TECHNICAL FIELD
The following disclosure relates generally to soil retaining systems, and more specifically to cellular sheet pile retaining systems with unconnected sheet pile tail walls, and associated structures and methods.
BACKGROUND
Marine related bulkheads constructed along the coast of Alaska experience some of the most severe environmental conditions known, including high waves and wave scour, earthquakes, ice, high tide variations, high phreatic water levels, weak soils, exposed or near-surface bedrock, heavy live loads, and difficult construction conditions. The need for low-cost, high load capacity docks and structures that allow field adaptation to changing field conditions has resulted in a development of various sheet pile retaining structures.
Flat steel sheet piles have been used in simple structures featuring primarily tension or membrane action. Foundation designs of cellular cofferdams are discussed in detail in the text by Joseph E. Bowles, Foundation Analysis and Design (1977) herein incorporated in its entirety by reference. One configuration, a closed cell flat sheet pile structure, had been successfully used for many years for a wide variety of structures including cofferdams and docks. The most common use for flat sheet piles has been in closed cellular bulkhead structures of various geometrical arrangements. Another configuration includes a diaphragm closed cell structure. By closing the cell structure, the entire structure acts as a deadman anchor in the retaining system to provide additional retaining support. However, positive structural aspects of these closed cell structures are often offset by high construction costs. Several factors have contributed to higher costs, including, for example: multiple templates required for construction alignment; close tolerances; difficulty with driving through obstacles and holding tolerance; backfilling operations using buckets or conveyors; and difficulty compacting the backfill.
Another sheet pile retaining form has been the tied back wall masterpile system with flat sheet piles acting as a curved tension face. Tieback anchors with deadmen are connected to the curved tension face to provide lateral retaining strength. This configuration allows a higher load to be retained with fewer sheet piles used as the anchors and the sheets work in concert to retain the earth load. However, tied back sheet pile walls often require deep toe embedment for lateral strength, and if that toe embedment is removed for any number of reasons, wall failure will result. This configuration further requires excavation for placement of the soil anchors, or an expensive and time consuming drilling operation to install the soil anchors, at the appropriate depth to integrate them with the sheet pile wall. Additionally, tied back walls are at risk in environments where waves overtop the wall and result in scour. Scour undermines the base of the bulkhead and the needed toe support resulting in failure of the bulkhead. The tied back walls are subject to failure during seismic events at the tied back connection to the wall and failure due to corrosion either at the tied back connection to the wall or the wall itself where corrosion of the exposed wall at the air/water interface occurs.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A-1E are a series of plan schematic views of soil retaining systems configured in accordance with an embodiment of the disclosure.
FIG. 2 is a cross-sectional side view taken substantially along lines 2-2 of FIG. 1A.
FIGS. 3-6 are a series of cross-sectional side views of systems configured in accordance with further embodiments of the disclosure.
DETAILED DESCRIPTION
Several embodiments of the disclosure are described below with reference to soil retaining systems, and more particularly, with reference to cellular sheet pile retaining wall systems with unconnected tail walls, and associated methods of use. In one embodiment, for example, a retaining system includes a face wall having a plurality of interconnected face wall sheet piles. The individual face wall sheet piles have a first length and extend a first depth into soil. The face wall sheet piles form an exterior surface facing an exterior environment, such as water, shoreline, beach, river, valley, etc. The system also includes a first tail wall including a plurality of interconnected first tail wall sheet piles extending from the face wall away from the exterior environment. The individual first tail wall sheet piles anchor the face wall and have a second length greater than the first length. Moreover, the individual first tail wall sheet piles extend a second depth into the soil that is greater than the first depth. The system further includes a second tail wall spaced apart from and unconnected to the first tail wall. The second tail wall has a plurality of interconnected second tail wall sheet piles extending from the face wall away from the exterior environment to further anchor the face wall. The individual second tail wall sheet piles have a third length approximately equal to or greater than the second length. Moreover, individual second tail wall sheet piles extend a third depth into the soil, the third depth being equal to or greater than the second depth.
Specific details are identified in the following description with reference to FIGS. 1A-6 to provide a thorough understanding of various embodiments of the disclosure. Other details describing well-known structures or processes often associated with sheet pile retailing walls, however, are not described below to avoid unnecessarily obscuring the description of the various embodiments of the disclosure. Moreover, although the following disclosure sets forth several embodiments of different aspects of the invention, other embodiments can have different configurations and/or different components and structures than those described in this section. In addition, further embodiments of the disclosure may be practiced without several of the details described below, while still other embodiments of the disclosure may be practiced with additional details and/or features.
Many of the details, dimensions, angles and/or other portions shown in the Figures are merely illustrative of particular embodiments of the disclosure. Accordingly, other embodiments can have other details, dimensions, angles and/or portions without departing from the spirit or scope of the present disclosure. In addition, further embodiments of the disclosure may be practiced without several of the details described below, while still other embodiments of the disclosure may be practiced with additional details and/or features.
FIG. 1A is a plan schematic view of a cellular sheet pile retaining system 100a (“system 100a”) configured in accordance with an embodiment of the disclosure. The illustrated system 100a includes multiple cell sheet pile structures 102 (identified individually as a first through third cell structures 102a-102c). Each cell structure 102 is formed from multiple interconnected sheet piles. More specifically, each cell structure 102 includes an exposed sheet face wall 104 extending between corresponding unconnected sheet tail walls 106 (identified individually as first through fourth tail walls 106a-106d). Adjacent cell structures 102 accordingly share a single tail wall 106. When viewed in plan as shown in FIG. 1A, the system 100a includes multiple interconnected U-shaped cell structures 102. The face walls 104 and tail walls 106 of each cell structure 102 are at least partially embedded in soil, and the tail walls 106 act as anchors for the corresponding face walls 104. The face walls 104 are exposed to an exterior environment 101, such as water. In certain embodiments, the face walls 104 and tail walls 106 can be interconnected and/or include integral soil anchors as described in U.S. Pat. No. 6,715,964 to William Dennis Nottingham, entitled “Earth Retaining System Such as a Sheet Pile Wall with Integral Soil Anchors,” filed Jul. 30, 2001; U.S. Pat. No. 7,018,141 to William Dennis Nottingham, entitled “Earth Retaining System Such as a Sheet Pile Wall with Integral Soil Anchors,” filed Mar. 15, 2004; and U.S. Pat. No. 7,488,140 to William Dennis Nottingham, entitled “Earth Retaining System Such as a Sheet Pile Wall with Integral Soil Anchors,” filed Feb. 1, 2006, each of which is incorporated herein by reference in its entirety.
As described below in detail with reference to FIGS. 2-6, portions of the individual tail walls 106, such as individual piles, can be embedded in the soil (e.g., in a direction into the plane of FIG. 1A) at a greater or lesser depth than that of the corresponding face walls 104. Moreover, portions of the individual tail walls 106, such as individual piles, can have a greater or lesser length (e.g., in the direction extending into the soil) than the corresponding face walls 104.
FIGS. 1B-1E are a series of plan schematic views of cellular sheet pile retaining systems with unconnected tail walls configured in accordance with further embodiments of the disclosure. The systems illustrated in FIGS. 1B-1E include several features that are generally similar in structure and function to the corresponding features of the system 100a shown in FIG. 1A. For example, the system 100b illustrated in FIG. 1B includes cell structures 102 (identified individually as first through third cell structures 102a-102c) having face walls 104 extending between corresponding unconnected tail walls 106 (identified individually as first through fourth tail walls 106a-106d). The embodiments shown in FIGS. 1B-1E illustrate several possible configurations of the tail walls. In the embodiment illustrated in FIG. 1B, for example, several of the tail walls 106 have curved portions to account for various obstructions or site conditions. More specifically, for example, a mid-segment of the first tail wall 106a has a curved portion 103. Moreover, the second and third tail walls 106b, 106c each includes a bifurcated end including a first end portion 105a curved away from or otherwise diverging from a second end portion 105b. In addition the fourth tail wall 106d has a single curved or non-linear end portion 107. In other embodiments, the tail walls 106 can include other portions having other shapes or extending in other suitable directions to accommodate site conditions. In still further embodiments, the tail wall 106d can be staggered up or down.
Referring next to FIG. 1C, the system 100c illustrated in FIG. 1C includes cell structures 102 (identified individually as first through fifth cell structures 102a-102e) having face walls 104 extending between corresponding tail walls 106. In the embodiment illustrated in FIG. 1C, however, the third cell structure 102c is curved to span or otherwise form a corner in the system 100c. As such, the third cell structure 102c includes corresponding first and second tail walls 106a that are curved away from one another so as not to intersect one another at an interior portion of the third cell structure 102c. In other embodiments, however, the tail walls 106 of a corresponding corner cell structure 102 can be shortened so as to not intersect one another. In still further embodiments, the tails walls 106 of a corner cell structure can intersect one another or any other corresponding tail wall.
In FIG. 1D, the illustrated system 100d also includes multiple cell structures 102 (identified individually as first through fourth cell structures 102a-102d) having face walls 104 extending between corresponding tail walls 106 (identified individually as first through fifth tail walls 106a-106e). In the embodiment illustrated in FIG. 1D, however, the tail walls 106 extend varying lengths away from the corresponding face walls 104. The tail walls 106 of varying length can accordingly account for various site conditions, seismic conditions, etc.
In FIG. 1E, the illustrated system 100e also includes multiple back-to-back or opposing cell structures 102 (identified individually as first through fifth cell structures 102a-102e opposite corresponding sixth through tenth cell structures 102f-102j). First tail walls 106a extending from the corresponding first through fifth cell structures 102a-102e and are positioned adjacent to second tail walls 106b extending from the corresponding sixth through tenth cell structures 102f-102j. The back-to-back system 100e shown in FIG. 1E can accordingly provide an economical alternative to closed cell systems, which can be more difficult and expensive to construct. As one of ordinary skill in the art will appreciate, embodiments of the present disclosure are not limited to the configurations shown in FIGS. 1A-1E.
FIG. 2 is a side cross-sectional view taken substantially along lines 2-2 of FIG. 1A illustrating several additional features of the system 100a. For example, and as shown in the illustrated embodiment, the face wall 104 includes a series of interconnected face wall sheets or piles 213 that are partially embedded in soil 216. The face wall piles 213 form an exposed surface 210 of the face wall 104 that faces an exterior environment 212 (e.g., water, shoreline, beach, river, valley, etc.). In certain embodiments, the exterior environment 212 can have a lower exterior level or surface 214 (e.g., ground, sea floor, river bed, valley floor, etc.). The tail wall 106 includes a series of interconnected tail wall sheets or piles 215 extending away from the face wall 104. The individual tail wall piles 215 are at least partially embedded in the soil 216 and at least partially covered with backfill material 218. More specifically, the backfill material 218 can include at least a first backfill 220 (e.g., granular fill) covered by a second backfill 222 (e.g., surfacing and/or grading fill). In certain embodiments, utility or fuel lines and the like can be buried in the second backfill 222 and/or the first backfill 220. In this manner, these lines can be protected from freezing and also be readily accessible for repair, leakage clean-up, replacement, etc.
The face wall piles 213 and the tail wall piles 215 can be made from various materials including, for example, steel, aluminum, vinyl, plastic, wood, concrete, fiberglass, metallic and non-metallic alloys, and any other suitable materials. In certain embodiments, the tail wall 106 can include an anchor 237 spaced apart from the face wall 104. The anchor can be configured to increase the pull-out resistance of the face wall 104. For example, the anchor 237 can be a tie-back anchor or dead weight that is operably coupled to the tail wall 106. In certain embodiments, the anchor 237 can be integrally formed with the tail wall 106. For example, the anchor 237 can be integrally formed with the final tail wall pile 215 in the tail wall 106. In other embodiments, however, the anchor 237 can be attached to the tail wall 106 (e.g., by welding, via a cable or rod, etc.).
According to one feature of the illustrated embodiment, the tail wall 106 is embedded in the soil 216 at a depth that is deeper than that of the face wall 104. Moreover, at least some of the tail wall piles 215 are longer than the face wall piles 213 (i.e., in the axial direction of these piles). More specifically, the tail wall 106 includes a first group G1 of tail wall piles 215 and a second group of tail wall piles G2. In the illustrated embodiment, the first group G1 includes 8 tail wall piles 215, and the second group G2 includes 31 tail wall piles 215. In other embodiments, however, the first group G1 and the second group G2 can include greater than or less than 8 and 31 tail wall piles 215, respectively. The face wall piles 213 and the tail wall piles 215 of the first group G1 have a first length, and the tail wall piles 215 of the second group G2 have a second length that is greater than the first length. In one embodiment, for example, the first length can be approximately 69 feet and the second length can be approximately 77 feet. In other embodiments, however, the first and second lengths can be greater than or less than 69 feet and 77 feet, respectively, depending, for example, on the conditions and environment where the system 100a is constructed.
As also shown in the illustrated embodiment, the first group G1 of tail wall piles 215 forms an upper staggered or stepped portion 224 of the tail wall 106 extending from a first upper surface 226 of the face wall 104 to a second upper surface 228 of the tail wall 106. The tail wall 106 also includes a lower staggered or stepped portion 225 extending from a first lower surface 234 of the face wall 104 to a second lower surface 236 of the tail wall 106. In one embodiment, for example, the individual tail wall piles 215 in the first group G1 can be staggered from each other by a height of approximately 6-18 inches, or approximately 12 inches. In other embodiments, however, these piles can be staggered by a height less than 6 inches or greater than 18 inches.
Several more features of the tail wall 106 are described with reference to a tail wall elevation 230 at the second upper surface 228 of the tail wall 106. For example, the first upper surface 226 is at a first height H1 from the tail wall elevation 230, and an exterior surface 232 of the backfill 218 is at a second height H2 from the tail wall elevation 230. Moreover, the lower exterior level 214 of the exterior environment 212 is at a third height H3 below the tail wall elevation 230. In addition, the first bottom surface 234 of the face wall 104 is at a fourth height H4 from a second bottom surface 236 of the tail wall 106. In certain embodiments, the first height H1 can be approximately 10 feet, the second height H2 can be approximately 9 feet, the third height H3 can be approximately 30 feet, and the fourth height H4 can be approximately 18 feet. In other embodiments, however, these heights can be greater than or less than these values to allow staggering tail walls both up and down.
As also shown in FIG. 2, at the second upper surface 228 of the tail wall 106 following the transition from the first group G1 to the second group G2 of tail wall piles 215, upper portions 227 of several of the initial tail wall piles 215 of the second group G2 can be cut-off or otherwise removed at the elevation of the second upper surface 228 of, as shown by broken lines. The upper portions 227 can be removed because the tail wall piles 215 may be available only in certain predetermined lengths. Moreover, removing these portions of the tail wall piles 215 allows the second upper surface 228 to be generally flat while the lowered staggered portion 225 of the tail wall 106 continues to extend deeper into the soil 216. In addition, the first staggered portion 224 of the tail wall 106 extends away from the face wall 104 by a shorter distance than that of the second staggered portion 224 of the tail wall 106.
The staggered portion of the tail wall 106 allows the second group G2 of tail wall piles 215 to be embedded in the soil 216 at a greater depth than the face wall 104. Moreover, the tail wall piles 215 of the second group G2, which are longer in the longitudinal direction than the face wall piles 213, contribute to the extended depth of the second bottom surface 236 of the tail wall 106 with reference to the first bottom surface 234 of the face wall 104. In certain embodiments, for example, the second bottom surface 236 of the tail wall 106 can be approximately 18 feet below the first bottom surface 234 of the face wall 104. Accordingly, the second bottom surface 234 of the tail wall 106 can be approximately 78 feet from the first upper surface 226 of the face wall 104. In other embodiments, however, these distances can be greater or less than these values.
These features of the tail wall 106 (e.g., that the tail wall 106 that is embedded deeper than the face wall 104, and the longer tail wall piles 215 of the second group G2) provide several advantages over conventional retaining walls. For example, the illustrated tail wall 106 provides an increased pull-out resistance of the face wall 104, which accordingly yields a higher ultimate tension. This configuration also improves the stability of the system 100a while also advantageously allowing the tail wall 106 to have a shorter distance D extending away from the face wall 104 compared to conventional retaining wall systems. For example, in areas with limited property rights or in soft soils, the deeper tail wall 106 with longer tail wall piles 215 can reduce the distance D of the tail wall 106 extending away from the face wall 104. These deeper tail wall piles 215 can also anchor the tail wall 106 into denser or stiffer soil below the soil failure zone as described below with reference to FIG. 5. The illustrated tail wall 106 can also reduce the cost of the system 100a because fewer tail wall 106 materials are required due to the reduced distance D of the tail wall 106.
FIG. 3 is a cross-sectional side view of a system 300 configured in accordance with another embodiment of the disclosure. The illustrated system 300 includes several features that are generally similar in structure and function to the corresponding features of the systems described above with reference to FIGS. 1A-2. For example, the system 300 includes a cell structure 302 with multiple tail wall sheet piles 315 forming a tail wall 306, and multiple face wall piles 313 forming a face wall 304. In the illustrated embodiment, however, the tail wall 306 includes a first group G1, a second group G2, and a third group G3 of the tail wall piles 315. As shown in FIG. 3, the first group G1 includes 8 tail wall piles 315, the second group G2 includes 2 tail wall piles 315, and the third group G3 includes 27 tail wall piles 315. In other embodiments, however, the first group G1, the second group G2, and the third group G3 can include greater than or less than 8, 2, and 27 tail wall piles 315, respectively. Moreover, in certain embodiments the face wall piles 313 and tail wall piles 315 in the first group G1 have a first length, the tail wall piles 315 in the second group G2 have a second length, and the tail wall piles 315 in the third group G3 have a third length. In one embodiment, the first length can be approximately 69 feet, the second length can be approximately 77 feet, and the third length can be approximately 80 feet. In other embodiments, however, the first, second, and third lengths can be greater than or less than these values.
As also shown in the embodiment illustrated in FIG. 3, at an upper surface 328 of the tail wall 306 following the transition from the first group G1 to the second group G2, and from the second group G2 to the third group G3 of the tail wall piles 315, upper portions 327 of several of the initial tail wall piles 315 of the second group G2 and third group G3 can be cut-off or otherwise removed at the elevation of the second upper surface 328 of, as shown by broken lines similar to the system 100a described above with reference to FIG. 2.
FIG. 4 is a cross-sectional side view of a system 400 configured in accordance with yet another embodiment of the disclosure and particularly suited for expansion of a tail wall at a later date. The system 400 illustrated in FIG. 4 includes several features that are generally similar in structure and function to the corresponding features of the systems described above with reference to FIGS. 1A-3. For example, the system 400 includes a cell structure 402 with a tail wall 406 extending away from a face wall 404. The tail wall 406 includes multiple interconnected tail wall sheet piles 415, and the face wall 404 includes multiple interconnected face wall sheet piles 413. In the illustrated embodiment, however, the tail wall 406 includes a first group G1 and a second group G2 of the tail wall sheet piles 415. The tail wall sheet piles 415 in the first group G1 represent tail wall sheet piles 415 that have been installed in the system. The second group G2 of tail wall sheet piles 415, however, have been added at later time after the initial and completed installation of the first group G1 of the tail wall sheet piles 415.
The system 400 illustrated in FIG. 4 is particularly suited for situations where additional support from the tail wall 406 may be needed after the initial installation of the tail wall 406. For example, in situations with poor fill material surrounding the first group G1 of tail wall sheet piles 415, the second group G2 of tail wall sheet piles 415 can be added to the tail wall 406 to extend the tail wall 406 and provide additional anchor support without removing the entire wall system 400 or otherwise rebuilding the system 400. The second group G2 of tail wall sheet piles 415 can also provide additional pull-out support where the system 400 may be required to support additional loads or loads that are larger than initially anticipated.
FIG. 5 is a cross-sectional side view of a system 500 configured in accordance with yet another embodiment of the disclosure. The system 500 includes several features that are generally similar in structure and function to the corresponding features of the systems described above with reference to FIGS. 1A-4. For example, the system 500 includes a cell structure 502 with a tail wall 506 extending away from a face wall 504. The tail wall 506 includes multiple interconnected tail wall sheet piles 515, and the face wall 504 includes multiple interconnected face wall sheet piles 513. In the illustrated embodiment, however, the tail wall sheet piles 515 and the face wall sheet piles 513 are at least partially embedded in soil 516 with sections having varying or different densities. More specifically, the soil includes a first section 517 positioned above and adjacent to a second section 519. The first section 517 has a first density, and the second section 519 has a second density greater than the first density. The soil 516 also includes a global stability plane 529, as well as a sliding block failure plane 531. The sliding block failure plane 531 illustrates how the second section 519 can provide the required lateral resistance to prevent failure of the system 500 where soils above this level (e.g., the first section 517) are too soft to provide the required stability. As shown in the illustrated embodiment, the face wall sheet piles 513 extend at least partially through the first section 517. The face wall sheet piles 513 do not, however, extend into the denser section 519 of the soil 516 or beyond the sliding block failure plane 531. The tail wall sheet piles 515 extend through the first section 517 and at least partially into the second section 519 beyond the sliding block failure plane 531. In this manner, the tail wall sheet piles 515 provide sufficient retaining support for the face wall 504 even when the less dense first section 517 would be unsuitable for retaining the face wall 504. In further embodiments, the system 500 can be installed in soil 516 having more than two different densities. Moreover, although the face wall sheet piles 513 do not extend into the second section 519 in the illustrated embodiment, in other embodiments the face wall sheet piles 513 can extend into at least a portion of the second section 519 and beyond the sliding block failure plane 531.
FIG. 6 is a cross-sectional side view of a system 600 configured in accordance with yet another embodiment of the disclosure. The system 600 includes several features that are generally similar in structure and function to the corresponding features of the systems described above with reference to FIGS. 1A-5. For example, the system 600 includes a cell structure 602 with a tail wall 606 extending away from a face wall 604. The tail wall 606 includes multiple interconnected tail wall sheet piles 615, and the face wall 604 includes multiple interconnected face wall sheet piles 613. The system 600 can also include a backfill material 618 at least partially disposed around the tail wall sheet piles 615. In the illustrated embodiment, however the tail wall sheet piles 615 and the face wall sheet piles 613 extend at least partially through a first soil section 616 without extending into a denser second soil section 621. In some embodiments, for example, the second soil section 621 can be a very dense soil, such as rock or bedrock. As such, the tail wall sheet piles 615 can have a staggered pattern aligned with the profile of the second soil section 621 and extending away from the face wall 604.
Although the staggered pattern of the embodiment shown in FIG. 6 shows the lower end portions of the tail wall sheet piles 615 stepped or staggered upwardly with each successive tail wall sheet pile 615 having a progressively shorter length, in other embodiments the tail wall sheet piles 615 can be staggered in the opposite direction (e.g., sloping downwardly with each successive tail wall sheet pile 615 having a progressively longer length). Moreover, although the upper end portions of the tail wall sheet piles 615 form a generally flat or even upper surface 632 aligned with an upper surface of the face wall 604, in other embodiments the upper surface 632 of the tail wall can be higher or lower than the upper surface of the face wall.
From the foregoing, it will be appreciated that specific embodiments have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the disclosure. Certain aspects and/or features described in the context of particular embodiments may be combined or eliminated in other embodiments. Further, although advantages associated with certain embodiments have been described in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments need necessarily exhibit such advantages to fall within the scope of the disclosure. The following examples provide further embodiments of the disclosure.
Patent Application
20190100893
