US3404533A - Self-stabilizing shoring system - Google Patents

Description

7 Wm v 5 W m 3 m c, 7 s/sssysse/ /w M 5 J w M F 4 0 r L 4 w Z W M Z x Z Oct. 8, 1968 United States Patent 3,404,533 SELFSTABILIZING SHORING SYSTEM James L. Brunton, 20924 Avis Ave., Torrance, Calif. 90503 Filed Aug. 26, 1966, Ser. No. 575,400 3 Claims. (Cl. 61-41) ABSTRACT OF THE DISCLOSURE A trench-shoring system is disclosed including a pair of wall-supporting rails which are coupled together by a pair of expendable hydraulic jacks. The jacks are simply pivotally coupled to one of the rails at their axis of elongation. However, at their other ends, the jack couplings have pivot points which are offset along the rail from their axes of elongation. Thus, the force-transfer paths between the rails (through the jacks) are of greater length than the direct distance between the rails, resulting in economy and stability in a collapsible parallel-rail shoring unit. The system also includes a hydraulic-fluid supply, coupled to the jacks through individual valves.

This invention relates generally to shoring devices and systems and more particularly to novel improvements therein which provide advantageous features of stability and safety.

Although the present invention is particularly useful in the field of trench shoring by remotely controlled hydraulic jacks expanded against wall support rails or the like, and although, for purposes of conciseness and clarity herein, the major portion of the following discussion of examples of the invention relates thereto, it is to be understood that the advantages of shoring system improvements of the invention are equally well manifest and applicable in other fields wherein shoring type jacks between wall supporting rails or panels are desirable.

The desirability and, often, necessity of shoring for trenches as, for example in pipeline operations is well known. However, in recent years with the development of practical continuous trenching machines along with the increase in labor costs and other economic pressures for faster operations, the demand for quick automatic shoring by very small crews and which can be emplaced and removed and reemplaced as behind a moving trencher has vastly increased.

Typical modern systems in accordance with the prior art include parallelogram type shoring devices which comprise a pair of vertical wall support rails and a pair of hydraulic jacks pivotally interconnecting them to form a collapsible parallelogram which can be dropped into the trench, pivotally rotated into a rectangle, and then expanded by means of pressurizing the jacks to compress the juxtaposed rail members against the trench walls.

Although such systems provide significant speed and safety, the latter in that the parallelogram units can be handled from without the trench without the necessity of personnel being between the trench walls until the shoring is completed, it has been found that two serious disadvantages are incumbent with the use of typical such devices. One of these disadvantages or limitations is that, at times, the operator from his viewpoint above the shoring unit being emplaced may have difiiculty in determining whether the parallelogram has completely rotated into a stable rectangle and not beyond such position. This aspect of typical prior art devices either causes the operator to take additional time to make certain that the proper rectangle has been achieved or causes the emplacement of a parallelogram shoring device which is manifestly unstable with respect to collapse due to various causes.

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The other limitation to be noted of typical prior art shoring devices is that even if they are properly emplaced, they occasionally rotate out of the rectangular form due to earth motion or shocks imparted to the earth from various causes. Such causes may be from the inherently proximate operations of heavy equipment, the unloading, for example, of a load of pipe to be laid in the trench, or the like. In any event, shock strains in the earth may cause one of the wall supporting rails to move upwardly or donwardly with respect to the other. Such motion is particularly dangerous because (1) it removes the rectangular shoring device from its position of equilibrium of compression the trench walls and into a position which is manifestly not only unstable but virtually not even in equilibrium with the compressive forces applied thereto and (2) the soil itself usually is unstable whereby if initial motion thereof is permitted, it becomes exceedingly difiicult to prevent an avalanche of soil movement into the trench; while if initial lateral movement of the soil is prohibited it is relatively easy to preclude further motion.

It is accordingly an object of the present invention to provide a shoring system which is not subject to these and other disadvantages and limitations of the prior art.

It is another object to provide such a system which is automatically and non-defeatably rotatable into a stable rectangle in cooperation with reactive forces exerted by the shored walls.

It is another object to provide such a system which is mechanically relatively simple, rugged, reliable and inexpensive to manufacture, use and maintain.

It is another object to provide such a shoring system which is readily emplaced or removed from a trench by a single, unskilled person.

It is another object to provide such a system which is readily adaptable to embodiments thereof which incorporate various forms of expandable jacks for supplying the compressive shoring forces.

Very briefly, these and other objects are achieved inv accordance with structural aspects of one example of the invention which includes a pair of vertical support rails which are pivotally interconnected. into a parallelogram configuration by a pair of hydraulic jacks. Each of the jacks has one end pivotally connected to one of the rails with its pivotal axis, horizontal, intersecting orthogonally the axis of elongation of the jack. The other end of each jack includes a pad member having a length in a vertical plane orthogonal to the axis of the elongation of the jack. The pad member is of the character in a specific form of the invention, to bear compressively against its associated support rail and its ends are disposed laterally off the axis of the jack on opposite sides thereof, A pivotal connection, having a horizontal axis which is non-intersecting with the jack axis, between the jack and second support rail is provided at the lower end of the pad member. By drawing two lines, one from the pad member pivot point orthogonally to the jack axis and theother between the pivot points, there is formed with the jack axes a right triangle, the hypotenuse of which is the line between the pivot points.

Further details of these and other novel features and their principles of operation as well as additional objects and advantages of the invention will become apparent and bebest understood from a consideration: of the following description taken in connection with the accompanying drawing which is presented by way of illustrative example only and in which:

FIGURE 1 is a sectional schematic view illustrating an example of a self stabilizing, expandable, c0llapsibleshoring system constructed in accordance with the principles of the present invention;

FIGURE 2 is a view, shown partially in section, of a portion of an example of certain details of the shoring system of FIGURE 1; and

FIGURE 3 is a view, similar to that of FIGURE 2 illustrating the shoring system of this invention and in a different stage of its utilization.

With specific reference now to the figures in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and the structural concepts of the invention. In this regard, no attempt is made to show structural details of the apparatus in more detail than is necessary for the fundamental understanding of the invention. The description taken with the drawing will make it apparent to those in the mechanical arts in general, and the shoring field in particular, how the several forms of the invention may be embodied in practice. Specifically, the detailed showing is not to be taken as a limitation upon the scope of the invention which is defined by the appended claims, forming, along with the drawing a part of this specification.

The example of the shoring apparatus illustrated in FIGURE 1 include-s a pair of juxtaposed shoring rail members 10, 12 interconnected in a pivotable parallelogram manner by a pair of expandable, compressive force supporting jack members 14, 16, which are indicated, in this example, as being hydraulic in character and remotely actuable through hydraulic pressure lines 18, respectively, from a control set 22. The controls are shown schematically as including a unison valve 24 from a line 26, coupled to a source 28 of hydraulic fluid under pressure, which feeds a pair of individual valves 30, 32, for exerting independent control of respective ones of the jack members 10, 12 as when, for example, greater static forces are desired or needed at the bottom of the trench 34 than at its upper portion. It should be understood that the hydraulic fluid may be simultaneously applied to the jack members.

The jack member 14 is connected at one end by a pivot pin member 36 to the rail member 10 and at its opposite end by a pivot pin member 38 to the rail member 12. Similarly, the jack member 16 is connected at its opposite ends by pivot pin members 40-, 42 to the rail members 10, 12 respectively. The relationship between the axis of these various pivot pin members is discussed more fully below in connection with the subsequent figures; it suffices here to note that the parallelogram shoring assembly may be emplaced within the trench 34 with the rail member 10 in contact with one wall thereof and the opposite rail member 12 is then permitted to drop into a rectangular configuration there-with. The valves 34, 3t}, 32 may then be actuated as desired to extend the jack members until the rail member 12 is compressively, shoringly bearing upon its respective trench wall.

As will be made more apparent below, the rectangular shoring configuration is then highly stable in cooperation with the compression reaction forces exerted upon the rail members by the soil with respect to rotation, or virtual rotation, of the members into a non-stable parallelogram configuration due particularly to earth shock strain caused, for example, by heavy equipment operation in the vicinity of the trench 34, dumping operations, or natural seismic movements. As indicated above, if such soil movements can be resisted and prohibited initially, the static stability of the soil aids in holding the trench ope-n; if, however, the initial movement is permitted, the static stability may be seriously diminished and results in a trench wall avalanche. It is therefore deemed to be of considerable importance to resist by the illustrated shoring system any initial tendency to rotate it out of its rectangular, stable configuration. This is accomplished as discussed immediately below by utilizing the reactive soil compressive forces to stabilize the shoring apparatus such that any virtual motion tends to increase the shoring forces rather than to diminish them. This, by definition, therefore constitutes a system which is in stable equilibrium with the reactive forces exerted thereupon.

In FIGURE 2 the jack member 14 is shown pivotally interconnected between the rail members 10, 12 by virtue of the pivot pin members 36, 38. Pin member 36 has a pivot axis which is orthogonal to the axis of elongation 44 of the jack member and normal to the plane of the rail members 10, 12. The jack member 14 comprises an end portion 46 which may be the hydraulic cylinder, connected to the pin member 36, and an end portion 48, which may be the piston slidably positioned in the cylinder, which is rigidly affixed to a pad member 50 which in turn is connected to the pivot pin member 38 as shown.

The pad member 50 has a length in the plane of the rail members 10, 12 which defines an imaginary stabilizer line extending between the axis of the pivot pin member 38 and a contact point 54 on the opposite end of the pad member 50.

While the axis of the pivot pin member 36 intersects the jack member axis 44, the axis of the pin member 38 is laterally displaced therefrom along the stabilizer line 55 in one direction, with the bearing contact point 54 disposed laterally apart from the axis 44 in the opposite direction. Of particular note is the relation that the distance from the pivot axis of the pivot member 36 to the pivot axis 38 is significantly greater than the distance from the pivot axis 36 to the stabilizer line 55.

Thus it may be seen that when the rail member 12 has been dropped into place into a rectangular form and the jack member 14 extended to provide shoring force, further rotation of the pivot pin members 36, 38 is precluded unless the spacing between the rail members is increased or decreased; and such cannot be accomplished without respectively, overcoming the considerable reactive forces of the shored trench wall or releasing the hydraulic pressure. The automatic stability of the shoring system due in particular to the relation of the pivot point axes 36, 38 and the jack member axis 44 is thereby manifest.

Referring to FIGURE 3, the specific relationship of the two pivot 36, 38 axes to the jack member axis 44 is graphically illustrated. As is shown therein a first line 56 drawn through the pivot points 36, 38, when taken with a line 57 drawn through pivot point 38 orthogonal to jack member axis 44, forms the hypotenuse of a right triangle, the base being along jack member axis 44. To collapse the shoring device of the present invention the pivot point 38 must be rotated in the direction of the arrow 60 beyond the horizontal. If the jack has hydraulic fluid under pressure applied thereto as is otherwise locked in position, such rotation can occur only by the bearing face 13 of the rail 12 moving outwardly from the position shown in dotted lines for a distance equal to the difference between the length of the base and the hypotenuse of the right triangle, for example a distance B. When the shoring system is in use the side wall of the trench against which the rail surface 13 presses precludes such outward motion. Therefore, the system of the present invention is extremely stable, the only way for it to collapse after insertion is to remove the hydraulic pressure therefrom.

There has thus been disclosed a shoring system which is extremely stable under all conditions of operation, is simple to operate and maintain, and automatically drops into a self locking position when inserted into a trench.

What is claimed is:

1. An expandable-collapsible shoring system comprising:

first and second wall-supporting rail members;

at least two expandable jack means each having first and second ends and an axis of elongation extending therethrough;

first separate pivotal coupling means for connecting said first end of each of said jack means to said first wallsnpporting rail member, the pivotal axis of each said first separate pivotal coupling means being disposed substantially to intersect said axis of elongation of the respective jack means;

second separate pivotal coupling means for connecting said second end of each of said jack means to said second wall-supporting rail member, whereby to couple said first and second rail members together, the pivotal axis of each of said second pivotal coupling means being at a location offset from said axis of elongation;

the distance between said pivotal axes of each pivotal coupling means being greater than the spacial distance between said first and second rail members when said rails are in aligned, opposed, load-supporting position.

2. An expandable-collapsible shoring system according to claim 1 wherein said jack means comprise hydraulically-actuated units for variously spacing said first and second rail members apart.

3. An expandable-collapsible shoring system according to claim 2 including a hydraulic means for supplying hydraulic fluid to said jack means, and. further including plural individual valve means for coupling each of said jack means to said hydraulic means.

JACOB SHAPIRO, Primary Examiner.

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