GB2272468A - Infilled wall - Google Patents

Abstract

An infilled wall (16) such as a spandrel wall or a culvert wall is strengthened by the incorporation into infill (19) adjacent the wall of tensile elements (17) which are either independant of the wall (16) or connected only to that wall (16). <IMAGE>

Description

MASONRY ARCH SUPPORT The present invention relates to the strengthening of earth-backed walls used in the construction of arches, and in particular to the strengthening of spandrel walls used in masonry arch bridges and of culvert walls.

In the construction of a masonry bridge over, for example, a gulley containing a river or a railway, foundations are laid at the sides of the gulley and a former of curved section is positioned to span the gulley. A stone arch is then laid over the former. Walls, known as spandrel walls, are built at the sides of the arch and the volume between the arch and the spandrel walls infilled with an infill consisting of, for example, rubble and earth. The construction for which the bridge is required, which may be, for example, a road, is then laid over the rubble.

The spandrel walls are a known source of weakness that can reduce the life of the bridges, as compaction of the infill results in outward pressure on the spandrels. Imminent failure can usually be recognised by bulging of the walls. One known method for combating this problem is to link the walls together with tie bars. However, it has been found that although this arrangement does increase the life of the walls pressures build up increasing the tension in the tie bars until a sudden breakdown, such as snapping of a tie bar or rupture of a fastening, causes a sudden breakdown in the structure.

The present invention provides an improved strengthening means which avoids the sudden breakdown that can occur with tie bars.

According to the present invention an infilled wall is strengthened by the incorporation into infill adjacent to the wall of tensile elements which are either independant of the wall or connected only to that wall.

The tensile elements associated with a particular wall preferrably extend normal to the wall and are preferrably, though not necessarily, secured to thereto. For a first spandrel wall elements extending normal therefrom towards a second spandrel wall may overlap elements extending from the second spandrel wall, but will not be attached to the second spandrel wall.

Tensile elements can be incorporated in a structure during construction, but may also be introduced to existing structures by, for example, introduction through holes drilled in a wall at suitable intervals. A hole might be extended into the infill material, after which an element is introduced and might be centrally located by means of centralizers attached at suitable intervals along its length. The hole can then be filled1 with a chemical such as cement grout injected under low pressure1 or with sand which might be compacted into the hole using compressed air by a tremie pipe arrangement.

Anchor pieces might be included in each tensile element to increase its resistance to movement relative to surrounding material.

For elements introduced to an existing construction the anchor pieces might be rotatable attached to the elements so as to lie flush therewith during insertion of the elements, being rotated into positions transverse of the elements after insertion under the action of means such as moveable rods within and coaxial with the elements.

The anchor pieces might also act as centralizers.

The infill adjacent to a wall or between walls might also be strengthened in axes other than those normal to the wall or walls by tensile elements extending normal to those axes.

One embodiment of the invention will now be described, by way of example only9 with reference to the accompanying diagrammatic drawings, of which: Figure 1 is a side elevation of a masonry arch bridge, Figure 2 is an end elevation, in section along line II-II of Figure 1, of the bridge. and Figure 3 is a plan view, in section along line III-III of Figure 2, of the bridge.

A masonry arch bridge 10 over a gulley 11 is formed by the placing of a former 12 over foundations 13 at the sides 14 of the gulley. A stone arch 15 is then built over the former 12. Walls 16, having inwardy extending tensile members 17 incoLporated therein, are built on the arch 15 and the volume 18 between the arch 15 and walls 16 filled with an infill 19 of suitable and available material such as rubble and earth. A surface 20, such as a road surface, is then laid on the infill 19.

The tensile members 17 might have anchor members or barbs 21 extending therefrom.

In addition, or as an alternative, to the tensile members 17 attached to the walls 16 unattached tensile members 22 having anchor members or barbs 23 might be positioned normal to the walls 16, and the infill material 19 might be strengthened in axes parallel to the walls 16 and radial to the arch 15 by tensile members 24, 25, similar to the tensile members 17, 21, extending parallel to the walls 16 and radial to the arch 15.

The former 12 will usually be removed once the construction of the bridge 10 is completed.

It will be realised that tensile members 17, 21 may be introduced into an existing masonry bridge 10 by drilling holes through the walls 15. The holes might be extended to allow the members to be introduced, the holes then being filled with, for example, concrete or sand. The tensile members 17, 21 might be centalized in the holes by centralizers, which may double as anchors or barbs 21,23, swung from a position flush with the members to a position extending outwardly therefrom by, for example, operation of moveable rods position within the members.

It will be realised that whilst the invention has been described above with reference to a masonry arch bridge it will be equally applicable to other wall structures, such as culvert walls, backed with an infill.

The action of tensile members 17, 21 in strengthening earth and similar foundations is well known in the art and will not be described here. Similarly methods of introducing items such as tensile members 17, 21 into existing structures, and of makin g and then filling holes in existing structures are well known in the civil engineering arts and do not need discussion here.

Claims (11)

1. What is claimed is; 1. An infilled wall strengthened by the incorporation into infill adjacent to the wall of tensile elements which are either independant of the wall or connected only to the wall.
2. 2. A wall as claimed in Claim 1 having tensile elements extending normal to the wall.
3. 3. A wall as claimed in Claim 2 wherein the tensile elements are secured thereto.
4. 4. A wall as claimed in Claim 2 or in Claim 3 wherein the wall is a spandrel wall.
5. 5. A wall as claimed in Claim 4 wherein wall elements extending towards a second spandrel wall overlap elements extending from the second spandrel wall.
6. 6. A wall as claimed in Claim 2 or in Claim 3 wherein the wall is a culvert wall.
7. 7. A wall as claimed in any one of Claims 2 to 6 including tensile elements extending in planes other than normal to the wall.
8. 8. A wall as claimed in any one of Claims 1 to 7 wherein the tensile elements are installed during construction.
9. 9. A wall as claimed in any one of Claims 2 to 6 wherein the tensile elements are installed after construction.
10. 10. A wall substantially as herein described with reference to Figures 1 to 3 of the accompanying drawings.
11. 11. A wall substantially as herein described.