Patent Application
20110129306
This invention relates generally to the field of excavation, and in particular includes excavation for the purposes of creating trenches and cavities for underpinning structures, for example for reinforcing foundations of buildings and the like.
Subsidence is a common problem affecting buildings and other such structures. Displacement and movement of earth on which structures are built can occur for a variety of reasons. Common reasons are the build-up of excessive groundwater causing softening of the earth, the drying out of earth leading to shrinkage and so forth.
Subsidence commonly manifests itself by the slippage of foundations below ground level, leading to movement of the structure above, possibly resulting in cracks appearing in the walls and in extreme circumstances failure of the structure.
The effects of subsidence can be mitigated by taking the remedial action of underpinning the structure, commonly underpinning the foundations below ground level. Various methods of underpinning are routinely employed.
One method involves excavating a trench adjacent the structure (or a relevant portion of the structure). The trench often extends below the level at which the foundations terminate. It is then necessary to excavate a cavity directly below the foundation down to firm strata. The cavity can then be filled with a suitable material which replaces the excavated earth and will act to bridge the gap between the foundation and firm strata, thus supporting the weight of the foundation and reinforcing the foundation from below. The cavity can be filled with concrete, but other suitable materials can be used. The underpinning is usually performed by sequentially excavating sections or bays below the foundations so that the foundations are at all times throughout the process fully supported and the foundations are thus gradually underpinned in stages.
Often, in the case of very large structures, supporting pillars can be introduced into the cavity, such pillars can be made of steel fibre-reinforced concrete, steel or other suitable material.
Another method involves introducing or casting reinforced concrete beams into a pocket created in an existing structure below ground level but above the level at which the existing foundations terminate. Each beam can then be supported by pillars or piles driven into the earth below the exiting foundations and down to firm strata. Each beam is typically supported by two piles one either side of the existing structure, although variations exist wherein two piles can be driven on the same side and the beam forms a cantilever which supports the existing structure.
Whichever method is used, there is a necessity to excavate a hole or trench adjacent to a portion of the structure to be underpinned. Where it is necessary to create cavities below the foundations, it is commonly necessary to excavate below the level of the existing foundation and extend laterally underneath. Excavating in this manner is difficult to achieve with machine-based tools due to the inconvenience of the location and angles necessary for correct operation.
As a consequence, it is typically necessary for trenches and cavities to be dug, at least in part, manually by laborers. The laborers are consequently positioned in the trench and lateral excavation work to define the cavities must be carried out by hand.
This type of manual excavation has a number of drawbacks. The work can be slow and time-consuming, thus increasing costs. Furthermore, there is increased danger associated with such manual work. For example, the earth underneath structures requiring underpinning is often unstable and there is an increased risk of collapse of cavities which can endanger manual laborers.
There is therefore a need for alternative tools and methods for excavation which allows such trenches and cavities to be created by machine operated from the ground level, thus avoiding the need for manual laborers. As such, the excavation process can be speeded up, reducing costs as well as increasing safety for workers.
It is an object of the present invention to overcome or at least mitigate at least some of the problems inherent in such prior art tools and methods.
According to a first aspect of this invention there is provided an excavation tool assembly comprising a base and an excavation tool having a tool shaft connected to the assembly and extending downwards from the base at an angle, the assembly further comprising a connector portion for attachment to a mechanical power source.
The tool shaft can be set at an angle relative to the assembly base such that mechanical power can be transmitted through the angle to a tool, which tool can then be operated below ground level for excavation purposes. Such an angle can be created by many different methods. For example, an angle could be created by welding, bolting, screwing etc the tool to the assembly base in a manner which creates a fixed downward angle. Persons skilled in the art will immediately appreciate that there are many means by which such an angle could be created.
The introduction of a downward angle between the tool shaft and the assembly base allows an excavation tool to be used to create trenches and cavities by operation of the tool from ground level, particularly in the process of underpinning structures as described above. It will be appreciated that the angle dimension will vary depending upon the particular requirements of the excavation task to be carried out. This will be dictated, for example, by the depth of the excavation relative to the ground level and so on.
Thus, according to a first aspect of this invention the device allows trenches and cavities to be excavated by machine operating at, or near to ground level, and avoids the need for manual laborers to excavate manually and enter the resulting trench to undertake further excavation work with attendant savings in both time and cost, as well as decrease in danger for operators.
The excavation tool can be removable from the assembly. Thus, various different tool types can be sequentially coupled to the assembly permitting a range of different excavation operations to be undertaken in a rapid and convenient manner.
The tool can be securable to the assembly by tool locking means, allowing precise orientations of the tool to fixed relative to the assembly and preventing unwanted movement of the tool, particularly during delicate excavation operations.
The tool locking means can be provided in an elongate receptacle forming part of the base of the assembly. Thus, for example, the tool shaft can be insertable into a receptacle in a complementary fashion and can be fastened therein.
The tool can be rotatable about its longitudinal axis and securable in a fixed position relative to the base of the assembly and/or the receptacle can be rotatable about its longitudinal axis and securable in a fixed position relative to the base of the assembly. As such, the tool can be securely positioned relative to the base in a manner which allows the head of the tool to be set in any desired position allowing significant versatility in the operation of the tool for excavation. Rotation of the tool or receptacle can be achieved by manual means or by automated means. This can provide yet further advantages when it is desired to excavate in awkward positions or locations.
The tool shaft can comprise two sections, a first section connected to the assembly and a second section bearing a tool head and connected to the first section by a movable joint. Furthermore, the second section can be movable to a position perpendicular to the first section. Such embodiments can provide a superior degree of flexibility with regard to the angles at which excavation work can be carried out.
The assembly can be attached to a mechanical power source by an intermediate connector such as a quick hitch device (a term of art). Quick hitch devices are well known to persons skilled in the art and allow tools of choice to be attached, in a bespoke manner, to a swing-arm/boom of a mechanical excavator or other similar device. Such intermediate connectors provide an additional degree of flexibility with respect to the types of mechanical power source which could be attached to the assembly.
In all embodiments of the above-described excavation tool assemblies, the excavation tool assembly can be an underpinning tool assembly and the excavation tool can be an underpinning tool. Thus, the assembly can be specifically adapted for the purposes of excavating trenches, channels, ditches, conduits and the like which will be used in the creation of structural support for foundations in buildings and the like. Here the underpinning excavation work can extend to below ground level.
In one particular embodiment, the elongate receptacle is integral with the base, the excavation tool is a removable underpinning tool, the tool is lockable into the receptacle by locking means which are provided in the elongate receptacle and the tool is rotatable about its longitudinal axis and securable in a fixed position relative to the base of the assembly. The connector portion can be attached to a swing-arm of a mechanical excavator by a quick hitch device.
In another aspect of the invention there is provided an excavation tool for use with any of the above-described tool assemblies. The tool comprises a shaft portion and a head portion and means for coupling the tool to the assembly.
In yet another aspect, the invention also provides a method of excavating comprising using the above-described assemblies. For example, the method may comprise excavating a trench adjacent to and/or underneath a portion of a structure to be underpinned. In this way, a cavity can be formed directly adjacent to or below the structure to be underpinned (for example a domestic property or the like) which structure can then be reinforced by introducing reinforcing means into the cavity. Such reinforcing means can include concrete, reinforced concrete, steel and other suitable materials.
A simple stylized embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which
Referring to
The tool has a head portion which can be in the form of any structure suitable for performing excavation functions. The shaft of the tool can be provided as any suitable elongate structure, such as a cylinder.
The connector portion (14) comprises means for connecting a mechanical power source to the assembly. Such means are intended to physically attach the power source to the assembly. Any suitable means can be employed. For instance, screws, bolts etc. In embodiments which further comprise an intermediate connector such as a quick hitch device, the power source is connected indirectly to the connector portion via the intermediate connector.
In embodiments having tool locking means, the shaft of the tool can be fixed in a plurality of positions relative to the base of the assembly such that the shaft of the tool can be rotated to the desired location and fixed in position. Any suitable locking means can be provided, such as a nut and bolt arrangement, a pin for insertion though aligned holes in both shaft and receptacle and so on. Persons skilled in the art will be familiar with such arrangements. Rotation of the tool can also be achieved by automated means using motors, hydraulics and the like. The skilled person would readily appreciate how to implement such automated means.
In certain embodiments the tool (and/or an elongate receptacle which accepts the tool) is rotatable about its longitudinal axis and can be fixed relative to the assembly base. Persons of skill in the art will appreciate that such a flexible coupling between the tool or receptacle and the base can be created by any suitable means. For example, the tool or receptacle could be provided with teeth which interdigitate with corresponding teeth or recesses provided on the assembly base. The tool or receptacle could then be rotated to any desired location relative to the coupling portion and locked in place by any suitable means such as bolts or screws or the like.
Referring to
The excavation can be performed for the purposes of underpinning a structure. In such cases, the tools used will be underpinning tools and the assembly is an excavation tool assembly. In some embodiments, such as that depicted in
The term “excavation”, is intended to encompass any activity related to the construction of structures such as trenches, cavities, holes, ditches, pits, elongate channels, conduits, pockets, recesses, caves and so on. Such excavations can be created below or adjacent a structure (for example the foundation of a wall).
The term “underpinning” is well known in the art.
An “excavation tool” for use with the assembly of the invention is envisaged to be any tool suitable for carrying out any type of activity associated with the creation of the above-described structures. Such tools include but are not limited to knifes, chisels, cutters, bolsters, diggers, buckets, spades, scrapers and so on.
The term “mechanical power source” is intended to encompass any suitable machine which can act as a source of power suitable for creating such excavation structures. Typical power sources will be swing-arm mechanical excavators, piledrivers, jack-hammers and the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0800023.4 | Jan 2008 | GB | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/GB08/04274 | 12/23/2008 | WO | 00 | 10/27/2010 |
