Ice slot construction

A method and apparatus are provided for forming an ice slot in an ice sheet by cutting discrete blocks of ice in the ice sheet, then gripping the blocks of ice with a claw-like attachment extending from a hydraulic arm and pushing the ice blocks downwardly with the hydraulic arm until the blocks reach a level with the underside of the ice sheet and then rotating the blocks under the surrounding ice sheet, whereby loads on the ice sheet are reduced and the ice blocks contribute to the load capacity of the ice sheet due to the buoyant upward pressure of the ice blocks.

BACKGROUND OF THE INVENTION 
During construction of pipelines, artificial islands, fabricated 
structures, etc., where operations are carried out from the surface of a 
floating ice sheet, large amounts of ice must be cut and cleared from the 
water surface. Often, the weight of the ice removed is such that it must 
further be removed to some distance away from the opening being formed in 
the ice in order to avoid overstressing of the ice sheet when work 
equipment is present. This second handling of removed ice is inconvenient, 
time consuming, costly and results in the need for additional heavy 
equipment for the removal operation. 
Applicant is not aware of any prior references which, in his judgment as 
one skilled in the pipeline art, would anticipate or render obvious the 
novel method and apparatus of the instant invention; however, for purposes 
of fully developing the background of the invention and establishing the 
state of the requisite art, the following is set forth: U.S. Pat. Nos. 
4,373,836; 4,205,928; 4,129,011; 4,126,013; 4,094,149; 4,053,406; 
3,977,345 and 3,950,955. 
SUMMARY OF THE INVENTION 
The primary purpose of the present invention is to provide a method and 
apparatus for forming an ice slot in an ice sheet floating on water, by a 
technique which effectively eliminates the loads that would otherwise be 
imposed by the ice removed from the slot and which may also strengthen the 
sides of the ice slot, which method and apparatus are relatively 
convenient and economical to use, which are not time consuming and which 
do not require the need for additional heavy equipment for the removal of 
ice, and which do not subject the ice to dangerous stresses. The ice sheet 
is first severed to form the dimensions of the ice slot, and then the ice 
slot is cleared of ice by pushing the ice which is severed under the ice 
sheet adjacent to the ice slot, whereby the buoyancy of the severed ice 
strengthens the sides of the ice slot. Preferably, the ice slot is formed 
by cutting discrete blocks of ice in the ice sheet, gripping the blocks of 
ice with a claw-like attachment extending from a hydraulic arm and then 
pushing the ice blocks downwardly with the hydraulic arm and under the 
surrounding ice sheet. More preferably, the ice blocks are rotated as they 
are pushed downwardly into position under the surrounding ice sheet. 
Other purposes, distinctions over the art, advantages and features of the 
invention will be apparent to one skilled in the art upon review of the 
following:

DESCRIPTION OF PREFERRED EMBODIMENTS 
The present invention pertains to an apparatus and method for constructing 
ice slots in an ice sheet. Preferably, the ice is cut into convenient 
sized blocks to form the ice slot by a cutting device, for example a Ditch 
Witch.TM. with a chain/bar cutter. Other severing means may be used: 
rotary or reciprocating saws; band saws; bucket wheel trenchers; for 
instance. The present invention requires that the ice, after being severed 
into convenient sized pieces, be submerged in place and then forced 
underneath the adjacent ice sheet. A relatively small hydraulic excavator 
is preferred for this operation, preferably equipped with a claw-like 
attachment, that exerts a downward force followed by a lateral or tilting 
force to force each block (or segment) of ice under the ice sheet to the 
side of the ice slot. Where a narrow, i.e., single block width slot is 
required, a single downward force applied off-center may be sufficient to 
cause a block to move or even to rotate under the sheet. When a wide slot 
is being prepared, preferably a gripping attachment is utilized which 
improves the ability to position the block and force it into place. A 
preferred apparatus is a standard backhoe bucket or an articulated 
attachment to replace the bucket, which has a claw-like attachment. A 
special purpose claw assembly having a rotational capability in both 
horizontal and vertical planes is most preferred for use with the 
invention as is shown in FIG. 3 hereof. 
The present invention enjoys numerous advantages over the prior art. Thus, 
it is no longer necessary to provide large, heavy lifting equipment for 
the removal of ice masses that may weigh several tons in air. 
Additionally, the vertical force requirement to submerge a block of 
floating ice is only about 10 percent of the vertical lift required to 
raise the same unit volume onto the ice sheet. Further, a clear work area 
results, providing access for equipment for construction. Deflection and 
flexural stress in the ice sheet is reduced, and a second handling of the 
ice is thereby avoided. Finally, the buoyant force of the ice under the 
ice sheet further reduces the deflection of the ice sheet under loading 
from construction equipment. 
Having thus generally described the apparatus and method of the present 
invention, as well as its numerous advantages over the art, the following 
is a detailed description thereof, given in accordance with specific 
reference to the drawings. 
FIG. 1 shows a backhoe 10 equipped with a hydraulic arm 11 and a claw-like 
device 12 at the end of the hydraulic arm which may be used to remove 
blocks of ice 13 from an ice sheet 14 and deposit the blocks of ice to one 
side of the ice sheet. While the claw-like attachment 12 of the present 
invention is highly useful for this purpose, it is more desirable in 
accordance with the invention to submerge the blocks of ice and place them 
under the ice sheet, which enjoys several advantages as above discussed. 
FIG. 2 shows the use of the backhoe 10 in accordance with the present 
invention wherein the hydraulic arm 11 and claw-like attachment 12 are 
used to force the block of ice 13 downwardly and even more preferably, to 
rotate the block of ice and insert it under the ice sheet 14. This is an 
especially advantageous technique, even where the ice sheet is very thick, 
inasmuch as the hydraulic arm 11 can reach well down into the ice sheet, 
for example as much as twenty feet. In addition, as above noted, once the 
ice blocks are installed under the edge of the ice sheet, they add 
considerable strength to the ice sheet, especially after the blocks of ice 
have effectively welded into the ice sheet and increased its thickness at 
the lips of the ice slot. Of particular value is the horizontal rotation 
capability of the attachment, which allows the claw to be oriented with 
the ice block no matter what the relative alignment of the machine itself 
may be; thus reducing maneuvering time and allowing the operator to assume 
the most attractive position while remaining away from the edge of the ice 
slot. 
FIG. 3 provides a more detailed view of the claw-like attachment of the 
present invention. The hydraulic arm 11 of the backhoe 10 is attached to 
the claw-like extension via a universal joint 15 which allows the claw 
means to be controllably rotated in a horizontal plane. A hydraulic 
extension 16 along with two fixed arms 17 and 18 allow the claw-like 
device to be tilted or rotated in a vertical plane. This permits rotating 
the ice block under the ice sheet. These arms are attached to a platform 
structure 19 from which levers 19 and 20 are attached to each of four legs 
21 which, in turn, are attached to a claw means 22 which grips the ice. 
The claw means 22 may be hydraulically actuated (not visible in the 
Figure) so as to grip the ice block securely. The levers 19 and 20 may 
also be arranged such that when the claw-like member is raised, the claws 
22 press inwardly, gripping the block of ice. The heavier the ice block, 
the more gripping force results from the lifting operation. 
The foregoing description of the invention is merely intended to be 
explanatory thereof, and various changes in the details of the described 
method and apparatus may be made within the scope of the appended claims 
without departing from the spirit of the invention.