METAL SHEET PILING

Abstract: A metal sheet pile includes a wall section which comprises a central flange flanked by outwardly inclined side walls along the free edges of which are longitudinally extending interlocks. At least one additional longitudinal interlock (18) is secured to the wall section of the sheet pile and extends generally parallel to the interlocks secured to the edges of the side walls of the pile.

Description: METAL SHEET PILING This invention relates to metal sheet piling. More especially, but not exclusively, the invention relates to steel sheet piling. Steel sheet piles are used in general and marine engineering as permanent structures inter alia for retaining walls, basements, underground car parks, pumping stations, bridge abutments, containment barriers and marine structures. These are only examples of such structures. Conventional sheet piles include those known as Larssen or LX sheet piles which are of generally "U" shape and includes a wall section comprising a pan defined by a central flange flanked by outwardly inclined side walls along the free edges of which are formed interlocks. These interlocks (also known as clutches) normally extend over the entire height of the pile and typically comprise a locking toe of generally triangular cross-section which stands proud of a lip which extends along each side edge of the pile, the lip lying generally normal to the adjoining pile surface. The space between the toe and the lip defines an elongate cavity for receiving the locking toe of an adjoining pile. The lip defines the bottom wall of this recess. Other known sheet piles include Frodingham piles which are of generally "Z" profile and typically comprise a wall section including an inclined central web flanked by outwardly extending flanges along the free edges of which are formed interlocks. Conventionally sheet piling structures are produced by sequentially driving a plurality of piles to produce the barrier required, the interlocks of neighbouring piles being connected one to the other during the driving process. In cases where water- tightness is required, methods of enclosing sealant n the interlocks may be adopted. For ease of understanding, this conventional process will be described with reference to Figures 1 and 2. Figure 1 shows a grounded sheet pile 1 before the driving of a neighbouring pile 2 (see Figure 2). The piles 1 , 2 have interlocks 3, 4 (only one for each pile being shown) along each of their side edges. As will be seen, the cavity 5 defined between the toe 6 and lip 7 of interlock 3 is closed by an angled metal strip 8 which extends over the entire height of the pile 1 and is welded to the pile at the junction between the interlock and the adjoining pile wall. The cavity is filled with a sealant 9. Only one interlock of each pile carries an angled strip 8. For assembly of the pile 2, the interlock 4 is positioned immediately above the interlock 3 and the strip 8 flexed to allow entry of the interlock 4 into the space defined between the interlock 3 and the strip 8. The pile 2 is then driven downwardly to the position shown in Figure 2, the so formed joint being sealed by the presence of the sealant 9 and the angled strip 8. In the majority of cases, the joint produced is effective in preventing migration of water and other fluids into and through the joint. On occasions, however, driving of the second pile 2 is not straightforward and results in misalignment of the piles and the cooperating interlocks. In these cases it is necessary to withdraw the second pile 2 and restart the assembly procedure. Withdrawal of the second pile 2 disturbs the sealant 9 and can result in damage to the integrity of the joint. Although it is possible to introduce additional sealant, it is not possible to guarantee that the repaired joint will provide the required insulation against water migration over the entire length of the interlock. The integrity of the joint formed between the neighbouring piles is therefore suspect. Repairs to conventional sheet pile structures can be expensive and time consuming. This can entail excavating the soil alongside a suspect joint to enable a repair to be effected. Alternatively, individual piles are removed and replaced, the integrity of the joints between replaced and retained piles being suspect for the reasons explained above. It is also the case that structural modifications are required after completion of a piling structure, for example the installation of pipe or service crossings, the replacement of damaged piles, the creation of openings, and the change of direction and positioning of an existing barrier structure to accommodate the building of other structures. According to the present invention in one aspect, the invention provides a metal sheet pile which includes a wall section comprising a central flange flanked by outwardly inclined side walls along the free edges of which are longitudinally extending interlocks, and at least one additional longitudinal interlock secured to the wall section of the sheet pile and extending generally parallel to the interlocks secured to the edges of the side walls of the pile. In another aspect, the invention provides a sheet piling structure which comprises a plurality of sheet piles each of which includes a wall section comprising a central flange flanked by outwardly inclined side walls along the face edges of which are longitudinally extending interlocks through which neighbouring piles are interconnected, at least some of the sheet piles of the structure including at least one additional longitudinal interlock which extends generally parallel to the interlocks secured to the edges of the side walls of the respective pile. The sheet piles formed with one or more additional interlocks may be spaced one from another by one or more sheet piles not being formed with one or more additional interlocks. The invention will now be described by way of example only with reference to the accompany diagrammatic drawings in which: - Figures 3 and 4 illustrate typical sheet piles in accordance with the invention; Figure 5 illustrates a detail of a piling structure in accordance with the invention; Figures 6a and 6b show typical pile structures in accordance with the invention; and Figures 7 to 9 illustrate further sheet pile structures incorporating a plurality of sheet piles in accordance with the invention. As will be seen from Figure 3, the sheet pile conventionally comprises a wall section including a pan 11 defined by a central flange 12 flanked by outwardly inclined side walls 14 along the free edges of which are longitudinally extending interlocks 15. As for the known piles illustrated in Figures 1 and 2, an angle plate 16 is provided to seal the cavity defined between the toe and lip of one interlock and sealant is located within this cavity. No angle plate is provided to seal the cavity of the other interlock. Interlock sealing apparatus or methods different from that shown in the drawings may be adopted. Also, in some cases, no interlock sealing will be required. What is not conventional is the provision of an additional interlock 18. As shown, this additional interlock is welded to the pile surface of the central flange 12 and extends in a direction generally parallel to the interlocks 15. An angled strip 19 is welded to the interlock to provide a seal for sealant located within the interlock cavity. Sealant 20 is positioned within the interlock interior. The interlock 18 can be welded or otherwise secured to the pile wall at locations other than that illustrated. Also, more than one additional interlock may be provided. The or each interlock 18 may extend over the entire height of the pile. Alternatively, two or more spaced interlocks of lessor height may be provided. As shown in Figure 4, the additional interlock 18 is welded to the pile surface at the junction between the central flange 12 and one side wall 14. In Figure 4, a neighbouring sheet pile is shown connected to the pile through adjoining interlocks 15. In Figure 5, opposite piles of two generally parallel wall structures are joined together through the additional interlocks 18. Figures 6a and 6b illustrate piling structures which comprise a plurality of interconnected sheet piles, two of which include additional interlocks 18. In Figure 6a the interlocks are sealed; in Figure 6b, the interlocks 15 are not provided with sealing apparatus. As will be seen from Figures 7 to 9, the presence of the additional interlock 18 enables other sheet piles to be added to the pile structure should this be necessary. Thus, if through difficulties experienced during driving the joint formed between the interlocks of neighbouring sheet piles 21, 22 is suspect, additional piles 23 can be driven to create a barrier around the suspect or leaking joint to ensure that where water and other fluids may pass through the joint formed between piles 21 and 22, this water does not pass through the structure as a whole. In Figure 7, additional piles 23 have been employed to create an enclosed area between sheet pile rows 26, 27 which can, if necessary, be excavated to facilitate, for example, repairs to existing sheet piles of the rows. Connection between the existing piles and the additional piles 23 is facilitated through the additional interlocks 18 or, in the case of one connection, through an interlock coupling 26. As will be seen from Figures 8a, 8b and 8c, different structures can be created from the single piling structure shown in Figure 8a. Two typical possible structures are illustrated in Figures 8b and8C. Again, existing interlocks are connected to newly installed piles through the additional interlocks 18. A further alternative structure is shown in Figure 9.. In this embodiment, neighbouring piles 28, 29 are welded together prior to driving instead of the angle plate and sealant arrangement discussed previously. The presence of the additional interlock also enables damaged piles to be replaced and pipe or service crossings to be installed by installing a second barrier as described, and excavating the space between the original structure and the barrier to provide a space in which the required work can be carried out. Changes in direction or position of the original structure can readily be achieved by linking fresh sheet piles with the original structure through the additional interlocks 18. Importantly, the presence of the additional interlocks 18 will enable an installer to provide a guarantee of the integrity of a sheet piling structure. It will be appreciated that the foregoing is merely exemplary of pile constructions in accordance with the invention and that modifications can readily be made thereto with departing from the true scope of the invention. Thus, interlock sealant apparatus other than that discussed above may be adopted. Also, in some cases, interlock sealing may be unnecessary. Furthermore, welding can be carried out on joints if the piles are installed in pairs to be incorporated in the structure.

Claims: CLAIMS 1. A metal sheet pile which includes a wall section comprising a central flange flanked by outwardly inclined side walls along the free edges of which are longitudinally extending interlocks, and at least one additional longitudinal interlock secured to the wall section of the sheet pile and extending generally parallel to the interlocks secured to the edges of the side walls of the pile. 2. A sheet pile as claimed in claim 1 wherein the interior of at least one interlock is sealed by an angle plate. 3. A sheet pile as claimed in claim 1 or claim 2 wherein sealant is positioned within the interior of at least one interlock. 4. A sheet pile as claimed in any one of claims 1 to 3 wherein the length of the additional interlock is equal to or less than the height of the sheet pile. 5. A sheet piling structure which comprises a plurality of sheet piles each of which includes a wall section comprising a central flange flanked by outwardly inclined side walls along the face edges of which are longitudinally extending interlocks through which neighbouring piles are interconnected, at least some of the sheet piles of the structure including at least one additional longitudinal interlock which extends generally parallel to the interlocks secured to the edges of the side walls of the respective pile. 6. A piling structure as claimed in claim 5 in which sheet piles formed with one or more additional interlocks are spaced one from another by one or more sheet piles not being formed with one or more additional interlocks. 7. A metal sheet pile substantially as herein described and as described with reference to Figures 3 and 4 of the accompanying drawings. A sheet piling structure substantially as herein described and as described with reference to Figures 5 to 9 of the accompanying drawings.

Inventors: WHITE GRAHAM ROBERT, WHITE, GRAHAM, ROBERT
Applicants: CORUS UK LTD, WHITE GRAHAM ROBERT, CORUS UK LIMITED, WHITE, GRAHAM, ROBERT
Application year: 2000
Main classification: E02D5
IPC codes: E02D5