REINFORCED CONCRETE PANEL AND METHOD OF MANUFACTURE

Abstract

A reinforced concrete panel is formed by embedding a stretched steel chain link mesh unit within concrete. The panel can be used to form a building or a flood dyke, or an earth reinforcing wall. The earth reinforcing wall is formed by digging a trench in the soil. Vertical posts are positioned in the trench, the posts spaced apart by a distance corresponding to a width of a panel. The panels are lowered between adjacent pairs of posts, and the edges of each panel slide within grooves formed in the posts. Finally, the trench is filled with concrete to encase the panels and posts.

Description

BACKGROUND OF THE INVENTION

[0002] This invention relates to the manufacture of a reinforced concrete panel, and installation of a uniquely prestressed, high strength/to weight modular reinforced concrete wall from the panels which is rapid to manufacture and install. The panel is primarily used for the construction of buildings or the reinforcement of soil or the deflection of flood waters.

[0003] Floodwaters annually take a toll on life, health, property, and well being in the United States of America. As human population values continue to increase in areas known or unappreciated as being part of a flood plane, injuries of the same will continue. Current methods of flood water protection in the form of property elevation, levee building, or particularly, wall construction are often difficult to initiate when implementation or maintenance costs are taken into account. These costs are often staggering due to the large amount of equipment, machinery, materials, labor and time involved to cause a project of this type to come to its fruition. This is especially true if there is a short time frame allotted for the construction or installation of the same to circumvent flooding which although may not be common for a particular geographical area, it has been predicted to be in imminent danger of such an occurrence happening there as a result of actions by man, nature, or a combination of both.

SUMMARY OF THE INVENTION

[0004] One aspect of the invention relates to a reinforced structural panel which comprises a concrete body having a pretensioned metallic chain link unit embedded therein and extending across a substantial portion of the concrete body. The panel can be used to construct a building or a soil retaining wall, or a flood dyke for example.

[0005] Another aspect of the invention relates to an apparatus for forming a reinforced structural concrete panel. The apparatus comprises a frame which includes side walls and a backing wall forming a cavity. The frame is pivotable about a horizontal axis for being pivoted between horizontal and vertical orientations. The cavity is upwardly open when the frame is in a horizontal orientation and is adapted to receive poured concrete for forming a concrete panel. The backing wall is adapted to support a chain link unit and a concrete body when the frame is in a horizontal orientation. At least two of the side walls of the frame have holes formed therethrough for enabling wires to pass from the cavity to the exterior to hold a chain link unit in a pretensioned state. The stretching mechanism is removably mounted on the frame when the frame is in a horizontal orientation. The stretching mechanism includes tensioning members disposed in the cavity and adapted to engage a chain link unit. The stretching mechanism also includes a displacement device for displacing the tensioning members relative to the frame for pretensioning a chain link unit prior to the pouring of concrete into the cavity.

[0006] Another aspect of the invention relates to a method of forming a reinforced structural concrete panel comprising the steps of:

[0007] A. positioning a metallic chain link unit in a cavity formed by a frame;

[0008] B. applying tensioning forces to the chain link unit for stretching and pretensioning the chain link unit;

[0009] C. pouring concrete into the cavity while maintaining the chain link unit in a pretensioned state, to embed the chain link unit in the concrete;

[0010] D. allowing the concrete to harden; and

[0011] E. releasing the tensioning forces from the chain link unit.

[0012] Another aspect of the invention relates to a method of forming an earth retaining wall comprising the steps of:

[0013] A. digging a trench in the ground;

[0014] B. anchoring panel-retaining members in the trench;

[0015] C. lowering reinforced concrete panels into the trench between respective pairs of panel-retaining members such that opposite vertical edges of each panel become connected to the respective pair of panel-retaining members by a tongue-and-socket coupling; and

[0016] D. pouring concrete into the trench to embed the panels and the panel-retaining members therein.

[0017] The floodwater deflection wall manufacturing and installation system comprise various components, and methodologies. During the manufacturing phase various platforms, forms, molds, tools, materials, and techniques are utilized in the production of panels and posts.

[0018] A skeletal frame composed of rebar is welded. This framework is suspended within the post casting mold. The rebar extends outside of the posts cast bottom surface plane, unless this is not necessary such as being incorporated into a cast post which is to be pile driven.

[0019] A marriage band is shipped to the job site with each post. This is a welded unit utilizing rebar its function is described later in the installation process description.

[0020] Outer casting border mold frames are clamped to a tilt up panel casting platform. A galvanized woven wire mesh with is placed in the form. This woven wire is more commonly known as chain link fence fabric. Rebar is inserted into the end sections which run at the top and bottom of the panel left to right within the panel in relationship to an upright panel. The same type of rebar components may be inserted in the same manner within the mesh at intervals proceeding down the panel's vertical plane. The woven wire mesh is then pulled in tension at bottom panel station until the mesh has at this point become suspended under tension. This will give the reinforcement mediums an added element in maintaining structural strength. The individual uninterrupted wire strands which make up the woven wire proceed from left to right. They have 45 degree bends up and down as they traverse to the right. This provides the panel's concrete several reinforcement benefits. The wire is not at only one uniform plane, in reference to x, y, and z coordinates it has several lines of reinforcement amplification. It being pre-stressed with the uninterrupted wire run proceeding from left to right in relationship to an upright panel allows the hardened concrete a degree of pressure resistance with flexibility, yet will retain its binary compounds which are in the form of portland cement and aggregates in various embodiments from falling out of a state of cohesion. The incorporation rebar into this weave provides an additional redundant static reinforcement. In conjunction with these, rebar is laid on a vertical plane in relationship to an erected panel at the left and right edges, center, and left and right ⅓rd measurements on top of the woven wire mesh. This is a redundant factor which is used for additional reinforcement in a positive fashion. The concrete is now poured, and the surface finished smoothly.

[0021] A quarter radius void bar is placed at the left, and right side of the forms in relationship to an upright panel in the wet concrete. These void bars run from the top to the bottom of the mold at their respective placements. The purpose of these two voids will be described at the installation process description once the panel has cured the forms and molds are stripped, tie wires cut, the tilt up casting platform elevated to an upright position, the panel slides down on the anchor/panel resting stop, a forklift picks it up and it is loaded out to the job site.

[0022] At the installation location shot points and grades are established. At predetermined intervals holes are bored to a predetermined depth below established grade. Upon completion of the weekly production quota of hole, a chain trencher commonly known as a “Ditch witch” with a cutting certain width of will trench a line center of the hole lines to a predetermined depth below grade. Upon completion of the trenching phase adjustable site leveled prepostioning post holding template rack stands are laid out and adjusted.

[0023] Then the prepositioning post holding template rack is lowered onto the stands, adjusted, and clamped down in place. The posts are then lowered in their respective holes arid held at a predetermined height by a height retention stand, unless they are pile driven into the ground. The rebar which protrudes beyond the bottom perimeter of the “H” shaped post is pushed down below surface of the bottom of the bore holes. The marriage band is then lowered to a point that it encompasses the bottom length of the “H” post. Cement is poured downhole to within close proximity of the bottom of the panel holding slot in the “H” post. The rebar protruding from the post to below the borehole subsurface and the marriage band serves as a reinforcement measure to bind the precast post in place with the newly poured concrete.

[0024] Upon the curing of the newly poured concrete downhole, the post holding templates will be removed.

[0025] Wood forms will be inserted into the slots of the “H” posts and rest on the anchoring pour which was previously done. A second pour of concrete will be initiated down hole on one side of the “H” post to the ground surface. The concrete will dry, and the forms will be removed.

[0026] The panels will be slid down the slots on the sides of the “H” post. The panels will have grout pumped down the quarter radius void cast in the panel and resting within the confines of the slots of the cast posts. This will provide a static surface movement area between the “H” post, and the panel. Upon completion of this phase grout, or cement will be pumped down the void between concrete panel and the trench walls subsurface. The remainder of the bore hole void on the side of the, “H” post will be filled with grout.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The objects and advantages of the invention will become apparent from the following detailed description of preferred embodiments thereof in connection with the accompanying drawings in which like numerals designate like elements and in which:

[0028] FIG. 1A is a side elevational view of a panel-forming mechanism according to the present invention, with a frame thereof in a vertical orientation;

[0029] FIG. 1B is a front perspective view of FIG. 1A;

[0030] FIG. 2 is a top perspective view of the apparatus depicted in FIG. 1, when a frame thereof is in a horizontal orientation, and a stretching mechanism is mounted thereof;

[0031] FIG. 3A is a side elevational view of the apparatus depicted in FIG. 2;

[0032] FIG. 3B is a perspective view of the stretching mechanism;

[0033] FIG. 4 is a side elevational view depicting a chain link unit being pretensioned in the frame;

[0034] FIG. 5A is a top plan view of a section of a conventional chain link unit;

[0035] FIG. 5B is a top plan view of an edge section of the conventional chain link unit;

[0036] FIG. 6 is a top plan view of the unit depicted in FIG. 2 as the stretching mechanism is pretensioning a chain link unit disposed in a cavity of the frame;

[0037] FIG. 7 is a view similar to FIG. 6 after the chain link unit has been fully pretensioned, and the stretching mechanism has been removed;

[0038] FIG. 8 is a top plan view of the frame after concrete has been poured into the cavity to embed a pretensioned chain link unit therein, with a portion of the concrete broken away to reveal the chain link unit;

[0039] FIG. 9A is a sectional view taken through the frame and concrete panel;

[0040] FIG. 9B is a perspective view of members inserted into the cavity to form quarter-circle recesses in the concrete panel;

[0041] FIG. 10 is a front perspective view of the frame after the chain link tensioning wires have been severed, a bottom wall of the cavity has been removed, the frame has been pivoted to a vertical orientation, and the concrete panel has slid slightly downwardly onto a stop surface;

[0042] FIG. 11 is a front perspective view of a finished reinforced concrete panel according to the invention, with a portion of the panel broken away to reveal the reinforcement;

[0043] FIG. 12A is a side elevational view of a first type of framework;

[0044] FIG. 12B is a side elevational view of a second type of framework;

[0045] FIG. 12C is a top plan view of a concrete post in which the frameworks of FIGS. 12A and 12B are disposed as reinforcement;

[0046] FIG. 13 is a front perspective view of the post depicted in FIG. 12C;

[0047] FIG. 14 is a front perspective view of a framework;

[0048] FIG. 15 is a front perspective view of the post of FIG. 13 disposed in the ground, and with the framework of FIG. 14 inserted downwardly around the post;

[0049] FIG. 16 is a perspective view of vertical holes being drilled into the ground;

[0050] FIG. 17 is a view similar to FIG. 16 as a trench is being dug into the ground in intersecting relationship to the holes;

[0051] FIG. 18 is a front perspective view of a stand adapted to support a post holding template, the stand being erected over the trench;

[0052] FIG. 19A is a top plan view of a template rack that is supported on a plurality of the stands depicted in FIG. 18;

[0053] FIG. 19B is a front elevational view of the arrangement depicted in FIG. 19A;

[0054] FIG. 20 is a top plan view depicting the post of FIG. 13 being lowered through the template and into one of the holes shown in FIG. 17;

[0055] FIG. 20A is a perspective view depicting a manner of adjusting support rollers of the template;

[0056] FIG. 21A is a front elevational view of a post holding template with a post projecting therethrough;

[0057] FIG. 21B is a perspective view of an upper end of the post depicted in FIG. 21A;

[0058] FIG. 22 is a view depicting the posts being lowered through the template;

[0059] FIG. 23 is a view through the earth depicting the post disposed in one of the holes;

[0060] FIG. 24 is a view similar to FIG. 23 after concrete has been inserted into the hole to anchor the post;

[0061] FIG. 25 is a view similar to FIG. 24 after forms have been inserted into an upper portion of the post;

[0062] FIG. 26 is a view similar to FIG. 25 after additional concrete has been poured into the trench to fully anchor the post;

[0063] FIG. 27 is a sectional view taken along the line 27-27 in FIG. 26;

[0064] FIG. 28 is a view showing panels of the type depicted in FIG. 11 being lowered into the trench;

[0065] FIG. 29 is a top plan view of FIG. 29 depicting panels arranged in tongue-and-socket connection with adjacent ones of the posts;

[0066] FIG. 30 is a view similar to FIG. 29 after additional concrete has been poured into the trench; and

[0067] FIG. 31 is a perspective view of an alternative form of frame for forming a reinforced panel, with a portion of the frame being broken away to reveal the panel.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0068] Reinforced Panel:

[0069] Referring now to the drawings, particularly to FIGS. 1A-3, there can be seen a rectangular steel box tubing which serves as a stable footing 101a for a tilt up casting platform 99. A steel barrel hinge 102 allows the tilt up casting platform to be tilted up in the direction 100i. The hinge 102 is welded to portions of square steel box tubing that is welded to the bottom of a steel frame 104 of the tilt up casting platform 99 in which other items are either welded to or attached to. A stationary leg 105 made from steel box tubing is secured to the frame 104. When the tilt up casting platform 99 is rotated to a horizontal state, the leg 105 supports the weight of the upper half of the unit. The frame 104 includes a top I-beam section 106a, a bottom I-beam section 106b, and two side I-beam sections 106c, 106d interconnecting the top and bottom sections in any suitable manner, e.g. by welds or clamps. A steel casting deck 107 is welded to the frame 104. A wire retention bar 108 passes beneath an anchor/panel resting stop 109 which has been welded to the frame 104. The bar 108 is affixed to fingers 108a that are affixed to the frame 104.

[0070] Referring to FIG. 2, the tilt up casting platform 99 is shown in a horizontal state, and a chain link tensioning apparatus 100 is in place resting on the anchor/panel resting stop 109.

[0071] Referring to FIGS. 3A and 3B, the chain link stretching apparatus 100 comprises a hand wheel 100e attached to a rod 10g which passes through a machined block 10d and includes a threaded section 100f. The section 100f passes through a threaded hole of a machined steel block 100c. When 100e is turned in direction 100h, the block 100c and its direct associated parts namely, a bar 100b and legs 100a, are drawn in direction 100i′. The block 100d is anchored upon stop 109 and has resistance provided by a tension bar 100j held by a lower end of a conventional woven steel chain link mesh 101a, an upper end of which is attached to a portable wire retention bar 100k situated above, and held snug by, the outer surface of the top section 106a of frame 104 (see FIG. 3A).

[0072] Referring to FIG. 3A, the chain link tensioning apparatus 100 is set upon the anchor/panel resting stop 109 and the deck 107. The fingers 100a, which are rigid steel fingers, rest on the surface of the deck 107 and pull against the tension bar 100j. That bar is secured by tie wires 101b which pass through respective holes 106 formed in the bottom section 106b of the frame 109. The tie wires 101b extend to the wire retention bar 108 on which they are wrapped (see FIG. 4).

[0073] In the same fashion, at the top of the mold this step is repeated. That is, the bar 100k is held tight against the outer face of frame section 106a by the tension exerted from the woven chain link mesh 101a held in place by the tension bar 100j′ which has been inserted in the end runs of the wire weave, as that same force is transferred to the wires 101b′ that pass through holes 106e′ formed in the frame top section 106a.

[0074] In reference to FIG. 5A, a section of the conventional chain link mesh 101a is presented. When an independent strand of wire 102a of the mesh 101a is twisted in the direction 100h, the independent strand of wire 102a will weave into the matrix of the mesh 101a as it follows the direction 100i″. Subsequently, if a twist in a direction reversely of 100h is initiated, the strand 102a will travel in the reverse direction, and eventually disengage itself from the whole mesh. It is in this conventional fashion that the individual wire strand members are woven to make up the matrix of a section of woven chain link mesh.

[0075] In FIG. 5B, there is shown a fragmented singular wire strand 102a with a fragmented portion of the tension bar 100j inserted within the weave. In FIG. 4, this bar 100j, as well as bar 100j′, is under tension.

[0076] In reference to FIG. 6, three additional pieces of rebar designated as 100z are provided in the section of chain link. These are redundant rebars that are not involved in the stretching or tensioning acts, but rather serve as redundant concrete reinforcement as will become apparent. In FIG. 6, the stretching apparatus 100 is in the process of stretching the mesh 101a.

[0077] In reviewing FIG. 7, the chain link mesh 101a has been stretched to within close proximity of frame section 106b. Redundant rebars 100x have been laid on top of the mesh, and are not inserted into the chain link mesh. The stretching apparatus 100 has been removed since it has completed its use. The tie wires 101b have been wrapped around the bar 108 to cause the chain link mesh 101a to remain in tension, so that the concrete can be poured within the confines of the frame 104, as shown in FIG. 8.

[0078] In reference to FIG. 8 an optional additional wire retention bar 108′ is shown on the left hand side of the tilt up casting platform. There is an additional anchor/panel resting stop 109′ and that in place of original frame sections 106d, and 106c, additional frame sections identical to frame sections 106b, and 106a have been provided. The purpose of this is so that a second layer of chain link mesh, if required for some purpose, may be installed in the same fashion as the steps depicted in FIG. 6, and in FIG. 7. In this redundant application, instead of the direction of the weave going from left to right at the base of the mold, it would proceed left to right in relationship to the side of the mold. The tilt up casting platform would still tilt up in the same direction as shown in FIG. 1A.

[0079] In reference to FIGS. 8-10, concrete 110 has been poured and smoothed out. As seen in the broken away section of this concrete, items associated with the chain link mesh 101a are embedded inside the concrete. Bar molds 106e have been placed on the wet concrete after the finish work has been done. The purpose of these bar molds 106e is to leave a quarter circle imprint 111 at the outer surface edge of two sides of the cast concrete panel 110′. When the concrete has “cured” the 106e bar molds are stripped away from the panel 110.

[0080] Then, the tie wires 101b and 101b′ are cut loose, and the sections 106d, 106a, 106c and 106b of the frame 104 are removed (FIG. 10). Referring to FIG. 10, the casting platform 99 has been tilted up, and the concrete panel 110′ is allowed to slide down in direction 100h to rest upon the anchor/panel resting stop 109.

[0081] In reference to FIG. 11 a perspective cutaway view of a finished concrete panel 110′ is shown in its upright position with the woven chain link mesh 101a under tension, and bound by the concrete.

[0082] That panel 110′ is uniquely strong and can be used in the fabrication of highly durable buildings or flood dykes, or, as will be described below, as an earth reinforcement wall.

[0083] Earth Reinforcement Wall:

[0084] Meanwhile, in FIG. 12A, three vertical sections of rebar 120′ have been welded to horizontal sections of rebar 120″ to form a skeletal framework 120 that is to be used in fabricating the earth reinforcing wall. In FIG. 12B, two vertical sections of rebar 121′ have been welded to horizontal rebar sections 121″ to form a skeletal framework 121a.

[0085] In FIG. 12C, the completed framework 120, and two of the completed frameworks 121 a have been welded together to form a matrix which is embedded in concrete 122a to form a post 122. Two slots 123a formed in the post 122 constitute rest stops aw will be described (see FIG. 13). The post 122 includes a hole 122b at its upper end which goes from one side of the post to the other.

[0086] In FIG. 14 there are shown four skeletal frameworks 125 each formed of vertical rebars 125a and horizontal rebars 125b. The four frameworks 125 have been welded together to form a unit 126 hereinafter called a marriage band.

[0087] FIG. 15 shows how the marriage band 126 is to be combined with the post 122 in a vertical hole 127 formed in the ground, as will be explained subsequently.

[0088] In reference to FIG. 16, there is shown a conventional tractor-mounted drilling unit 428 traveling along the ground surface 129 drilling the holes 127 to a predetermined depth, at a predetermined distance apart. The holes 127 are sized to accommodate the concrete posts 122 and the marriage bands 126 shown in FIG. 15.

[0089] In reference to FIG. 17 and 18, there is shown a tractor mounted trenching unit 432 traveling along the surface 129 digging a trench 131 to a predetermined width W and depth D through the previously drilled holes 127.

[0090] In reference to FIG. 18 a perspective view of a template rack stand 138 is viewed straddling the trench 131. The stand 138 includes base plates 132 resting stationarily on the ground at predetermined positions. A cylindrical piece of cut tubing 133 is welded to each base plate 132. The inside void of each tube 133 accommodates, and maintains, the vertical position of a threaded rod 134 which is capable of rotating freely within the confines of the tube 133. Steel blocks 135 having a threaded passageway in the center are welded to an end of a steel I beam 137. A handcrank 136 is attached to the top of the threaded rod 134. Turning of the handcrank 136 will cause rods 134 to turn in the same direction and, depending on the direction of rotation, cause blocks 135 to travel up or down.

[0091] A plurality of stands 138 is provided to hold a post holding template rack 200, as shown in FIG. 19a, 19b. The template rack 200 has two identical vertically spaced support levels, one of which being depicted in FIG. 20.

[0092] FIG. 20 depicts from above, a post holding template rack 200 which includes stationary members 207a, 207b, 207c, 207d. The member 207a carries two rollers 206 which will roll, but are incapable of back and forth travel. The same is true of roller 206a attached to the member 207b. Mobile members 209a, and 208a carry rollers 206c, 206d. The members 209a, 208a are able to be slid back or forth in the direction of the respective arrows, depending on which direction a respective threaded rod 202a, 202b passing through the main framework 200 is turned. Member 208a rests upon a piece of plate steel 203 welded to the bottom of the main framework 200. Member 209a rests atop members 207a, 208a, and 207c.

[0093] These resting places allow units 209a, and 208a to remain in a fixed horizontal plane and be pressed firmly in their respective directions of travel against a post 122 or 124. An arrangement identical to that shown in FIG. 20 is provided in vertically spaced relationship to that shown in FIG. 20.

[0094] A plurality of the posts 122 are brought by a suitable transport vehicle 402 to the template rack 200, as shown in FIG. 22. Each post is lowered downwardly through the template rack 200 and into a respective hole 127. Base members 213 are supported atop the template rack 200 (see FIG. 21A, 21B), and a pipe 212 is inserted through the hole 122a formed in the upper end of the post 122. Ends of the pipe 212 are supported in recesses formed in the base members 213. Thus, the posts are suspended.

[0095] A vertical position of the post 122 can be controlled by rotation of the hand cranks 136.

[0096] The rollers 206c, 206d are moved into engagement with the respective posts to maintain the posts in vertical orientations as they are moved downwardly.

[0097] Then, the marriage bands 125 are lowered down around respective posts 122, as shown in FIG. 23.

[0098] Then, as shown in FIG. 24, a concrete base 311 is poured. Pieces of wood 310 were previously installed to act as temporary forms for controlling the shape of the concrete above the level of the holes 127. Then, the forms 310 are removed.

[0099] Then, forms 320 are positioned within the recesses 123a of the post, as shown in FIGS. 25-27. Each form 320 includes a portion extending into a respective recess 123a, and a portion 320a engaging a side of the trench 131, whereby a space is formed between the trench 131, the post 122, and the forms 320. Concrete 319 is then poured into that space as shown in FIGS. 26 and 27. Then, the forms 320 are removed.

[0100] A vehicle 402 then brings previously-described reinforced concrete panels 110′ and lowers them such that opposite vertical edges thereof enter the recesses 123 of adjacent ones of the posts 122, as shown in FIGS. 28 and 29. Thus, the posts 122 constitute panel retaining members. The panels 110′ descend until coming to rest on the bottom 130 of the trench 131.

[0101] Then, the rest of the holes 127 and trench 131 is filled with concrete 319 to completely embed the panel, as shown in FIG. 30. The quarter-circle voids 111 formed in the panel have also been filled with concrete 319.

[0102] It will be appreciated that modifications are possible within the scope of the invention. For example, the method of inserting the marriage band 126 into the ground (FIG. 23) depends upon the ground being relatively soft. If, on the other hand the ground is hard, then the holes 127 would not be drilled; only the trench 131 would be dug. The posts 122 would be provided with pointed bottoms and would be hammered into the ground within the trench 131 in order to become anchored. No marriage bands would be used.

[0103] Also, the frame 104′ which forms the cavity in which the concrete panel 110′ is fabricated could alternatively be formed by elements 200 having a U-shaped cross section, as shown in FIG. 31. The elements 200 are welded together, and the elements and the backing plate 107, form part of the finished reinforced panel, along with the concrete and the chain link unit 101a.

[0104] Although the present invention has been described in connection with preferred embodiments thereof, it will be appreciated by those skilled in the art that additions, deletions, modifications, and substitutions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A reinforced structural concrete panel comprising a concrete body having a pre-tensioned metallic chain link mesh unit embedded therein, the chain link mesh unit extending across a substantial portion of the concrete body.

2. The reinforced structural panel according to claim 1 wherein the chain link mesh unit comprises steel.

3. The reinforced structural panel according to claim 1 wherein the panel is of substantially rectangular shape.

4. The reinforced structural unit according to claim 3 wherein two parallel corners of the panel include respective quarter-circle recesses formed therein.

5. Apparatus for forming a reinforced structural concrete panel comprising: a frame including side walls and a backing wall forming a cavity, the frame being pivotable about a horizontal axis for being pivoted between horizontal and vertical orientations, the cavity being upwardly open when the frame is in a horizontal orientation and adapted to receive poured concrete for forming a concrete panel, the cavity including a backing wall adapted to support a metallic chain link mesh unit and a concrete body when the frame is in a horizontal orientation, at least two of the side walls having holes formed therethrough for enabling wires to pass from the cavity to the exterior to hold the chain link mesh unit in a pre-tensioned state; and a stretching mechanism removably mounted on the frame when the frame is in a horizontal orientation and including tensioning members disposed in the cavity and adapted to engage the chain link mesh unit, and a displacement device for displacing the tensioning members relative to the frame for pre-tensioning the a chain link mesh unit prior to the pouring of concrete into the cavity.

6. A method of forming a reinforced structural concrete panel comprising the steps of: A) positioning a metallic chain link mesh unit in a cavity formed by a frame; B) applying tensioning forces to the chain link mesh unit for stretching and pre-tensioning the chain link mesh unit; C) pouring concrete into the cavity while maintaining the chain link mesh unit in a pre-tensioned state, to embed the chain link mesh unit in the concrete; D) allowing the concrete to harden; and E) releasing the tensioning forces from the chain link mesh unit.

7. The method according to claim 6 wherein at least steps C and D are performed while the cavity and chain link mesh unit are oriented horizontally, and including the further step of rotating the form about a horizontal axis for raising the panel to a vertical state subsequent to step D.

8. The method according to claim 6 wherein step B comprises engaging the chain link mesh unit with fingers of a stretching member and rotating a shaft that is threadedly connected to the stretching ember to cause one end of the chain link mesh unit to be displaced while holding an opposite end thereof stationary.

9. The method according to claim 8 wherein the opposite end of the chain link mesh unit is held stationary by extending wires through respective holes in the form and attaching one end of each wire to the chain link mesh unit and another end thereof to a stationary member situated outside of the cavity.

10. A method of forming an earth retaining wall comprising the steps of: A) digging a trench in the ground; B) anchoring panel-retaining members in the trench; C) lowering reinforced concrete panels into the trench between respective pairs of panel-retaining members such that opposite vertical edges of each panel become connected to the respective pair of panel-retaining members by a tongue-and-socket coupling; and D) pouring concrete into the trench to embed the panels and the panel-retaining members therein.

11. The method according to claim 10 further including making the reinforced concrete panel by the steps of: A) positioning a metallic chain link mesh unit in a cavity formed by a frame; B) applying tensioning forces to the chain link mesh unit for stretching and pre-tensioning the chain link mesh unit; C) pouring concrete into the cavity while maintaining the chain link mesh unit in a pre-tensioned state, to embed the chain link mesh unit in the concrete; D) allowing the concrete to harden; and E) releasing the tensioning forces from the chain link mesh unit.

12. The method according to claim 10 further including, prior to step A, the step of digging vertical holes in the ground, with centers thereof lying on a common line, step A being performed such that the trench is dug along the common line to intersect the holes, the trench being shallower than the holes, step B being performed by anchoring the panel-retaining members in respective ones of the holes.

13. The method according to claim 12 wherein a lower portion of each panel-retaining member is embedded in the ground beneath the respective hole.

14. The method according to claim 10 wherein step C comprises lowering each panel such that vertical edges thereof slide downwardly within vertical slots formed in respective panel-retaining members to form the tongue-and-groove coupling.