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(11) | EP 0 113 661 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Modular roadway construction method and prefabricated units therefor |
| (57) Structural elements for use in constructing roadways, turnways, viaducts and the
like comprise a rigid shell, a freeflowing filler material and at least one reinforcing
rod or cable extending across the filler and tying at least two opposite walls of
the shell. |
[0001] The present invention concerns novel structural elements and their use in construction in general including the construction of roads, runways, motorways, viaducts, aqueducts and the like, all to be referred to collectively as "roadways".
[0002] In the following the utilization of structural elements according to the invention will be described mainly with respect to the construction of roadways, it being understood that the utilization of the said structural elements is not restricted thereto.
[0003] In recent years the rate of construction of new roadways is ever increasing, both for the expansion of existing networks of motorways and for establishing roadway networks in areas where until now there have almost been no modern roadways. At the same time the cost for the construction of roadways is also ever increasing, the contributing factors being the cost of labour, the cost for the preparation of the ground on which the roads run by grading and/or filling so that a relatively smooth substrate is prepared for the roadway surface, and the cost of the materials required for roadway surfacing which is in particular high when the surface has to be adapted for heavy duty. Taking the case of a road, depending on the economics of the area where the road is being constructed, either a large labour force is used for preparing the ground or large amounts of heavy construction equipment are used, or both. The cost of the road increase of course even more where, for example, the road is laid across a swamp area or along a waterfront. Thus where the roadway goes through a swamp area, then to prepare the ground for the road it is necessary to drain the swamp, fill the drained area and level and/or grade the fill. In case of a roadway that is to run along a waterfront where the soil is usually very soft and the ground water level is close to the surface, the problems are even more complex and special means are required to keep away the ground water. Many times in fact the cost of placing a read across a swamp area or along a waterfront is so high that an alternative route around the wet area is chosen even though this is also extremely expensive.
[0004] The need for careful levelling and grading of the ground before laying a road surface could be obviated if the road surface were to be made of a heavy duty mass that is resistant to the forces to which it is subjected in use even if supported from below only at selected points and not over the entire lower face. Such a surface mass could be laid directly on an uneven ground or mounted on pillars so as to be in fact supported at selective spots only rather than over the entire lower face and still withstand all the forces acting on the upper face thereof. The only known material that would practically come into consideration for such requirements would be massive reinforced concrete but the material and handling costs of such a roadway surface are so high as to cancel out any saving achieved by not fully or not at all levelling and grading the ground. Thus, while the idea is theoretically sound it could hitherto not be practically realised.
[0005] The need for heavy-duty highly resistant structural elements arises also in connection with other forms of civil engineering such as the construction of buildings, factory halls, bridges, aqueducts, viaducts for railways, etc.
[0006] It is an object of the present invention to provide heavy-duty stress-resistant structural elements that are lighter and cheaper than conventional structural elements of similar size and mechanical properties.
[0007] It is a further object of the present invention to provide a new method for the construction of roadways making use of the new structural elements according to the invention.
[0008] In accordance with the invention there is provided a struc- tural element comprising a rigid shell, a free-flowing filler material within the shell and at least one reinforcing rod or cable extending across the filler and tying at least two opposite walls of the shell.
[0009] The free-flowing filler material of a structural element according to the invention may be granular solid, e.g. sand; clay and the like or a liquid such as water. Where the filler is a free- flowing granular material such as sand, it is preferably moistened by liquid lubricant, e.g. water, which enables to maximize the dense packing of the filler.
[0010] Structural elements according to the invention may be in the form of slabs, panels, beams, blocks, walls, pillars with or.without headplates, etc.
[0011] The reinforcing rods or cables in structural elements according to the invention may be prestressed, post-stressed or not stressed at all.
[0012] It has been found that structural elements according to the invention are extremely strong. If concrete is used in the shell the amount of concrete required is about half or even less than that needed.for conventional structural elements of similar size and mechanical properties and at the same time are also less expensive to make. These unique properties are due to the action of the filler which co-acts with the shell to withstand the compressive forces that act upon it. The filler material whether free-flowing granular or liquid, acts as a high viscosity liquid for transmitting forces in all directions, thereby to spread the compressive forces exerted thereon by transmission from the shell.
[0013] The shell may be of any suitable rigid material having the desired mechanical properties such as, for example, concrete, iron, steel, aluminium and the like.
[0014] The structural elements according to the invention may be prefabricated or may be made in situ. Whether the one or the other way is preferred will depend on the surrounding circumstances such as size of the elements and their cost of transportation.
[0015] For the manufacture of a unit according to the invention it is possible to first cast the shell without one of its walls with the reinforcing cable (s) or rod (s) anchored in one or more existing walls. The rod (s) or cable (s) may be prestressed or post-stressed or remain unstressed as may be required. This is then followed. by the insertion of the filler, at which stage the open side of the structure is uppermost. During the insertion of the filler the still open element is preferably placed on a vibrator which in case of a granular filler ensures dense packing and in the case of a liquid; filler such as water, ensures the escape of air bubbles. When the filler has been fully inserted and compacted or degased, as the case may be, the missing wall is applied to the element. Where the shell is of concrete, some of the moisture of the wet filler or some of the filler water is taken up by the concrete during setting.
[0016] Slabs according to the invention can be used to advantage for the construction of roadways. By one method the slabs according to the invention are placed directly on the ground. Where this method is practised the ground will have to be prepared somewhat but to a much lesser degree of refinement than in conventional roadway construction techniques.
[0017] Another method of constructing a roadway in accordance with the invention comprises implanting prefabricated pillars in the ground to protrude from the ground at a desired height and placing slabs according to the invention on such pillars.
[0018] The pillars may comprise headplates for better supporting the slabs. If desired, beams may be used and placed.across adjacent pillars with or without head portions and the slabs according to the invention are then placed on such beams. Any pillars and beams used in the performance of constructions in accordance with the invention may themselves be constructional elements according to the invention or else they may be conventional, e.g. of reinforced concrete or steel.
[0019] The pillars and beams are preferably prefabricated while the slabs may be prefabricated or be made in situ, depending on their size.
[0020] Prefabricated pillars used for the construction of roadways in accordance with the invention may be of modular design, that is they may be so designed that one fits on top of the other in a manner such that the plurality form a practically integral pillar without change of static characteristics. Accordingly a plurality of such pillars can be joined together to form an integral pillar of the desired height.
[0021] In a roadway according to the invention built on pillars, the pillars act as the foundation and as supporting columns at the same time.
[0022] With the aid of such modular pillars it is possible to provide any desired grading by varying the extent of protrusion of the pillars from the ground in accordance with a desired pattern. In this way a graded, sloping roadway is produced.
[0023] In the construction of a roadway in accordance with the invention using pillars the underground portion of the pillars is so shaped as to fulfil the function of piles or poles. Such pillars are preferably placed in the ground with the aid of a vibrating implanter which forces the pillars into the ground to the desired protrusion height. On the protruding portion of the pillars connecting plates may be placed and sustaining pillars may then be mounted on the connecting plates and slabs be placed thereon. In any way the bottom part of the slabs stays clear of the highest topographical protrusion of the ground and this way the need for ground preparation is generally eliminated.
[0024] Preferably the slabs are so designed that juxtaposed slabs interengage, e.g. by way of interlock or overlap of end and/or side portions.
[0025] The invention is illustrated by way of example only in the accompanying drawings in which:
Fig. 1 is a perspective view, partly torn open, of a slab according to the invention;
Fig. 2 is a longitudinal section along line II-II of Fig. 1 drawn to a larger scale;
Fig. 3 is a section along line III-III of Fig. 2;
Fig, 4 is a diagrammatic sectional view of a phase in the production of a slab according to Figs. 1 to 3;
Fig. 5 is a section through a pillar according to the invention taken along line V-V of Fig. 6;
Fig. 6 is a section along line VI-VI of Fig. 5:
Fig. 7 is a pictorial view of different roadways constructed in accordance with the invention; and
Figs. 8, 9 and 10 are perspective views of respectively a modular beam, a modular pillar and a modular edgebeam all for use in the performance of construction methods according to the invention.
[0026] Slab 1 according to the invention shown in Fig. 1 comprises a main portion 2 and a set off end portion 3 that serves for overlap with a correspondingly shaped end portion of another slab according to the invention. The slab is made of a concrete shell 4, a compact granular filler material 5, e.g. wet sand with a moisture content of 10-20% by weight, and a plurality of rows of reinforcing rods or struts 6, each such row being arranged in this particular case in the form of recurring V-shaped segments. The shell 4 comprises an expanded metal grid 7 embedded therein as shown in Figs. 2 and-3.
[0027] The wet sand used as filler in the embodiment of Figs. 1. to 3 may be replaced by other materials such as clay, by a flowing wet mass such as grout or by a pure liquid such as water.
[0028] Depending on size and logistic considerations, a slab of the kind of Figs. 1 to 3 may be prefabricated or produced in situ. It can be made large, e.g. about 100 m. long, and slabs of such a size will obviously have to be produced in situ. Such large slabs are used for placing directly on the ground. For other applications, such as pillar supported roadways, wall construction and the like, smaller slabs will be used.
[0029] In order to prevent corrosion of the reinforcing rods or struts these may be enclosed in cells 61 created by the provision of two partitions extending across the width of the slab and separating the said rods or struts from the filler material 5.
[0030] One way of producing a slab according to Figs. 1 to 3 is illustrated in Fig. 4. As shown a trough-shaped concrete shell 9 with an expanded metal grid 10 embedded therein is cast in a form assembly comprising an outer form 11 and an insert 12, the latter .being shown in Fig. 4 in the extracted position. At first the bottom plate of shell 9 is cast in form 11 with an expanded metal grid embedded therein and a plurality of reinforcing rods 14 anchored in the bottom plate in the manner shown. Thereafter the insert 12 is inserted and the side walls of the shell 9 are cast in the spaces between form 11 and insert 12, again with an expanded metal' grid embedded therein. Before or after the setting of shell 9 a filler material 15, e.g. wet sand, is poured into the shell and then insert 12 is removed. If desired the shell 9 may be extracted from form 11 prior to the introduction of the filler material 15. After the filler material 15 has been poured in, the shell 9 either within form 11 or after removal therefrom, is placed on a vibrator in order to compact the filler and thereafter an upper concrete plate with an expanded metal grid embedded therein is cast on top of the filled shell 9 so that the apexes of grid 14 or rods 6, as the case may be, become embedded in the upper plate similar as the lower apexes are embedded in the bottom of shell 9.
[0031] The pillar according to the invention shown in Figs. 5 and 6 comprises a pole 17 and a headplate 13. Pole 17 is of conventional design, e.g. massive, reinforced concrete.
[0032] Headplate 18 comprises a concrete shell 19 and a filler mass 20, e.g. of wet sand or solid concrete. Inside shell 19 there are two rows of identical, satellite boxes 21a to 25a and 21b to 25b, all of which are filled with a filler material which may be the same or different from the filler material 20. The boxes 21a, 23a and 25a accomodate concrete-filled tubes 26a to 30a and likewise boxes 21b, 23b and 25b accomodate concrete filled tubes 26b to 30b. Each of the concrete filled tubes 26a through 30a and 26b through 30b accomodates 3 vertical reinforcing rod such as, for. example, rod 31 in box 21b and rod 32 in box 25b. All the vertical reinforcing rods such as rod 31 and 32 are thus sheathed and they extend through a filler between two opposite walls of the headplate 18, namely the top and the bottom walls. Preferably the vertical reinforcing rods are post-stressed.
[0033] The headplate 18 further comprises two horizontal tubes 34, 35 both filled with concrete accomodating respectively reinforcing rods 36 and 37. These two reinforcing rods are thus also sheathed similar as all vertical reinforcing rods and they extend between two opposite side walls of the concrete shell across the filler 20. Preferably reinforcing rods 36 and 37 are also post-stressed.
[0034] The headplate 18 according to the invention weighs less and in the case of sand filler is about 30% less expensive than a headplate of massive reinforced concrete with the same mechanical properties.
[0035] If desired the headplate 18 may be adapted for standing thereon other structural elements, e.g. block shaped elements of similar construction as headplate 18.but higher. Where this is practiced the vertical reinforcing rods such as rods 31 and 32 shown in Figs. 5 and 6 will pass through all stacked elements connecting them to each other. This means that the vertical rods will be positioned only after the elements are stacked and they may, if desired, be post-stressed.
[0036] The ensuing vertical assembly may be capped by another headplate similar to plate 18 and the vertical rods are anchored in the lowermost and uppermost plates thus holding together all the elements stacked on the lowermost headplate 18. In this way an integral pillar may be produced in which the vertical tying rods may be post-stressed. Where a more massive pillar is required it is possible to juxtapose in an interengaging manner two or more pillars and headplates of the kind shown in Figs. 5 and 6 with horizontal rods such as rods 36 and 37 connecting the juxtaposed headplates 18. Here again rods 36 and 37 may be post-stressed.
[0037] The pictorial illustration of Fig. 7 shows by way of example some surface ways that can be constructed in accordance with the invention. For example at 40 there is a graded roadway starting at a level and rising to a height while 41 shows the surfaceway being used as a landing strip and 42 shows the component parts of a surfaceway being used as a viaduct to hold rails for railroad vehicles. At 43 there is shown a ground depression bridged by a roadway 44.
[0038] The main component parts of the roadway shown in Fig. 7 are modular pillars shown in two different forms as pillars 45 and 46; modular beams which are shown in two different forms, modular beam 47 and modular beam 48, and the slabs 49. The pillars 45 and 46 may have a head portion according to the invention of the kind shown in Figs. 5 and 6 and slabs 49 may for example be in the form shown in Figs. 1 to 3.
[0039] Grading utilized in the system is controlled by monitoring the amount by which the pillars protrude from the ground. The nodular pillars are placed one on top of the other to obtain the desired height. Thus for example in the roadway 40 a single pillar is shown at 50 while pillars 46 are each made out of two modular portions. In this way the roadway climbs to the desired height at a desired slope.
[0040] Fig. 8 shows a beam 52 that can be used in the construction of a roadway with slabs and pillars according to the invention. It has an inverted T-shaped profile and two hollow channels 53 and 54 which if desired may be filled with a filler material or else serve for the accommodation of functional elements such as, for example, electric cables and wires. Shoulders 55 and 56 serve for receiving the end portions of the slabs such as slab 1 of Fig. 1.
[0041] The modular pillar 57 shown in Fig.9 comprises at one end a socket 58 and at the other end a protuberance 59 whereby it is adapted for interlocking alignment with similar modular pillars. However the pillar 57 may also be directly fixed in the ground and may support at its top a slab such as-slab 1 of Figs. to 3, either directly or with the interposition of other structural elements such as a headplate or a beam.
[0042] Beam 60 of Fig. 10 is an edge beam. Similar as beam 52 of Fig. 8 it comprises channels 61 and 62 and a shoulder 63 while the other shoulder in the beam of Fig. 8 is replaced here by a wall portion 64.
[0043] The structural elements of Figs. 8 to 10 may or may not be made in accordance with the invention. In any event they are useful for constructing roadways using slabs and pillar heads according to the invention of the kind described hereinbefore. For constructing a roadway with slabs according to the invention on pillars a vibrating unit may be used to force the pillars into the ground surface that does not have to be prepared in any manner. The vibrating unit forces the pillars into the ground to the desired protrusion height. The height may be measured with any suitable instrument such as a laser altitude measuring device which is accurate and easily utilized. One or more pillars can be placed on top of an inset pillar to obtain the height desired for the roadway. When a number of pillars are placed in position beams are placed over the pillars and/or the pillars are fitted with headplates, e.g. as shown in Figs. 5 and 6.
[0044] The new methods of roadway construction with slabs and other structural elements according to the invention are extremely versatile and cost effective since almost the entire roadway is prefabricated or made from elements fabricated in situ. Where pillars are used the roadway runs overhead the topmost topographical protrusion so that no ground surface preparation is necessary at all. Where slabs are placed directly on the ground some ground preparation is required but to a much lesser degree than in conventional road construction methods.
1. A structural element comprising a rigid shell, a free- flowing filler material
within the shell and at least one reinforcing rod or cable extending across the filler
and tying at least two opposite walls of the shell.
2. The structural element claimed in claim 1 characterised thereby that the said reinforcing
rod or cable is enclosed within a cell created by partitions extending across the
interior space of the shell.
3. An element according to Claim 1 or 2, wherein the shell is of concrete.
4. An element according to Claim 1 or 2, wherein the shell is of metal.
5. An element according to any one of Claims 1 to 4, wherein the filler is a solid
granular material.
6. An element according to Claim 5, wherein said granular material.has a moisture
content.
7. An element according to Claim 5 or 6, wherein the filler material is sand.
8. An element according to any one of Claims 1 to 4, wherein the filler material is
liquid.
9. An element according to Claim 8, wherein the filler material is water.
10. An element according to any one of Claims 1 to 9, being a slab.
11. A slab according to Claim 10 adapted for interengagment with other slabs.
12. An element according to any one of Claims 1 to 9 being a pillar.
13. A pillar according to Claim 12 being a modular unit adapted for intergration in
alignment with other units.
14. An element according to any one of Claims 1 to 9 being a beam.
15. An element according to any one of Claims 1 to 9 being a pillar headplate.
16. A headplate according to Claim 15 comprising a concrete shell, a main central
filler mass and satellite boxes with filler mass and vertical and horizontal reinforcing
rods extending across said main and satellite filler masses between opposite shell
walls.
17. A headplate according to Claim 16, wherein said reinforcing rods are sheathed
in concrete.
18. A headplate according to any one of Claims 15 or 16 adapted for association with
other elements according to the invention.
19. A method of red construction comprising laying slabs according to Claim 10 or
11 directly on the ground.
20. A method of constructing a roadway comprising implanting prefabricated pillars
in the ground to protrude from the ground at a desired height and placing the slabs
according to Claim 10 or 11 on sach pillars, if desired with the interposition of
other structural elements.
21. A method accordinc to Claim 19, wherein beams are interposed between the villars
and slabs.
22. A method according to Claim 19 or 20, wherein headplates are mounted on the pillars.