Abstract
A method of enlarging the space beneath a masonry arch bridge which includes a masonry arch and a spandrel wall at each end of the masonry arch includes forming a movable portion of the masonry arch bridge by cutting the spandrel walls to form a cut on each side of the masonry arch. A lifting force is applied to the masonry arch to raise the masonry arch to a raised position. The masonry arch is then secured in the raised position.
Claims
1. A method of enlarging the space beneath a masonry arch bridge, the masonry arch bridge comprising a masonry arch and a spandrel wall at each end of the masonry arch, the method comprising forming a moveable portion of the masonry arch bridge by cutting the spandrel walls to form a cut on each side of the masonry arch, applying a lifting force to the moveable portion to raise the masonry arch to a raised position, and securing the masonry arch in the raised position.
2. A method as claimed in claim 1, wherein no strengthening means is applied to the masonry arch prior to lifting.
3. A method as claimed in claim 1, wherein a strengthening means is applied to the masonry arch prior to lifting.
4. A method as claimed in claim 3, wherein applying the strengthening means comprises applying a compressive force to the masonry arch.
5. A method as claimed in claim 3, wherein the strengthening means is applied by anchoring one or more tendons relative to the masonry arch and applying a tensioning force to the tendon(s).
6. A method as claimed in claim 5, wherein a first and a second tendon overlap in a lateral direction in a region above a crown of the masonry arch.
7. A method as claimed in claim 3, wherein the strengthening means comprises a saddle, and wherein the saddle is applied to an upper surface of the masonry arch.
8. A method as claimed in claim 7, wherein applying the saddle to the upper surface of the masonry arch comprises casting a reinforced concrete saddle to the upper surface of the masonry arch and allowing the concrete to cure.
9. A method as claimed in claim 8, wherein applying the saddle to the upper surface of the masonry arch further comprises post-tensioning the reinforced concrete saddle.
10. A method as claimed in claim 3 wherein the strengthening means comprises one or more devices being located and orientated to apply a force to the masonry arch, the force having at least a component in the horizontal direction.
11. A method as claimed in claim 3, wherein: the masonry arch bridge is a multi-span masonry arch bridge comprising one or more additional masonry arches and respective one or more piers between adjacent masonry arches; and the strengthening means is applied to the additional masonry arch(es).
12. A method as claimed in claim 1, further comprising providing a bearing in the cut.
13. A method as claimed in claim 1, further comprising, prior to applying the lifting force: forming wedge-shaped gaps in the spandrel walls laterally outward of the masonry arch; forming first and second moveable masonry arch portions by cutting through the masonry arch.
14. A method as claimed in claim 13, wherein securing the masonry arch in the raised position comprises inserting or forming a wedge between the first and second moveable masonry arch portions.
15. A method as claimed in claim 1, wherein during lifting the lifting force is applied such that arch action of the masonry arch is sufficiently maintained to ensure that the masonry arch maintains its structural integrity.
16. A method as claimed in claim 1, wherein the lifting force is provided at a lower portion of the masonry arch.
17. A method of enlarging the space beneath a masonry arch bridge, the masonry arch bridge comprising a masonry arch and a spandrel wall at each end of the masonry arch, the method comprising applying a strengthening means to the masonry arch, applying a lifting force to the masonry arch to raise the masonry arch to a raised position, and securing the masonry arch in the raised position wherein the strengthening means comprises at least one of: one or more tendons, wherein the one or more tendons are applied by anchoring the one or more tendons relative to the masonry arch and applying a tensioning force to the tendon(s); a saddle, wherein the saddle is applied to an upper surface of the masonry arch; and one or more devices being located and oriented to apply a force to the masonry arch, the force having at least a component in the horizontal direction.
18. A method as claimed in claim 17, further comprising, prior to applying the lifting force, forming a moveable portion of the masonry arch bridge by cutting the spandrel walls to form a cut on each side of the masonry arch.
19. A masonry arch bridge comprising a masonry arch having an upper surface, a spandrel wall at each end of the masonry arch, and a strengthening means applied to the masonry arch wherein the strengthening means comprises at least one of: one or more tendons anchored relative to the masonry arch; a saddle applied to the upper surface of the masonry arch; and one or more devices being located and orientated to apply a force to the masonry arch, the force having at least a component in the horizontal direction.
Description
(1) Certain preferred embodiments will now be described by way of example only and with reference to the accompanying drawings, in which
(2) FIGS. 1 to 9 illustrate the steps of an embodiment of the present invention;
(3) FIGS. 10 to 17 illustrate the steps of another embodiment of the present invention;
(4) FIGS. 18 to 26 illustrate the steps of another embodiment of the present invention;
(5) FIGS. 27 to 29 illustrate a method of strengthening the masonry arch;
(6) FIGS. 30 and 31 illustrate respective methods of lifting the masonry arch without added strengthening; and
(7) FIGS. 32 to 34 illustrate another embodiment of the present invention.
(8) Regarding the first embodiment, FIG. 1 shows a single-span masonry arch bridge 1 and a space 2 beneath the masonry arch bridge. The masonry arch bridge 1 comprises a masonry arch 3, a spandrel wall 4 at each end of the masonry arch 3, and a parapet 6 above each spandrel wall 4 and the masonry arch 3. The masonry arch 3 is supported on respective piers 9 at each side of the masonry arch 3. The masonry arch bridge is supported by embankments 5. Between the spandrel walls 4, the embankment 5 and the masonry arch 3, the masonry arch bridge is filled with fill material.
(9) The first phase of the method comprises installing lifting truss foundations 10 in the fill material and the embankments 5, installing debris netting and shield 11 to the masonry arch 3 and the masonry arch bridge 1 and installing a truss 12 on the truss foundations 10.
(10) With reference to FIG. 2, the method further comprises bracing the parapets 6, bracing the spandrel walls 4, excavating the fill material to uncover the masonry arch 3, and battering back the remaining fill material 7. It should be noted that the masonry arch may heave when excavation occurs.
(11) With reference to FIG. 3, the method comprises further jetwashing the upper surface 8 of the masonry arch 3, casting a reinforced concrete saddle 20 onto the upper surface 8 of the masonry arch 3 and allowing the concrete to cure.
(12) With reference to FIG. 4, the method further comprises post-tensioning 21 the reinforced concrete saddle 20, installing lifting strands 13, cutting spandrel walls to form vertical or near-vertical cuts 30 and cutting the piers 9 to form horizontal cuts 31, thus forming a moveable portion 32 of the masonry arch bridge 1.
(13) With reference to FIG. 5, the method further comprises jacking the truss foundations 10 at the location where the truss 12 meets the truss foundations 10, thus lifting the moveable portion 32 to the desired height. A gap 33 is formed at the location of the horizontal cut 31.
(14) With reference to FIG. 6, the method further comprises installing masonry, mortar and/or grout 40 to fill gap 33, allowing this to cure, de-jacking the truss 12, removing the truss 12, removing the truss foundations 10 and backfilling the excavated region, preferably with foamed concrete, the previously excavated material or new graded backfill material. The road level 14 may be adjusted to a suitable level.
(15) FIG. 7 provides another view of the excavated masonry bridge 1, showing the masonry arch 3, the spandrel walls 4, the parapets 6, the piers 9, the embankments 5, the remaining fill material 7, the truss foundations 10, the truss 12, the lifting strands 13, the saddle 20 and the moveable portion 32.
(16) FIG. 8 shows the reinforced concrete saddle 20 in more detail. The saddle 20 comprises two lifting beams 22 to which the lifting strands 13 are connected. The lifting beams 22 extend in the longitudinal direction of the saddle 20. The two lifting beams 22 are disposed on each side of the crown of the saddle 20, equidistant from the crown. The saddle comprises mechanical anchors 23 to provide and/or enhance anchoring between the saddle 20 and the masonry arch 3.
(17) The saddle comprises two sets of tendons 24 connecting first and second live ends 25 to first and second dead ends 26 respectively. The tendons 24 are spaced longitudinally from each other and extend in the lateral direction. The tendons 24 are evenly spaced.
(18) The first and second live ends of each set of tendons 24 extend longitudinally. The first and second live ends 25 are positioned at the crown of the saddle 20. The first and second dead ends are positioned at the lower portions of the sides of the saddle. The first live end 25 is positioned nearer the second dead end 26 than the first dead end 26, and the second live end 25 is positioned nearer the first dead end 26 than the second dead end 26. This allows the two sets of tendons 24 to overlap at the crown of the saddle 20.
(19) FIG. 9 shows the truss jacking mechanism in more detail. A jack 15 is positioned between the truss foundation 10 and the truss 12.
(20) Regarding the second embodiment, FIG. 10 shows a three-span masonry arch bridge 101 and a space 102 beneath the masonry arch bridge 101. The masonry arch bridge 101 comprises a central masonry arch 103, a first side masonry arch 116, a second side masonry arch 117, a spandrel wall 104 at each end of the central masonry arch 103, and a parapet 106 above each spandrel wall 104. The central masonry arch 103 is supported on respective piers 109 at each side of the central masonry arch 103. Between the spandrel walls 104 and the central masonry arch 103, the first masonry side arch 116 and the second masonry side arch 117, the masonry arch bridge 101 is filled with fill material.
(21) The first phase of the method comprises installing debris netting and shield 111 to the masonry arch bridge 101
(22) With reference to FIG. 11, the method further comprises bracing the parapets 106, bracing the spandrel walls 104, excavating the fill material to uncover the central masonry arch 103, the first masonry side arch 116 and the second masonry side arch 117, and battering back the remaining fill material 107. It should be noted that the masonry arches may heave when excavation occurs.
(23) With reference to FIG. 12, the method comprises further jetwashing the upper surfaces 108, 118, 119 of the central masonry arch 103 and the first and second masonry side arches 116, 117, casting a reinforced concrete saddle 120 onto the upper surfaces 108, 118, 119 and allowing the concrete to cure. The reinforced saddle has two saddle portions 128, 129. Further, jacking pockets 134 are formed in the piers 109.
(24) With reference to FIG. 13, the method further comprises post-tensioning 121 the reinforced concrete saddle 120, cutting spandrel walls 104 and parapets 106 to form vertical cuts or wedge-shaped gaps 130, cutting the piers 109 at the location of the jacking pockets 134 to form horizontal cuts 132, cutting the central masonry arch 103 and the parapets 106 at the crown to form vertical cut 135, thus forming first and second moveable portions 131, 136 of the masonry arch bridge 101.
(25) With reference to FIG. 14, the method further comprises jacking the first and second moveable portions 131, 136 using jacks 115 (see FIG. 26) located in the jacking pockets 134. The first and second moveable portions 131, 136 pivot about respective first and second pivot points 137, 138. The first and second pivot points 137, 138 are located at a position laterally outwardly from the side masonry arches 116, 117. This position may be at or near where the side masonry arches 116, 117 meet outer piers 144. The tip of each wedge-shaped gap 130 is respectively positioned at each pivot point 137, 138.
(26) Upon lifting, gaps 133 are formed between the masonry arches 103, 116, 117 and the piers 109. A crown gap 143 is also formed between the two movable portions 131, 136. Further, in addition to the jacks, shim wedges (not shown) may be inserted into the cuts 132 and/or jacking pockets 134 adjacent the jacks to support the masonry arch during lifting. Such shim wedges can be used in any of the embodiments of the present invention (e.g. regardless of whether jacks are used) to support the masonry arch when gaps are formed at the cuts during lifting. The shims may preferably be around 50 mm in thickness.
(27) A wedge, masonry, mortar and/or grout 140 is installed to fill gaps 133, 143. This is allowed to cure and the jacks 115 are de-jacked. The jacking pockets 134 can then be filled.
(28) With reference to FIG. 15, the method further comprises backfilling the excavated region, preferably with foamed concrete. The road level 114 may be adjusted to a suitable level. The original profile 145 of the bridge can be seen as being lower than the raised profile.
(29) FIG. 16 provides another view of the excavated masonry bridge 101, showing the central masonry arch 103, the first side masonry arch 116, the second side masonry arch 117, the spandrel walls 104, the parapets 106, the piers 109, the outer piers 144, the jacking pockets 134, the saddle 120, the moveable portions 131, 136 and the wedge-shaped gaps 130.
(30) FIG. 17 shows one of the reinforced portions 128, 129 of the concrete saddle 120 in more detail. The saddle comprises mechanical anchors 123 to provide and/or enhance anchoring between the saddle 120 and the central and side masonry arches 103, 116, 117.
(31) The saddle portion 128, 129 comprises a set of tendons 124 connecting live end 125 to dead end 126. The tendons 124 are spaced longitudinally from each other and extend in the lateral direction. The tendons 124 are evenly spaced.
(32) The live and dead ends 125, 126 of the set of tendons 124 extend longitudinally. The dead end 126 is positioned at the crown of the saddle 120. The live end 125 is positioned at the lateral periphery of the saddle portion 128, 129. The tendons 124 are upwardly inclined in a laterally inward direction from the outer periphery to the crown of the saddle 120.
(33) The concrete saddle 120 is cast such that the upper surface of saddle 120 is approximately at the original road level 114.
(34) Regarding the third embodiment, similarly to the second embodiment, FIG. 18 shows a three-span masonry arch bridge 101 and a space 102 beneath the masonry arch bridge 101. The masonry arch bridge 101 comprises a central masonry arch 103, a first side masonry arch 116, a second side masonry arch 117, a spandrel wall 104 at each end of the central masonry arch 103, and a parapet 106 above each spandrel wall 104. The central masonry arch 103 is supported on respective piers 109 at each side of the central masonry arch 103. Between the spandrel walls 104 and the central masonry arch 103, the first masonry side arch 116 and the second masonry side arch 117, the masonry arch bridge 101 is filled with fill material.
(35) The first phase of the method comprises installing debris netting and shield 111 to the masonry arch bridge 101. The shield can be seen in further detail in FIGS. 24 and 25. The shield has a shape that generally follows the shape of the masonry arch, such that the tracks underneath the arch may be used whilst the present method is carried out. The shield extends beyond the longitudinal extremity of the bridge. Such a shield can be used in any of the embodiments in the present invention, and can be used under any number or all of the masonry arches where multiple masonry arches are present.
(36) With reference to FIG. 19, the method further comprises bracing the parapets 106, bracing the spandrel walls 104, excavating the fill material to uncover the central masonry arch 103, the first masonry side arch 116 and the second masonry side arch 117, and battering back the remaining fill material 107. It should be noted that the masonry arches may heave when excavation occurs. Further, a plurality of cores 150 are formed at the crown of the central masonry arch 103. Inside these cores, horizontal jacks are installed.
(37) With reference to FIG. 20, jacking pockets 134 are formed in the piers 109 and rotation-clearance wedges 130 are cut in the two side arches 116, 117. Jacks are installed into jacking pockets 134.
(38) With reference to FIG. 21, all of the jacks (both the vertically orientated jacks in pockets 134 and the horizontally orientated jacks in the cores 150) are loaded. The remaining masonry between the pockets 134 is then cut, forming horizontal cuts 132. This may be done using a wire saw. The masonry between the cores 150 may be cut at this time or may have been cut prior to jack loading. The cut in the crown 135, the wedges 130 and the horizontal cuts 132 thus form first and second moveable portions 131, 136 of the masonry arch bridge 101.
(39) With reference to FIG. 22, the method further comprises jacking the first and second moveable portions 131, 136 using jacks 115 located in the jacking pockets 134. The first and second moveable portions 131, 136 pivot about respective first and second pivot points 137, 138. The first and second pivot points 137, 138 (and the wedges 130) are located at a position one-quarter of the span of the side arches 116, 117 from the outer lateral extremity of the respective side arches. The tip of the wedge-shaped gap 130 is positioned at the pivot point 137, 138.
(40) Upon lifting, gaps 133 are formed between the masonry arches 103, 116, 117 and the piers 109. A crown gap 143 is also formed between the two movable portions 131, 136. To ensure arch compression is maintained during jacking, the horizontal jacks located in the cores 150 are inflated during jacking. Further, in addition to the vertical and horizontal jacks, shim wedges (not shown) may be inserted adjacent the vertical and horizontal jacks 115 (e.g. in the cores 150, the jacking pockets 134, the horizontal cut 132 and/or the crown cut 135) to support the masonry arch during lifting.
(41) A wedge, masonry, mortar and/or grout 140 is installed to fill gaps 133, 143. This is allowed to cure and the jacks 115 are de-jacked. This may be achieved by using grout bags that are inserted into the gaps 133, 143 and inflated/filled with grout. Once the jacks are removed, the jacking pockets 134 and the cores 150 can be filled.
(42) With reference to FIG. 23, the method further comprises backfilling the excavated region, preferably with foamed concrete, the previously excavated material or new graded backfill material. The road level 114 may be adjusted to a suitable level. The brickwork can be checked and made good if necessary. The original profile 145 of the bridge can be seen as being lower than the raised profile. The netting and shield 111 are also removed.
(43) FIGS. 24 and 25 provide other views of the excavated masonry bridge 101, showing the central masonry arch 103, the first side masonry arch 116, the second side masonry arch 117, the spandrel walls 104, the parapets 106, the piers 109, the outer piers 144, the jacking pockets 134, the cores 150, the crown cut 135, the moveable portions 131, 136, the shield 111 and the wedge-shaped gaps 130.
(44) FIG. 26 shows the jacking mechanism in more detail. A plurality of jacks 115 are positioned in respective jacking pockets 134 in the piers 109.
(45) FIG. 27 illustrates an alternative strengthening means. In this embodiment, the strengthening means is applied by anchoring tendons 224 to the masonry arch bridge 201 and applying a tensioning force to the tendons. As can be seen, first and second tendons 224 overlap in the lateral direction in the region of the crown of the masonry arch 203.
(46) The tendons may be anchored to the spandrel wall 204. One end of each tendon 224 is anchored to one side of the crown, and the other end of each tendon 224 is anchored to the other side of the crown. The tendons 224 are upwardly inclined in an inward lateral direction. One tendon extends from an upper anchor position 225 on a first side of the crown and another tendon extends from an upper anchor position 225 on a second side of the crown. The tendons may extend to respective lower anchor positions 226. The upper anchor positions 225 are live ends, the lower anchor positions 226 are dead ends. The angle each tendon 224 makes with the horizontal is approximately equal.
(47) As shown in FIG. 28, which shows one example of section A-A, four tendons may be used, one attached to each surface of the spandrel walls 204.
(48) As shown in FIG. 29, which shows another example of section A-A, the masonry arch bridge 201 may comprise outer spandrel walls 204 inner spandrel walls 204. Further tendons 224 are attached to the inner spandrel walls 204.
(49) Another embodiment of the method is illustrated in FIG. 30. As shown, in this embodiment, a moveable portion 332 is formed by cuts 330 which may be inclined in a laterally outward direction. The cuts 330 extend from a masonry arch 303 to the upper surface of the bridge 301. Lifting devices 313 are attached to the lower portions of the moveable portion 332, preferably the lower-most block of the masonry. Further, the lifting devices are angled inward toward a point above the crown of the arch 303. The lifting devices may meet at this point or may be attached to a lifting beam or frame. As the moveable portion is lifted vertically by lifting force 350, the masonry is also subjected to a compression force since, due to the positioning of the lifting devices 313, there is a component of the lifting which acts to compress the masonry. Further, since the moveable portion 332 is being lifted from its lower portion, arch action continues to act to maintain the structural integrity of the masonry arch 303 during the lift. Although not shown in FIG. 30, the gap formed between the moveable portion 332 and the remainder of the bridge 301 can be filled after the lift to maintain the moveable portion in its raised position. Once this has occurred, the lifting force 350 may be removed and arch action continues to maintain the structural integrity of the masonry arch 303 now in its raised position. The masonry 333 of the masonry arch 303 is shown in enlarged schematic form. As shown in FIG. 30, the lifting devices 313 are lifting strands.
(50) However, alternatively (or additionally to the lifting from above shown in FIG. 30), as shown in FIG. 31, the lifting devices 313 may be provided by jacks. These jacks are inclined. The jacks are positioned between the moveable portion 332 and the remainder of the bridge 301 in the cuts 330.
(51) FIGS. 32 to 34 show an embodiment of the present invention in which a bearing 451 is provided at the laterally outward sides of a moveable portion 432.
(52) FIG. 32 shows a plan view of such a bearing 451.
(53) FIGS. 33(a) and (b) schematically shows the bearing 451 without the surrounding grout/concrete 456. A planar portion 452 slides upwards, but remains in contact with, another planar portion 453. FIG. 33(a) shows the relative positions of the two planar portions 452, 453 before lifting and FIG. 33(b) shows the relative positions of the two planar portions 452, 453 after lifting.
(54) FIGS. 34(a) and (b) shows the location of the cored holes 460 in relation to the cut 430 and the moveable portion 432. FIG. 34(a) shows a side-on view of the bridge 401 and FIG. 34(b) shows a plan view of the bridge 401.
(55) The bearing 451 acts to maintain compression and hence arch action of the masonry arch 403. The bearing 451 also reduces friction and allows for a more controlled lift. This is achieved by having a cut 430 comprising a plurality of cored holes 460. The cored holes 460 are substantially vertical. The cored holes 460 have a generally circular cross-sectional shape. The cored holes 460 are positioned adjacent one another and collectively extend along substantially the entire longitudinal length (i.e. in a horizontal direction) of the cut 430. The cored holes 460 are not present in the spandrel walls.
(56) A bearing 451 is located in each of the cored holes 460. The bearing 451 comprises two planar portions 452, 453 which are substantially identical to one another. The width of the planar portions 452, 453 is substantially the same as the diameter of the cored holes 460. The length of the planar portions 452, 453 is substantially the same as the depth of the cored holes 460.
(57) The bearing 451 comprises a friction reducing means 455, such as grease. The friction reducing means 455 is located between planar portions 452, 453. The friction reducing means 455 has an area that is substantially similar to that of the planar portions 452, 453.
(58) The planar portion 452 is attached to the moveable portion 432 by grout/concrete 456. The planar portion 452 is attached to the grout/concrete 456 by pegs 454. The pegs 454 are embedded in the grout/concrete 456. The bearing 451 may be positioned in the cored hole 460, and the grout/concrete 456 is then poured into the cored hole 460 and allowed to set around the pegs 454. Planar portion 453 is attached to the remainder of the bridge 401 in a similar fashion.
(59) When in use, the planar portions 452, 453 are in slidable contact with one another. Thus, as the moveable portion 432 is lifted (by any of the above-discussed methods) the planar portion 453 provides a lateral support to the planar portion 452. The planar portion 452 provides a lateral support to the moveable portion 432. The bearing 451 thus provides a lateral reaction force to the moveable portion 432, and helps to maintain the form of the moveable portion 432 and the remainder of the masonry arch bridge 401.
(60) As shown in FIG. 33(b), the bearing may contain a compressible material, such as rubber, 457 which can accommodate minor mis-alignment of the bearing 451 with respect to the intended slip plane whilst still maintaining pressure across the slip plane.
