TECHNICAL FIELD OF THE INVENTION

The present invention relates to heavy equipment. In particular, the present invention relates to an apparatus for preparing terrain for excavation.

BACKGROUND OF THE INVENTION

It is common in carrying out infrastructure and industrial projects for there to be a need to dig into the ground at an excavation site. Various prior art technologies exist for such excavation. However, such excavation may be impractical, extremely difficult or impossible under certain circumstances.

One example of such circumstances is extremely cold weather which results in freezing of the ground surface and underlying material. For ex ample, a utility line may need to be repaired under a frozen paved street. It is desirable to prepare the excavation site for excavation by thorough ground thawing. Prior art methods have used propane tanks as a source of fuel to thaw the frozen ground, but such tanks require frequent refilling. The present invention provides a mobile, efficient, safe apparatus for ground excavation preparation.

SUMMARY OF THE INVENTION

There is provided a ground excavation preparation apparatus consisting of a trailer; a housing connected to the trailer; mobility means attached to the trailer for moving the apparatus; heat generation means above the housing for supplying thawing energy; heat distribution means within the housing for transferring heat into the ambient air within the housing; and hydraulic means connecting the trailer to the housing for raising and lowering the housing at an excavation site. The housing may be a rectangular, open-bottomed box of between 6 and 10 feet wide, preferably 8 feet wide, and between 12 and 30 feet long, preferably 20 feet long.

The mobility means may comprise a frame and hitch assembly for connection of the apparatus to a towing vehicle, and a wheel assembly having at least one pair of wheels joined by an axle, the assembly pivotally connected to the second end of the housing.

The heat generation means may comprise a diesel burning unit and a diesel fuel storage tank. The heat distribution means may comprise heat transfer piping within the housing having a first end connected to the heat generation means and a second end connected to an exhaust pipe. The heat transfer piping may be between 45 and 90 feet, preferably 65 feet long. The heat transfer piping may have a diameter of between 8 and 12 inches, preferably 10 inches, and the exhaust pipe may have a diameter of between 2 and 6 inches, preferably 4 inches.

The hydraulic means may comprise an engine and a hydraulic pump for lowering and raising the housing at an excavation site.

There is further provided a method of ground excavation preparation comprising the steps of: transporting a ground excavation preparation apparatus as described herein to a site; lowering the housing by hydraulic means until the housing rests on the surface of the ground, forming an enclosed space within the housing above the ground surface; starting the diesel burning unit to generate hot exhaust distribution into the heat transfer piping and out the exhaust pipe to effect thawing of the adjacent ground surface; raising the housing by hydraulic means; transporting the apparatus away from the thawed site; and excavating the thawed site.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the preferred embodiments is provided by way of example only and with reference to the following drawings, in which: Fig. 1 depicts an end view of the ground excavation preparation system of the present invention, showing the system in a lowered position for thawing; Fig. 2 depicts a side view of the ground excavation preparation system of the present invention, showing the system in a lowered position for thawing;

Fig. 3 depicts the ground excavation preparation system of the present invention, showing the system in a raised position after thawing, and showing the thawed site ready for excavation; and

Fig. 4 depicts the underside of the housing, showing one embodiment of the piping pattern.

In the drawings, one embodiment of the invention is illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, which are not intended as a definition of the limits of the invention.

DETAILED DESCRIPTION OF THE INVENTION

As depicted in the figures, the apparatus of the present invention comprises a trailer having a housing; mobility means; heat generation means; heat distribution means; and hydraulic means.

According to one embodiment, the housing may comprise an inverted rectangular open-bottomed metal box 2 approximately 8 feet wide, 20 feet long, and 2 feet deep. Other box dimensions are also within the scope of the invention.

The mobility means may comprise, at a first end of the housing, a frame 4 and hitch 6 assembly, as is know in the prior art, for reversible connection of the system to a towing vehicle for transportation of the system to and from an excavation site. At a second opposing end of the housing, the mobility means may further comprise a wheel assembly 8, preferably having at least one pair of wheels joined by an axle, the assembly pivotally connected to the second end of the housing, whereby lowering of the wheel assembly effects raising of the second end of the housing off of the ground and raising of the wheel assembly effects lowering of the second end of the housing to the ground. The heat generation means preferably may comprise one or more diesel burning units 10 adjacent the housing and a fuel storage tank 1 1. Other heat generation means are also within the scope of the invention.

The heat distribution means may comprise heat transfer piping 13 to carry the heated exhaust generated by the diesel burning unit throughout the housing an directed towards the frozen ground surface. Preferably, the heat transfer piping is approximately 10 inches in diameter and approximately 65 feet in length, extending in a path which traverses the length of the housing approximately three times, ideally along each lateral side and the middle of the housing, as depicted in Fig. 4. The heated exhaust is vented through a vertical pipe 12 preferably having a diameter of 4 inches. The reduction in diameter of the exhaust pipe relative to the piping within the housing slows the release of the heated exhaust, increasing heat transfer from the housing piping into the surrounding air enclosed within the housing box, effecting thawing of the adjacent ground surface. Other piping and exhaust pie dimensions are also possible and within the scope of the invention. The hydraulic means may comprise an engine and hydraulic pump 14 for lowering the housing onto the ground surface at a desired excavation site prior to ground thawing, and for raising the housing away from the ground surface after ground thawing.

In operation, the ground excavation preparation apparatus is transported to a site to be thawed, the housing is lowered to the ground, and the diesel burning unit is started. The hot exhaust generated within the piping causes thawing of the adjacent ground surface below the housing. Thawing of the ground surface may be achieved within 5 minutes of operation of the diesel burning unit. Once thawing is complete, the hydraulics may be used to raise the housing and the apparatus may be moved from the prepared site to permit excavation manually or with the use of excavation machines. Thawing of a frozen asphalt surface will also melt the asphalt to convert the asphalt to gravel to permit excavation. Accordingly, the apparatus of the present invention may also be used in non- frozen conditions to remove asphalt for excavation. The flat vertical sides of the housing pressing against the melting asphalt produce clean, straight vertical edges to the excavation site. The system of the present invention thaws the ground only within the area below the housing, leaving the surrounding area frozen. This reduces or eliminates the need for any showing of the surrounding area or the use of trench cages.

It will be appreciated by those skilled in the art that other variations of the preferred embodiment may also be practised without departing from the scope of the invention.