GB2534848A

GB2534848A - Reinforcement cage assembly

Info

Publication number: GB2534848A
Application number: GB1501419.4A
Authority: GB
Inventors: Hughes Jason; Calleja Paul; Francis Lee Jimmy
Original assignee: Cementation Skanska Ltd
Current assignee: Cementation Skanska Ltd
Priority date: 2015-01-28
Filing date: 2015-01-28
Publication date: 2016-08-10
Also published as: GB201501419D0

Abstract

The assembly comprises a cage 3 having elongate bars 6 encircled by hoops, and stabilisers 10 on its outer perimeter, each stabiliser having an arm 13, 14, a surface for engaging the surface of a pile bore and an actuator 15 for moving the arm. The actuator may be a screw mounted on first and second blocks 16, 21, with first and second ends of the arm pivotably connected to an elongate bar and the second block respectively. Rotation C of the screw may cause movement A of the second block, and movement B of the engaging surface towards a bore wall 8. The actuator may be a spring-like section with the arm connected to a first end. The stabiliser may have a hook on the actuator for connection to a cage hoop. Also claimed are a method of using the assembly and a method of forming a pile.

Description

REINFORCEMENT CAGE ASSEMBLY

FIELD OF THE INVENTION

[1] The invention relates to a reinforcement cage assembly for a pile foundation, and to a stabiliser for anchoring the reinforcement cage in a pile bore. The invention also relates to a method of stabilizing a reinforcement cage during the formation of a pile foundation.

BACKGROUND OF THE INVENTION

[2] The construction of structures, such as buildings, bridges etc., typically involves the use of foundations to provide subsurface/underground support for the structure.

[3] In situations where the bearing capacity of the surface soils is not adequate to support the loads imposed by the structure, a deep foundation rather than a shallow foundation is utilised. A shallow foundation is generally a foundation where the founding depth is less than 3m. A deep foundation is a foundation where the founding depth is 3m or more.

[4] A pile foundation (hereinafter referred to as a "pile") is a common type of deep foundation, and may be in the form of a driven pile (e.g. wherein the pile is prefabricated off site and then driven into the ground), or a bore pile (e.g. that is poured in situ).

[5] Rotary bored piling uses a bored piling machine with specially designed drilling tools, buckets and grabs to remove soil and rock.

[6] The rotary bored pile construction process is typically as follows.

[7] An auger is bored into the ground, withdrawn, and the spoil removed so as to form a short pilot hole. A casing is then inserted into the pilot hole to stabilise the upper section of the pile bore. Alternatively, the pile bore can be "mudded" to a depth sufficient to enable the insertion of a casing.

[8] The casing can he temporary or permanent and is handled by a rig or by cranes, depending on the size and weight of the casing.

[9] The boring and spoil removal process is then repeated until the design depth is reached. If the surrounding ground will not stand open as the auger passes up and down beyond the casing, or where the pile diameter or depth is so great a longer casing would be too long or heavy, or where groundwater would flood the pile bore, drilling fluid such as bentonite is used to prevent closure of the ground. The pile base is then cleaned when the required depth is reached.

[10] A reinforcement cage may then he placed in the pile bore, such that it remains at a required level and in a correct position/orientation in accordance with the drawings and specification of the foundation. The recognised industry tolerance is +150mm and -50mm at any depth to the top of the cage. Typically, this is achieved by suspending the cage by means of hanging chains if the cage is not to sit on the base of the pile bore. The hanging chains are generally hung off a top hoop of the cage.

[11] A concreting operation is then carried out.

[12] During the concreting operation, the hanging chains are removed when the concrete is just below the point of suspension, i.e. the top hoop. At this point, only the fresh concrete prevents the cage from moving, for example due to settling under its own weight into the freshly placed concrete.

[13] After removal of the chains, concreting proceeds to fill the pile bore to the desired level. If a temporary casing has been used, it is first extracted.

[14] Typically the movement of concrete to fill the space vacated by the extracted casing and any over dig behind the casing is downwards. This exacerbates the natural tendency of the reinforcement cage to settle under its own weight into the freshly placed concrete.

[15] At shallow levels, any small movement of the cage can easily he assessed and he remedied as the cage is within handling range.

[16] When the cage is positioned at a low cut off level, a tell-talc bar is generally used to help assess any movement of the cage. The tell-tale bar is coupled to the cage and monitored to determine how much the bar may have moved during concreting, and casing extraction if carried out. Any movement of the reinforcement cage is noted by monitoring the initial and final level of the tell-tale bar at ground level.

[17] A resultant problem of using a permanent tell-tale bar is that it impedes any follow on excavation. As such, it is known to use a reusable threaded bar with a threaded coupler welded to a hoop within the cage. The tell-tale can then he removed before the concrete sets, for example after extraction of the temporary casing if such a casing is used.

[18] Unlike at shallow levels, should the cage move out of tolerance in a vertical direction, there is no method of recovery to within tolerance. This will result in the reinforcement cage not being in positional compliance with the drawing or specification.

[19] There is therefore a need for a way of reducing or eliminating the possibility of the reinforcement cage moving out of tolerance once it has been released from the hanging chains.

SUMMARY OF THE INVENTION

[20] A first aspect of the invention provides a reinforcement cage assembly for a pile comprising: a reinforcement cage comprising a plurality of elongate bars arranged in a predetermined configuration, and a plurality spaced apart hoops encircling the plurality of elongate bars; and a plurality of stabilisers located on an outer perimeter of the reinforcement cage and configured to restrict movement of the reinforcement cage within a pile bore, each stabiliser comprising: an arm movable between a first condition and a second condition, an engagement surface for engagement with an internal surface of the pile bore when the arm is in the second condition in order to restrict movement of the reinforcement cage within the pile bore, and an actuator configured to move the arm between the first condition and the second condition.

[21] A reinforcement cage assembly in accordance with the invention can he anchored relative to an internal wall of a pile bore when placed to a low cut-off level by means of the plurality of stabilisers. In the first condition, the stabilisers arc in a retracted condition which allows the reinforcement cage to be moved freely in a vertical direction within the pile bore. The movement of the arm of each stabiliser to the second condition would put the engagement surface of the respective stabiliser into engagement/contact with an internal surface of the pile bore. The engagement/contact between the engagement surfaces of the stabilisers and the internal surface of the pile bore will counteract the tendency of the reinforcement cage to move under its own weight thus reducing the likelihood of the location of the reinforcement cage moving out of the required industrial tolerances when freely suspended in concrete.

[22] Preferably, the plurality of elongate bars are arranged in a circular configuration.

[23] The plurality stabilisers may be positioned at equidistance from each other about the outer perimeter of the reinforcement cage.

[24] Placing the plurality of stabilisers at equidistance from each other ensures that the reinforcement cage will he held substantially stable by the stabilisers when counteracting against the tendency of the reinforcement cage to move under its own weight.

[25] In an exemplary configuration, each stabiliser is configured such that rotational movement of a component of the actuator moves the aim between the first and second conditions, and that movement of the arm between the first and second conditions translates into linear movement of the engagement surface in a direction substantially perpendicular to a longitudinal axis of the reinforcement cage.

[26] The stabiliser may further comprise a first block and the actuator of each stabiliser comprise a threaded screw defining said component of the actuator, the threaded screw having a head with a specially formed shape configured to receive a tool for turning or driving the threaded screw and an end opposite the head, wherein the end of the threaded screw is mounted in the first block and is freely rotatable therein.

[27] The arm of at least one of the stabilisers may comprise a two-bar linkage having a first link bar and a second link bar, the first end of the first link bar being pivotably coupled to the first end of the second link bar at a first pivot point.

[28] Preferably, a second end of the second link bar is pivotably mounted on a component of said at least one stabiliser, preferably to the first block or a clamp configured to secure said at least one stabiliser to an elongate bar of the reinforcement cage.

[29] Said at least one stabiliser may further comprise a second block mounted on the threaded screw and a second end of the first link bar is pivotably coupled to the second block, the second block being mounted on the threaded screw such that rotational movement of the threaded screw results in linear movement of the second block along the threaded screw. In this way, movement of the second block along the threaded screw would cause movement of the arm between the first and second conditions.

[30] In exemplary embodiments, the engagement surface of said at least one stabiliser is in the form of a leading edge of the arm proximate the first pivot point.

[31] The arm of at least one of the stabilisers may alternatively he in the form of an elongate member having a first end fixedly coupled to an elongate bar of a reinforcement cage, preferably by a weld joint or adhesive bonding.

[32] The elongate member preferably extends at an angle from the first end towards a second end of the elongate member.

[33] Preferably, the first block of said at least one stabiliser comprises a first side coupled to the elongate member proximate the first end of the elongate member.

[34] In exemplary embodiments, said at least one stabiliser further comprises a second block mounted on the threaded screw such that rotational movement of the threaded screw results in linear movement of the second block along the threaded screw, the second block being mounted on the threaded screw between the head of the threaded screw and the first block and comprises a size and dimension which is greater than the first block. In this way, movement of the second block along the threaded screw would cause movement of the arm between the first and second conditions.

[35] Preferably, the engagement surface of said at least one stabiliser is in the form of a leading edge of the elongate arm defined by a section of the elongate arm furthermost from said elongate bar to which it is coupled.

[36] In exemplary embodiments, at least one of the stabilisers comprises a frame and said at least one stabiliser is mounted on an elongate bar of the reinforcement cage via the frame.

[37] The engagement surface of said at least. one stabiliser preferably comprises a plate, and the arm of said at least one stabiliser preferably comprises a bolt having a first end connected to the plate, the bolt arranged to extend through a threaded aperture in the frame and configured to move linearly with respect to the frame in a direction perpendicular to an elongate bar of the reinforcement cage when the arm is moved between the first condition and the second condition.

[38] The actuator of said at least one stabiliser may comprise a rotatable shaft having a head with a specially formed shape configured to receive a tool for turning the rotatable shaft, and a universal joint having a first end connected to a second end of the bolt and a second end coupled to a first end of the rotatable shaft, rotation of the rotatable shaft actuating the universal joint to move the bolt linearly with respect to the frame.

[39] In another exemplary configuration, the actuator of at least one of the stabilisers comprises a spring-like section and the arm is connected to a first side of the springlike section.

[40] The spring-like section of said at least one stabiliser comprises a second side and a third side connecting the first side to the second side, and an apex of the first side is biased towards an apex of the second side.

[41] Said at least one stabiliser may further comprise a hook section connected to the second side of the spring-like section for facilitating the connection of the stabiliser to a hoop of a reinforcement cage.

[42] In exemplary embodiments, said at least one stabiliser further comprises a removable spacer locatable between the first and second sides of the spring-like section for facilitating the maintenance of the arm in the fu-st condition.

[43] Said at least one stabiliser may also comprises a cable or cord connected to the removable spacer. The cable or cord facilitates removal of the removable spacer from between the first and second sides of the spring-like section.

[44] The arm of said at least one stabiliser may be in the form of a substantially rectangular panel or a pole, and the engagement surface of the at least one stabiliser is preferably defined by a bottom edge of the rectangular panel/pole.

[45] A second aspect of the invention provides a method of stabilising a reinforcement cage during the formation of a pile comprising the steps of: - providing a reinforcement cage assembly according to the first aspect; - placing the reinforcement cage in a pile bore at a required location in the pile bore; - moving the arm of each stabiliser from the first condition to the second condition so as to put the engagement surface of each stabiliser into engagement with an internal wall of the pile bore.

[46] A third aspect of the invention provides a method of forming a pile comprising the steps of: (a) creating a pile bore; (h) coupling a plurality of stabilisers to a reinforcement cage; (c) suspending the reinforcement cage in the pile bore at a required location in the pile bore via a suspension arrangement; (d) moving the stabilisers into engagement with an internal wall of the pile bore to restricting or reducing movement of the reinforcement cage under its own weight; (e) concreting the pile bore to a level below said hoop; (I) releasing the reinforcement cage from the suspension arrangement; and (g) concreting the pile bore to a level above said hoop.

[47] In exemplary embodiments the reinforcement cage is suspended by means of hanging chains coupled to a hoop of the reinforcement cage and released by removing the hanging chains from the reinforcement cage.

[48] A fourth aspect of the invention provides a stabiliser locatable on an outer perimeter of a reinforcement cage and configured to restrict movement of the reinforcement cage within a pile bore, the stabiliser comprising: an arm movable between a first condition and a second condition; an engagement surface for engagement with an internal surface of the pile bore when the arm is in the second condition in order to restrict movement of the reinforcement cage within the pile bore; and an actuator configured to move the arm between the first condition and the second condition.

[49] In exemplary embodiments, the stabiliser further comprises a first block and the actuator comprises a threaded screw, the threaded screw having a head with a specially formed shape configured to receive a tool for turning or driving the threaded screw and an end opposite the head, the end of the threaded screw being mounted in the first block and being freely rotatable therein. The stabiliser is configured such that rotational movement of the threaded screw moves the arm between the first and second conditions, and that movement of the arm between the first and second conditions translates into linear movement of the engagement surface in a direction substantially perpendicular to a longitudinal axis of the threaded screw.

[50] The arm of the stabiliser may comprise a two-bar linkage having a first link bar and a second link bar, the first end of the first link bar being pivotably coupled to the first end of the second link bar at a first pivot point.

[51] A second end of the second link bar may be pivotably mounted on a component of the stabiliser, preferably to the first block or a clamp configured to secure the stabiliser to an elongate bar of a reinforcement cage.

[52] The stabiliser may further comprise a second block mounted on the threaded screw and a second end of the first link bar is pivotably coupled to the second block, the second block being mounted on the threaded screw such that rotational movement of the threaded screw results in linear movement of the second block along the threaded screw.

[53] Preferably, the engagement surface of the stabiliser is in the form of a leading edge of the arm proximate the first pivot point.

[54] The arm of the stabiliser may be in the form of an elongate member having a first end configured to be fixedly coupled to an elongate bar of a reinforcement cage, preferably by a weld joint or adhesive bonding.

[55] Preferably, the elongate member extends at an angle from the first end towards a second end of the elongate member.

[56] The first block may comprise a first side coupled to the elongate member proximate the first end of the elongate member.

[57] The stabiliser may further comprise a second block mounted on the threaded screw such that rotational movement of the threaded screw results in linear movement of the second block along the threaded screw, the second block being mounted on the threaded screw between the head of the threaded screw and the first block and comprises a size and dimension which is greater than the first block.

[58] In exemplary embodiments, the stabiliser may further comprise a frame for mounting the stabiliser on an elongate bar of a reinforcement cage.

[59] Preferably, the engagement surface comprises a plate and the arm comprises a bolt having a first end connected to the plate, the bolt arranged to extend through a threaded aperture in the frame and configured to move linearly with respect to the frame in a direction perpendicular to an elongate bar of the reinforcement cage when the arm is moved between the first condition and the second condition.

[60] Preferably, the actuator comprises a rotatable shaft having a head with a specially formed shape configured to receive a tool for turning the rotatable shaft, and a universal joint having a first end connected to a second end of the bolt and a second end coupled to a first end of the rotatable shaft, rotation of the rotatable shaft actuating the universal joint to move the bolt linearly with respect to the frame.

[61] In exemplary embodiments, the actuator of the stabiliser comprises a spring-like section and the arm is connected to a first side of the spring-like section.

[62] The spring-like section preferably comprises a second side and a third side connecting the first side to the second side, and an apex of the first side is biased towards an apex of the second side.

[63] The stabiliser may further comprise a hook section connected to the second side of the spring-like section for facilitating the connection of the stabiliser to a hoop of a reinforcement cage.

[64] The stabiliser may further comprise a removable spacer locatable between the first and second sides of the spring-like section for facilitating the maintenance of the arm in the first condition.

[65] A cable or cord may be connected to the removable spacer.

[66] The arm of the stabiliser may he in the form of a substantially rectangular panel or a pole, and the engagement surface is preferably defined by a bottom edge of the rectangular panel/pole.

BRIEF DESCRIPTION OF THE DRAWINGS

[67] Embodiments of the invention will now be described with reference to the accompanying drawings, in which: [68] Figure 1 is a schematic view of a pile bore with a casing and a reinforcement cage positioned therein; [69] Figurc 2 is a schematic view of a first configuration of a stabiliser in accordance with a first embodiment; [70] Figure 3 is a schematic view of a second configuration of a stabiliser in accordance with the first embodiment; [71] Figures 4a to 4i depict the steps of an exemplary method of forming a pile using the stabiliser of the first embodiment; [72] Figure 5 is a schematic view of a stabiliser in accordance with a second embodiment; [73] Figurc 6 is a schematic view of a stabiliser in accordance with a third embodiment; [74] Figures 7a-c are schematic views of a stabiliser in accordance with a fourth embodiment; and [75] Figures 8a-c are schematic views of a stabiliser in accordance with a fifth embodiment.

DETAILED DESCRIPTION OF EMBODIMENT(S)

[76] Referring to Figure 1, a schematic representation of a pile bore 1 forming part of a deep foundation prior to concreting is shown. A casing 2 is positioned within the pile bore 1 and extends below ground level to a required depth di For example, the casing 2 may extend below ground level to a depth d2 of 7m.

[77] A reinforcement cage 3 is positioned within the pile bore 1 at a required depth d and is of a length such that a section of the reinforcement cage 3 extends beyond the casing 2. For example, the reinforcement cage 3 may be positioned at a required depth di of 3m below ground level. In this embodiment, the reinforcement cage 3 has a plurality of elongate bars 6 (not all bars are shown in Figure 1), and a plurality of spaced apart hoops 5 encircling the elongate bars. The reinforcement cage 3 may he a single structure or be made of smaller sized cages joined together to obtain the required length of cage.

[78] A plurality of fixed spacers 4 are coupled to the reinforcement cage 3 and are sized such that a minimum gap of 75mm is maintained between the reinforcement cage 3 and an internal wall 7 of the pile bore 1.

[79] Referring to Figure 2, a first configuration of a first embodiment of a stabiliser 10 attachable to a reinforcement cage is shown. The stabiliser 10 facilitates maintenance of the reinforcement cage within the required tolerance in the pile bore.

[80] The stabiliser 10 includes an arm 12 movable between a first condition and a second condition; an actuator configured to move the arm 12 between the first condition and the second condition, and an engagement surface configured for engagement with an internal surface of a pile bore, i.e. the internal wall of the pile bore, when the arm 12 is in the second condition. In the first condition, the arm 12 is in a retracted condition which allows the reinforcement cage to be moved freely in a vertical direction within the pile bore (i.e. when in the first condition, the stabiliser 10 will not impede movement of the reinforcement cage).

[81] The arm 12 is connected to the actuator such that rotational movement of a component of the actuator moves the arm 12 between the first and second conditions. The engagement surface is associated with the arm 12 such that the movement of the arm 12 between the first and second conditions translates into linear movement of the engagement surface in a direction substantially perpendicular to a longitudinal axis of the reinforcement cage.

[82] In the embodiment shown, the stabiliser 10 further incudes a block 16 and the actuator includes a threaded screw 15 having head (not shown) and an end mounted in a block 16. In this embodiment, the threaded screw 15 is said component of the actuator. The end of the threaded screw 15 is located in the block 16 such that it is freely rotatable therein. The head of the threaded screw 15 has a specially formed shape which allows the threaded screw 15 to be turned or driven by a correspondingly formed tool (not shown).

[83] The arm 12 is in the form of a two-bar linkage having a first link bar 13 and a second link bar 14. Each link bar 13, 14 has a first end, and the first end of the first link bar 13 is pivotably coupled to the first end of the second link bar 14 at a first pivot point 18. The first and second link bars 13, 14 each have an opening in the form of a threaded hole through which the threaded screw 15 passes.

[84] A second end of the second link bar 14 is pivotably mounted on a clamp 17 configured to secure the stabiliser 10 to an elongate bar 6 of the reinforcement cage. While the second end of the second link bar 14 is shown pivotably mounted on the clamp 17, it would be understood that it may be pivotably mounted on another component the stabiliser 10.

[85] Duc to the arrangement of the first and second link bars 13, 14 with respect to the threaded screw 15, rotational movement of the threaded screw 15 in the direction indicated by arrow C in Figure 2 will cause inner sides 13a, 14a of the first and second link bars 13, 14 to move towards each other and be drawn together in a direction indicated by arrow A in Figure 2 (i.e. movement of the arm 12 towards the second condition). As a result, the engagement surface of the stabiliser, which in the embodiment shown is in the form of a leading edge 20 proximate the first pivot point 18, is caused to move in a direction perpendicular to the longitudinal axis of the elongate bar 6 (and perpendicular to the longitudinal axis of the threaded screw) as indicated by arrow B in Figure 2. Movement of the threaded screw in a direction opposite to that indicated by arrow C in Figure 2 will cause inner sides 13a, 14a of the first and second link bars 13, 14 to move away from each other (i.e. movement of the arm 12 towards the first condition).

[86] Referring to Figure 3, a second configuration of a first embodiment of the stabiliser 10' is shown. In the second configuration, the first and second link bars 13', 14' do not have a threaded hole nor does the threaded screw 15 pass through the first and second link bars 13', 14'. Instead, the stabiliser 10' includes a second block 21 having a threaded hole through which the threaded screw 15 passes, and a second end of the first link bar 13' is pivotably coupled to the second block 21 at a pivot point 22. Rotational movement of the threaded screw 15 causes the second block 21 to move linearly along the threaded screw 15 thus actuating the arm 12 to move between the first and second conditions (i.e. cause inner sides 13'a, 14'a of the first and second link bars 13', 14' to move towards or away from each other).

[87] An exemplary method of forming a pile using a reinforcement cage 33 incorporating a plurality of the stabilisers 10, 10' will now he described with reference to Figures 4a to 4i.

[88] A pile bore 31 is first created and a casing 32 located in the pile bore 31 as known in the art (see Figure 4a). The method will be described with the use of a temporary steel casing, however it would he understood that the casing may he made from any suitable material and/or may be in the form of a permanent casing.

[89] During excavation of the pile bore 31, a record will he made of the levels of a bottom edge 39 of the steel casing 32 and of any cohesive soil/stratum 38. From this record, the level at which the stabilisers 10, 10' will be fitted to the reinforcement cage 33 will be determined.

[90] The stabiliser 10, 10' must be placed below the bottom edge 39 of the casing 32 and preferably at a location such that the leading edge 20 of the stabiliser 10, 10' will come into engagement with an internal wall 37 of the pile bore 31 and into a cohesive stratum 38.

[91] The stabilisers 10, 10' arc then fitted to the reinforcement cage 33 at the appropriate position prior to inserting the reinforcement cage 33 into the pile bore 31 (see Figure 4b). The stabilisers are preferably 3 or 4 in number depending on the weight and diameter of the reinforcement cage 33 (although two stabilisers or more than four stabilisers may be used), and are spaced at an equidistance from each other around a perimeter of the reinforcement cage 33.

[92] A tale-tell bar 40 is then fitted to the upper most vertical hoop 35a of the reinforcement cage, and a tool 41 (only one tool is shown for clarity) for driving the threaded screw 15 of each stabiliser 10, 10' is located with each head of the threaded screw 15 in order to allow the threaded screw 15 to be driven when required (see Figure 4c). The tool 41 is of a length such that it is able to be operated to drive the threaded screw 15 from above ground level 30.

[93] The reinforcement cage 33 is then lowered into the pile bore by means of hanging chains 42 suspended from a top hoop 35a of the reinforcement cage 33 in a conventional manner, as known in the field. It would he understood that other suitable suspension arrangements may be used instead of hanging chains.

[94] When the reinforcement cage 33 is at the required level, the hanging chains are secured in a conventional manner, as known in the field (see Figure 4d).

[95] The tools 41 are then operated in order to move the arms 12 from the first condition towards the second condition (see Figure 4e). As the arms 12 are moved towards the second condition, the leading edge 20 of each stabiliser will come into contact with the internal wall 37 of the pile bore 31 and be embedded in the cohesive stratum 38. The fitting of the stabilisers 10, 10' will be monitored to ensure that the required extension of the leading edge 20 of the stabilisers 10, 10' into the cohesive stratum 38 is achieved and to maintain a central positioning of the reinforcement cage 33 within the pile bore 31. Ideally, the leading edge 20 of each stabiliser only moves between 10-20mm in distance prior to engagement with the cohesive stratum 38.

[96] If required, the stabilisers 10, 101 may be disengaged from the internal wall 37 of the pile bore 31 in order to adjust the positioning of the reinforcement cage 33.

[97] The tools 41 are then removed and the concreting operation commences. Concreting will continue until the concrete 43 is above the stabilisers 10, 10' and just below the level of the hanging chains 42 i.e. to the underside of the top hoop 35a (see Figure 40.

[98] The hanging chains 42 are then removed leaving the weight of the reinforcement cage 33 buoyed by the concrete 43 and restrained by the stabilisers 10, 10' (see Figure 4g). Concreting then proceeds to fill the casing to the desired level 44.

[99] The temporary casing is then extracted (see Figure 4h).

[100] Any movement of the reinforcement cage 33 is noted by monitoring the initial and final level of the tell-tale bar 40 at ground level.

[101] The tell-tale bar 40 is then removed to leave a completed pile (see Figure 4i).

[102] Referring to Figure 5, a second embodiment of a stabiliser 110 for use with a reinforcement cage is shown.

[103] The stabiliser 110 includes an arm 112 movable between a first condition and a second condition; an actuator configured to move the arm 112 between the first condition and the second condition; and an engagement surface configured for engagement. with an internal surface of a pile bore when the arm 112 is in the second condition.

[104] Similar to the first embodiment, the actuator includes a threaded screw 115 having an end mounted in a first block 116. The end of the threaded screw 115 is located in the first block 116 such that it is freely rotatable therein. The threaded screw 115 also has a head (not shown) having a specially formed shape which allows the threaded screw 115 to be turned or driven by a tool (not shown).

[105] The arm 112 is in the form of an elongate member having a first end 123 configured to be fixedly coupled to an elongate bar 6 of a reinforcement cage. In the embodiment shown in Figure 5, the first end 123 of the elongate member 112 is coupled to the elongate bar 6 by a weld joint 117, however it would be understood that other suitable means may be utilised, for example adhesive bonding etc. [106] The elongate member 112 extends at an angle from the first end 123 towards a second free end 124 of the elongate member 112 such that when connected to the elongate bar 6, a gap 125 is defined between the elongate member 112 and the elongate bar 6.

1107] The first block 116 has a first side coupled to the elongate member 112 proximate the first end 123 of the elongate member 112. The first block 116 is coupled to the elongate member 112 such that when the elongate member 112 is connected to the elongate bar 6, the first block 116 is positioned within the gap 125. A second side of the first block 116, opposite the first side, is he coupled to the elongate bar 6 by any suitable means.

[108] The stabiliser 110 further includes a second block 121 having a threaded hole through which the threaded screw 115 passes. The second block 121 is located within the gap 125 at a position below the second end 124 of the elongate member 112. The second block 121 is mounted on the threaded screw 115 such that rotational movement of the threaded screw 115 causes the second block 121 to move linearly along the threaded screw 115.

[109] The second block 121 is of a greater size and dimension than the first block 116 such that the gap 125 has a first spacing ti directly above the first block 116 that is less than a second spacing t2 directly below the second block 121.

[110] In use, rotational movement of the threaded screw 115 in the direction indicated by arrow C in Figure 5 will cause the second block 121 to move downwards in a direction indicated by arrow A in Figure 5. This will result in an increase in the second spacing tn and an increase in the angle of orientation of the elongate member 112 thus moving the second end 124 of the elongate member 112 further away from the elongate bar 6 (i.e. movement of the elongate member 112 towards the second condition). As a result the engagement surface, which is in the form of a leading edge 120 of the elongate member 112 defined by a section of the elongate member 112 furthermost from the elongate bar 6 of the reinforcement cage, is caused to move in a direction perpendicular to the longitudinal axis of the elongate bar 6 and the threaded screw 115 as indicated by arrow B in Figure 5. Movement of the threaded screw 115 in a direction opposite to that indicated by arrow C in Figure 5 will cause a decrease in the second spacing t2 and angle of orientation of the elongate member 112 thus moving the second end 124 of the elongate member 112 closer to the elongate bar 6 (i.e. movement of the elongate member towards the first condition).

[111] The use of a stabiliser 110 in accordance with the second embodiment in a method of forming a pile is similar to that described above. However, unlike the first embodiment, the leading edge 120 of the elongate member 112 defining the engagement surface will not be embedded in the cohesive stratum. Instead, the leading edge 120 will come into strong frictional contact with the internal wall 7 of the pile bore, said frictional contact restricting or reducing movement of the reinforcement cage under its own weight in the concrete once the hanging chains have been removed.

[112] Referring to Figure 6, a third embodiment of a stabiliser 210 for use with a reinforcement cage is shown.

[113] The stabiliser 210 includes an arm 212 movable between a first condition and a second condition; an actuator configured to move the arm 212 between the first condition and the second condition; and an engagement surface for engagement with an internal surface of a pile bore when the arm 212 is in the second condition.

[114] The stabiliser 210 further includes a frame 227 for mounting the stabiliser 210 on an elongate bar 6 of a reinforcement cage.

[115] The engagement surface of the stabiliser 210 is in the form of a plate 229 configured to engage with an internal wall 7 of a pile bore. The plate 229 is orientated in a substantially vertical direction. A side/face of the plate 229 which contacts the internal wall 7 of the pile bore may be substantially flat, knurled, or non-planar.

[116] The arm 212 is in the form of a bolt 228 having a first end connected to the plate 229. The bolt 228 extends through a threaded aperture in the frame 227 and is configured to move linearly with respect to the frame 227.

[117] The actuator includes a rotatable shaft 215 and a universal joint 226. The universal joint 226 has a first end connected to a second end of the bolt 228 and a second end coupled to a first end of the rotatable shaft 215. The rotatable shaft 215 includes a head (not shown) having a specially formed shape which allows the rotatable shaft 215 to be turned/rotated by a tool (not shown).

[118] In use, rotational movement of the rotatable shaft 215 in the direction indicated by arrow C in Figure 6 will cause the bolt 228 to be driven via the universal joint 226 so as to move in a direction indicated by arrow B in Figure 6. This will cause the plate 229 to also move in the direction indicated by arrow B in Figure 6 thus moving the plate 229 away from the frame 227 (i.e. movement of the arm towards the second condition). Rotational movement of the rotatable shaft 215 in a direction opposite the direction indicated by arrow C in Figure 6 will cause the bolt 228 to move the plate towards the frame 227 (i.e. movement of the arm towards the first condition).

[119] The use of a stabiliser 210 in accordance with the third embodiment in a method of forming a pile is similar to that described above. Similar to the second embodiment, the engagement surface of the stabiliser 210 is not intended to be embedded in the cohesive stratum. Instead, the plate 229 is intended to come into strong frictional contact with the internal wall 7 of the pile bore, said frictional contact restricting or reducing movement of the reinforcement cage under its own weight in the concrete once the hanging chains have been removed.

[120] With reference to Figures 7a-c, a fourth embodiment 310 of a stabiliser for use with a reinforcement cage will now be described.

[121] The stabiliser 310 comprises an arm 312 movable between a first condition (as shown in Figure 7a) and a second condition (as shown in Figure 7b). In the embodiment shown, the arm 312 is in the form of a substantially rectangular panel. As in the previously described embodiments, the stabiliser 310 has an engagement surface configured for engagement with an internal surface of a pile bore.

[122] The stabiliser 310 further includes a spring-like section 351 having a first side 355 to which the aim 312 is connected, and a second side 356 to which a hook section is connected. The spring-like section 351 has a third side 357 connecting the first side 355 to the second side 356, and an apex of the first side 355 is biased towards an apex of the second side 356. The spring-like section 351 is made of a single material which is bent into the shape of a right-angle triangle such that the tension along the third side 357 forces the apex of the first side 355 towards the apex of the second side 356. The spring-like section 351 may he made from any suitable material for example spring steel.

[123] The hook section 352 is sized and shaped to fit over a vertical hoop 5 of a reinforcement cage (see Figure 7c).

[124] A removable spacer 353 is positioned between the first and second sides 355, 356 of the spring-like section 351 in order to retain the arm 312 in the first condition. The removable spacer 353 prevents the apex of the first side 355 moving towards the apex of the second side 356. Removal of the removable spacer 353 in a direction indicated by arrow A in Figure 7b will free the first side 355 for movement and due to its apex being biased towards the apex of the second side 356, incline the first side 355 towards the second side 356 and thus move the arm 312 towards the second condition.

[125] While the arm 312 has been shown to as a separately formed component to the spring-like section 351, it would be understood that they may be integrally formed from a single piece of material.

[126] In use during a method of forming a pile, a plurality of stabilisers 310 are positioned at equidistance from each other on a vertical hoop 5 of the reinforcement cage which will be located below the casing when the reinforcement cage is positioned within the pile bore. The stabilisers 310 are positioned on the vertical hoop 5 with the arms 312 in the first condition.

[127] Prior to lowering the reinforcement cage into the pile bore, a cable 354 is connected to each spacer 353 so as to allow the spacers 353 to he removed. Pulling of the cables 354 will result in the removal of the respective spacer 353 and in the arms 312 moving into their respective second condition. This will result in the engagement surface of each stabiliser 312, defined by a bottom edge 320 of the arms 312, coming into contact with the internal wall of the pile bore and being embedded in the cohesive stratum.

[128] The cables 354 should ideally he pulled all at approximately the same time, or if an even number of stabilisers 312 are utilised in diametrically opposing pairs.

[129] With reference to Figures 8a-c, a fifth embodiment 410 of a stabiliser for use with a reinforcement cage will now be described.

[130] The stabiliser 410 includes an arm 412 movable between a first condition (as shown in Figure 8b) and a second condition (as shown in Figure 8c). In the embodiment shown, the arm 412 is in the form of a pole. As in the previously described embodiments, the stabiliser 410 has an engagement surface configured for engagement with an internal surface of a pile bore when the arm 412 is in the second condition.

[131] The stabiliser 410 is similar to the stabiliser of the fourth embodiment and also includes a spring-like section 451 with the arm 412 connected to a first side 455 thereof, a second side 456, and a third side 457 connecting the first side 455 to the second side 456. The apex of the first side 455 is biased towards an apex of the second side 456. The spring-like section 451 is made of a single material which is bent into the shape of a right-angle triangle such that the tension along the third side 457 forces the apex of the first side 455 towards the apex of the second side 456. The spring-like section 451 may be made from any suitable material for example spring steel.

[132] Unlike the fourth embodiment, the stabiliser 410 does not have a hook section, instead the stabiliser 410 is configured to be coupled to a vertical hoop 5 of a reinforcement cage via the second side 456 of the spring-like section 451 (see Figure 8a). The second side 456 may be bonded to the vertical hoop 5 by any suitable means, for example by welding or by adhesive bonding.

[133] A removable spacer 453 is positioned between the first and second sides 455, 456 of the spring-like section 451 in order to move the arm 412 into the first condition. The spacer 453 prevents the apex of the first side 455 moving towards the apex of the second side 456. Removal of the spacer 453 will free the first side 455 for movement and due to its apex being biased towards the apex of the second side 456, incline the first side 455 towards the second side 456 and thus move the arm 412 towards the second condition.

[134] While the arm 412 has been shown in the form of a pole, it would he understood that arm 412 may be of any suitable shape, for example the arm 412 may be in the shape of a panel similar to the fourth embodiment.

[135] In use during a method of forming a pile, a plurality of stabilisers 410 are positioned at equidistance from each on a vertical hoop 5 of the reinforcement cage which will be located below the casing when the reinforcement cage is positioned within the pile bore. The stabilisers 410 are positioned on the vertical hoop 5 with the arm 412 in the first condition as shown in Figure 8b.

[136] Prior to lowering the reinforcement cage into the pile bore, a cable 454 is connected to each spacer 453 so as to allow the spacers 453 to he removed. Pulling of the cables 454 will result in the removal of the respective spacer 453 and in the arms 412 moving into their respective second condition. This will result in the engagement surface of each stabiliser 412, defined by a bottom edge of the arm 412, coming into contact with the internal wall of the pile bore and being embedded in the cohesive stratum.

[137] The cables 454 should ideally be pulled all at approximately the same time, or if an even number of stabilisers 412 are utilised in diametrically opposing pairs.

[138] While the invention has been described with reference to reinforcement cages having a circular cross sectional profile, it would be understood that the invention may he utilised with reinforcement cages of other cross-sectional profiles.

[139] In addition, a reinforcement cage assembly in accordance with the invention (i.e. a reinforcement cage with a plurality of stabilisers coupled to the reinforcement cage) may have identical stabilisers or may have a combination of the above described stabilisers.

[140] It would be understood that the method for forming a pile described above is just an example of one possible method of forming a pile utilising reinforcement cage assembly in accordance with the invention. The order in which certain steps are carried out may be changed etc. or a different method may be employed.

[141] In addition, it would he understood that a stabiliser or a reinforcement cage assembly in accordance with the invention may be utilised in other suitable foundation techniques.

[142] Although the invention has been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.

Claims

Claims 1 A reinforcement cage assembly for a pile comprising: a reinforcement cage comprising a plurality of elongate bars arranged in a predetermined configuration, preferably in a circular configuration, and a plurality spaced apart hoops encircling the plurality of elongate bars; and a plurality of stabilisers located on an outer perimeter of the reinforcement cage and configured to restrict movement of the reinforcement cage within a pile bore, each stabiliser comprising: an arm movable between a first condition and a second condition, an engagement surface for engagement with an internal surface of the pile bore when the arm is in the second condition in order to restrict movement of the reinforcement cage within the pile bore, and an actuator configured to move the arm between the first condition and the second condition.
2. A reinforcement cage assembly according to claim I. wherein the plurality stabilisers are positioned at equidistance from each other about the outer perimeter of the reinforcement cage.
3. A reinforcement cage assembly according to claim 1 or claim 2, wherein each stabiliser is configured such that rotational movement of a component of the actuator moves the um between the first and second conditions, and that movement of the arm between the first and second conditions translates into linear movement of the engagement surface in a direction substantially perpendicular to a longitudinal axis of the reinforcement cage.
4. A reinforcement cage assembly according to claim 3, wherein the stabiliser further comprises a first block and the actuator of each stabiliser comprises a threaded screw defining said component of the actuator, the threaded screw having a head with a specially formed shape configured to receive a tool for turning or driving the threaded screw and an end opposite the head, wherein the end of the threaded screw is mounted in the first block and is freely rotatable therein.
5. A reinforcement cage assembly according to claim 3 or claim 4, wherein the arm of at least one of the stabilisers comprises a two-bar linkage having a first link bar and a second link bar, the first end of the first link bar being pivotably coupled to the first end of the second link bar at a first pivot point.
6. A reinforcement cage assembly according to claim 5, wherein a second end of the second link bar is pivotably mounted on a component of said at least one stabiliser, preferably to the first block or a clamp configured to secure said at least one stabiliser to an elongate bar of the reinforcement cage.
7. A reinforcement cage assembly according to claim 6 when dependent directly or indirectly on claim 4, wherein said at least one stabiliser further comprises a second block mounted on the threaded screw and a second end of the first link bar is pivotably coupled to the second block, the second block being mounted on the threaded screw such that rotational movement of the threaded screw results in linear movement of the second block along the threaded screw.
8. A reinforcement cage assembly according to any one of claims 5 to 7, wherein the engagement surface of said at least one stabiliser is in the form of a leading edge of the arm proximate the first pivot point.
9. A reinforcement cage assembly according to claim 3 or claim 4, wherein the arm of at least one of the stabilisers is in the form of an elongate member having a first end fixedly coupled to an elongate bar of a reinforcement cage, preferably by a weld joint or adhesive bonding.
10. A reinforcement cage assembly according to claim 9, wherein the elongate member extends at an angle from the first end towards a second end of the elongate member.
11 A reinforcement cage assembly according to claim 9 or 10, wherein the first block of said at least one stabiliser comprises a first side coupled to the elongate member proximate the first end of the elongate member.
12. A reinforcement cage assembly according to claim 11 when dependent directly or indirectly on claim 4, wherein said at least one stabiliser further comprises a second block mounted on the threaded screw such that rotational movement of the threaded screw results in linear movement of the second block along the threaded screw, the second block being mounted on the threaded screw between the head of the threaded screw and the first block and comprises a size and di mension which is greater than the first block.
13. A reinforcement cage assembly according to any of claims 9 to 12, wherein the engagement surface of said at least one stabiliser is in the form of a leading edge of the elongate aim defined by a section of the elongate arm furthermost from said elongate bar.
14. A reinforcement cage assembly according to any one of claims 1 to 3, wherein at least one of the stabilisers comprises a frame and said at least one stabiliser is mounted on an elongate bar of the reinforcement cage via the frame.
15. A reinforcement cage assembly according to claim 14, wherein the engagement surface of said at least one stabiliser comprises a plate, and the arm of said at least one stabiliser comprises a bolt having a first end connected to the plate, the bolt arranged to extend through a threaded aperture in the frame and configured to move linearly with respect to the frame in a direction perpendicular to an elongate bar of the reinforcement cage when the arm is moved between the first condition and the second condition.
16. A reinforcement cage assembly according to claim 15, wherein the actuator of said at least one stabiliser comprises a rotatable shaft having a head with a specially formed shape configured to receive a tool for turning the rotatable shaft, and a universal joint having a first end connected to a second end of the bolt and a second end coupled to a first end of the rotatable shaft, rotation of the rotatable shaft actuating the universal joint to move the bolt linearly with respect to the frame.
17. A reinforcement cage assembly according to claim 1 or claim 2, wherein the actuator of at least one of the stabilisers comprises a spring-like section and the arm is connected to a first side of the spring-like section.
18. A reinforcement cage assembly according to claim 17, wherein the spring-like section of said at least one stabiliser comprises a second side and a third side connecting the first side to the second side, and an apex of the first side is biased towards an apex of the second side.
19. A reinforcement cage assembly according to claim 18, wherein said at least one stabiliser further comprises a hook section connected to the second side of the spring-like section for facilitating the connection of the stabiliser to a hoop of a reinforcement cage.
20. A reinforcement cage assembly according to any of claims 17 to 19, wherein said at least one stabiliser further comprises a removable spacer locatable between the first and second sides of the spring-like section for facilitating the maintenance of the arm in the first condition.
21. A reinforcement cage assembly according to claim 20, wherein said at least one stabiliser further comprises a cable or cord connected to the removable spacer.
22. A reinforcement cage assembly according to any one of claims 17 to 21, wherein the arm of said at least one stabiliser is in the form of a substantially rectangular panel or a pole, and the engagement surface of the at least one stabiliser is defined by a bottom edge of the rectangular panel/pole.
23. A method of stabilising a reinforcement cage during the formation of a pile comprising the steps of: -providing a reinforcement cage assembly according to any one of claims 1 to 22; - placing the reinforcement cage in a pile bore at a required location in the pile bore; - moving the arm of each stabiliser from the first condition to the second condition so as to put the engagement surface of each stabiliser into engagement with an internal wall of the pile bore.
24. A method of forming a pile comprising the steps of: (a) creating a pile bore; (1)) coupling a plurality of stabilisers to a reinforcement cage; (c) suspending the reinforcement cage in the pile bore at a required location in the pile bore via a suspension arrangement, preferably by means of hanging chains coupled to a hoop of the reinforcement cage; (d) moving the stabilisers into engagement with an internal wall of the pile bore to restricting or reducing movement of the reinforcement cage under its own weight; (e) concreting the pile bore to a level below said hoop; (t) releasing the reinforcement cage from the suspension arrangement, preferably by removing the hanging chains from the reinforcement cage; and (g) concreting the pile bore to a level above said hoop.
25. A stabiliser locatable on an outer perimeter of a reinforcement cage and configured to restrict movement of the reinforcement cage within a pile bore, the stabiliser comprising: an arm movable between a first condition and a second condition,; an engagement surface for engagement with an internal surface of the pile bore when the arm is in the second condition in order to restrict movement of the reinforcement cage within the pile bore; and an actuator configured to move the arm between the first condition and the second condition.
26. A stabiliser according to claim 25, wherein the stabiliser further comprises a first block and the actuator comprises a threaded screw, the threaded screw having a head with a specially formed shape configured to receive a tool for turning or driving the threaded screw and an end opposite the head, the end of the threaded screw being mounted in the first block and being freely rotatable therein, and wherein the stabiliser is configured such that rotational movement of the threaded screw moves the arm between the first and second conditions, and that movement of the arm between the first and second conditions translates into linear movement of the engagement surface in a direction substantially perpendicular to a longitudinal axis of the threaded screw.
27. A stabiliser according to claim 26, wherein the arm comprises a two-bar linkage having a first link bar and a second link bar, the first end of the first link bar being pivotably coupled to the first end of the second link bar at a first pivot point.
28. A stabiliser according to claim 27, wherein a second end of the second link bar is pivotably mounted on a component of the stabiliser, preferably to the first block or a clamp configured to secure the stabiliser to an elongate bar of a reinforcement cage.
29. A stabiliser according to claim 28, further comprising a second block mounted on the threaded screw and a second end of the first link bar is pivotahly coupled to the second block, the second block being mounted on the threaded screw such that rotational movement of the threaded screw results in linear movement of the second block along the threaded screw.
30. A stabiliser according to any one of claims 27 to 29, wherein the engagement surface is in the form of a leading edge of the arm proximate the first pivot point.
31. A stabiliser according to claim 26, wherein the arm is in the form of an elongate member having a first end configured to be fixedly coupled to an elongate bar of a reinforcement cage, preferably by a weld joint or adhesive bonding.
32. A stabiliser according to claim 31, whcrcin the clongatc member extends at an angle from the first end towards a second end of the elongate member.
33. A stabiliser according to claim 31 or 32, whcrcin the first block comprises a first side coupled to the elongate member proximate the first end of the elongate member.
34. A stabiliser according to claim 33, further comprising a second block mounted on the threaded screw such that rotational movement of the threaded screw results in linear movement of the second block along the threaded screw, the second block being mounted on the threaded screw between the head of the threaded screw and the first block and comprises a size and dimension which is greater than the first block.
35. A stabiliser according to claim 25, further comprising a frame for mounting the stabiliser on an clongatc bar of a reinforcement cage.
36. A stabiliser according to claim 35, wherein the engagement surface comprises a plate, and the arm comprises a bolt having a first end connected to the plate, the bolt arranged to extend through a threaded aperture in the frame and configured to move linearly with respect to the frame in a direction perpendicular to an elongate bar of the reinforcement cage when the arm is moved between the first condition and the second condition.
37. A stabiliser according to claim 36, wherein the actuator comprises a rotatable shall having a head with a specially formed shape configured to receive a tool for turning the rotatable shaft, and a universal joint having a first end connected to a second end of the bolt and a second end coupled to a first end of the rotatable shaft, rotation of the rotatable shaft actuating the universal joint to move the bolt linearly with respect to the frame.
38. A stabiliser according to claim 25, wherein the actuator comprises a spring-like section and the arm is connected to a first side of the spring-like section.
39. A stabiliser according to claim 38, wherein the spring-like section comprises a second side and a third side connecting the first side to the second side, and an apex of the first side is biased towards an apex of the second side.
40. A stabiliser according to claim 39, further comprising a hook section connected to the second side of the spring-like section for facilitating the connection of the stabiliser to a hoop of a reinforcement cage.
41. A stabiliser according to any of claims 38 to 40, further comprising a removable spacer locatable between the first and second sides of the spring-like section for facilitating the maintenance of the arm in the first condition.
42. A stabiliser according to claim 41, further comprising a cable or cord connected to the removable spacer.
43. A stabiliser according to any one of claims 38 to 42, wherein the arm is in the form of a substantially rectangular panel or a pole, and the engagement surface is defined by a bottom edge of the rectangular panel/pole.