AU2016250437A1 - A Method of constructing a column, a tunnel, and a tunnel made from the method - Google Patents

Abstract

Abstract The present invention provides a method of constructing a tunnel (11) and a column (19) for use in same. The method comprising the steps of installing retaining walls (15, 17) along the perimeter of the proposed tunnel, creating a plurality of holes (18) and forming columns therein, the holes being spaced between the retaining walls. The method comprises forming a slab supported by the ground, retaining walls and the plurality of columns, the slab to provide the tunnel roof (35). The area under the tunnel roof is excavated to provide the tunnel. '~0 ______________________________ rL~ K r I * I I-I Ii~ *---Th~-I I ii a -. 'F I- I F-

Description

1 2016250437 27 Oct 2016

A Method of constructing a column, a tunnel, and a tunnel made from the method TECHNICAL FIELD

[0001] The present invention generally relates to a method of constructing a tunnel. BACKGROUND ART

[0002] Conventionally, tunnels such as tunnels for vehicles, are built by excavating a pit, building the tunnel and then reinstating the surrounding soil. This form of construction typically first requires the excavation of a large pit to a depth equal to where the lowermost part of the tunnel will be formed. In order to construct the pit and to provide access for various construction services, this form of construction requires a much larger construction footprint when compared to the footprint of the tunnel. This form of construction is therefore problematic in built up areas, and creates significant traffic disruption during the construction phase. Alternatively, piles or diaphragm walls may first be driven through the soil to retain the surrounding earth and allow for excavation of the soil so the tunnel may be constructed. While this does not require as large a footprint, it does require the walls or piles to be anchored or propped as excavation to the lowermost part of the building proceeds.

[0003] For those tunnels having significant site constraints and limited construction time, an alternative form of construction is to use a drill to bore the tunnel. This can be quite a slow process and is very costly, especially for small projects.

[0004] Another form of construction is a top-down construction method. This method builds the permanent structure members of the basement from the top to the bottom, and then excavates the area between the permanent structure members. Once the tunnel roof is cast, work above the tunnel can proceed at the same time or before the soil is excavated from the tunnel.

[0005] In top down construction, retaining walls are constructed first to support the later excavation. Eventually the retaining walls form the final external structural walls of the tunnel. From the ground level, permanent piles (typically steel beams) or a central diaphragm wall are installed internally between the soil retaining walls to reduce the span of the future roof of the tunnel. The walls are then propped and the soil there 2 2016250437 27 Oct 2016 between and below can be excavated. Once the soil has been excavated the base of the tunnel can be constructed. As the permanent piles / diaphragm walls are generally located centrally the piles or central diaphragm wall are required to support more load than the retaining walls. As a result the piles / diaphragm walls need to penetrate deeper than that required by the retaining walls to develop higher load carrying capacity.

[0006] The top down method of construction is designed to enable above ground construction work to be carried out while the tunnel is excavated resulting in significant saving of time and cost on a project as well as minimising the time traffic is disrupted.

[0007] Top-down construction also greatly reduces the likelihood of damage to adjoining buildings otherwise associated with soil movement as before excavation proceeds the basement walls are propped by the tunnel roof slab. This eliminates the need for sheet piling or any other form of temporary propping. In addition, on wet sites, construction dewatering is reduced as the path of entry is elongated around the external walls. These advantages make top down construction ideal for constructing tunnels in congested areas.

[0008] Furthermore, as top down construction provides progressive propping of the basement perimeter retaining walls, the walls are not required to be as thick.

[0009] While top-down construction has many advantages, the construction method does have some disadvantages. For instance, the construction method presents limited space and restricted access for excavation and construction of the tunnel floor below. This also presents the need for additional ventilation in order to vent fumes from machinery to ensure a safe working environment.

[0010] With top-down constructions there is also the risk that the exterior walls and/or centre columns exceed specified installation tolerances and impact the interior space. As excavation occurs after the walls and columns are formed in the soil the accuracy of the wall/columns and their position is unknown during the construction process. If the walls and/or columns are incorrectly orientated and/or incorrectly positioned then additional work may be required to the wall/columns after excavation.

[0011] With any subterranean structure the potential for water leakage through the sub-structure can be problematic. As the installation is conducted without excavating 3 2016250437 27 Oct 2016 the surrounding soil it is not possible to install external waterproofing on the outside of the retaining/external walls.

[0012] The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

SUMMARY OF INVENTION

[0013] It is an object of this invention to provide a method of constructing a tunnel which has a reduced impact on traffic.

[0014] The present invention provides a method of casting a column in soil, the method comprises: creating a hole in the soil; filling the hole with a settable liquid; lowering an elongate assembly into the hole wherein the elongate assembly is supported such that the elongate element is lowered in a substantially vertical orientation; adjusting the elongate assembly once received in the hole so that the elongate assembly is substantially vertical; excavating the soil once the settable liquid has set to provide the column.

[0015] The method may comprise the step of casting/installing a guide means at the surface to assist in guiding an auger to form the hole.

[0016] The method may comprise the step of filling the hole with the settable liquid as the hole is created.

[0017] The method may comprise the step of layering an outside surface of a hollow pipe of the elongate assembly with a protective layer, whereupon excavation, the protective layer may be removed from the hollow pipe, wherein the outer surface of the hollow pipe provides the finished surface of the column. 4 2016250437 27 Oct 2016 [0018] The method may comprise the step of securing one or more shear connectors to the elongate element wherein the one or more shear connectors are substantially 90° thereto.

[0019] The present invention further provides a column for supporting a structure, such as a roof of a tunnel, the column having a first portion embedded in the ground, and a exposed second portion between the first portion and the structure, the column comprises an elongate assembly cast in a material formed from a settable material, such as concrete, and a plurality of shear connectors extending from the elongate assembly, wherein the elongate assembly comprises: a hollow pipe, the outer surface of which provides the exposed surface of the column after excavation; a reinforcing portion secured relative to the hollow pipe, the reinforcing portion extending downwardly from the bottom of the hollow pipe; an elongate element secured to the hollow pipe and extending upwardly from the top of the hollow pipe.

[0020] Preferably the outer surface of the hollow pipe is pre-treated to achieve an aesthetically acceptable finish.

[0021] Preferably the reinforcing portion extending at least partially through the hollow pipe.

[0022] The column may comprise a third portion adjacent the second portion. The third portion is adapted to be incorporated within or connected to the structure supported by the column (e.g. the tunnel roof).

[0023] Preferably the column is cast using the aforementioned method.

[0024] The shear connectors may be in the form of one or a combination of the following: shear studs, bars, beams, plates.

[0025] The shear connectors may be secured to the third portion so that in use the shear connectors are embedded in the structure. 5 2016250437 27 Oct 2016 [0026] The shear connectors may be secured to at least part of the elongate element wherein they provide a shear connector between the elongate element and the settable material.

[0027] In one aspect of the invention the hollow pipe extends along the second portion of the column.

[0028] In another aspect of the invention at least part of the hollow pipe extends along the second portion of the column.

[0029] In another aspect of the invention the hollow pipe extends along at least part of the second portion of the column.

[0030] An upper end of the second portion may support a collar. The collar takes part of the load from the structure the column is supporting (e.g. roof tunnel) so that the settable material is exposed to less stress.

[0031] Preferably the upper portion of the elongate element extends upwardly from the top of the hollow pipe.

[0032] The upper portion of the elongate element may extend above the settable material. A further column, elongate element, or other structure may be secured to the upper portion of the elongate element.

[0033] The elongate element may extend through the hollow pipe to extend from both the bottom and the top of the hollow pipe.

[0034] The column may further comprise a reinforcement assembly comprising a reinforcement portion and a plurality of reinforcement connections for connecting the reinforcement portion to the hollow pipe, and/or to the elongate element.

[0035] The reinforcing portion of the elongate assembly may have an end region which terminates in the first portion of the column.

[0036] The reinforcement connections may be in the form of a plurality of bars welded to the hollow pipe and extending downwardly therefrom. The reinforcing portion may be welded to the bars. 6 2016250437 27 Oct 2016 [0037] The reinforcing portion may extend through the hollow pipe from the top of the hollow pipe.

[0038] The reinforcing portion may be flexible to accommodate any curvature in the hole as the reinforcing portion is positioned in the hole.

[0039] In one aspect of the invention an end region of the first portion may have an enlarged diameter.

[0040] In another aspect of the invention an end region of the first portion may be supported on a support.

[0041] A footing may be provided between the first portion and the second portion.

[0042] Shear connectors may be secured to the hollow pipe wherein they provide a shear connector between the hollow pipe and the footing.

[0043] The column may comprise an expansion means to prevent the column from being damaged during a fire. The expansion means may comprise a plurality of holes in the collar.

[0044] When the column is used to support a number of tunnels on top of each other, the column may comprise the first portion, and one or more pairs of second portion and third portion therebetween. The number of pairs of second portion and third portion will be dictated by the number of tunnels on top of each other.

[0045] The hollow pipe can take any shape or configuration, for instance the pipe can be square, rectangular or round, thick walled or thin walled.

[0046] The elongate element may take the form of any rigid beam like structure, such as an I-beam, and may be made from any suitable material.

[0047] The present invention further provides a tunnel comprising a plurality of columns as hereinbefore described and a progressive strength element, the progressive strength element comprising a thickened section and a support wall, the thickened section being formed as part of a floor of the tunnel and extending substantially from one end of the tunnel to the other end, the support wall extending between columns and tied thereto, wherein the progressive strength element adds strength to the tunnel. 7 2016250437 27 Oct 2016 [0048] The present invention provides a method of constructing a tunnel comprising the steps of: installing retaining walls along the perimeter of the proposed tunnel; creating a plurality of holes and forming columns therein, the holes being spaced between the retaining walls; forming a slab supported by the ground, retaining walls and the plurality of columns, the slab providing the tunnel roof; excavating under the tunnel roof; wherein after excavation is complete the tunnel floor is cast.

[0049] The holes may be positioned centrally between the retaining walls. The holes may be 5-6m apart from adjacent holes.

[0050] The method may comprise the step of incorporating a progressive strength element. The progressive strength element may be formed by forming a thickened band in line with the columns. The thickened band may be tied into/linked to the tunnel columns. The thickened band may be tied into/integral with the tunnel floor.

[0051] The thickened band may comprise a thickened section and a support wall.

[0052] The thickened section may form part of the tunnel floor and extend substantially from one end of the tunnel to the other end. The thickened section may be 2m wide.

[0053] The support wall may act as a beam. The support wall may be tied into the thickened floor section. The columns may have a plurality of shear connectors to which the support wall and thickened section of floor may be tied. The support walls may comprise permanent formwork extending between adjacent columns which are filled with a settable material, such as concrete. The support wall may be formed on aesthetically acceptable permanent formwork. 8 2016250437 27 Oct 2016 [0054] The thickened section and support wall co-operate to provide strength to the tunnel structure and reduce the load the columns are required to carry. As a result the thickened section and support wall reduce the depth the columns are required to penetrate.

[0055] The method may comprise the step of laying a thick flexible sheet material, such as polyethylene, on the ground before casting the slab for the tunnel roof thereon. This ensures the roof soffit finish is aesthetically acceptable. The polyethylene material may be 1,3mm in thickness.

[0056] The method may comprise the step of post tensioning the slab.

[0057] The method may comprise the step of post tensioning the retaining/diaphragm walls.

[0058] The method may comprise the step of establishing an access way to access the area under the slab when forming the slab. The access way may be formed in the slab as the slab is formed. The access way may be provided through the ends of the tunnel.

[0059] Preferably, the method further comprises the step of finishing the tunnel. Finishing the tunnel may further comprise one or more of the following steps: forming a plurality of lanes and/or rail tracks, installing services such as power and water, installing walkways, installing safety barriers.

[0060] The method may further comprise the step of constructing roads or other structures on the tunnel roof.

[0061] The method may be repeated to construct one or more further tunnels thereunder.

[0062] Each of the plurality of holes may be created by drilling the soil with a continuous auger.

[0063] Preferably each hole is filled with a settable fluid as the auger is removed therefrom.

[0064] Each column may be cast according to the aforementioned method of casting a column. 9 2016250437 27 Oct 2016 [0065] The present invention provides a method of constructing a tunnel under an existing road having a central median strip , the method comprising the steps of: installing a first retaining wall alongside a first side of the existing road; installing a second retaining wall alongside a second side of the existing road; creating a plurality of holes in the median strip and forming columns therein, the holes being spaced between the retaining walls; divert the traffic from the first side of the road and prepare the surface; forming a slab supported by the ground, the first retaining wall and the plurality of columns, the slab providing the tunnel roof; divert the traffic from the second side of the road and prepare the surface; forming a slab supported by the ground, the second retaining wall and the plurality of columns, the slab providing the tunnel roof; excavating under the tunnel roof; wherein after excavation is complete the tunnel is provided.

[0066] The method may comprise the step of incorporating a progressive strength element. The progressive strength element may be formed by forming a thickened band formed in line with the columns. The thickened band may be tied into/linked to the columns. The thickened band may be tied into/integral with the tunnel floor.

[0067] The thickened band may comprise a thickened section and a support wall.

[0068] The thickened section may form part of the tunnel floor and extend substantially from one end of the tunnel to the other end. The thickened section may be 2m wide.

[0069] The support wall may act as a beam. The support wall may be tied into the thickened section. The support wall may be formed with aesthetically acceptable permanent formwork. 10 2016250437 27 Oct 2016 [0070] The thickened section and support wall co-operate to provide strength to the tunnel structure and reduce the load the columns are required to carry. As a result the thickened section and support wall reduce the depth the columns are required to penetrate [0071] The method may further comprise the step of reinstating the first side of the road before diverting the traffic from the second side of the road.

[0072] The method may further comprise the step of reinstating the road upon completion of the slab.

[0073] The present invention further provides a method of constructing a tunnel comprising the steps of: installing at least one retaining wall; creating at least one hole and forming a column therein; forming a slab supported by the at least one retaining wall the at least one column; when forming the slab forming an access way for access under the slab; excavating under the slab; wherein after excavation is complete the tunnel is provided.

[0074] The method may comprise the step of incorporating a progressive strength element. The progressive strength element may be formed by forming a thickened band formed in line with the columns. The thickened band may be tied into/linked to the tunnel columns. The thickened band may be tied into/integral with the tunnel floor.

[0075] The thickened band may comprise a thickened section and a support wall.

[0076] The thickened section may form part of the tunnel floor and extend substantially from one end of the tunnel to the other end. The thickened section may be 2m wide. 11 2016250437 27 Oct 2016 [0077] The support wall may act as a beam. The support wall may be tied into the thickened section. The support wall may be formed on aesthetically acceptable permanent formwork.

[0078] The thickened section and support wall co-operate to provide strength to the tunnel structure and reduce the load the columns are required to carry. As a result the thickened section and support wall reduce the depth the columns are required to penetrate.

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Further features of the present invention are more fully described in the following description of a non-limiting embodiment thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings in which:

Figure 1 is a cross section of a guide for use in forming a hole for constructing a column of a tunnel according to a first embodiment of the present invention;

Figure 2 is a cross section of the hole of figure 1 formed and having a settable material therein;

Figure 3 is a cross sectional view of a column formed in the hole of figure 2,

Figure 4 is a view of an alternative column without a reinforcing cage;

Figure 5 is a cross sectional view of a first portion and second portion of the column in figure 4 with the reinforcing cage included,

Figure 6 is a cross sectional view of a further alternative column formed in the hole of figure 2,

Figure 7 is a cross sectional view of yet a further alternative column formed in the hole of figure 2, 12 2016250437 27 Oct 2016

Figure 8 is a cross sectional view of still yet a further alternative column formed in the hole of figure 2;

Figure 9 is a schematic of a cross section of a road tunnel according to the first embodiment of the present invention;

Figure 10 is a schematic of a cross section of a rail tunnel according to a second embodiment of the present invention;

Figure 11 is a cross sectional view through a central wall of figure 9 and figure 10; and

Figure 12 is a cross sectional view through 1 -1 of figure 11.

[0080] In the drawings like structures are referred to by like numerals throughout the several views. The drawings shown are not necessarily to scale, with emphasis instead generally being placed upon illustrating the principles of the present invention.

DESCRIPTION OF EMBODIMENTS

[0081] The present invention, according to a first embodiment of the invention is directed to a subterranean structure being a tunnel 11, and a method of constructing the tunnel 11. The method of construction involves the installation of retaining walls 15, 17 along the sides of the proposed tunnel, and the casting of a plurality of columns 19 within between the retaining walls 15. Once the walls 15,17 and columns 19 are cast a slab 17 may be poured whereby the slab 17 is supported by the ground, the retaining walls 15, 17 and the columns 19.

[0082] The top down construction method of creating the tunnel is particularly advantageous in congested areas but also delivers a finished building in a shorter period of time when compared to traditional building methods. The present invention seeks to improve upon this by providing an improved method of constructing a tunnel based on the top down method. This is partly achieved by casting the columns 19 in a manner which largely negates the need to further dress the columns 19 once the tunnel has been excavated. The method of casting the columns 19 also greatly improves the accuracy of the vertical orientation of each column 19. By increasing the predictability of the columns angle and their orientation, the retaining walls 15, 17 and columns 19 do 13 2016250437 27 Oct 2016 not need to be designed to accommodate excessive inaccuracies, allowing the thickness of the walls and columns to be reduced, enabling a more efficient use of resources [0083] Figure 9 is a schematic of a road tunnel constructed according to a first embodiment of the present invention.

[0084] The tunnel comprises a first retaining wall 15 and a second retaining wall 17. Each retaining wall 15, 17 is in the form of a diaphragm wall. However, other type of suitable wall constructions can also be used. Each diaphragm retaining wall 15, 17 is constructed by first digging a trench, wherein the trench is filled with an engineered fluid, such as bentonite. Once the trench is constructed a mesh panel is inserted and the trench filled with concrete, displacing the engineered fluid. The concrete then sets to provide the retaining walls 15, 17.

[0085] The tunnel 11 comprises a plurality of columns 19 spaced centrally between the retaining walls 15, 17 and extending along the length of the tunnel. The columns 19 may be 4-5m apart from adjacent columns.

[0086] Referring to figures 1 to 3, each column 19 is cast by first forming a hole 18 through the surface 13 using a continuous auger (not shown). To assist in forming the hole 18 a guide 20 is cast around the periphery of the proposed hole 18. The guide 20 adds stability to the auger during the drilling process and ensures the auger maintains the desired drilling direction.

[0087] As the hole 18 is formed the hole 18 is filled with a settable material 21 which helps maintains the integrity of the hole during the drilling process. Upon extraction of the auger the hole 18 remains filled with the settable material, as shown in figure 2.

[0088] Once the auger is extracted an elongate assembly 23 is lowered into the hole 18. The elongate assembly 23 is suspended from a crane or similar lifting device (not shown) such that the elongate assembly 23 is maintained in a substantially vertical orientation. Maintaining the elongate assembly 23 in a substantially vertical orientation will ensure the resulting column 19 is within the specified tolerances for such construction. 14 2016250437 27 Oct 2016 [0089] To ensure that the elongate assembly 23 is able to be inserted as a vertical assembly, the hole 18 is larger in diameter than the elongate assembly 23. This will also allow the orientation of the elongate assembly 23 to be adjusted once inserted in the hole, as discussed below.

[0090] The elongate assembly 23 comprises a hollow pipe 25, the outer surface 27 of which will provide the exposed surface of the column 19 after excavation of the tunnel 11.

[0091] As shown in figure 3, the elongate assembly 23 comprises a reinforcing portion in the form of a reinforcement cage 29. The reinforcement cage 29 is secured relative to the hollow pipe 25, such that it extends downwardly from the bottom of the hollow pipe 25. A plurality of rods/bars 30 are secured to the end of the hollow pipe 25 allowing the reinforcement cage 29 to be readily secured relative to the hollow pipe 25.

[0092] The elongate assembly 23 also comprises an elongate element 31 secured relative to the hollow pipe 25 such that it extends upwardly from the top of the hollow pipe 25. The elongate element 31 extending above the hollow pipe 25 supports a shear connector in the form of a beam 33. Once the slab is poured the beam 33 will be embedded therein.

[0093] The elongate element 31 allows the vertical orientation of the elongate assembly 23 to be adjusted once the elongate assembly 31 is received in the hole. This is a further measure to ensure the vertical orientation of the column is within the specified tolerances.

[0094] Prior to inserting the elongate assembly 23 in the hole, the hollow pipe 25 is wrapped in a protective layer for reasons which will be described below.

[0095] In a variation of the process, the reinforcement cage 29 may not necessarily be connected to the hollow pipe prior to lowering the elongate assembly 23 into the hole. The reinforcement cage 29 may be lowered into the hole and supported adjacent the hole opening. The hollow pipe 25 can then be positioned thereover and the reinforcement cage 29 secured to the hollow pipe 25 before the reinforcement cage is further lowered into the hole. 15 2016250437 27 Oct 2016 [0096] Once the column 19 is cast the column of the present embodiment will comprise a first portion 61, a second portion 63, a third portion 65 and a fourth portion 67.

[0097] The first portion 61 is embedded in the ground and can have an enlarged end 71, as shown in figure 3 for providing more support, or may be of relatively uniform diameter, as shown in alternative columns in figures 5, 6 and 7. The reinforcement cage 29 of the elongate assembly 23 has an end region 73 which terminates in the first portion of the column.

[0098] The second portion 63 extends from the first portion 61 to the tunnel roof 35. The second portion 63 incorporates the hollow pipe 25 which, in this embodiment, extends along the second portion. After excavation is complete and the protective coat removed, the outer surface 27 of the hollow pipe 25 is exposed to provide the finished surface of the column.

[0099] The upper end of the second portion 63 supports a collar 75. The collar 75 distributes the load from the roof to the column 19.

[00100] As an alternative, or in addition to the enlarged ends of the first portion 61, a footing 83 can be provided between the first portion 61 and the second portion 63, as shown in figure 5. In this arrangement additional shear connectors in the form of studs 133 are secured to the hollow pipe 25 and are embedded in the footing 83 once poured.

[00101] The third portion 65 is adjacent the second portion 63. The third portion 65 is incorporated within the tunnel roof 35. The third portion supports the shear connector beam 33.

[00102] The fourth portion 67 is adjacent the third portion and extends above the tunnel roof 35. An upper portion 77 of the elongate element 31 provides the fourth portion 67. As shown in figure 3 and 4 the fourth portion 67 provides an anchor/support for a part of the structure being built above the tunnel roof 35. For example, a wall/ column 79 of the superstructure may be formed around the fourth portion 67.

[00103] As noted in figure 8, it may be the case that the fourth portion 67 is not required, as would be typical with tunnel construction. 16 2016250437 27 Oct 2016 [00104] The elongate element 31 can be a unitary beam which extends from the first portion 61 to the fourth portion 67, as shown in figure 4, or which extends from the second portion 63 to the fourth portion 67, as shown in figure 3. Alternatively the elongate element 31 comprises two beams 31a, 31b wherein the two beams are secured together at a flange 81 which, once cast, is embedded in the tunnel roof 35, as shown in figures 6 and 7.

[00105] The tunnel also comprises a slab which provides the tunnel roof 35. The tunnel roof 35 may be formed once the retaining walls 15, 17 and columns 19 are cast. In order to form the tunnel roof 35 the ground is first prepared. The tunnel roof 35 can then be formed whereby it is supported by the retaining walls 15, 17, the columns 19 and the ground. As the slab, which provides the tunnel roof 35, is supported by the ground the slab only needs to be designed to support the loads it will be exposed to in normal service.

[00106] The tunnel incorporates a progressive strength element which acts as a beam to strengthen the tunnel. Referring to figures 11 and 12, the progressive strength element is in the form of a thickened band 85 extending centrally through the tunnel 11.

[00107] The thickened band 85 comprises a thickened section 87 and a support wall 89.

[00108] The thickened section 87 forms part of the tunnel floor 36 and extends substantially from one end of the tunnel to the other end. The thickened section 87 is tied into the tunnel floor 36 by a plurality of shear connectors 233.

[00109] The support wall 89 is tied into the thickened section 87 and extends between the columns 19. The columns 19 have a plurality of shear connectors 133 to which the support wall 89 is tied. The height of the support wall 89 varies depending on the requirement for the tunnel.

[00110] Once the tunnel roof 35 is completed, any previously existing infrastructure can be reinstated above the tunnel roof 35. Simultaneously, the soil between the retaining walls 15, 17 can be excavated. Once the tunnel is excavated, the tunnel floor 36 is formed and construction of the road (figure 9) or rail (figure 10) on the tunnel base 36 can be completed. With this form of construction, the disruption of traffic in the area of construction is minimised. 17 2016250437 27 Oct 2016 [00111] Once excavation is complete, the protective layer around the hollow pipe 25 can be removed. This removes the settable material which has adhered to the side of the hollow pipe 25, and provides a clean, finished surface of the column 19, negating the need for the columns 19 to undergo any further treatment. With prior methods, the columns require extensive work after the excavation is complete to provide a column having a surface which is aesthetically acceptable. In the event that the column is not vertical, as occurs in prior methods, the finish will need to be applied to the column so that column appears as though it is vertically orientated.

[00112] As the process of casting the columns ensures the columns are substantially vertical, the tunnel does not require any further strengthening otherwise required if the columns were not correctly orientated, as can be the case with prior art methods of construction. According to other top down construction methods it is not possible to ensure the columns are formed vertically. Where the columns are not correctly orientated the load capacity of these columns can be reduced. In these scenarios additional beams and/or columns are required to support the tunnel. This not only adds cost to the process but can also limit the expected utility/capacity of the tunnel.

[00113] During construction of the tunnel such services as ventilation 37, escape walkways 39, barriers 41 and platforms 43 may be constructed.

[00114] With this form of construction the effect to the local traffic and nearby buildings is greatly diminished. Furthermore, as excavation is contained the amount of dust and noise is reduced significantly.

[00115] As would be understood by those skilled in the art the shear connectors may take any form. For example, the shear connectors may be in the form of beams secured to the column 19 and embedded in the tunnel roof 35, as shown in at least figure 3, studs secured to the column and embedded in the footing, as shown in figure 5, rods secured to the column and embedded in the settable material (not shown), or a combination of these.

[00116] Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention. The present invention is not to be limited in scope by any of the specific embodiments described herein. These embodiments are intended for the purpose of exemplification only. Functionally 2016250437 27 Oct 2016 18 equivalent products, formulations and methods are clearly within the scope of the invention as described herein.

[00117] Reference to positional descriptions, such as lower and upper, are to be taken in context of the embodiments depicted in the figures, and are not to be taken as limiting the invention to the literal interpretation of the term but rather as would be understood by the skilled addressee.

[00118] While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

[00119] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The term “structure” includes part of a structure. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

Claims (56)

1. A method of casting a column in soil, the method comprises: creating a hole in the soil; filling the hole with a settable liquid; lowering an elongate assembly into the hole wherein the elongate assembly is supported such that the elongate element is lowered in a substantially vertical orientation; adjusting the elongate assembly once received in the hole so that the elongate assembly is substantially vertical; excavating the soil once the settable liquid has set to provide the column.

2. The method according to claim 1 comprising the step of casting/installing a guide means at the surface to assist in guiding an auger to form the hole.

3. The method according to claim 1 or 2 comprising the step of filling the hole with the settable liquid as the hole is created.

4. The method according to claim 1, 2 or 3 comprising the step of layering an outside surface of a hollow pipe of the elongate assembly with a protective layer, whereupon excavation, the protective layer may be removed from the hollow pipe, wherein the outer surface of the hollow pipe provides the finished surface of the column.

5. The method according to any one of claims 1 to 4 comprising the step of securing one or more shear connectors to the elongate element wherein the one or more shear connectors are substantially 90° thereto.

6. A column for supporting a structure, such as a roof of a tunnel, the column having a first portion embedded in the ground, and a exposed second portion between the first portion and the structure, the column comprises an elongate assembly cast in a material formed from a settable material, such as concrete, and a plurality of shear connectors extending from the elongate assembly, wherein the elongate assembly comprises: a hollow pipe, the outer surface of which provides the exposed surface of the column after excavation; a reinforcing portion secured relative to the hollow pipe, the reinforcing portion extending downwardly from the bottom of the hollow pipe; an elongate element secured to the hollow pipe and extending upwardly from the top of the hollow pipe.

7. The column according to claim 6 wherein the outer surface of the hollow pipe is pre-treated to achieve an aesthetically acceptable finish.

8. The column according to claim 8 or 7 wherein the reinforcing portion extends at least partially through the hollow pipe.

9. The column according to claim 6, 7 or 8 comprising a third portion adjacent the second portion, the third portion is adapted to be incorporated within or connected to the structure supported by the column.

10. The column according to any one of claims 6 to 9 being cast according to the method as described in any one of claims 1 to 5.

11. The column according to claim 9, 10 or 11 wherein the shear connectors are in the form of one or a combination of the following: shear studs, bars, beams, plates.

12. The column according to any one of claims 9 to 11 wherein the shear connectors are secured to the third portion so that in use the shear connectors are embedded in the structure.

13. The column according to any one of claims 6 to 12 wherein the shear connectors are secured to at least part of the elongate element wherein they provide a shear connector between the elongate element and the settable material.

14. The column according to any one of claims 8 to 13 wherein the hollow pipe extends along the second portion of the column.

15. The column according to any one of claims 6 to 13 wherein at least part of the hollow pipe extends along the second portion of the column.

16. The column according to any one of claims 6 to 13 wherein the hollow pipe extends along at least part of the second portion of the column.

17. The column according to any one of claims 6 to 13 wherein an upper end of the second portion supports a collar.

18. The column according to any one of claims 6 to 17 wherein an upper portion of the elongate element extends upwardly from the top of the hollow pipe.

19. The column according to claim 18 wherein the upper portion of the elongate element extends above the settable material.

20. The column according to claim 18 or 19 wherein a further column, elongate element, or other structure is secured to the upper portion of the elongate element.

21. The column according to any one of claims 6 to 20 wherein the elongate element extends through the hollow pipe to extend from both the bottom and the top of the hollow pipe.

22. The column according to any one of claims 6 to 21 comprising a reinforcement assembly, the reinforcement assembly comprising a reinforcement portion and a plurality of reinforcement connections for connecting the reinforcement portion to the hollow pipe, and/or to the elongate element.

23. The column according to claim 22 wherein the reinforcing portion of the elongate assembly has an end region which terminates in the first portion of the column.

24. The column according to claim 22 or 23 wherein the reinforcement connections are in the form of a plurality of bars welded to the hollow pipe and extending downwardly therefrom.

25. The column according to claim 24 wherein the reinforcing portion are welded to the bars.

26. The column according to any one of claims 22 to 25 wherein the reinforcing portion extends through the hollow pipe from the top of the hollow pipe.

27. The column according to any one of claims 22 to 26 wherein the reinforcing portion is flexible to accommodate any curvature in the hole as the reinforcing portion is positioned in the hole,

28. The column according to any one of claims 6 to 27 wherein an end region of the first portion has an enlarged diameter.

29. The column according to any one of claims 6 to 27 wherein an end region of the first portion is supported on a support.

30. The column according to any one of claims 6 to 29 wherein a footing is provided between the first portion and the second portion.

31. The column according to claim 30 wherein the shear connectors are secured to the hollow pipe wherein they provide a shear connector between the hollow pipe and the footing.

32. The column according to any one of claims 6 to 31 comprising an expansion means to prevent the column from being damaged during a fire.

33. The column according to any one of claims 6 to 32 comprising one or more pairs of second portion and third portion therebetween.

34. A tunnel comprising a plurality of columns according to any one of claims 6 to 33, and a progressive strength element, the progressive strength element comprising a thickened section and a support wall, the thickened section being formed as part of a floor of the tunnel and extending substantially from one end of the tunnel to the other end, the support wall extending between columns and tied thereto, wherein the progressive strength element adds strength to the tunnel.

35. The tunnel according to claim 34 wherein the support wall acts as a beam.

36. The tunnel according to claim 34 or 35 wherein the support wail is tied into the thickened floor section.

37. The tunnel according to claim 34, 35 or 36 wherein the columns have a plurality of shear connectors to which the support wall and thickened section of floor are tied.

38. The tunnel according to any one of claims 34 to 37 wherein the support wails comprise permanent formwork extending between adjacent columns which are filled with a settable material.

39. The tunnel according to claim 38 wherein the support wall is formed on aesthetically acceptable permanent formwork.

40. A method of constructing a tunnel comprising the steps of: installing retaining walls along the perimeter of the proposed tunnel; creating a plurality of holes and forming columns therein, the holes being spaced between the retaining walls; forming a slab supported by the ground, retaining walls and the plurality of columns, the slab providing the tunnel roof; excavating under the tunnel roof; wherein after excavation is complete the tunnel floor is cast.

41. The method according to claim 40 wherein the holes are positioned centrally between the retaining walls.

42. The method according to claim 40 or 41 wherein the holes are positioned 5-6m apart from adjacent holes.

43. The method according to claim 40, 41 or 42 comprising the step of incorporating a progressive strength element, the progressive strength element being formed by forming a thickened band in line with the columns, the thickened band being tied into/linked to the tunnel columns, and/or the thickened band can be tied into/integral with the tunnel floor.

44. The method according to any one of claims 40 to 43 comprising the step of laying a thick flexible sheet material on the ground before casting the slab for the tunnel roof thereon.

45. The method according to any one of claims 40 to 44 comprising the step of post tensioning the slab.

46. The method according to any one of claims 40 to 45 comprising the step of post tensioning the retaining/diaphragm walls.

47. The method according to any one of claims 40 to 46 comprising the step of establishing an access way to access the area under the slab when forming the slab.

48. The method according to claim 47 comprising the step of providing the access way through the ends of the tunnel.

49. The method according to any one of claims 40 to 48 comprising the step of finishing the tunnel, finishing the tunnel comprising one or more of the following steps: forming a plurality of lanes and/or rail tracks, installing services such as power and water, installing walkways, installing safety barriers.

50. The method according to any one of claims 40 to 49 comprising the step of constructing roads or other structures on the tunnel roof.

51 .A method of constructing a tunnel under an existing road having a central median strip , the method comprising the steps of: installing a first retaining wall alongside a first side of the existing road; installing a second retaining wall alongside a second side of the existing road; creating a plurality of holes in the median strip and forming columns therein, the holes being spaced between the retaining wails; divert the traffic from the first side of the road and prepare the surface; forming a slab supported by the ground, the first retaining wall and the plurality of columns, the slab providing the tunnel roof; divert the traffic from the second side of the road and prepare the surface; forming a slab supported by the ground, the second retaining wall and the plurality of columns, the slab providing the tunnel roof; excavating under the tunnel roof; wherein after excavation is complete the tunnel is provided,

52. The method according to claim 51 comprising the step of incorporating a progressive strength element, the progressive strength element being formed by forming a thickened band formed in line with the columns, the thickened band being tied into/linked to the columns and/or the thickened band is tied into/integral with the tunnel floor.

53. The method according to claim 51 or 52 comprising the step of reinstating the first side of the road before diverting the traffic from the second side of the road.

54. The method according to claim 51, 52 or 53 comprising the step of reinstating the road upon completion of the slab.

55. A method of constructing a tunnel comprising the steps of: installing at least one retaining wall; creating at least one hole and forming a column therein; forming a slab supported by the at least one retaining wail the at least one column; when forming the slab forming an access way for access under the slab; excavating under the slab; wherein after excavation is complete the tunnel is provided.

56, The method according to claim 55 comprising the step of incorporating a progressive strength element, the progressive strength element being formed by forming a thickened band formed in line with the columns, the thickened band being tied into/linked to the tunnel columns and/or the thickened band being tied into/integral with the tunnel floor.