apertures are formed in the tube between the conduit and an exterior of the tube; a resiliently deformable sleeve is fitted tightly around the exterior of the tube and expands when pressure is applied from within the conduit; and a plurality of second apertures are formed through the resiliently deformable sleeve, the second apertures are closed when the injection lance is driven and are opened when the resiliently deformable sleeve expands when an internal pressure in the conduit exceeds a user defined threshold.

2. A driven injection lance according to claim 1 wherein the second apertures that are formed through the sleeve have a characteristic dimension of less than 0.5 mm. 3. A driven injection lance according to claim 2 wherein the characteristic dimension of the second apertures is less than 0.

3 mm, preferably less than 0.2 mm and most preferably less than 0.1 mm.

4. A driven injection lance according to any preceding claim wherein the resiliently deformable sleeve is formed from a rubber or synthetic plastics material.

5. A driven injection lance according to claim 4 wherein the rubber or synthetic plastics material has an internal mesh or webbing.

6. A driven injection lance according to any preceding claim wherein the ends of the resiliently deformable sleeve are secured around the tube by swaging.

7. A driven injection lance according to any preceding claim wherein the driving tip has a maximum diameter which is not smaller than the diameter of the unexpanded resiliently deformable sleeve.

8. A driven injection lance according to any preceding claim wherein ends of the resiliently deformable sleeve are secured to the tube by collars, which fit around ends of the resiliently deformable sleeve, and clamp the tube and the resiliently deformable sleeve together.

9. A driven injection lance according to any preceding claim wherein the plurality of first apertures are located intermediate the ends of the resiliently deformable sleeve and the sleeve fits over the plurality of first apertures.

10. A driven injection lance according to any preceding claim wherein the resiliently deformable sleeve is of substantially equal length to the tube.

11. A driven injection lance according to any preceding claim wherein the second apertures open, as the resiliently deformable sleeve expands and stretches under pressure in excess of at least 5 bar, preferably in excess of at least 7 bar and most preferably in excess of at least 15 bar.

12. A driven injection lance according to claim 11 wherein the second apertures close when the pressure within the resiliently deformable sleeve drops below the user defined threshold pressure.

13. A driven injection lance according to any preceding claim wherein the second apertures are formed by piercing the resiliently deformable sleeve without removing material therefrom.

14. A driven injection lance according to any preceding claim wherein when the resiliently deformable sleeve is tight around the tube none of the first apertures overlap or are coincident with any of the second apertures.

15. A driven injection lance according to any preceding claim comprising: a plurality of sets of second apertures, each set of second apertures comprising a plurality of second apertures at substantially the same distance along the length of the resiliently deformable sleeve and the plurality of sets of second apertures being regularly spaced along the length of the resiliently deformable sleeve.

16. A driven injection lance according to any preceding claim comprising an end seal for sealing an end of the conduit of one of the one or more stages.

17. A driven injection lance according to any preceding claim wherein the one or more stages comprises a plurality of stages.

18. A driven injection lance according to claim 17 wherein the plurality of stages are releasably connectable one to another with a stage connector.

19. A driven injection lance according to claim 18 wherein the plurality of stages are releasably connectable one to another such that the conduits defined by their tubes are interconnected to define a continuous conduit along the injection lance.

20. A driven injection lance according to claim 19 wherein connecting tubes are fitted into and held within annular seals within the ends of the interconnected conduits of adjacent tubes of the interconnected stages.

21. A driven injection lance according to claim 20 wherein the annular seals are resiliently deformable.

22. A driven injection lance according to any preceding claim comprising an end valve for fitting into an end of a conduit defined by the tube of one of the stages.

23. A driven injection lance according to claim 22 wherein the end valve is a one way valve.

24. A system includes: the driven injection lance according to any preceding claim; a reservoir for storing liquid grout and a pump for pumping the grout.