System for Stabilizing Structural Elements

This invention relates to a system for stabilizing spaced structural elements so that the elements maintain a fixed position relative to one another.

The system has particular application to load bearing structural elements. Examples are underground utility enclosures and associated cover frames, as well as other ground or pad mounted equipment and structures.

The most common approach for stabilizing structural load bearing elements such as underground enclosures and their associated frames is to employ cementous grout. Even when quick setting cementous grout is employed for such purpose, a tremendous investment in labor and time is involved. For example, installation of quick setting cementous grout between an underground utility vault and its frame quite typically runs in the order of 4 to 6 hours. Then too, there is an extended set time before full traffic loads can be withstood. It is not uncommon for set time of quick setting cementous grout to run in the order of three days or more. Because of the long period of time between installation of cementous grout and load bearing set time, a crew will have to make a separate trip to the site to reopen the street or perform such other actions as may be necessary, again adding to the cost of the project.

Waste can also be a problem when cementous grout or other materials are mixed on site. In fact, loss is virtually bound to occur when typical techniques are employed to fill a void space between load bearing structural elements. Often too much grout or other similar material is mixed simply because it is difficult to estimate requirements. And, of course, when employing conventional approaches a good portion of the grout or other mixture regularly ends up where it is not required.

The present invention, by contrast, relates to a system for stabilizing load bearing structural elements quickly and efficiently. In fact, in most applications, the time from initial installation to full load bearing capacity will normally run one hour or so. Thus, when the present system is employed, labor time and costs are significantly reduced as compared to the prior art approach of utilizing cementous grout.

The present system also conserves materials by virtually eliminating waste. The amount of material to be employed can be estimated readily. In addition, spillage almost never occurs and the material is confined to where it is actually needed.

According to the teachings of the present invention, a semi-permeable, flexible container containing a structural foaming agent is positioned in a void space between two structural elements, for example, an underground enclosure and a frame spaced from the underground enclosure. The components of the structural foaming agent are mixed just prior to placement of the container in the void space. When the agent foams, it expands, filling the flexible container, and a portion of the agent migrates from the interior of the container to the outer surface thereof through a plurality of openings in the container.

The migrating agent portion from the one or more containers in the void space contacts the structural elements during foaming. When the foam is hardened in place, a bond will thus be established between the container (or the containers) in the void space and the structural elements whereby the structural elements are stabilized in position.

FIG. 1 is a somewhat schematic illustration of the step of combining the foaming agent components during the initial stage of the mixing procedure;

FIG. 2 is a perspective view, also in somewhat schematic fashion, showing the mixed foaming agent being poured into a container of a type employed in the present system;

FIG. 3 is a perspective view of the container closed at both ends after the structural foaming agent has been placed therein;

FIG. 4 illustrates the container of FIG. 3 being flattened prior to its placement in operative position between structural elements;

FIG. 5 is a perspective view of two structural elements having a plurality of containers filled with structural foaming agent positioned therebetween;

FIG. 6 is an enlarged, perspective, cross-sectional view illustrating portions of two structural elements and a container filled with foaming agent, prior to foaming, disposed therebetween;

FIG. 7 is a cross-sectional end view of the structural elements and container illustrating how the configuration of the container changes during the foaming operation;

FIG. 8 is a plan view of structural components illustrating a plurality of containers positioned therebetween in partial overlapping fashion so as to form a fluid-tight seal; and

FIG. 9 illustrates two containers folded over and in partially overlapping relationship.

Referring now to the drawings, and in particular to FIGS. 5-7, a structural element in the form of an underground utility enclosure or vault 10 is illustrated. Disposed above enclosure 10, as is conventional, is a second load bearing structural element 12 in the form of a traffic frame. For purposes of illustration, elements 10 and 12 are positioned in a roadway 14 and traffic frame 12 carries lids 16 substantially coplanar with the roadway.

It will be appreciated that the system of the present invention is employed to stabilize traffic frame 12 relative to enclosure 10 in such a way as to transfer any load imparted to traffic frame 12 to the enclosure. Prior to carrying out the method of the present invention, the frame and enclosure must be relatively positioned so as to provide a void space therebetween. This may be done through use of any suitable conventional hardware such as the spacer shown in FIG. 7 and identified generally by reference numeral 20. Spacer 20 includes a rod 22 having screw threads formed thereon. Rod 22 is threadedly engaged with a bracket 24 positioned on enclosure 10 and a nut 26. Rod 22 projects through an aperture in traffic frame 12 so that the frame rests upon nut 26. It will be appreciated that the nut may be adjusted along the length of rod 22 to adjust the spacing between elements 10 and 12. Of course, a number of spacers 20 are suitable deployed along the periphery of elements 10 and 12 to provide substantially uniform spacing therebetween.

Referring now to FIG. 1, such Figure merely illustrates the fact that structural foaming agents of the type employed in the present invention are of a multi-component nature, said components being mixed to initiate the chemical processes involved in the foaming action. For purposes of illustration, the foaming agent is a two component system. One such system which has been found to be effective is a liquid epoxy foam system having a ceramic filler, such as the foam marketed by Insitu Corporation under the trademark "InsituFoam" and incorporating materials disclosed in U.S. Pat. No. 4,092,296. The epoxy resin associated with such system can be contained in receptical 30 and the curing agent contained in bottle 32. The operator pours the contents of bottle 32 into receptical 30 to complete the foam system. The system is then thoroughly mixed by any suitable expedient within receptical 30.

As is shown in FIG. 2, the contents of receptical 30, having been thoroughly mixed, are then poured into a container 34. Container 34 is of a specific type, namely a bag or tube constructed of flexible material such as mylar or nylon. The material is water repellant and semi-porous and, preferably, the container or bag 34 includes seam 36 loosely stitched along the full length thereof along two sides. When filled, container 34 is closed at the lower end as by means of a metal or plastic tie 38. After the desired amount of foaming agent is poured into container 34, the other end thereof is also closed off by a tie 38 or by some other suitable means so the container has the appearance shown in FIG. 3.

The operator now positions container 34 on a flat surface as shown in FIG. 4, preferably with the seams 36 being disposed at the top and bottom of the container. With a roller 40 or other suitable expedient, the operator levels out the contents within the container.

The next step is to place the container 34 in the void space defined by structural elements 10 and 12. As can be seen in FIG. 5, the operator will normally position a plurality of such containers in the void space. In the FIG. 5 layout, a number of containers 34 are disposed in a single layer end-to-end about the periphery defined by the enclosure 10 and frame 12. If a water-tight seal is desired between the structural elements the containers 34 can be overlapped at their ends as shown in FIG. 8.

As perhaps best shown in FIGS. 6 and 7, the container or bag 34, when initially positioned in place, does not contact frame 12. Also, it should be noted that a seam 36 faces the frame while its companion underneath (not shown) is oriented toward enclosure 10.

Foaming of the contents of the container now takes place and the flexible material of the container allows two things to happen. First, the container distorts as pressure builds up inside due to foaming of the agent. As shown in FIG. 7, this distortion brings the upper container surface (in the position shown in broken line) into contact with frame 12. The following second action is equally important to the operation of the present system. Due to the openings formed in the surface of the container (which in this case are defined by the porosity of the material caused by loose weaving of the filaments thereof) a portion of the foaming agent migrates through the openings and is disposed externally of the container. A portion also migrates between the stitching forming seams 36 and is thus somewhat concentrated where the container contacts the enclosure and frame.

It will be appreciated that the two actions just described cooperate to create a bond between the container and both structural elements 10 and 12. That is, the portion of the foaming agent which has migrated through the openings is in direct engagement with both structural elements. The foaming agent thus foams one continuous body of foam between the structural elements 10 and 12.

The foam is now allowed to harden in place. Employing the "InsituFoam" product referred to above, it has been found that a load bearing cure can be effected within an hour or so. Because of this quick stabilization of the two structural elements it will not be necessary for the road crew or other workers employing the system to make a return trip days later to reopen the street or perform such other work as is normally necessary.

It will be appreciated that in some instances the void space existing between structural elements may be too great to allow stabilizing thereof by foam agent filled containers disposed in a single layer. The present system works just as well when more than one layer of bags is employed. The system, due to the migration of the agent portion through the containers, will bond the containers to each other as well as to the structural elements with which they are employed. The layering may be accomplished in any suitable fashion. FIG. 9 shows one approach to doing this wherein a double layer of containers is required to fill a void space. Referring to that Figure a first container 34 is folded over prior to placement thereof in a void space. The overlying segment 50 of container 34 is approximately half the size of the underlying segment 52. A second container 34a of like construction is then folded as shown in the broken lines in FIG. 9 so that the upper segment 50a thereof partially extends over segment 52. The lower segment 52a of container 34a is in end to end relationship with segment 52. Of course, other suitable stacking schemes for establishing multi-layers of containers may be employed as long as an integral bond and connection is maintained between the structural elements and the foaming agent of the stacked containers.