GB2311081A

GB2311081A - Combating soil movement pressure in foundation ditches

Info

Publication number: GB2311081A
Application number: GB9605143A
Authority: GB
Inventors: Richard Simmons; Anthony Lawson
Original assignee: COMBAT POLYSTYRENE GROUP Ltd
Current assignee: COMBAT POLYSTYRENE GROUP Ltd
Priority date: 1996-03-11
Filing date: 1996-03-11
Publication date: 1997-09-17
Anticipated expiration: 2016-03-11
Also published as: GB2344362B; GB2344362A; GB9605143D0; GB0005369D0; GB2311081B

Abstract

A method of combating soil movements in a foundation trench 18 filled with poured concrete in which prior to filling the trench 18 with poured concrete a compressible fill material 22 is fixed to a wall 14 of the trench using fixing elements 32. The fixing elements 32 are passed into the trench wall 14 to fix the compressible material 22 to the trench wall 14 by means of an applicator 34 which is actuated from outside the trench. By means of the remotely actuated applicator, the compressible fill material is simply, easily and quickly fixed by the fixing elements to the trench wall without workmen being exposed to the potential risk of injury presented by collapsing trench walls, because they do not need to be inside the trench positively to restrain the fill material against the trench wall. Other embodiments of the applicator and the supporting of the compressible material 22 against the trench wall are described.

Description

IMPROVEMENTS IN OR RELATING TO COMBATING SOIL MOVEMENT PRESSURE IN FOUNDANON TRENCHES FILLED WITH CONCRETE The present invention relates to the combating of soil movement pressure in foundation trenches filled with concrete for buildings and more particularly but not exclusively to the combating of clay heave pressure in such trenches.

In the construction of all buildings, it is fundamental that sound underground foundations are first laid. The basic steps in the process of preparing such foundations essentially involve digging a trench in the soil down to a depth at which stable land is reached, laying a compressible fill material against at least one wall of the trench and retaining the compressible fill material in position against at least one wall of the trench whilst filling the trench with poured concrete.

The purpose of the compressible fill material is to minimise the risk of the foundations cracking due to soil movements and settlement of the ground. This problem is especially acute in soils having a high clay content. The compressible fill material acts as a cushioning barrier between the concrete and the walls of the trench, by deforming under the pressure exerted by the swelling and shrinking of the soil. In effect, the compressible fill material absorbs soil movement pressures.

The depth to which the foundation trenches have to be dug depends upon the nature and characteristics of the soil including the depth of any underlying bed rock, which govern the depth at which stable land will be reached at the base of the trench. With some soils such as dense clay, or where the bedrock is relatively close to ground level, the depth of the trench may be as little as 1 to 1.2 metres. However, with more unstable soils, such as those encountered on reclaimed land and those from which trees have been removed, it is not unusual for foundation trenches to be dug to a depth of up to 4 metres before stable land is reached. Typical depths of trench range from about 2.5 to about 3 metres.

To the best of the Applicants' knowledge, compressible fill materials such as expanded polystyrene (EPS) in sheet form have been used for combating soil movement in relation to foundation trenches for some 14 years. For the same period, the Applicants have been involved in the development and manufacture of suitable EPS compressible fill materials.

The problem which is routinely experienced with utilisation of EPS compressible fill materials is due to EPS having a density which is considerably less than that of the liquid concrete used for the foundation. The liquid concrete being poured into the trench exerts an upwardly acting force on the EPS sheet as it gradually fills the trench which results in the EPS sheet floating on the concrete and being lifted completely out of its position where it lies on the base of the trench and against the trench wall. This unrestrained movement of the EPS sheet can also result in breakage of the EPS sheet which if left can reduce its ability to combat soil movements with potentially disastrous effects on the foundations of the building. For example, it has been known for clay heave pressure acting on unprotected concrete foundations to move a building supported thereon and cause substantial damage to the building.

Accordingly, it is essential to restrain the EPS sheet against movements in the trench during pouring of the concrete to fill the trench. The construction industry has devised various methods of EPS restraint, all of which are in one way or another commercially impractical, and/or do not work, and/or are downright dangerous.

Most of the known methods that have been tried necessitate workmen having to climb down a ladder into the trench, to restrain the EPS sheets by some form of mechanical fixing means.

Unfortunately, ever present in foundation trenches is the grave danger of the trench walls collapsing inwards; the deeper the trench and the more unstable the soil the greater the danger. Thus, it will readily appreciated that this presents a potentially fatal risk to workmen installing EPS fill materials in this way. Indeed, it is not uncommon for injuries and even fatalities to occur. Moreover, the longer the foundation trenches are open to complete a fixing operation, the greater is the danger to the workmen in the trench. This is because on any construction site there is construction equipment such as mechanical diggers moving about the site which engender vibrations in the soil which have caused collapse of the trench walls onto workmen in the trench.

One such method involves the use of steel shuttering which is applied to the trench walls with the EPS sheets being held against the shuttering by means of screw props. This method may require as many as 20 workmen in the trench at any one time. Moreover, even with screw props in position, the concrete being poured may still find its way between the steel shuttering and the sheets resulting in splitting of the sheets. Once the poured concrete has set, the expensive steel shuttering has to be removed which is not easily achieved and the gap left by the removal of the shuttering has to be back filled.

Sometimes the shuttering cannot be removed without damaging the recently set foundations. This method is not without danger, is expensive in manpower, time and materials and is therefore no longer in use.

Attention has been directed to overcoming the problem from outside the foundation trench which avoids workmen having to enter the trench. Thus, in another known method, which has not found acceptance because of its time consuming expense and potential for damaging the foundations and the EPS sheets, the concrete is firstly poured into the trench. Then, after the concrete has set a supplemental trench is dug on at least one side of the foundation into which the EPS sheets are inserted, followed by the backfilling of any remaining gaps between the EPS sheets and the wall of the supplemental trench.

Because of the difficulties and expense encountered with the aforementioned known methods, the only method which is currently in common use is one which is comparatively simple and considerably less time consuming and is effective in providing a positive restraint but which still puts the lives of workmen continually at risk because they have to enter the trench. In this method, the workmen manually hold the EPS sheets in position against the trench wall whilst hammering metal fixing elements through the EPS sheet and into the trench wall.

The only earlier published patent specification of which the Applicants are aware and which relates to the combating of soil movement pressure in relation to foundation trenches using compressible EPS fill materials, is GB Patent Specification No. A-2 268 951. This specification is concerned with the problem of minimising the effect of EPS breakage during handling and fixing of the fill material to the trench walls without adversely affecting the compressible characteristics of the EPS. If this breakage results in loose pieces of EPS entering the trench then the desired resistance to soil movements is not achieved. This problem is solved by the use of a compressible fill material in the form of an EPS board with a semi-rigid sheet material bonded to one face thereof to add rigidity to the EPS material, thereby providing improved load distribution across the EPS. Although the EPS fill material is provided with fixing holes for fixing elements constituted by earth bolts, this specification is devoid of any disclosure as to the actual method employed in passing the earth bolts through the holes and into the trench wall to fix the EPS fill material to the trench wall prior to the pouring of concrete.

The- rising concern for the safety of workmen in foundation trenches has recently been recognised by the National House Building Council (NHBC) and Government Health & Safety Office which latter are in process of preparing a directive banning workmen from climbing down into foundation trenches to fix the compressible fill material to the trench walls.

The construction industry has long been crying out for a safe and commercially viable method of restraining EPS sheets against the walls of foundation trenches which does not put workmen in danger of their health and lives. With this in mind, the applicants have been carrying out research and on-site experiments into safe restraining methods over the past six years.

Applicants have experimented with wooden fixing poles which were not viable because they split and with steel T-shaped fixing pins which were discarded because they did not avoid workmen having to climb into the foundation trench.

Furthermore, Applicants have also carried out experiments with a known method of restraining the EPS sheets from outside a foundation trench which avoided the use of fixing elements and workmen having to climb into the trench. This method involved the use of several lengths of waterproof 75mm wide building contractors' tape tied at one of their ends to a weight such as a brick or a length of precast concrete. The weight at the ends of the tapes was lowered to the bottom of the trench to lie adjacent the trench wall and the free ends of the tapes were tied to earth bolts hammered into the earth outside the trench. Concrete was then poured up to a depth of 500mm (BS 60311581) to form the requisite "toe" at the bottom of the trench which held the weight in position.

The free ends of the tapes were then untied, moved to the opposite side of the trench and after a suitable concrete setting period (about 15 minutes), an EPS sheet was positioned on the concrete toe and against the trench wall. The tapes were then tensioned around the EPS sheet by pulling on their free ends and the tensioned tapes were retied to the earth bolts to restrain the EPS sheet against the trench wall. Unfortunately Applicants' experiments with this restraining method proved unsuccessful because the restraint was not positive enough to prevent poured concrete from forcing its way between the EPS sheet and the trench wall and causing splitting of the EPS sheet. Therefore Applicants were forced to discard yet another fixing method.

These failures led Applicants to research into devising ways of using positive fixing elements such as metal pins to restrain the EPS sheets in foundation trenches without necessitating workmen entering the trench. Applicants then proceeded to devise a method which evolved over 2 years of intense site investigation. They interviewed many civil engineers, NHBC inspectors and Health and Safety Officials. Information relating to problems on clay heave was also obtained from the British Research Establishment (BRE). By observing the flow surges of concrete in trenches and by gaining more understanding of the many geological problems in fixing compressible fill materials including EPS sheets, to the walls of foundation trenches, Applicants were able to compile many case studies relating to the problems of fixing compressible materials to the walls of foundation trenches. The result of all this information gathering, research, discussions and on-site experimentation finally enabled applicants to devise a method of fixing compressible fill materials to the walls of foundation trenches that involves the use of fixing elements and that solves the problem of workmen having to enter foundation trenches, a solution which has hitherto long been sought for in vain.

Accordingly, in its broadest aspect the invention provides a method of combating soil movements, such as clay heave, in a foundation trench filled with poured concrete, in which prior to filling the trench with poured concrete, a compressible fill material, such as an EPS sheet, is fixed to a wall of the trench using fixing elements, characterised in that the fixing elements are passed into the trench wall to fix the compressible material to the trench wall by means of an applicator which is actuated from outside the trench.

By means of the remotely actuated applicator, the compressible fill material is simply, easily and quickly fixed by the fixing elements to the trench wall without workmen being exposed to the potential risk of injury presented by collapsing trench walls, because they do not need to be inside the trench positively to restrain the fill material against the trench wall.

Another benefit of the invention is that installation of the compressible fill material is faster than in known methods, and so not only can the overall foundation work be completed more quickly, but also the amount of time that the trench walls are left exposed to soil vibrations engendered by on-site mobile construction equipment with the ever increasing risk of collapse is considerably reduced.

Moreover, the workforce that has hitherto been required can be considerably reduced.

For example one workman only is required to actuate the applicator.

The applicator may be of any appropriate construction consistent with remote actuation to apply the fixing elements to the fill material in the trench.

In one embodiment, the applicator is inclined at an angle to the trench walls by a workman standing on the ground adjacent the trench. In this instance the applicator may be provided with a plunger which is remotely actuated by the workman at one end and engages with a fixing element at the other end to push each fixing element in turn into the tench wall to fix the fill material thereto at successive locations. However, this method is suitable only for trenches up to 1.2 metres depth because beyond 1.2 metres and within the typical depth range of 2.5 to 3.00 metres, the required angle of the applicator with respect to the relatively narrow trench is too great successfully to pass the fixing elements through the fill material.

Accordingly, a preferred method of carrying the invention into effect, comprises charging the applicator with at least one fixing element, lowering the applicator into the trench, and actuating the applicator at successive locations in the trench to pass the fixing elements into the trench wall and fix the fill material thereto at said locations. By lowering the applicator substantially vertically into the trench, the fixing elements can be successively quickly and easily passed through the fill material in a succession of locations at the bottom, middle and upper regions of the foundation trench, no matter how deep the foundation trench.

Moreover, this form of applicator can be supported on the bottom of the trench in a substantially vertical position which considerably simplifies operation of the applicator because the free end is stabilised against movement and the workman can concentrate on actuating the applicator to drive the fixing elements into the trench wall at the selected locations.

The Applicants have found that the use of a jacking action, which is preferably lever operated, is a most effective way of fixing the fill material to the trench walls.

The invention has been carried into effect under experimental site conditions and Applicants are confident that not only will the invention fulfil a long felt want in the construction industry but also it will meet the safety requirements about to be imposed by the NHBC and Health and Safety Office.

Another problem encountered in combating soil movement pressures in foundation trenches filled with concrete, using compressible fill material is the requirement to provide a concrete "toe" of 500mm at the base of the trench, on which "toe" the fill material rests. In methods involving the use of fixing elements, this has hitherto necessitated in workmen having to measure the distance of 500mm from the bottom of the trench to the lower end of the EPS sheets, hold the fill material in position against the wall at the measured distance and then continue to hold the fill material until sufficient fixing elements are hammered in for the workmen to let go of the fill material and hammer in the remaining fixing elements. This is a time consuming and labour intensive operation. Whilst in the discarded method using tensioned waterproof tapes, marking or knotting of the tapes at the requisite distance is used, this method is inappropriate when using fixing elements.

In order to overcome this problem and from another aspect, the invention provides, in a method of combating soil movements in foundation trenches filled with poured concrete, supporting a compressible fill material from the bottom of the trench with its lower edge spaced a predetermined distance, such as about 500mm, from the trench bottom, and fixing the compressible fill material to the trench wall with fixing elements which are preferably used to fix the fill material by means of an applicator which is actuated from outside the trench.

When the fill material is propped on the trench bottom, it is conceivable that the lowermost of the fixing elements applied to the fill material may not be so securely fixed from a location outside the trench which may result in the concrete being poured after the toe has been formed forcing its way between the lower edge region of the fill material and the trench wall. Moreover, if the toe concrete is poured before any fixing of the fill material to the trench walls, uplift of the supported fill material will almost certainly occur.

In order to guard against poured concrete being forced between the fill material and the trench wall and any uplift of the fill material in such instances, the method preferably includes the step of anchoring the fill material to the trench bottom utilising the concrete poured to form the toe.

The supporting and anchoring steps of these aspects of the method of the invention may be conveniently achieved by the provision of a propping member which remains in the trench after the trench is filled with concrete and is preferably of L-shaped cross-section.

The leg of the L is secured, as by nails, to a surface of the fill material in its lower edge region, at such a position that the length of the leg of the L taken from the lower edge of the fill material to the foot of the L corresponds to the predetermined distance (say 500mm) of the lower edge from the trench bottom to provide the specified concrete toe.

The use of a propping member increases the safety advantages of the present invention because it is secured to the fill material outside the trench. The securing ensures that the foot of the L lies beneath the lower edge of the fill material.

With the fill material positioned in the trench, the foot of the propping member rests on the trench bottom and extends beneath the lower edge and in the direction away from the trench wall to support the fill material from the trench bottom. When the initial pour of concrete is made to form the 500mm toe, the concrete engages with, and exerts a downward pressure on the foot of the propping member to anchor the fill material in the trench. Thus, the foot of the propping member also serves as an anchor to prevent uplift of the fill material during pouring of the concrete, as well as a support for the fill material.

A further problem encountered in fixing compressible fill material to the walls of foundation trenches is that of maintaining the compressible fill material in a substantially vertical position to avoid poured concrete getting behind the fill material in the region of the trench opening. If this occurs, the pressure of the concrete may snap the fill material and mean that the contractor would be forced to remove the concrete and start again, an operation which is expensive in both time and materials.

With a view to solving this problem, and from a further aspect, the invention provides, in a method of combating soil movements in a foundation trench filled with poured concrete in which prior to filling the trench with poured concrete, compressible fill material is positioned against at least one wall of the trench and is fixed by means of fixing elements to the trench wall, exerting a holding pressure against oppositely facing surfaces of the upper end regions of a trench wall and fill material or oppositely facing surfaces of the upper end regions of the fill material in the region of the trench opening to hold the compressible fill material in a substantially vertical position.

Obviously, the fixing elements are preferably used to fix the fill material to the trench wall by means of an applicator which is actuated from outside the trench.

The holding pressure may conveniently be discontinued after the trench has been filled with concrete.

In one way of exerting the holding pressure, a telescopic means is provided which caters for different widths of trench opening. The telescopic means may be of tubular form and composed of at least two interengaging members. The telescopic means can easily be removed after the trench is filled with concrete.

An ever present danger with recently dug foundation trenches is that the edges of the trenches at the trench opening are particularly vulnerable to collapse when carrying out the methods of the present invention because the installation of the fill material and fixing elements and pouring of the concrete must be undertaken from the ground level adjacent the trench.

Applicants have found that it is not enough with regard to ensuring overall safety, just to avoid workmen entering the trench to install the fill material. Care should also be taken to avoid serious injury or loss of life to workmen falling into the trench by sudden and substantial collapse of the trench edges defining the trench opening whilst positioning the fill, pouring the concrete toe and actuating the applicator for the fixing elements.

Although the presence of the holding pressure at the trench opening achieves some stabilisation of the trench opening to guard against collapse by assisting in maintaining the integrity of the trench opening, this does not necessarily overcome the ever present danger of collapse due to construction equipment engendered vibrations and workmen working close to the trench opening during fixing and whilst the concrete is being poured to fill the trench. With workmen safety being of such paramount importance, Applicants have devised further ways to militate against collapse of the trench opening edges by crumbling and breaking away of the soil.

Accordingly, from a still further aspect, the invention provides, in a method of combating soil movements in foundation trenches filled with poured concrete in which prior to filling the trench with poured concrete a compressible fill material is fixed to a wall of the trench with fixing elements applied by means of an applicator which is actuated from outside the trench, positioning support means for a workman in relation to the trench opening such that the workman can actuate the applicator from the support means whilst being protected against collapse of the trench edge.

By virtue of the workman support means, not only is the workman's safety ensured even if the trench opening should collapse but access to the trench for remote application of the fixing elements is considerably improved.

The workman support means may be in form of a platform that is supported at that side which is remote from a trench edge by the ground adjacent to, but a relatively safe distance back from, the trench edge, with the opposite side of the platform being supported by an upright, such as a frame, from the bottom of the trench. This method has the considerable safety advantage that the edge of the trench does not bear the weight of the platform and any worker thereon. Even if the trench edge collapses for reasons unconnected with the fixing operation, eg due to soil vibrations engendered by on-site construction vehicles, the workman is still safe.

In order to accommodate different trench depths and for ease of installation, handling and transport, the upright of the support means conveniently comprises a plurality of modular sections which can be easily and quickly connected to one another and to the platform on site.

An alternative form of workman support means comprises a platform that bridges the trench opening, like a plank, for a sufficient distance beyond the trench edges to be supported on safe ground. Advantageously, the plank-like platform may be provided with two depending members of which one may be moveable in relation to the other to accommodate different widths of trench opening and is releasably fixable relative thereto to exert a holding pressure on the upper edge regions of a trench wall and fill material or oppositely facing surfaces of the upper end regions of the fill material.

In situations where a trench wall is uneven or has collapsed, leaving voids between the installed fill material and the wall, whilst the concrete is being poured into the trench it exerts an outward pressure against the fill material. Where the voids are located, this pressure will cause the fill material to break and enter the voids which could damage the foundation and reduce the cushioning effect to such an extent as to prevent the fill material from working.

Accordingly, from another aspect of the present invention, in a method of combating soil movements, such as clay heave, in a foundation trench filled with poured concrete, in which prior to filling the trench with poured concrete, a compressible fill material is fixed to a wall of the trench which is uneven or has collapsed leaving at least one void between the fill material and the trench wall, placing discrete quantities of compressible material such as a bag of EPS fragments, lumps or beads in said at least one void prior to the pouring of concrete.

On completion of the concrete pour, the bag can be removed for re-use and the void backfilled. If the void is large then two or more bags can be used, in which case plastics sheeting such as that marketed under the trade mark TWINFLUTE is preferably interposed between the bags and the compressible fill material. If there is more than one void the procedure is repeated. TWINFLUTE plastics sheeting is self-supporting, formed by extrusion and comprises a corrugated plastics layer interposed between two flat outer plastics layers.

In situations where a steel beam is supported on piles in the bottom of a foundation trench, TWINFLUTE plastics sheeting may be made available cut to size for placing over the compressible fill material so that when the steel beam is put in place the compressible fill material is not damaged. Such plastics sheeting will also prevent spacer blocks from damaging the compressible fill material as the plastics sheeting helps to spread the load. Another use of such plastics sheeting in the method of the invention is that it can be used as a slip membrane.

Preferably, actuation of the applicator causes the fixing elements to be pushed, pressed, urged, driven, propelled, shot, fired or otherwise passed into the trench wall to fix the fill material thereto.

The fixing elements may be passed through the material of the fill material which is preferred because of the frictional engagement of the fixing elements with the fill material or through preformed holes in the fill material.

Alternatively, the fixing elements may be engaged with the periphery of the compressible material and passed into the trench wall by the actuation of the applicator in a clipping action. Indeed the Applicants have envisaged providing the compressible material with peripheral fixing elements in the form of clips already mounted along the periphery of the fill material.

Whilst the invention contemplates any suitable form of fixing elements such as clips, bolts, T-shaped pins and L-shaped pins, Applicants specially designed U-shaped pins for passing through the fill material are preferred for ease of application and security of fixing. Such U-shaped pins facilitate fixing at any depth, ie at the top, middle and base of the trench.

Moreover, such U-shaped pins can be of any appropriate length, eg 12, 16 or 18 inches long which enables any size or thickness of compressible fill material currently in use to be fixed. The U-shaped pins are preferably of a suitable metal such as 6 to 8mm steel.

It should be appreciated that the invention not only provides safe methods of installing fill materials in foundation trenches but also provides a system and kit of parts for carrying out any of the methods defined hereinabove.

Accordingly, from yet another aspect, the present invention consists in a system or kit of parts for use in combating soil movement pressures in foundation trenches filled with concrete, prior to filling with poured concrete, said system or kit of parts comprising, in its most fundamental form, compressible fill material which is adapted to be positioned against a wall of a foundation trench, a plurality of fixing elements and an applicator which is actuatable from outside the trench to pass the fixing elements through the fill material and into the trench wall.

Ideally, the system or kit of parts additionally includes any one or all of the propping member, the holding pressure means, the workman support means, the void filling material and TWINFLUTE plastics sheeting.

In order that the invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings, in which: Fig. 1 illustrates diagrammatically, one way of carrying out the method of the prese Figs 5 to 7; Fig. 10 is a plan view of the fixing element carrier shown in Fig. 9; Fig. 11 is a side elevation of a slider which cooperates with the fixing element carrier shown in Figs. 9 and 10; Fig. 12 is a plan view of the slider shown in Fig. 11; Fig. 13 is a perspective view of a modular section of a workman support means shown in Fig. 5; Fig. 14 is a perspective view of three interconnected modular sections formed of the modular section shown in Fig. 13; Fig. 15 is a perspective view of a platform for interconnection to the uppermost modular section shown in Fig.13, Fig. 16 is an exploded view of a means for exerting a holding pressure at the trench opening; and Fig. 17 shows the holding means of Fig. 16 in an assembled condition in position in a trench opening.

In the drawings, the same reference characters are used to indicate the same or similar parts.

Referring to Figs. 1 and 2 of the drawings, there is shown a foundation trench 10, to be filled with poured concrete to form a foundation for a building, dug to a depth of 1.2 metres below ground level 12. The trench 10 has oppositely facing side walls 14, a bottom 16 and an opening 18 defined by edges 20. A compressible fill material in the form of an EPS sheet 22 has been lowered into the trench 10 and is positioned against the right hand one, as illustrated, trench wall 14. The EPS sheet 22 is spaced from the trench bottom 16 by a propping member 24 which is L-shaped in cross-section and is formed of plastics sheet material. The leg 26 of the propping member 24 is secured as by nails 28 to the lower end region of the EPS sheet 22 with the foot 30 of the propping member lying beneath the lower edge of the EPS sheet 22 and resting on the trench bottom 16 so that the sheet 22 is supported against the right-hand side wall 14 from the trench bottom.

The length of the leg 26 of the propping member 24 is such that when the propping member is secured to the sheet 22, the distance from the trench bottom 16 to the lower edge of the EPS sheet 22 is 500mm so that, when the concrete is poured, the requisite toe of concrete will be provided at the trench bottom 16. The foot 30 of the propping member serves as an anchor for the EPS sheet 22 when the concrete is poured because the concrete will exert a downward force on the sheet through the foot, thereby holding the sheet in position against the trench wall 14.

In order to combat soil movement pressures, such as clay heave, when the foundation trench 10 is filled with poured concrete and forms the foundation of a building, the EPS sheet 22 is fixed to the trench wall 14 by means of fixing elements which in Figs. 1 and 4 are shown as being L-shaped pins 32.

The fixing pins 32 are applied by means of an applicator 34 which actuatable from outside the trench 10 by a workman 36 standing on the ground 12 adjacent the trench opening 18 to pass the pins 32 through the material of the EPS sheet 22 and into the right-hand trench wall 14, with the head 38 of each pin 36 engaging with the exposed surface of the EPS sheet 22, as will be appreciated from Fig. 1. To fix the pins 32 to the EPS sheet 22, the applicator 34 must be inclined at an angle to the sheet with its distal end positioned close to or touching the sheet. A succession of pins 32 is passed through the sheet 22 at locations near the lower edge, the middle and near the upper edge whereby the sheet is fixed securely to the trench wall.

Referring now to Figure 3, the applicator 34 comprises upper and lower elongate channel members 40 and 42 respectively which are secured at an angle to each other by struts 44. The struts 44 are fixed to tubular housings 46, 48 which surround the channel members 40 and 42 respectively at the proximal end of the applicator 34. At the proximal end of the applicator 34, there is an actuating handle 50 fixed to a plunger 52 which slides in the lower channel member 42. In use, pins 32 are fed by the workman 36 into the upper channel member 40 in which they slide down into a receiving portion 54 of the lower channel member at the distal end of the applicator 34. With the applicator in the position shown in Fig.1, with its distal end close to or contacting the EPS sheet 22, the workman grabs the handle 50 and pushes the plunger inwards which drives a pin 32 occupying the receiving portion through the EPS sheet 22 and into the trench wall 14. The process is repeated at a succession of locations until the sheet 22 is adequately fixed to the trench wall. The trench is then filled with poured concrete.

Whilst the applicator 34 is suitable for trench depths of up to 1.2 metres, on-site tests have established that this applicator is impracticable for trench depths exceeding this depth. This is because the angles at which the applicator has to operate at increased depths are too steep to drive the pins through the EPS sheet and into the trench wall.

Accordingly, Applicants have devised another embodiment of applicator which is generally indicated by the reference 60 in Figs. 5 to 7 to which reference will now be made.

In Fig 5, a workman 36 is standing at the left-hand edge 20, as illustrated, of the trench 10 on a platform 62 of a workman support means 64 including an upright 66 connected to the platform 62. The platform 62 is supported at that side which is remote from the left-hand trench edge 20 by the ground 12 adjacent to, but at a relatively safe distance (2 metres) back from, the trench edge. At this remote side, the platform is provided with two pegs such as 68 which dig into the ground to assist in stabilising the platform and thereby increase safety. At the other side of the platform 62, adjacent the trench edge 20, the platform is supported by the upright 66 from the bottom 16 of the trench 10. The upright 66 comprises three one metre length modular sections 70 which are releasably interconnected, with the uppermost modular section being releasably connected to the platform 62.

From the platform 62, the workman 36 has lowered the EPS sheet 22 into position against the right-hand, as illustrated, trench wall 14 and has lowered the applicator 60 substantially vertically into the trench 10 where it rests on the trench bottom 16 in a substantially vertical position ready to discharge a fixing element through the EPS sheet 22 and into the trench wall 14.

Referring now to Figures 5 to 12, the applicator 60 comprises a stationary rod 72 carrying at that end which is the lower in use, a stabilising peg 74 which digs into the trench bottom 16, as shown, and a trench bottom abutment plate 76 which guards against the rod 72 penetrating too deeply into the soil of the trench bottom 16. At its upper end in use, the rod has an actuating lever 78 pivoted thereto which is manually operated by the workman 36. Between its ends, the rod 72 is provided with a series of spaced apart grooves 80 for a purpose to be described.

The rod 72 is mounted in and projects from both ends of an elongate channel member 82 having a series of spaced apart notches 84 extending therealong and which is movable along, and with respect to, the rod 72 through the actuating lever 78 by virtue of a pivotable link 84. A carrier 86 for a fixing element in the form of a U-shaped pin 88 (Fig. 8) is mounted on the rod 72 at a location defined by one of the grooves 80 by means of a spring loaded bolt (not shown).

The carrier 86 comprises two side members such as 90 which support the spring loaded bolt which are joined rigidly by a top member 92 for supporting the fixing pin 88 (Figs.

and 10). The top member 92 has two slide channels 94 for a slider 96 comprising two sliding members 98 which slide in the channels 94. The slider 96 has a fixing pin engaging member 97 of angled configuration to facilitate reception and driving of a fixing pin 88 when such fixing pin is supported on the top member 92 of the pin carrier.

The slider 96 is pivoted to one end of an arm 100 which carries at its other end a shaft 102 which releasably engages in one of the notches 84 and turns in that notch 84 as will be appreciated from Figures 5, 6 and 7.

In use, the workman 36 charges the pin carrier 86 with a fixing pin 88 with the curved end of the pin abutting the angled pin engaging member 97 and lowers the applicator 60 into the position shown in Fig. 5 with the free edge of the pin carrier 86 close to or touching the exposed surface of the EPS sheet 22. The workman then actuates the lever 78 in the direction illustrated by the arrow 104 which moves the channel member 82 in relation to the rod 72 in the direction of the arrow 106. Through the engagement of the shaft 102 in a notch 84, movement of the channel member causes movement of the arm 100 which moves the slider 96 along the guide channels 94 until the arm 100 occupies the position shown in Fig. 7, thereby driving the pin 88 through the EPS sheet 22 and into the trench wall 14 with a jacking action. The process is repeated at a succession of locations at one level within the trench, eg the middle level as illustrated in Fig.S and then by momentarily releasing the spring-loaded bolt, the carrier 86 can be moved to another location, (eg that corresponding to an upper level of the trench) on the rod 72 defined by another groove 80 for applying another fixing pin 88 at another location in the trench wall 14. The fixing process is continued until the sheet 22 is adequately fixed to the trench wall. The trench is then filled with poured concrete.

It will be appreciated that the workman support means 64 provides an important safety feature. Even if the left-hand trench edge 20 collapses as indicated at 108 in Fig. 5 and then falls in, the workman 36 will still be safely supported on the platform 62 and his life will not be endangered.

Further details of the workman support means 64 may be understood from Figs. 13 to 15 to which reference will now be made. Each of the modular sections 70 is of framelike construction and is provided at its upper ends in use with two female socket members 71. At their lower ends, in use, each modular frame section 70 is provided with two complementary male projection members 73 which engage in the socket members 71 of the section just beneath. Likewise, the platform 62, which is one metre wide like the modular frame sections 70, is provided with male projection members 73 which engage in the female socket members 71 of the uppermost modular frame section 70. The whole construction is connected for added safety by means of securing pins such as 75 which releasably engage in holes 77 and 79 in the female socket and male projection members respectively. The final touch with regard to workman safety is the provision of a safety rail 81 on one side of the platform 62.

In Fig. 16 two tubes 83 and 85 of cardboard are slidably mountable one inside the other to provide a telescopic means 87 which is fixed in the position shown in Fig. 17 as by staples from a staple gun that is normally readily available on a building site. The staples (not shown) pass through the two cardboard tubes 83 and 85. The two tubes are provided with plastics end caps 89.

The telescopic means 87 through the end caps 89 exerts a holding pressure against oppositely facing surfaces of the upper end regions of the left-hand, as illustrated, trench wall 14 and EPS sheet 22 against the right-hand, as illustrated, trench wall in the region of the trench opening 18 to maintain the sheet 22 in a substantially vertical position and avoid poured concrete getting behind the sheet in the region of the trench opening. The telescopic means 87 can easily be removed after the trench is filled with concrete.

It will be appreciated that various modifications may be made in the methods described and in the components used in the methods described without departing from the scope of the invention. For example, the fixing pins 32 may be used as clips to secure the EPS sheet 22 around its periphery with the heads 32 of the pins engaging with the edge regions on the exposed surface of the sheet adjacent the periphery and with the legs of the pins missing the sheet by extending past the sheet periphery and into the trench wall.

The applicator 60 of Figs. 5 to 7 may be provided with two or three fixing pin carriers 86 along the length of the rod 72 so that pins may be applied at two or three levels of the trench 10 in one operation before recharging the pin carriers and moving along sideways to the next location in the trench. This will reduce the number of times that the applicator has to be removed from the trench for recharging with fixing pins. The number of times the applicator 60 has to be removed from the trench for recharging with fixing pins can be further reduced or avoided by constructing the or each pin carrier with a pin magazine.

Claims

1. A method of combating soil movements in a foundation trench filled with poured concrete in which prior to filling the trench with poured concrete a compressible fill material is fixed to a wall of the trench using fixing elements characterised in that the fixing elements are passed into the trench wall to fix the compressible material to the trench wall by means of an applicator which is actuated from outside the trench.

2. A method according to claim 1, comprising supporting a compressible fill material from the bottom of the trench with its lower edge spaced a predetermined distance from the trench bottom.

3. A method of combating soil movements in a foundation trench filled with poured concrete, comprising supporting a compressible fill material from the bottom of the trench with its lower edge spaced a predetermined distance from the trench bottom and fixing the compressible fill material to the trench wall with fixing elements.

4. A method according to any of claims 1 to 3, comprising charging the applicator with at least one fixing element lowering, the applicator into the trench and actuating the applicator at successive locations in the trench to pass the fixing elements into the trench wall and fix the fill material thereto at said locations.

5. A method according to claim 4, wherein the applicator is lowered into the trench in a substantially vertical position.

6. A method according to claim 4 or claim 5, wherein the applicator is supported on the bottom of the trench during actuating.

7. A method according to claim 5 or claim 6, wherein the fixing elements are passed into the trench wall by means ofajacking action

8. A method according to any of claims 1 to 3, wherein the applicator is lowered at an angle into the trench and is inclined at an angle to the trench wall when the applicator is actuated.

9. A method according to claim 8, wherein the fixing elements are passed into the trench wall by means of a plunger action

10. A method according to claim 7 or claim 9, wherein the jacking action or plunger action is lever operated.

11. A method according to any of claims 2 to 10, including anchoring the fill material to the trench bottom using the poured concrete.

12. A method according to claim 11, wherein the compressible fill material is supported and anchored by providing a propping member which remains in the trench after the trench is filled with concrete.

13. A method according to claim 12, wherein the propping member is of L-shaped cross section and is secured to a surface of the fill material in its lower edge region at such a position that the length of the leg of the L taken from the lower edge of the fill material to the foot of the L corresponds to the predetermined distance of the lower edge from the trench bottom.

14. A method according to claim 13, further comprising pouring concrete into the trench such that the concrete engages with and exerts a downward pressure on the foot of the L to anchor the fill material in the trench

15. A method according to any preceding claim, further comprising exerting a holding pressure against oppositely facing surfaces of upper end regions of a trench wall and fill material or oppositely facing surfaces of upper end regions of the fill material in the region of the trench opening to hold the compressible fill material in a substantially vertical position.

16. A method of combating soil movements in a foundation trench filled with poured concrete in which prior to filling the trench with poured concrete a compressible fill material is positioned against at least one wall of the trench and is fixed by means of fixing elements to the trench wall and in which a holding pressure is exerted against oppositely facing surfaces of the upper end regions of a trench wall and fill material or oppositely facing surfaces of the upper end regions of the fill material in the region of the trench opening to hold the compressible fill material in a substantially vertical position.

17. A method according to claim 15 or claim 16, wherein the holding pressure is exerted by telescopic means.

18. A method according to claim 17, wherein the telescopic means is removed after the trench is filled with concrete.

19. A method according to any preceding claim, further comprising positioning support means for a workman in relation to the trench opening such that the workman can actuate the applicator from the support means whilst being protected against collapse of the trench edge.

20. A method of combating soil movements in a foundation trench filled with poured concrete in which prior to filling the trench with poured concrete a compressible fill material is fixed to a wall of the trench with fixing elements applied by means of an applicator which is actuated from outside the trench positioning support means for a workman in relation to the trench opening such that the workman can actuate the applicator from the support means whilst being protected against collapse ofthe trench edge.

21. A method according to claim 19 or claim 20, wherein the support means is a platform which is supported at that side which is remote from a trench edge by the ground adjacent to, but a relatively safe distance back from, the trench edge, with the opposite side of the platform being supported by an upright from the bottom of the trench

22. A method according to any of claims 19 to 21, wherein an upright of the support means comprises a plurality of modular sections which are connectable to one another and to the platform on-site.

23. A method according to claim 19 or claim 20, wherein the support means comprises a platform that bridges the trench opening for a sufficient distance beyond the trench edges to be supported on safe aground.

24. A method according to claim 23, wherein the platform is provided with two depending members of which one may be moveable in relation to the other to accommodate different widths of trench opening and is releasably fixable relative thereto to exert a holding pressure on the upper edge regions of a trench wall and fill material or oppositely facing surfaces of the upper end regions of the fill material.

25. A method according to any preceding claim, wherein the compressible fill material is fixed to a wall of the trench which is uneven or has collapsed leaving at least one void between the fill material and the trench wall and wherein at least one bag of compressible material is placed in said at least one void prior to the pouring of concrete.

26. A method of combating soil movements in a foundation trench filled with poured concrete in which prior to filling the trench with poured concrete a compressible fill material is fixed to a wall of the trench which is uneven or has collapsed leaving at least one void between the fill material and the trench wall and wherein at least one bag of compressible material is placed in said at least one void prior to the pouring of concrete.

27. A method according to claim 25 or claim 26, wherein, after filling the trench with poured concrete, the at least one bag is removed for re-use and the void b kfilled.

28. A kit of parts for combating soil movements in a foundation trench filled with poured concrete comprising a compressible fill material which is adapted to be positioned against a wall of a foundation trench, a plurality of fixing elements and an applicator which is actuated from outside the trench to pass the fixing elements into the trench wall to fix the fill material thereto.

29. A kit of parts according to claim 28, including any one or all of a propping member, a holding pressure means, a workman support means and a void filling material.

30. A method of combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 4 of the accompanying drawings.

31. A method of combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 5 to 12 ofthe accompanying drawings.

32. A method of combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 4 and 13 to 15 ofthe accompanying drawings.

33. A method of combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 5 to 12 and 13 to 15 ofthe accompanying drawings.

34. A method of combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 4 and 16 to 17 ofthe accompanying drawings.

35. A method of combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 5 to 12 and 16 to 17 ofthe accompanying drawings.

36. A method of combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 4 and 13 to 17 ofthe accompanying drawings.

37. A method of combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 5 to 17 ofthe accompanying drawings.

38. A kit of parts for use in combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 4 of the accompanying drawings.

39. A kit of parts for use in combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 5 to 12 ofthe accompanying drawings.

40. A kit of parts for use in combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 4 and 13 to 15 of the accompanying drawings.

41. A kit of parts for use in combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 5 to 12 and 13 to 15 ofthe accompanying drawings.

42. A kit of parts for use in combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 4 and 16 to 17 of the accompanying drawings.

43. A kit of parts for use in combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 5 to 12 and 16 to 17 ofthe accompanying drawings.

44. A kit of parts for use in combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 4 and 13 to 17 ofthe accompanying drawings.

45. A kit of parts for use in combating soil movement in a foundation trench filled with poured concrete, substantially as hereinbefore described with reference to, and as shown in, Figures 5 to 17 of the accompanying drawings.