Patent Application
20150167260
1. Field of the Invention
This invention relates to a method and to an apparatus to be embedded within a precast concrete panel or slab to enable the panel to be lifted from a transport, lowered towards a road bed, and secured in place above the road bed. The apparatus has particular application in roadway construction and/or repair where several panels must be laid end-to-end and/or side-by-side one another.
2. Background Art
As new communities are built, it is essential to have a roadway system to link each community with neighboring communities. Therefore, a series of highways and freeways are constructed to support vehicular traffic. A common technique for building such roadways is to lay a number of heavy precast concrete panels or slabs end-to-end and side-by-side one another. However, all of the panels must be reliably secured in place and made level with respect to one another to establish a smooth and continuous driving surface.
The foregoing is typically accomplished by grading the road bed upon which each concrete panel will be laid. The process of grading requires the availability and deployment of road grading machinery and the manpower to operate the machinery. Grading the road bed must be relatively precise so that adjacent panels will all be aligned with one another at approximately the same elevation above the road bed. Then, each panel must be secured in place so that it is unlikely to shift in response to being exposed to weather conditions and physical forces over time. Where an existing roadway is being repaired and replaced, the road work usually occurs at night and requires that the roadway be closed to traffic. In this case, the new concrete panels must be installed and retained quickly so that the repaired roadway can reopen the next morning. However, having to first precisely grade the road bed before the panels can be laid adds to the labor force, raises the corresponding construction costs, and increases the time necessary to complete the job. What is even more, the completion time and cost are further increased, because different apparatus are required to be carried by the conventional pre-cast concrete panel to enable the panel to first be lifted and moved to the road bed and then fixed in place alongside adjacent panels.
Reference may be made to patent application Ser. No. 13/594,604 filed Aug. 24, 2012 for an example of an apparatus to be embedded in a precast concrete panel to enable the panel to be lifted, laid upon a road bed, and elevated above the road bed to be made level with adjacent panels.
In general terms, a lifting and grout delivering apparatus is disclosed to be embedded within a precast concrete panel or slab to enable the panel to be lifted off its transport, lowered towards a road bed, and secured in place above the road bed to be held stationary with respect to adjacent panels that are employed during the construction and/or repair of a roadway. In accordance with the preferred embodiment, a lifting and grout delivering apparatus is embedded near each corner of the concrete panel while the panel is being cast in order to establish convenient and reliable lifting points at which the panel is relatively quickly and easily lifted.
The lifting and grout delivering apparatus includes a hollow, cylindrical threaded sleeve that extends through the panel between the top and bottom thereof. A pair of retaining bars are bent around the sleeve to help anchor the sleeve in place within the precast panel. A threaded end cap is rotated into removable mating engagement with the top of the threaded cylindrical sleeve.
Prior to moving the concrete panel from its transport to the road bed, a set of corner support blocks (e.g., shims) are laid on the road bed so that the panel will be supported above the road bed by the support blocks. The end cap is now removed from the cylindrical sleeve of the lifting and grout delivering apparatus. A hoisting cylinder having a hoist coupler pivotally connected thereto is positioned on top of the panel, and a threaded lifting bolt is inserted through the hoist cylinder and rotated into detachable connection with the threaded sleeve of the lifting and grout delivering apparatus embedded within the precast panel. The hoist coupler and lifting bolt create a lifting point at which a crane can engage and lift the panel from its transport for relocation above the road bed so as to rest upon the support blocks. The crane is then detached from the lifting point, and the lifting bolt is rotated out of its connection with and removed from the sleeve. Next, a supply of grout or a similar curable filler material is pumped through the concrete panel by way of the hollow sleeve from which the lifting bolt has been removed and grout pipes that run through the panel. The grout fills the space between the bottom of the panel resting on the support blocks and the road bed. When the grout hardens, the panel will be fixed in place above the road bed so as to be made stationary relative to adjacent panels to thereby establish a smooth and continuous roadway to support vehicular traffic.
Turning now to the drawings, details are provided of an apparatus which is capable of performing the dual functions of enabling a concrete panel or slab to first be lifted and moved to a construction site and then fixed in place by means of delivering grout to fill a space between the bottom of the panel and a surface (e.g., an excavation, a road bed, or the like) over which the concrete panel is laid. The lifting and grout delivering apparatus herein disclosed has particular application for use during roadway (e.g., freeway) construction and/or repair where a large number of heavy precast concrete panels must be laid end-to-end and side-by-side one another to create a smooth and continuous driveway over which automotive traffic will travel. However, it is to be understood that the apparatus and the method of using this invention are applicable to the construction of any flat surface (such as, for example, an airport runway) to be produced by a series of panels or slabs that are manufactured from concrete or the like and laid over a road bed or a similar support foundation.
Referring initially to
The retaining bars 5 and 7 are preferably welded to the sleeve 3. Each of the retaining bars may be, for example, a rebar that is bent around the sleeve 3 so as to extend away therefrom and in opposite directions. The retaining bars 5 and 7 serve as anchors to prevent a displacement of the sleeve 3 during the casting and curing of the concrete panel when the dual function apparatus 1 is being embedded therewithin. Moreover, the retaining bars 5 and 7 affixed to the sleeve 3 cooperate with the rebars (designated 20 in
A set of screw threads 9 (best shown in
After the concrete panel 30 has been manufactured and moved to a work site, the panel must be lifted off its transport and moved above the road bed next to one or more adjacent panels. To accomplish the foregoing, the detachable plug 10 is removed from the top of the hollow sleeve 3. By way of a second application for the screw threads 9 inside the cylindrical sleeve 3, a threaded lifting bolt 24 is detachably connected to the threaded sleeve 3 of the lifting and grout delivering apparatus 1 that is embedded within the concrete panel 30 (best shown in
More particularly, and referring now to
With the hoisting cylinder 26 connected to the concrete panel 30 by means of the lifting bolt 24 being mated to the threaded sleeve 3 of the lifting and grout delivering apparatus 1, a crane 50 (of
Prior to moving the concrete panel 30 to the road bed, a set of corner support blocks or spacers 32 are seated on the road bed to receive thereupon each corner of the panel 30. The corner blocks 32 may be shims that are manufactured from a material (e.g., steel or plastic) capable of supporting the weight of the panel 30. The corner blocks 32 can be shaped and dimensioned as is necessary to elevate the panel 30 above the road bed so as to be level with adjacent concrete panels. After the concrete panel 30 has been lowered towards the road bed and laid on the support blocks 32, the crane 50 is detached from the hoist couplers 28. The lifting bolt 24 is now rotated out of its mating engagement with the threaded sleeve 3, and the hoisting cylinder 26 and hoist coupler 28 are removed from the top of the panel 30. When the panel 30 is laid alongside another panel of a new or a repaired roadway, the panel must be fixed in place to prevent shifting and movement relative to the adjacent panel in response to changing weather conditions and the effect of physical forces to which the panel 30 is exposed over time. By virtue of the hollow sleeve 3 of the apparatus 1 that is embedded therewithin, the panel 30 can be reliably held stationary above the road bed.
When the concrete panel 30 is resting upon the support blocks 32, a space 34 is established between the road bed and the bottom of the panel 30 (best shown in
After the grout pumping process has been concluded and the concrete panel 30 is fixed in place as just described, the depression 22 which lies above the sleeve 3 is filled with cement, grout, or the like to create a flat surface across the top of the panel. By virtue of embedding the presently-disclosed lifting and grout delivering apparatus therewithin, additional precast concrete panels can be lifted, positioned, laid end-to-end and/or side-by-side one another, and retained in place to efficiently create a new roadway or repair an existing roadway within less time and with the expenditure of less man hours and cost than had the road bed been precisely graded as is customary in traditional road building techniques.
