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1. WO2020115460 - TRENCH SHORING APPARATUS AND ITS METHOD OF USE

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

TRENCH SHORING APPARATUS AND ITS METHOD OF USE

TECHNICAL FIELD OF THE INVENTION

This invention relates to a trench shoring apparatus and its method of use. In particular, this invention relates to a trench shoring apparatus that can be quickly and easily deployed to provide a temporary earth retaining structure which prevents the excavated sides of a trench from collapse.

BACKGROUND

The skilled person will appreciate that with most forms of residential, commercial and light industrial property construction, the first stages of the work generally involve ground preparation and levelling of the site, prior to excavation of trenches or ditches that ultimately form the foundation footings of the property. Equally, earth excavations can be needed for the installation of pipelines, structures and water, drainage, sewerage, gas and other sub-surface utilities. Work of this nature is usually carried out using heavy construction equipment, such as excavators or diggers.

Depending upon the soil and environmental conditions, there is often the risk of the vertical or near vertical sides of the excavation collapsing into the trench, which not only requires significant rework, introducing associated delays and costs, but more importantly, this presents a danger to construction workers and other personnel working on, or near, the excavation site.

In order to address this problem, builders and construction or utilities workers can sometimes use trench boxes which generally comprise a simple two-sided support system. These are normally constructed with side walls of varying thicknesses and which are held apart by steel or aluminium props, jacks or spreaders. In addition to commercial trench boxes, workers often construct ad hoc structures, made up of boarding to contact the excavated sides of the trench and utilising anything to hand that can act as a prop or jack, which by their very nature are not particularly stable or secure. Commercial trench boxes available in the marketplace, are also are time consuming to install, often requiring the construction or utilities worker to enter the trench, with the associated risk of death or injury from a cave-in or collapse.

It is an object of the present invention to provide a trench shoring apparatus and its method of use which overcomes or reduces the drawbacks associated with known products of this type, or other ad hoc shoring structures. It is a further object of the present invention to provide a trench shoring apparatus that can be quickly and easily deployed to provide a temporary earth retaining structure which prevents the excavated sides of trenches or ditches from cave-in or collapse. The insertion and deployment of the trench shoring apparatus of the present invention being at all times from above the surface of the trench and requiring no work inside the trench. It is a further object of the present invention to provide a trench shoring apparatus that can be deployed without the use of hand tools and which occurs automatically using a pivoting hinge mechanism as the trench shoring apparatus is lowered into the bottom of the trench, such that the space between the side walls of the trench and the side panels of the apparatus are taken up automatically. It is a further object of the present invention to provide a trench shoring apparatus that can be quickly retrieved from the trench after use, again without the need for a worker to enter, reach or lean into the trench or ditch.

SUMMARY OF THE INVENTION

The present invention is described herein and in the claims.

According to the present invention there is provided a trench shoring apparatus, comprising:

first and second side panels connected in a parallel spaced-apart configuration by a connecting rod pivotally connected to one end of one or more pairs of lateral arms, the other opposite end of the one or more pairs of lateral arms being hingedly connected to the side panels, such that translational movement of the connecting rod in a direction parallel to the side panels causes the spaced-apart panels to move between retracted and extended parallel spaced-apart configurations.

An advantage of the present invention is that it can be used to quickly and securely provide a temporary earth retaining structure which prevents the excavated sides of a

trench or ditch from collapse. The deployment and subsequent retrieval of the trench shoring apparatus being at all times from above the surface of the trench, and requiring no work inside the trench.

Preferably, the first and second side panels are planar and each having an inner and outer surface.

Further preferably, the outer surfaces of the first and second side panels abut with the excavated sides of the trench when in use.

In use, the inner surfaces of the first and second side panels may be each connected to a plurality of elongate support members positioned from the top to the bottom of the side panels.

Preferably, the elongate support members are each secured to the inner surfaces of the first and second side panels using threaded fasteners which are received through apertures formed in the side panels and in the support members.

Further preferably, the first and second panels are formed from a material selected from the group consisting, but not limited to, any one of the following: treated plywood, aluminum, sheet steel, durable plastics material and the like.

In use, the retracted configuration may have a lateral dimension which is less than the width of the trench into which the apparatus is inserted when in use and which is less than the width of the extended configuration.

Preferably, the elongate support members form a fixed part of a hinge connection and having a generally square cross section with a pair of panels disposed either side thereof.

Further preferably, the pairs of lateral arms form a moving part of the hinge connection, the pairs of lateral arms further comprising triangular upper and lower hinge plates disposed towards the top and near the middle respectively of the trench shoring apparatus.

In use, the upper and lower hinge plates may be identical in size and shape.

Preferably, the upper hinge plate includes an elongated slot disposed along the top edge of the upper hinge plate, the slot securing a grille thereto using grille anchors.

Further preferably, the upper and lower hinge plates each include a proximal aperture for receiving an elongate bar running the length of the side panels to permit pivotal movement of the upper and lower hinge plates relative to the support members.

In use, the pivotal movement of the upper and lower hinge plates may be only possible in an upward direction as a side edge of the upper and lower hinge plates abuts against the inner surface of the side panels preventing movement in a downward direction.

Preferably, the upper and lower hinge plates are received in pairs along each side face of the support members.

Further preferably, one or more connecting rods are disposed between the two pairs of upper and lower hinge plates.

In use, the connecting rods may be elongate rods having apertures at each end thereof which meet with distal apertures disposed on the upper and lower hinge plates for receiving a top spacer bar and an elongate bar respectively.

Preferably, two or more hoisting loops disposed along the top spacer bar, the hoisting loops being received within slots disposed in the pair of grilles.

Further preferably, the pair of grilles are positioned either side of the top spacer bar.

In use, the trench shoring apparatus may further comprise a plurality of feet disposed at the bottom of the trench shoring apparatus and opposite to the upper facing grilles, each of the feet having legs which are received inside the cross section of each support member.

Preferably, the feet are adjustable in height using threaded fasteners which are received through apertures in the legs and corresponding apertures in the support members.

Further preferably, the trench shoring apparatus further comprises retrofittable extension boards or shims being placed on the outer surfaces of the side plates to further extend the lateral dimensions of the apparatus.

In use, the trench shoring apparatus may further comprise rollers or other support means being positioned on the top edge of the lower hinge plate to support utilities or temporary pipework running through the trench when in use.

Preferably, the lateral arms each further comprise complementary shaped elongate adjustable struts disposed towards the top and near the middle of the trench shoring apparatus.

Further preferably, the adjustable struts are each formed having a box-section construction.

In use, the complementary shaped elongate adjustable struts may comprise an inner strut which can be entirely received within the body of an outer strut.

Preferably, the adjustable strut being telescopically extendable and retractable, and locked in position by locating an adjustment pin in one of a plurality of apertures which are formed in the inner and outer struts.

Further preferably, the proximal end of the outer strut includes a proximal aperture for receiving a pin that is disposed between each side face of the backplate to permit pivotal movement of the adjustable strut.

In use, the proximal end of the inner strut may include a proximal aperture for receiving a pin that is pivotally connected to the connecting rod.

Preferably, the pivotal movement of the adjustable struts being only possible in an upward direction as the lowermost face of the the outer strut abuts against a stopper plate preventing movement in a downward direction.

Further preferably, the connecting rod is disposed between the two pairs of adjustable struts.

In use, the durable plastics material may comprise Polypropylene (PP), High-Density Polyethylene (HDPE), Polyethylene Terephthalate (PET), Polyvinyl Chloride (PVC) or Acrylonitrile Butadiene Styrene (ABS) or blends thereof.

Preferably, the trench shoring apparatus further comprises connectors which meet with appropriate fasteners on groundmats and the like.

Further preferably, the metalwork components forming the apparatus are selected from a material from the group consisting, but not limited to, any one of the following: mild, powder-coated or galvanised steel, or aluminium and the like.

Also according to the present invention there is provided a method of supporting the side walls of an excavated trench using the trench shoring apparatus as hereinbefore described, the method comprising the steps of:

coupling a sling adjacent the connecting rod of the trench shoring apparatus; hoisting the apparatus thereby causing the spaced-apart panels to move to the retracted spaced-apart configuration;

lowering the retracted apparatus into the excavated trench; and

pushing the connecting rod downwards such that the side panels splay apart into the extended spaced-apart configuration to abut against the side walls of the excavated trench.

It is believed that a trench shoring apparatus and its method of use in accordance with the present invention at least addresses the problems outlined above.

It will be obvious to those skilled in the art that variations of the present invention are possible and it is intended that the present invention may be used other than as specifically described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of example only, and with reference to the accompanying drawings, in which:

Figure 1 is an isometric view of a trench shoring apparatus in accordance with the present invention;

Figure 2 shows a perspective view from the side and above of the trench shoring apparatus of Figure 1 in a deployed configuration;

Figure 3 illustrates front and side plan views respectively of the side panel of the trench shoring apparatus;

Figure 4 is front and top plan views respectively of the backplate positioned on the inner face of the side panels;

Figure 5 shows front plan views of the top and bottom hinge plates respectively of the trench shoring apparatus of Figure 1;

Figure 6 illustrates a side plan view of the connecting rod used in the trench shoring apparatus of Figure 1 and side plan views of the bars respectively of the trench shoring apparatus of Figure 1;

Figure 7 shows front and side plan views respectively of the adjustable feet of the trench shoring apparatus of Figure 1;

Figure 8 is a top plan view of the grille located at the top of the trench shoring apparatus of Figure 1;

Figure 9 illustrates front, side and top views respectively of an extension board that can be placed on the outer surface of one or both of the side panels of the trench shoring apparatus to extend its lateral dimension when in use;

Figure 10 shows how the present invention can be implemented using at least one an apron clamp which receives an apron board as shown in Figure 11 and which preserves and protects the ground adjacent to the excavated trench during trafficking and/or wheeled access;

Figure 12 is a side plan view of a second embodiment of the present invention, and shows the trench shoring apparatus in an extended configuration; and

Figure 13 shows an exploded top plan view from above of the hinge mechanism shown in Figure 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention has adopted the approach of utilising a trench shoring apparatus that can be quickly and easily deployed to provide a temporary earth retaining structure which prevents the excavated sides of trenches or ditches from cave-in or collapse. Advantageously, the insertion and deployment of the trench shoring apparatus of the present invention being at all times from above the surface of the trench and requiring no work inside the trench. Further advantageously, the present invention provides a trench shoring apparatus that can be deployed without the use of hand tools and which occurs automatically using a pivoting hinge mechanism as the trench shoring apparatus is lowered into the bottom of the trench, such that the space between the side walls of the trench and the side panels of the apparatus are taken up automatically. Further advantageously, the present invention provides a trench shoring apparatus that can be quickly retrieved from the trench after use, again without the need for a worker to enter, reach or lean into the trench or ditch.

Referring now to the drawings, a trench shoring apparatus 10 according to the present invention is illustrated in Figures 1 and 2. Figures la, lb, lc and Id show side, front, top and bottom views of the trench shoring apparatus 10 respectively, and Figure 2 shows a perspective view thereof when deployed.

As perhaps best shown in Figure la, the trench shoring apparatus 10 is formed having first and second panels 12a, 12b held in a parallel spaced-apart configuration. The panels 12a, 12b are planar, each having an outer 14 and inner surface 16. When the apparatus 10 is deployed in a trench (not shown), it is the outer surface 14 of the panels 12a, 12b that are in contact with the excavated sides of the trench or ditch to prevent a cave-in or collapse. In a preferred embodiment of the invention, the first and second panels 12a, 12b are formed from treated plywood and the like. The inner surface 16 of the panels

12a, 12b is connected to a plurality of elongate backplates 18 which are positioned from the top to the bottom of the side panels 12a, 12b, as best shown in Figure 2. The backplates 18 are secured to the panels 12a, 12b through apertures 20 formed in the side panels 12a, 12b and secured using threaded fasteners 22 which meet with complementary apertures 28 disposed along the length of the backplate 18, as shown in Figures 1 to 4.

The skilled person will appreciate that, when in use, the side panels 12a, 12b can be replaced quickly and easily because of wear and tear and/or damage from contact with the excavated sides of the trench or ditch. Alternatively, the side panels 12a, 12b can be formed from an aluminium or steel sheet material and the like, and the above is in no way intended to be limiting.

The first and second side panels 12a, 12b are connected in a parallel spaced-apart configuration and the spaced-apart panels 12a, 12b are able to move between extended and retracted spaced-apart parallel configurations when being deployed in, or retrieved from, a trench (not shown). It will be appreciated that within this application, the term “extended configuration” means a spaced-apart parallel configuration of the side panels 12a, 12b in which the outer surfaces 14 of the side panels 12a, 12b abut against the side walls of the excavated trench. The term“retracted configuration” means a thinner spaced-apart lateral configuration or dimension between the side panels 12a, 12b. The retracted configuration has a spaced-apart dimension which is less than the extended configuration, and critically less than the width of the trench or ditch into which the apparatus 10 is to be deployed. Movement of the side panels 12a, 12b between retracted and extended spaced-apart configurations is via a pivoting hinge mechanism, as described below.

Disposed along the length of the inner surfaces 16 of the side panels 12a, 12b are the plurality of backplates 18. The backplates 18 form a fixed part of a hinge mechanism having a generally square cross section 24 with a pair of panels 26 either side of the central structural section 24. The panels 26 include a series of pre-drilled apertures 28. It is through these apertures 28 that the backplate 18 is secured to the inner surface 16 of the side panels 12a, 12b, as perhaps best shown in Figure 2.

Pivotally connected to the backplate 18 is the moving part of the hinge mechanism and being provided by hinge plates 30a, 30b disposed towards the top and near the middle respectively of the trench shoring apparatus 10, as shown in Figures la and 2. In particular, an upper support plate 30a is disposed towards the top section of the apparatus 10 and a lower hinge plate 30b disposed nearer the middle section of the apparatus 10.

Further detail of the triangular hinge plates 30a, 30b is shown in Figure 5. The upper and lower hinge plates 30a, 30b are identical in size and shape apart from the fact that the upper hinge plate 30a includes an elongated slot 32 disposed along the top edge 70 of the hinge plate 30a. It is through this slot that a grille 34 located towards the top of the apparatus 10 is secured through grille anchors 36. When deployed in the trench, the grille 34 provides a temporary flat surface for trafficking and wheeled access, as shown in Figure 2.

The upper and lower hinge plates 30a, 30b each include a proximal aperture 38 which receives an elongate bar 42 running the length of the side panels 12a, 12b, as perhaps best shown in Figures 1 and 2. The ends of the elongate bars 42 are secured using spring tension pins or Sellock pins 44 (as shown in Figure 1), or a threaded fastener 46 (as depicted in Figure 2). The skilled person will appreciate that such a configuration permits pivotal movement of the upper and lower hinge plates 30a, 30b relative to the backplate 18 in an upward direction only, since the side edge 76 of the upper and lower hinge plates 30a, 30b abuts against the inner surface 16 of the side panels 12a, 12b preventing movement in a downward direction.

The upper and lower hinge plates 30a, 30b are received in pairs along each side face 48 of the backplate 18. Disposed between the two sets of upper and lower hinge plates 30a, 30b are a series of connecting rods 50, as best shown in Figure 6a. The connecting rods 50 are elongated rods having apertures 52 at each end thereof which meet with distal apertures 40 disposed on the hinge plates 30a, 30b for receiving a top spacer bar 54 and an elongate bar 42 respectively.

The top spacer bar 54 is assembled from two complementary shaped pieces, which are secured using a collar 74. Disposed at two points in the top section of the grille 34a, 34b are two hoisting loops 56. The hoisting loops 56 sit within slots 58 disposed in each of the grilles 34a, 34b, as shown in Figures 2 and 8.

At the bottom of the trench shoring apparatus 10, opposite to the uppermost facing grilles 34a, 34b are a series of feet 60 having legs 64 which are received inside the cross section 24 of the backplate 18. The feet 60 can be adjusted in height via apertures 62 which meet with corresponding apertures 66 in the backplate 18 and secured using threaded fasteners and the like (not shown).

The skilled person will appreciate that when deployed, the trench shoring apparatus 10 comprises a box-shaped structure, the side panels 12a, 12b of which can be used to contact or abut against the excavated sides of trenches or ditches to prevent cave-ins or collapse.

The pivoting hinge mechanism formed by the pivotal connection of the backplate 18, hinge plates 30a, 30b and connecting rod 50 is such that movement of the connecting rod 50 in a direction parallel to the side panels 12a, 12b causes the spaced-apart panels 12a, 12b to move between an extended parallel spaced-apart configuration for deployment in a trench, and a retracted parallel spaced-apart configuration for insertion into the trench.

The metalwork components forming the apparatus 10 can be mild, powder-coated or galvanised steel, or aluminium and the like.

As shown in Figure la (not depicted in Figure 2), a U-shaped channel 68 runs from the top of the side panels 12a, 12b to the bottom of the side panel 12a, 12b and disposed on the inner surface 16 thereof. In to this U-shaped channel, a separate board (not shown) can be inserted to completely close off the trench shoring apparatus 10, when deployed in the trench, as detailed below.

The use of the present invention will now be described.

Typically, an open trench or ditch is excavated using an excavator, as mentioned above. Depending primarily upon the soil substrate and the weather conditions this open trench is at a risk of collapse or cave-in. To shore the trench, the trench shoring apparatus 10 of the present invention can be utilised, which enables a much quicker and secure shoring to be carried out by construction or utilities workers without the need to enter, lean or reach into the excavated trench or ditch.

To shore the excavated trench or ditch, the operator of the excavator connects a length of chain or other flexible sling (not shown) onto the pair of hoisting loops 56 disposed at the top of the apparatus 10. The length of chain is then connected or wrapped around the bucket or dipper arm such that the trench shoring apparatus 10 can be hoisted clear of the ground. In doing so, the translational movement of the connecting rod 50 in a direction parallel to the side panels 12a, 12b causes the spaced-apart panels 12a, 12b to move to a retracted spaced-apart configuration whereby the apparatus 10 can be inserted in the trench. The retraction being limited by the hypotenuse edge 74 of the hinge support plates 30a, 30b which abut against each other.

In this way, the hoisted apparatus 10 can then be lowered into the trench or ditch and the bucket of the excavator used to push down on the top of the grille 34a, 34b to then splay the spaced-apart side panels 12a, 12b apart into the extended configuration such that they abut against the side walls of the excavated trench or ditch. In this way, the deployed apparatus 10 acts to shore the trench or ditch without needing to enter the trench or ditch or lean into it, which is a much safer and quicker means of providing temporary support. In this configuration, the grille 34a, 34b at the top of the trench shoring apparatus 10 can be trafficked and indeed can take the weight of various industrial equipment, such as an excavator, which is able to traverse the trench without risk of collapse.

When it is needed to remove the apparatus 10, the above method is followed in reverse and the apparatus 10 lifted out cleanly without causing any damage to the walls of the excavated trench.

The apparatus 10 of the present invention can also be implemented using the following components which may be needed to take-up differences in trench sizes etc., and to further preserve the ground adjacent to the excavated trench. Figures 9a, 9b and 9c show front, side and top views respectively of an extension board 72 that can be placed on the outer surface 14 of one or both of the side panels 12a, 12b to extend the lateral dimension of the deployed apparatus 10 when in use. The extension board or shim 72 is formed from a pair of boards 72a, 72b that are connected in a parallel spaced-apart configuration either side of a series of ribs 74 which span the length of the boards 72a, 72b.

Disposed at the top of the assembled board 72 are a series of hooks or connectors 76 that permit the board 72 to be simply slotted onto the top of one or both of the side panels 12a, 12b should the lateral dimension of the apparatus 10 need to be extended. As perhaps best shown in Figure 9b, the hook 76 can receive panel 12a or 12b such that the outer surface 14 of panel 12, 12b abuts against the outer surface of board 72a, and it is the outer surface of board 72b which contacts the excavated side of the trench when deployed.

The materials forming the extension board 72 and ribs 74 being a recycled durable plastics material or the like.

Figures 10a, 10b and 10c are side, top and front views respectively of an apron clamp or connector 78 which can be used to support an apron board or groundmat 80 at one or both sides of the deployed apparatus 10 to preserve and protect the ground adjacent to the excavated trench during heavy trafficking and/or wheeled access. The apron clamp 78 is formed having a proximal end 82 having a slotted aperture 84 which spans the length of the clamp 78, as best shown in Figure 10a. The clamp 78 also comprises an opposite distal end 86 which is formed as a U-shaped channel 88. A separate apron board or groundmat 80, as shown in Figure 11, can be inserted into the U-shaped channel 88 and which is secured using thread fasteners (not shown) through apertures 90 on the clamp 78 and complementary apertures 92 on the apron board 80.

In use, the slotted apertures 84 meet with the elongate bar 42 running the length of the side panels 12a, 12b, such that the deployed apparatus 10 can be received inside the excavated trench and one or both apron boards or groundmats 80 extended from the sides of the apparatus 10 to cover the ground adjacent to the excavated trench to protect it during trafficking and/or wheeled access.

The materials forming the apron clamp 78 and groundmat 80 again being a recycled durable plastics material or the like.

Figures 12 and 13 show a second embodiment of the trench shoring apparatus 10. The construction of the second embodiment is very similar to that of the first embodiment and corresponding features have been given the same reference numerals. The second embodiment differs from the first embodiment in that instead of hinge support plates 30a, 30b forming pairs of lateral arms which are pivotally connected to the connecting rod 50 to form the moving part of the hinge connection disposed between the first and second side panels 12a, 12b, the lateral arms forming the second embodiment of the invention comprise pairs of box-section adjustable arms or struts 94.

As perhaps best shown in Figure 12, each adjustable strut 94 is elongate and formed from two complementary shaped struts 94a, 94b. The box-section inner strut 94a can be entirely received within the body of the box-section outer strut 94b. The adjustable strut 94 can be telescopically extended and retracted, and locked in position by locating an adjustment pin 96 in one of a plurality of apertures 98 which are formed in the inner lateral support strut 94a and outer lateral support strut 94b. In the embodiment shown in Figures 12 and 13, the pin 96 can be received inside the apertures 98 as a clearance or transition fit, although the skilled person will appreciate the other ways of locking the telescopically-adjustable strut 94 are possible.

Like the first embodiment of the invention, the moving part of the hinge mechanism provided by the lateral support struts 94a, 94b are disposed in pairs generally towards the top and near the middle of the trench shoring apparatus 10. The proximal end of each outer lateral support strut 94b is hingedly held in place using strut pins 100 that are disposed between each side face 48 of the C-section support member or backplate 18, as best shown in Figure 13.

Each proximal end of the inner lateral support strut 94a is pivotally connected to the centrally-disposed connecting rod 50 via a centre pin 102. The skilled person will appreciate that the distal end of each inner lateral support strut 94a is telescopically received within the distal end of the corresponding outer lateral support strut 94b, and can adjusted and locked in place, as described above.

In the embodiment shown in Figure 12, the trench shoring apparatus 10 is depicted in an extended configuration such that the connecting rod 50 has been fully extended downwards in the direction denoted by arrow A and the outer surfaces 14 of the side panels 12a, 12b abut against the side walls of the excavated trench (not shown). In this configuration, the lowermost face 104 of each outer lateral support strut 94b abuts against triangular-shaped stopper plate 106 to limit over-rotation thereof. Whilst not intended to be limiting, each adjustable strut 94 is adjustable from around 600mm to around 750mm to around 900mm using locating pins 96 inside apertures 98. In this way, the width of the trench that can be shored using apparatus 10 is between around 1.2m to around 1.8m. This range of trench width is encountered with most forms of residential, commercial and light industrial property construction and in earth excavations for the installation of pipelines, structures and water, drainage, sewerage, gas and other sub surface utilities.

To limit the pivoting action of the adjustable strut 94 when the apparatus 10 is hoisted in the direction denoted by arrow B (Figure 12) using lifting eye 56, the uppermost face 108 of the outer lateral support strut 94b contacts against a stop pin 110 is disposed in the side face 48 of the C-section support member or backplate 18. The skilled person will understand that the second embodiment of the invention can also be used having height-adjustable feet and also grille or supports to enable trafficking and it is also not intended to be limiting illustrating the second embodiment of the invention without these components. The second embodiment of the invention can also include a series of hoisting points 112 which can also be used to hoist the trench shoring apparatus 10.

The skilled person will appreciate that the side panels 12a, 12b can be formed from any number of synthetic plastics material, such as a thermoplastic or thermoset material, or any other suitable first or second generation plastics material. The above list is in no way intended to be limiting and exhaustive.

In a preferred embodiment, the panels 12a, 12b can be formed using Polypropylene (PP), High-Density Polyethylene (HDPE), Polyethylene Terephthalate (PET), Polyvinyl Chloride (PVC) or Acrylonitrile Butadiene Styrene (ABS) or blends thereof.

The skilled person will appreciate that different variations or densities of materials could also be provided which will allow for a generally low product weight which provides a good structural rigidity and durability. For safety and visibility, the panels 12a, 12b can be supplied in a number of different colours.

The skilled person will also appreciate that an additional advantage of the second embodiment of the present invention is an overall reduction in the weight of the apparatus 10. Because of stiction between the outer surfaces 14 of the side panels 12a, 12b and the side walls of the excavated trench when the apparatus 10 is deployed, the additional hoisting effort needed to hoist the initially stationary deployed apparatus 10 to break contact with the side walls of the excavated trench can be substantial, and a reduced apparatus 10 weight is highly desirable.

When used in this specification and claims, the terms“comprises” and“comprising” and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in the terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, separately, or in any combination of such features, can be utilised for realising the invention in diverse forms thereof.

The invention is not intended to be limited to the details of the embodiments described herein, which are described by way of example only. It will be understood that features described in relation to any particular embodiment can be featured in combination with other embodiments.

It is contemplated by the inventor that various substitutions, alterations, and modifications may be made to the invention without departing from the spirit and scope of the invention as defined by the claims. Examples of these include the following:

It is envisaged that rollers or other support means can be positioned on the top edge 70 of the lower hinge plate 30b to support utilities or temporary pipework running therethrough.