GB2354274A

GB2354274A - Refilling and resurfacing a highway excavation

Info

Publication number: GB2354274A
Application number: GB9921913A
Authority: GB
Inventors: John Matthew Mchale
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-09-17
Filing date: 1999-09-17
Publication date: 2001-03-21
Also published as: GB9921913D0

Abstract

A method of re-filling and re-surfacing a highway excavation has the step of producing a back-filling composition by mixing the earth previously excavated from the highway excavation with a binding agent and optionally, adding water to obtain the setting consistency required. The further step of back-filling the excavation by locating a pre-determined amount of the mixture from step (a) in the excavation and then re-surfacing the highway excavation is then carried out. The binder may be cement or lime and the resurfing material is a bitumen based material. The mixing may take place in the excavation. All the apparatus may be positioned on a vehicle which also has a clam shell bucket digger 12 for moving excavated material to and from the mixer 14.

Description

2354274 A METHOD OF RE-FILLING AND RE-SURFACING A HIGHWAY EXCAVATION The

present invention relates to a method of re-filling and re-surfacing a highway excavation and to a vehicle for use in such a method.

It is frequently necessary to excavate below highway surfaces to gain access to various utilities such as gas, electricity, water and telecommunication pipework. After work has been completed, it is necessary to re-fill and re-surface the excavation.

Unfortunately, the excavated earth is considered to have the wrong consistency and density for satisfactory refilling of the excavation. This may be due to the consistency of the excavated material, its moisture level or its nature being unpredictable and unsatisfactory for re-filling the excavation. The reason for its unsuitability is often due to the hardness and consistency criteria, which the re-surfaced highway will have to satisfy including local, national or regional legal requirements.

As a result of the above problems, it is usually necessary to remove the excavated earth to a landfill site or other suitable disposal location and to re-fill the excavation with materials having predictable consistency and properties. A typical material for such use is limestone which has the necessary consistency and predictability.

2 The limestone is used to fill the excavation prior to resurfacing.

The re-filling and re-surfacing contractors will, typically, arrive at the excavation site with a vehicle containing a suitable amount of limestone re-filling material. Typically, the vehicle also includes a mechanical digger, which is usually used both to remove the excavated earth from the site and place it in the vehicle and to remove the limestone from the vehicle for delivery to the excavation hole. After the excavation has been filled with the required amount of limestone and the excavated earth has been transferred onto the vehicle, the vehicle removes the excavated earth to a disposal site.

Although this process is an efficient one, it does result in additional costs both in relation to disposal of the excavated earth and in the cost of limestone re-filling material.

It is one of the objects of the present invention to overcome these problems.

According to a first aspect of the present invention there is provided a method of re-filling and re-surfacing a highway excavation comprising the steps of:- (a) producing a back-filling composition by mixing the earth previously excavated from the said highway excavation with a binding agent and optionally, 30 adding water to obtain the setting consistency required; and 3 (b) back-filling the excavation by locating a predetermined amount of the mixture from step (a) in the excavation; and (c) re-surfacing the highway excavation.

Typically, the binding agent is lime or cement. A suitable highway resurfacing material is a conventional bitumen based material. Preferably, any permanent highway re-surfacing material may be utilised which is, preferably, suitable for the subsequent highway use by vehicles. Bitumen substitute based surfaces may also be utilised. Preferably, the mixture from step (a) substantially fills the excavation. Preferably, it is at least 70% filled, more preferably, at least 80% filled, most preferably, at least 90% filled. Optionally, the back-filling step (b) may be carried out first and mixing may subsequently take place in the excavation. However, this method is not preferred and is unsuitable and impractical for most excavations. Preferably, therefore, a mechanical mixer is provided to execute the mixing step. In this manner, the required proportion of earth from the excavation, lime/cement and water may be mixed by adding the components to the mechanical mixer. The addition of water may not be required when the water content in the excavated earth is sufficiently high to provide the necessary binding properties for the binding agent.

In a preferred embodiment, the mixer is located on a vehicle. Preferably, the method includes the use of a mechanical digger such as a clam shell bucket to transfer the earth to the mixer. Preferably, the bucket and mixer 4 are arranged so that earth from the excavation may be transferred by the digger to the mixer.

The digger and mixer may each be located on a vehicle. 5 Preferably, both the mixer and digger are located on the same vehicle.

As the method includes the mixing of the excavated earth with binding agent and water, means are, preferably, provided for transferring the binding agent and water to the mixing location. Suitable mechanical means such as a pump or transfer conduit may be provided for this purpose.

Preferably, the binding agent is held in a container and, preferably, the container is also located on a vehicle, preferably, the same vehicle as the mixer and digger.

Similarly, the water is, preferably, held in a container and, preferably, the container is also located on a vehicle, preferably, the same vehicle as the mixer.

As an alternative to the conduits, the digger may be utilised to transfer the binding agent from the container to the mixer.

Preferably, after mixing the component materials for a suitable time, the mixture is transferred from the mixer to the excavation. The transfer step may be effected by mechanical or manual means. The mechanical means may utilise the said digger, a pumping mechanism or a spraying mechanism. Alternatively, it may be tipped or released under gravity from the mixer into the excavation.

After filling the excavation, suitable means are employed for tamping the mixture to the required density and height before applying re-surfacing materials and carrying out conventional re-surfacing steps. The resurfacing materials and means for the preparation thereof may also be located on the vehicle.

According to a second aspect of the present invention, there is provided a vehicle for re-filling and re- surfacing a highway excavation comprising a mixing station, and a mechanical digger for transferring earth located adjacent to the vehicle to the said mixer.

The cabin of such a vehicle may be replaceable and may, in some embodiments, be decoupled from the trailer with which the mixing station and mechanical digger are associated.

Preferably, the mixing station and/or mechanical digger are mounted on the vehicle, preferably, the trailer thereof. The trailer of the vehicle may or may not be decoupled from the cabin. Preferably, a source of binding agent is also located on the vehicle. Pref erably, at least one container is located on the vehicle, preferably, the trailer thereof. Preferably, the binding agent may be located in the said container. Preferably, water may be located in a further container, preferably, mounted on the trailer. Conduits may be provided to transfer binding agent and/or water from the said containers to the mixer. Preferably, means to re-surface a highway are also located on the vehicle.

6 Preferably, the mixer is mechanical. The digger may also be mechanised and is, preferably, a pneumatic digger, or possibly, a hydraulic digger.

Preferably, the relative proportions of the earth, binding agent and water are variable. In addition, the speed and duration of mixing is also variable. In both cases, the intention is to produce a re-filling mixture of the required consistency and hardness and this will depend upon the nature of the excavated material as well as the hardness and consistency requirements.

In all cases above, a preferred binding agent is lime or cement. The earth is generally soil, subsoil, clay or other sub-highway surface material known to those skilled in the art.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings in which:- figure 1 shows a vehicle in accordance with the present invention adjacent to an excavation site; figure 2 shows a vehicle in accordance with figure 1 during loading of excavated earth into the mixer; figure 3 shows a schematic cross-sectional view through the mixer, lime and water containers; figure 4 shows a schematic view of the re-filling step using the mixed material; and 7 figure 5 shows a schematic view of the re-surfacing step in accordance with the present invention.

Referring to figure 1 a lorry 2 has a cab 4 and a trailer 6 of conventional construction. The lorry 2 is shown parked adjacent to an excavation site 8 from which has been excavated a mound of earth 10, which mound is located adjacent to the excavation site 8. The trailer 6 of the lorry 2 has mounted thereon a clam shell bucket digger 12, a mixer 14, a lime/cement holding tank 16, a water holding tank 18 and a compressor 20. In addition, a bitumen holding tank 22 depends from the underside of the trailer 6. The clam shell bucket digger 12 comprises a clam shell bucket 114 connected to an arm 116. The arm 116 is mounted at its distal end on the front end of the trailer 6 and adjacent to the pneumatic compressor 20, which serves the clamshell bucket digger airlines (not shown).

The arm 16 comprises upper arm portion 26 and lower arm portion 28 and an elbow portion 30 located therebetween in the conventional manner. The clam shell bucket comprises first and second jaw parts 114a, 114b which are operable to move reversibly from a closed to an open position about respective pivots each located at and journalled through the distal end of the respective jaw parts 114a, 114b and each actuated by pneumatic control from the vehicle cabin 4. The compressor and distal arm part 26 are mounted on the front of the'trailer 6. Behind the compressor 20 in the direction of the rear of the vehicle 6 are sequentially located a mixer 14, a lime or cement holding tank 16 and a water tank 18. A lime conduit 32 connects the lime holding tank 16 to the mixer 14 and a water conduit 34 connects the water holding tank 18 to the mixer 14. The side of the mixer includes a gate 36to 8 facilitate release of the mixed material from the mixer after mixing has been effected. A bitumen holding tank 22 depends from the underside of the trailer 6 in a location immediately beneath the mixing tank 14. The trailer includes stabilising legs 40 which are of a conventional construction, being extendable to provide additional support for the vehicle 2 during re-filling and resurfacing.

Referring briefly to figure 3, the mixer 14 may be of any suitable construction, for instance, paddle blades may be used in the mixer. In the schematic drawing of figure 3, the mixer is shown with a centrally disposed upright shaft 42 which includes paddle members (not shown). The shaft may rotate clockwise or counter clockwise depending upon requirements. It is necessary for the mixer to be constructed so as to meet the requirements of the load to which it is to be exposed during use.

Referring to figures 1-5, an example of the method of the invention is shown. The clam shell bucket 12 gradually removes the mound of earth 10 to the mixer 14 until the required amount of earth is located in the mixer. Figure 3 depicts, schematically, the process of mixing wherein a suitable amount of lime 44 and water 46 are transferred via respective conduits 32,34 into the mixing tank 14 where they are subsequently mixed for a period of time with the excavated earth which has been loaded into the mixer by means of the clam shell bucket 12 as previously described. After mixing has been completed, gate 36 may be opened to allow the mixture to be transferred into the excavation 8. In practice, the consistency of the mixture would be such that pouring it through the opening gate 36 9 would not always be practical. Accordingly, it is also envisaged that no gate is located in the mixer and the clamshell bucket is utilised to transfer the mixed material from the mixer to the excavation. Alternatively, it is also envisaged that one complete side panel of the mixer may be removed or opened by pivoting about the base of the panel so that the panel itself provides means by which the mixture may be transferred, under gravity, from the mixer and slid off the trailer, via the panel, onto the ground adjacent to the trailer or, in some cases, directly into the excavation site.

Finally, once the relevant amount of mixture has been located in the excavation site and compressed to the required density and height using conventional tamping equipment (not shown), the bitumen container and nozzle 50 connected to the bitumen container may be utilised to resurface the excavation site as depicted in figure S.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extend to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A method of re-filling and re-surfacing a highway excavation comprising the steps of:- (a) producing a back-filling composition by mixing the earth previously excavated from the said highway excavation with a binding agent and optionally, adding water to obtain the setting consistency required; and (b) back-filling the excavation by locating a pre determined amount of the mixture from step (a) in the excavation; and (c) re-surfacing the highway excavation.

2. A method according to claim 1, wherein the binding agent is lime or cement.

3. A method according to claim 1 or 2, wherein a suitable highway re-surfacing material is a conventional bitumen based material.

4. A method according to claim 1 or 2 wherein any permanent highway re-surfacing material is utilised.

5. A method according to any preceding claim, wherein the mixture from step (a) substantially fills the excavation.

6. A method according to any preceding claim, wherein the back-filling step (b) is carried out first and mixing according to step (a) subsequently takes place in the excavation.

7. A method according to any of claims 1-5,, wherein a mechanical mixer is provided to execute the mixing step.

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8. A method according to any preceding claim, wherein the mixer is located on a vehicle.

9. A method according to any preceding claim which includes the use of a mechanical digger such as a clam 5 shell bucket to transfer the earth to the mixer.

10. A method according to any preceding claim, wherein the digger and mixer are arranged so that earth from the excavation may be transferred by the digger to the mixer.

11. A method according to any preceding claim, wherein the digger and mixer may each be located on a vehicle.

12. A method according to claim 11, wherein both the mixer and digger are located on the same vehicle.

13. A method according to any preceding claim, wherein means are provided for transferring the binding agent and water to the mixing location.

14. A method according to any preceding claim, wherein the binding agent is held in a container.

15. A method according to claim 14, wherein the container is located on a vehicle.

16. A method according to claim 15, wherein the container is located on the same vehicle as the mixer and digger.

17. A method according to any preceding claim, wherein the water is held in a container.

18. A method according to claim 17, wherein the container is located on a vehicle.

19. A method according to claim 18, wherein the container is located on the same vehicle as the mixer.

20. A method according to any of claims 14-19, wherein the digger may be utilised to transfer the binding agent from the container to the mixer.

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21. A method according to any preceding claim, wherein after mixing the component materials for a suitable time, the mixture is transferred from the mixer to the excavation.

22. A method according to claim 21, w herein the transfer step is effected by mechanical or manual means.

23. A vehicle for re-filling and re-surfacing a highway excavation comprising a mixing station, and a mechanical digger for transferring earth located adjacent to the vehicle to the said mixer.

24. A vehicle according to claim 23, the mixing station and/or mechanical digger are mounted on the vehicle.

25. A vehicle according to any of claim 23 or 24, wherein the mixing station and/or mechanical digger mounted on the vehicle are mounted on the trailer thereof.

26. A vehicle according to any of claims 23-25, wherein a source of binding agent is located on the vehicle.

27. A vehicle according to any of claims 23-26, wherein at least one container is located on the vehicle.

28. A vehicle according to any of claims 23-27, wherein the binding agent is located in the said at least one container.

29. A vehicle according to claim 28, wherein water is located in a further container.

30. A vehicle according to any of claims 28 or 29, wherein conduits are provided to transfer binding agent and/or water from the said container(s) to the mixer.

31. A vehicle according to any of claims 23-30, wherein means to resurface a highway are located on the vehicle.

32. A vehicle according to any of claims 26-31, wherein the binding agent is lime or cement.

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33. A vehicle according to any of claims 23-32, wherein the earth is generally soil, subsoil, clay or other sub-highway surface material known to those skilled in the art.

34. A method of re-filling and re-surfacing an excavation as hereinbefore described with reference to the drawings.

35. A vehicle for re-filling and re-surfacing an excavation as hereinbefore described with reference to the drawings.