Sheet pile retaining wall system

Abstract

A sheet pile retaining wall system employing corrugated sheet piles not requiring temporary shoring to be used when widening and/or stabilization of existing highway embankment. The wall system provides a front face wall having a plurality of resistance fins perpendicularly extending therefrom via three-way connectors. The fin sheet piles first include a brace fin sheet for reducing stresses in the front face wall, then a series of additional resistance fin sheets terminating at an elevation below the face wall for accommodating a pipe drainage/utility cradle. Between the slope of the existing embankment, a temporary excavation bench, an excavation backslope, and the higher front face wall is reinforced concrete backfill for pre-stressing the wall system when fluidand, when set, optionally engaging supplementary structural features within the set concrete backfill such as dowels/tie down anchors.

Claims

1. A sheet pile embankment retaining and/or stabilizing system, comprising: a face wall defining a front face of the embankment having an existing gradient; the face wall including a plurality of face wall sheet piles, wherein each face wall sheet pile terminates at a cantilever elevation located above the gradient; two or more spaced apart brace fin sheet piles, each brace fin sheet pile perpendicularly connected to the face wall, each brace fin sheet pile terminating at a brace elevation located between the cantilever elevation of the face wall and the gradient; a plurality of resistance fin sheet piles connected to each brace fin sheet pile so as to define a linear relationship relative to each other, each plurality of resistance fin sheet piles terminating at a cradle elevation located below the cantilever elevation; an excavation bench defined in part by a removed portion of the embankment between adjacent pluralities of the resistance fin sheet piles to at least eighteen inches below the cradle elevation but for less than half a vertical length of each resistance fin sheet pile and for a portion of a horizontal length of said adjacent pluralities of the resistance fin sheet piles; a reinforced concrete backfill disposed in a backfill space defined by the gradient, the excavation bench, the face wall, and adjacent pluralities of the resistance fin sheet piles; and a plurality of dowels/tie down anchors operatively associated with the reinforced concrete.

2. The sheet pile embankment retaining and/or stabilizing system of claim 1, further comprising: a drainage/utility cradle seated on the reinforced concrete backfill.

3. The sheet pile embankment retaining and/or stabilizing system of claim 1, further comprising: a three-way connector interconnecting each adjacent face wall sheet piles and each brace fin sheet pile.

4. The sheet pile embankment retaining and/or stabilizing system of claim 1, wherein all sheet piles are generally corrugated.

5. The sheet pile embankment retaining and/or stabilizing system of claim 1, further comprising an excavation backslope that further defines each backfill space.

6. The sheet pile embankment retaining and/or stabilizing system of claim 1, further comprising a step notch formed in the gradient so as to further define said backfill space.

7. A sheet pile embankment retaining and/or stabilizing system, comprising: a face wall defining a front face of the embankment having an existing gradient; the face wall including a plurality of face wall sheet piles, wherein each face wall sheet pile terminates at a cantilever elevation located above the gradient; two or more spaced apart brace fin sheet piles, each brace fin sheet pile perpendicularly connected to the face wall, each brace fin sheet pile terminating at a brace elevation located between the cantilever elevation of the face wall and the gradient; a plurality of resistance fin sheet piles connected to each brace fin sheet pile so as to define a linear relationship relative to each other, each plurality of resistance fin sheet piles terminating at a cradle elevation located below the cantilever elevation; an excavation bench defined in part by a removed portion of the embankment between adjacent pluralities of the resistance fin sheet piles and between eighteen and twenty-four inches below the cradle elevation for a horizontal length of said adjacent pluralities of the resistance fin sheet piles; a step notch formed in the gradient; a reinforced concrete backfill disposed in a backfill space defined by the gradient, the excavation bench, an excavation backslope, the face wall, the step notch, and adjacent pluralities of the resistance fin sheet piles; a plurality of dowels/tie down anchors operatively associated with the reinforced concrete; a drainage/utility cradle seated on the reinforced concrete backfill; a three-way connector interconnecting each adjacent face wall sheet piles and each brace fin sheet pile; and wherein all sheet piles are generally corrugated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an elevation view of an exemplary embodiment of the present invention;

(2) FIG. 2 is a schematic plan view of an exemplary embodiment of the present invention, taken along plane 2-2 of FIG. 1;

(3) FIG. 3 is a perspective view of an exemplary embodiment of an individual Z-shaped sheet pile of the present invention;

(4) FIG. 4 is an enlarged detail plan view of an exemplary embodiment of the present invention, taken along line 4-4 of FIG. 2;

(5) FIG. 5 is an enlarged detail plan view of an exemplary embodiment of the present invention, taken along line 5-5 of FIG. 4; and

(6) FIG. 6 is an enlarged detail plan view of an exemplary embodiment of the present invention, taken along line 6-6 of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

(7) The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.

(8) Broadly, an embodiment of the present invention provides an alternate sheet pile retaining wall system with dowels/tie down anchors to provide for additional stability comprised of corrugated (Z-shaped) sheets for widening and/or stabilization of existing highway/embankment under adjacent, active traffic conditionsnot requiring temporary shoring. The wall system may provide a front face wall having a plurality of interconnected fin sheets perpendicularly extending therefrom. Between the gradient of the existing embankment, a temporary excavation bench and the higher front face wall is reinforced concrete backfill for pre-stressing the wall system when fluidand, when set, being impervious and acting compositely with the engaged corrugated sheets while supporting the aforementioned cradle, from which the remaining construction can build off of while reducing overall earth pressure acting on the face wall upon completion of construction. In its set state, the backfill will result in a reduction of overall pressure acting on the face wall along with stress reduction in the face wall via composite steel/concrete backfill structural interaction not possible with earthen backfill only, the effect of which may be enhanced by optionally engaging supplementary structural features within the set concrete backfill such as dowels/tie down anchors to help hold back the face wall and resist sliding and overturning forces acting on the wall system and/or serve as supplementary deep foundation elements of the wall system. And atop this concrete backfill would be an optional, drainage cradle of sufficient width to accommodate highway drainage/utility construction.

(9) Referring to FIGS. 1 through 6, the present invention may include an alternate sheet pile retaining wall system 10 not requiring temporary shoring for its construction. The sheet pile retaining wall system 10 will include a fin sheet pile assembly 24 driven into an embankment having a gradient 17 for widening and/or stabilizing existing highway/embankment, bounded on the back by an excavation backslope 25. The wall system 10 provides a front face wall 22 including a plurality of interconnected Z-shaped sheet piles forming an exterior element facing an exterior environment of a linear nature (deriving the majority of its strength through bending resistance) which is preferable for highway retaining wall construction given typical right-of-way limitations and aesthetic considerations rather than similarly-concepted flat sheet piles requiring an outwardly-bowed face wall (deriving the majority of its strength solely through tension) more common in marine bulkhead construction where aesthetics are typically of much lesser concern. For increased aesthetics, vertically-aligned, non-structural, precast concrete or lighter weight, petroleum-based, plastic veneers of enhanced durability may be readily attached as panels to the structural steel face wall, with one wall panel generally required for every two face wall sheets. The system also includes a fin sheet pile assembly 24 comprised of Z-shaped sheet piles perpendicularly connected to and extending from the face 22 away from the exterior environment, as illustrated in FIGS. 1 and 2. The fin sheet pile assembly 24 includes a plurality of brace fin sheet piles 80 individually spaced apart along and connected to the face wall 22, substantially bracing the face wall 22 cantilevering above the fin sheet pile assembly 24. Connected to each brace fin sheet pile 80 is the remainder of fin sheet piles 81 which provide lateral resistance to earth pressure forces acting on the face wall 22, which in turn provide for an adjacent, depressed drainage/utility cradle 19. Those fin sheets located farther away from the face wall 22 provide more resistance to earth pressure acting on the wall than those closer given their distance from the face wall 22 based on earth pressure theory.

(10) It should be understood by those skilled in the art that the use of directional terms such as above, below, and the like are used in relation to the illustrative embodiments as they are depicted in FIG. 1, the above direction being further toward the top of the corresponding figures and a downward direction being further toward the bottom of the corresponding FIG. 1.

(11) The concrete backfill 18 may be used/considered as a pre-stressing measure described more in depth below. In certain embodiments, the concrete backfill 18 may be operatively engaged to the face wall 22 and fin sheets 24, e.g., via shear studs or mid-span mini-fins of lesser number than the aforementioned main fins) to help hold back the face wall 22 upon set. And following set, the reinforced concrete backfill mass may also serve as a medium through which drilling through it and beyond would occur to allow for the installation of dowels/tie down anchors which may be vertical or inclined away from the face wall with increasing depth founded within soil and/or rock materials outside/below the limits of sheeting to assist in resisting sliding and overturning forces acting on the wall system and/or serve as supplementary deep foundation enhancements to the wall system.

(12) Moreover, the concrete backfill 18 enables the seating of a drainage cradle 19 on the set cementitious backfill 18 at cradle elevation 31.

(13) Moreover, the concrete backfill 18 enables the seating or cradle elevation 31 of a drainage cradle 19 on the set cementitious backfill 18. Once the cementitious backfill 18 hardens, it no longer pushes directly against the face wall 22, but sits down vertically on its notched bottom within the embankment. From there, the hardened concrete backfill 18 may provide an impervious platform/pathway for the drainage cradle 19, which would be designed to accommodate pipes/utilities 33 behind the front face wall 22.

(14) Referring to FIGS. 3 through 6, each sheet pile 26 would be corrugated (Z-shaped) for the reasons stated above as it extends from a male interlocking end 28 to a female interlocking end 30 for enabling adjacent sheet piles 26 to be interlocked. In other words, a perpendicular, vertically planar soil anchor is provided by mating the male interlocking end 28 at one end of a first sheet 26 to a second female interlocking end 30 at the end of a second sheet 26. The interlocking of fin sheet piles and face wall sheet piles happens at the interface of two adjacent face wall sheets via a three-way connector 32, as illustrated in FIG. 6. The three-way connector 32 provides a profile and/or arrangement of male interlocking ends 28 and female interlocking ends 30 as illustrated in FIG. 6.

(15) Geotechnical Considerations

(16) The perpendicular sheets will serve as vertically planar, continuous tiebacks, i.e., fins providing resistance to lateral loading acting on the wall through the following mechanisms: a) soil/steel interaction, i.e., shear resistance including friction and cohesion and b) the dead weight of the fins including soil adhering to them extending some distance beyond the physical limits of the steel comprising the sheets, enhanced by vibratory densification during pile driving to provide yet additional restoring moment to the overall wall system. It being understood that the design of the alternate sheet pile wall system 10 as well as the designs of other wall typesparticularly those founded within slopeswill need to consider global stability as part of the overall design processas well as other design criteria peculiar to each wall type. It being understood that the embankment being retained has an upper surface, i.e., the inclined part of the embankment, or gradient 17.

(17) In one embodiment, the alternate sheet pile wall system 10 incorporates reinforced concrete backfill 18 in a wedge defined by the existing embankment gradient 17, the face wall 22, and temporary excavation bench 23, an excavation backslope 25, said backfill portion being bounded along its upper periphery by the drainage/utility cradle 19. The hydrostatic fluid pressure of the concrete backfill 18 will act to pre-stress the wall system 10 prior to set before placement of the overlying backfill and pavement structure. And by incorporating step notching 27, as illustrated in FIG. 1, into the existing embankment gradient, wedge-type, block loading acting on the face wall 22 will be eliminated upon set of the concrete backfill material 18 within the backfill space 50 defined by the face wall 22 and the step notching 27 into the gradient 17.

(18) Structural Considerations

(19) From a structural standpoint, the most critical point along the face wall is where it is cantilevered above the brace fin sheet pile 80 directly connecting to the face wall 22 with moment within the wall sheet being the controlling factor in its design. See FIG. 1. By limiting the cantilever height, the maximum moment (and required section modulus, which is a function of the square of the unsupported height) will be limited. This feature along with the pressure-reducing and bending moment-reduction effect provided by the composite, corrugated nature of the steel sheet piles interacting with the concrete backfill 18 (whether reinforced or not and whether serving as a medium through which dowels/anchors 90 may be optionally installed and engaged) is key to the design conceptand why it can be so competitive in cost when compared to other wall types in that relatively lighter, i.e., less expensive, face wall sheet sizes (weights) may be employed.

(20) The fin sheets 24 will act in tensionserving as vertically-planar, continuous anchorsproviding increased resistance to lateral movement of the face wall 22 as a direct result of the corrugations in the development of shearing resistance including both frictional and cohesive components along with restoring moment including the dead weight of the steel fin sheets and adhered cementitious backfill and adhered earthen material (enhanced in part as a result of densification of existing earthen embankment material as a result of the vibratory process associated with the driving of sheet piles). With the strength of steel being measured in tens of thousands of pounds per square inch, the interconnected, continuous nature of sheet piles results in loadings in tension being relatively low when compared to the available strengthand it is for this reason that fin sheet sizes (weights) may be considerably less than sheet sizes required for the face wall.

(21) In addition to eliminating the need for temporary shoring to allow for the construction of this particular, alternate sheet pile retaining wall system 10, the other big key to its economic success is the methodology for how it is constructed.

(22) Construction Methodology

(23) Basically, a temporary bench 23 would be excavated along an excavation backslope 25 to a depth of 18 inches to 2 feet below the proposed tops of the innermost fin sheets 24, i.e., those sheets situated higher on the embankment closer to the existing highway. (The 18 inch to 2 foot clearance would allow for the pile hammer to grab/secure these piles for subsequent driving and installation of dowels/tie down anchors 90 and subsequent placement of reinforced concrete backfill 18 to the top of the fin sheet assembly 24.)

(24) Backfilling with earthen (non-cementitious) material 21 beneath the roadway in the wall construction zone would occur. In conjunction with this construction would be the installation of optional roadway drainage (and utilities) within the specified drainage/utility cradle 19. At this point, construction of the overlying pavement structure 12 and moment slab/safety barrier (or guide rail)not shown on FIG. 1would then occur.

(25) Now with particular regard to the development of tension in the wall fins, a slight, inward transverse force could be applied to the fin sheet assembly 24 during vibrating/driving, thus removing play in the interlocks. As necessary to keep the face wall within horizontal tolerance, wall sheets at the 3-way connectors 32 would be re-visited and a slight, outward transverse force could be applied to the pile hammer. Vertical tolerance would be achieved by driving pile lengths longer than design lengths and cutting/burning off the excess, as may be required.

(26) It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claim.