BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a trench shielding unit for securing the sidewalls of a trench or excavation from cave-in, and particularly to a trench shielding unit having adjustable vertical panels to improve access and protection of workers and to underground utilities traversing the excavation area.
2. Description of the Prior Art
In construction, it is often required to excavate underground utilities such as water, gas or sewer lines, pipes, cables, drainage conduit and/or culverts, by digging ditches, trenches and the like of various lengths and depth. Trench shielding units are often used to protect workers and property from cave-ins or landslides by safeguarding against shifts or the collapse of the walls of the excavation. In fact, Occupational Safety and Health Administration (OSHA) regulations require that any excavation over five feet deep be properly shielded to prevent cave-ins or to protect workers inside an excavation in the event of a cave-in.
By contrast, shoring is often used as a more permanent landscaping structure to prevent the sidewall of earthen formations from moving or collapsing, so as not to damage nearby building foundations, shorelines, walkways, bridges, roadways or other architectural structures. More particularly, the positive supporting of a sidewall in this field is called “shoring” while the protection against collapse is called “shielding.”
As previously stated, the current practice in the construction industry is to use a trench shielding unit inside an excavation to protect workers, equipment and underground structures. These units are generally open between opposing walls and at the bottom so that digging can continue while the unit is in place. Of course, the top of the unit is also open for easy access by workers and machinery for removal of dirt or other debris, as well as pipe, equipment and/or tools.
Generally, the structure of a trench unit includes opposing side panels to hold the excavation in place. Additionally, the trench unit has a plurality of bars or beams, more commonly referred to as spreader bars, that transverse the lateral width of the trench unit to hold opposing side panels in spaced relationship. Upon completion of the excavation work, the trench unit is either removed or abandoned in place, and the excavation site is filled.
There are a variety of trench units in use, such as, for example, U.S. Pat. No. Re. 30,185 to Griswold which shows a typical trench shield assembly having protective sidewalls maintained in space relation by spreader bars. Further, U.S. Pat. No. 5,310,290 to Viollaz shows another such shielding unit having legs which telescopically adjust to provide clearance about a structure traversing the trench. Further yet, the shoring unit shown in U.S. Pat. No. 7,021,868 to Farrag et al. describes a lightweight unit that can be assembled above ground and lowered into the excavation to accommodate access to utility pipelines traversing the excavation area, in addition to protecting the worker from sidewall collapse. None of these systems, however, is able to accommodate easily and quickly unplanned obstructions or unanticipated traversing structures passing through the trench.
This invention improves the current field of trenching units by providing opposing sidewalls having a plurality of interengaging panels that are easily adjustable vertically without sacrificing structural strength and reliability of the unit.
SUMMARY OF THE INVENTION
An embodiment of this trench shield includes opposing protective walls, with each protective wall being formed by a plurality of adjustable, vertical panels having interengaging side edges. Each vertical panel has a height, opposing top and bottom ends, and a channel traversing the panel's height. Further, each adjustable panel is easily attached to a whaler, along an inner surface of the panel, by a fastener having a shank passing through a wall of the whaler to the corresponding channel of the panel. The channel is used to clamp the panel to the whaler by way of a retaining washer and nut secured against an inside of the channel and tightened by threads against the whaler. Further, the side edges of adjacent panels are segmented to inter-engage, preferably being concave and convex, respectively, to restrict twisting or torque of the panels caused by shifting or collapse of the excavation.
Notably, this invention is versatile. It allows for easy adjustment and securing of each panel in the desired vertical position to allow underground utilities or other known or unknown obstructions to pass through the excavation at various angles and elevations.
Further, this invention provides improved safety for workers, equipment, material and machinery, and provides the workers more flexibility, without sacrificing structural strength. In particular, the panels may be raised or lowered while in the trench as excavating continues inside the protective walls of the unit. More specifically, the invention facilitates small and large adjustments of individual panels, allowing the worker to adjust by lifting or lowering each panel individually as needed while the unit is in place.
Further yet, the engaging side edges of the adjustable vertical panels are strong and adjust easily into a composite shielding structure that is a safe work environment.
The scope of applicability of the preferred embodiment will become apparent from the following detailed description, claims and drawings. It should be understood, that the description and specific examples, although indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications to the described embodiments and examples will become apparent to those skilled in the art.
DESCRIPTION OF THE DRAWINGS
Having generally described the nature of the invention, reference will now be made to the accompanying drawings used to illustrate and describe the preferred embodiments thereof. Further, these and other advantages will become apparent to those skilled in the art from the following detailed description of the embodiments when considered in the light of these drawings in which:
FIG. 1 is a prospective view of the preferred embodiment of a trench shielding unit;
FIG. 2 is an end view of the trench shielding unit shown in FIG. 1;
FIG. 3 is a side view showing a wall of the shielding unit;
FIG. 4 is a cross sectional view taken along plane 4-4 of FIG. 3;
FIG. 5 is a side view of a sidewall taken along plane 5-5 of FIG. 4 showing a bottom cutting edge and top pounding plate spaced from the wall;
FIG. 6 is a top view of a panel of a sidewall attached to a whaler with the top plate removed and showing partial adjacent panels;
FIG. 7 is a top view of a panel;
FIG. 8 is an end view of a whaler;
FIG. 9A is an side view of a top plate;
FIG. 9B is a side view showing a top plate attached to a panel;
FIG. 9C is a top view showing a top plate attached to a panel;
FIGS. 10A and 10B are side and front views, respectively, of a knife edge assembly; and
FIG. 11 is top sectional view of the wedge assembly attached to a panel.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 7, a trench shielding unit 10 includes opposing first and second sidewalls 12, 14, with each sidewall having an inside face 12′, 14′ and an outside face 12″, 14.″ Each sidewall 12, 14 includes a plurality of vertical panels 20, each panel having a height and opposing concave and convex side edges 28, 29, respectively, which extend along the full height of the panel for inter-engaging with its adjacent panels. Each vertical panel 20 also includes a C-shaped channel 26 having a constant width traversing the panel's height at its center.
As shown in FIG. 5, two longitudinal beams 16, also known as whalers, each of which traverses the length of the trench unit 10 along an inside face 12′, 14′ of a sidewall 12, 14, are each secured to each panel 20 of the respective sidewall 12, 14. Each whaler 16 has a U-shaped cross section, as shown in FIG. 8. Each panel 20 is secured to each corresponding whaler 16 by a clamp-like fastener 42, which includes a threaded fastener 40 and a retaining washer 43 having a nut 46 secured thereto, preferably by a weld, as best seen in FIGS. 6 through 8. More specifically, each panel 20 is attached at its inner surface 12′, 14′ by the fastener 40, whose threaded shank 44 passes through a hole 50 in the whaler engagement wall 51, through an opening 47 in the C-shaped channel 26 of the panel 20, and through a central hole in washer 43. The panel 20 is then secured to the whaler 16 using fastener 40 by securing the head 45 of fastener 40 against the whaler wall 51, and driving the nut 46 into engagement with the threaded shank 44 such that the attached retaining washer 43 is located within the C-shaped channel 26 of the panel 20. The width of the retaining washer 43 is noncircular and slightly smaller than the width of the C-shaped channel 26; therefore, the nut 46 and washer 43 are prevented from rotating within the channel 26 when the fastener head 45 is tightened and loosened on the nut 46.
FIGS. 6 and 7 show that each panel 20 is formed with a concave edge 28 and a convex edge 29, located at the opposite side from the concave edge. The panels 20 are assembled such that the convex edge 29 of one panel nests in the concave edge 28 of the adjacent panel as seen in FIG. 4. Again viewing FIGS. 6 and 7, the concave edge 28 is formed by beveled surfaces 21 and a flat surface 22. The convex edge 29 is formed by beveled surfaces 23 and a flat surface 24. Any twisting or bending of panel 20 is resisted by contact engagement of its beveled surfaces 21, 23 with the corresponding beveled surfaces of the immediately adjacent panels. As an alternative, the flat surface 22, 24 may be scored with traversing teeth for added inter-engagement with the adjacent panels.
As best seen in FIGS. 1 and 2, the opposing first and second sidewalls 12, 14 are spaced mutually across the width of the trench shielding unit 10 by upper and lower spreader bars 75, located at oppose ends of the unit. One end of each spreader bar 75 is fitted into the channel of a whaler 16 located at one of the sidewalls 12, 14 and is secured to that whaler by an attachment pin 73, which passes through the holes 53 in the legs 52 of the whaler, best seen in FIG. 8. The width of the trench shielding unit 10 is incrementally adjustable because the male spreader bar component 71 is telescopically engaged in the female spreader bar component 70, and the spreader bar components are interconnected by bolts or pins 72 fitted in holes 74 mutually spaced along the length of the male spreader bar component 71 and a hole in the female spreader bar component 70. The incrementally adjustable length of the spreader bars 75 is typically established during assembly, before the trench unit 10 is placed inside the excavation.
Referring to FIGS. 1, 9A, 9B and 9C, the upper end of each panel 20 is fitted with a top plate 60 in the form of an angle having a top leg 61, a side leg 62 and a doubler 63, located under and secured to the top leg. The side leg 62 is secured to the panel 20 by a threaded fastener 64, whose head 65 bears against leg 62 and whose shank passes through a hole 66 in leg 62, through the opening 47 in the C-channel 26 of the panel 20 and through a hole in the retaining washer 43. The nut 46 is secure to the washer 43 so that they are retained as a unit in the C-shaped channel, as previously described with reference to attachment of the panels 20 to the whaler 16. Specifically, the width of the retaining washer 43 is noncircular and slightly smaller than the width of the C-shaped channel 26; therefore, the nut 46 and washer 43 are prevented from rotating within channel 26 when the fastener head 65 is tightened and loosened on the nut 46.
Referring to FIGS. 1 and 5, the lower end of each panel 20 is fitted with wedge assembly 80. Referring now to FIGS. 10A and 10B, each wedge assembly 80 includes an angle having a lateral leg 82 and a vertical leg 84, an inclined gusset 86 welded to the legs 82, 84, and a channel 88 welded to the lateral leg 82. The web of the channel 88 is formed with two holes 90. Gusset 86 and leg 84 form a wedge that facilitates staking the lower end of each panel 20 in the ground when force is applied to the top plate 60.
FIG. 11 shows that the wedge assembly 80 secured to the lower end of the panel 20 by installing the channel 88 over the C-channel 26 such that the web of channel 88 is adjacent the inner surface 12′ of the panel 20. The web of channel 88 is secured to the panel 20 by inserting the shank of a threaded fastener 92 into each of the holes 90 in the channel, through the opening 47 in C-channel 26 and through the holes in a retaining washer 43, which are aligned with holes 90. Again, nut 46 is secure to its respective washer 43 as described above. The head 94 of each fastener 92 bears against channel 88. The width of the retaining washer 43 is noncircular and slightly smaller than the width of the C-shaped channel 26; therefore, the nut 46 and washer 43 are prevented from rotating within channel 26 when the fastener head 94 is tightened and loosened on the nut 46.
In use, the trench unit 10 is typically assembled outside of the trench to a desired length and width, by assembling the walls 12, 14 using the appropriate length whalers 16 and attaching adjustable panels 20 thereto as shown in FIGS. 3 and 5. Each panel 20 is assembled with its pounding plate 60 and wedge cutting edge 80 attached as described above. The assembled walls 12, 14 are then spaced, raised and attached by the spreader bars 75. Before or after the assembled trench unit 10 is lifted and lowered into the trench, individual panels 20 may be vertically adjusted, as seen in FIGS. 1 and 3, from inside the unit 10 at its inner surfaces 12′, 14′. More specifically, fasteners 40 of an individual panel 20 are loosened, but not removed, from the corresponding whaler walls 51 to unsecure the panel 20. The panel is then raised or lowered as the retaining washer 43 of fasteners 40 run along and are retained inside of the panel's C-shaped channel 26. Once in place, the fasteners 40 are re-tightened such that each corresponding retaining washer 43 is secured against the C-shaped channel 26 of the panel 20.
As digging continues and the unit 10 is set, pounded or advanced further into the ground, individual panels 20 of walls 12, 14 may be continually adjusted to accommodate uncovered obstructions and underground utilities, such as traversing water, gas or sewer lines, pipes, cables, drainage conduit and/or culverts, as discussed above.
Notably, the invention described in this application pertains to a shoring unit, as with the shielding unit described herein. It should be further noted that the present invention can be practiced otherwise than as specifically illustrated and described, without departing from its spirit or scope. It is intended that all such modifications and alterations be included insofar as they are consistent with the objectives and spirit of the invention.
Patent Application
20100034597
