GB2477163A

GB2477163A - Flood-resistant building having a floating caisson

Info

Publication number: GB2477163A
Application number: GB1001228A
Authority: GB
Inventors: Christopher Callaghan; Simon Bovill
Original assignee: LINDUM GROUP Ltd
Current assignee: LINDUM GROUP Ltd
Priority date: 2010-01-26
Filing date: 2010-01-26
Publication date: 2011-07-27
Also published as: GB201001228D0

Abstract

The flood-resistant building is constructed on a hollow, waterproof caisson resting on foundations 3,11 located in a recess 1 in the ground that is as deep as the caisson. The caisson comprises a plurality of sub-caissons 12 secured together, each sub-caisson extending the full depth of the caisson such that the building floats during a flood. The sides 6 of the recess may extend obliquely to a horizontal base surface. The foundations may be piles driven into the base surface. Guide piles 5 passing through deck members that extend horizontally from opposing sides of the building may be used to constrain horizontal movement of the building when afloat. A water storage tank for the building may be provided in one of the sub-caissons. The sub-caissons may be formed of a waterproof concrete and be secured together using stainless-steel bolts and clamping plates. Use of sub-caissons makes them easily transportable because they are lighter and smaller than a single, monolithic caisson. A method of constructing a flood-resistant building is also claimed.

Description

FLOOD-RESISTANT BUILDING

Field of the Invention

This invention relates to a flood-resistant building, and to a method of construction.

Background to the Invention

In the UK, as in many countries, there is a need to provide a large num-ber of new homes, but limited land upon which to build them. Some land which might otherwise be suitable for new developments is, however, categorised by the UK Environment Agency as in a flood risk area. Flood risks have been ex-acerbated in recent years by changes in weather patterns arising from global climate changes. The availability of building land would be increased if houses could be built which resist the effects of flooding.

In the Netherlands, where much of the land is low-lying and therefore at risk of flooding, one solution used is to construct the building on a concrete caisson serving as a basement, the caisson standing normally on foundations, typically piles, provided in a void constructed with sheet piling around, in such a manner that, in the event of a flood, the building floats on the water in the void, thereby preventing ingress of water to the building. Since the caisson is to serve as a basement and must be water-impermeable, it needs to be a unitary construction by specialist concrete constructors off site, and is very large, mak-ing transport by road impossible. In the Netherlands, this problem is overcome by using waterways to transport the caisson from the factory to the building site, which can be located adjacent to the waterway. The caisson can therefore be simply floated to the desired location.

However, this option is not available where waterways are not present, or are unsuitable for transport of such large items. The weight of the caissons would also require heavy lifting cranes, and in many locations where there is a high water table, for example, the ground would not be capable of supporting the weights involved. In addition, the provision of vertical sheet piling around the void is very costly.

A further problem with the provision of a full basement is that the greater the weight of the building, the deeper the floodwater would need to be to float the building, thus requiring a greater void to be excavated to accommodate it.

Summary of the Invention

According to one aspect of the invention, there is provided a building constructed on a hollow waterproof caisson resting on foundations located in a recess in the ground having a depth substantially equal to the depth of the cais-son, whereby, in the event of a flood, the building floats with the upper edge of the caisson above the level of the water, wherein the caisson comprises a plu-rality of sub-caissons secured together, each sub-caisson extending for the full depth of the caisson.

The invention also provides a method of constructing a flood-resistant building, comprising excavating a recess in the ground and providing founda-tions in the base of the recess, constructing a plurality of sub-caissons, each having an area in plan less than that of the building and a depth substantially equal to that of the recess, positioning the sub-caissons to rest on the founda-tions side-by-side and securing the sub-caissons together to form a caisson, and constructing a building on the caisson, whereby, in the event of a flood, the caisson, with the building thereon, floats with the upper edge thereof above the level of the water.

The sides of the recess are preferably constructed to extend obliquely to a horizontal base surface in which the foundations are located.

The foundations suitably comprise piles driven into the base surface, the sub-caissons resting, for example, on caps formed on the tops of the piles.

Deck members may be constructed to extend horizontally from opposed sides of the building at the upper edge of the caisson, and guide piles extending from the recess pass through apertures in the deck members, whereby to con-strain horizontal movement of the building when the building floats.

The sub-caissons may be used to locate services, such as a water tank or heating system, as well as serving to provide storage.

The building of the invention may be constructed at any location without requiring especially heavy lifting gear or access to deliver the caissons by wa- ter, the sub-caissons being manufacturable under controlled conditions in a fac-tory, for example, and then delivered to the building site by an ordinary heavy goods vehicle. In the event of a flood, the building floats vertically, preventing ingress of water to the building, but simply sinks back on to its foundations when the flood water recedes.

Brief Description of the Drawings

In the drawings, which illustrate an exemplary embodiment of the inven-tion: Figure 1 is a plan view of the building base; and Figure 2 is a cross-sectional view on line A-A in Figure 1.

Detailed Description of the Illustrated Embodiment

The building of the invention is constructed by first excavating a void 1 having a plan area just larger than that of the building and provided with sloping sides at the angle of repose of the soil 2. Piles 3 are driven into the ground through the base 4 of the void in a grid pattern, and two guide piles 5 are driven through two opposed sloping sides 6. The sloping sides and the base are lined with a geotextile membrane and sand, and concrete grass blocks 7 (interlocking blocks having through apertures moulded in them to allow drainage, for exam-ple) are laid on the sides with concrete ground beams 8 and 9 constructed around the top and bottom of the void to anchor the blocks. The base 4 is pro-vided with a layer 10 of concrete cast with through apertures (for example Grass-crete GC2), the apertures in the layer 10 and the blocks 7 being filled with soil. Concrete caps 11 are cast on top of the piles. The apertured blocks allow water to drain away into the surrounding soil, while the geotextile layer prevents the surrounding soil from being washed into the void by flood water seeping in from the surrounding land.

A plurality of precast concrete sub-caissons 12 are located side by side on the caps 11, such that the corners of the sub-caissons rest on the caps. The sub-caissons 12 are cast in waterproof concrete, for example prepared using Everdure Caltite waterproofing additive, and each is sized so as to be readily transportable by road to the building site, for example being Sin x 3m in plan, and with an overall height of 1.9m. The individual sub-caissons 12 are bolted together in situ to allow them to act as a single caisson using stainless steel bolts and clamping plates so that the six sub-caissons (in this particular illus- trated example) act together structurally as one monolithic unit. While the di-mensions of the sub-caissons may be insufficient to allow them to function as a proper basement to the building, they will be sufficient for use for storage or for the positioning of services such as water tanks (a pumped system would be re- quired), helping to lower the centre of gravity of the building and therefore in-creasing its stability if flood waters cause it to float.

A floor can be created on top of the caisson in conventional manner, for example using concrete beams, and allowing access points to the interiors of the caissons for storage and other purposes as hereinbefore described. The building is then constructed on top, for example from pre-formed panels. Ac-cess to the building from the surrounding land across the sloping sides of the void will be afforded by a bridge platform fixed to the caisson and resting on the ground in normal conditions. It will thus rise with the caisson in the event of a flood. In order to stabilise the building if it is caused to float, a bridge platform will be constructed on at least two opposed sides of the building such that the guide piles pass therethrough and secure the building against undesired hori-zontal movement.

In normal use, the building is directly supported on the piles, the weight holding the building stable. In the event of a flood, the building can float on its caisson unit, preventing water from entering the building. It will be appreciated that services such as electricity and water will need to connect to the building via a flexible connection accommodating any vertical movement when the build-ing floats. As the flood subsides, the building will simply settle back on to the piles.

Claims

CLAIMS1. A flood-resistant building constructed on a hollow waterproof cais-son resting on foundations located in a recess in the ground having a depth substantially equal to the depth of the caisson, whereby, in the event of a flood, the building floats with the upper edge of the caisson above the level of the wa-ter, wherein the caisson comprises a plurality of sub-caissons secured together, each sub-caisson extending for the full depth of the caisson.
2. A flood-resistant building according to Claim 1, wherein the sides of the recess extend obliquely to a horizontal base surface in which the founda-tions are located.
3. A flood-resistant building according to Claim 2, wherein the foun-dations comprise piles driven into the base surface.
4. A flood-resistant building according to Claim 1, 2 or 3, comprising deck members extending horizontally from opposed sides of the building at the upper edge of the caisson, and guide piles extending from the recess and pass-ing through apertures in the deck members, whereby to constrain horizontal movement of the building when the building floats.
5. A flood-resistant building according to any preceding claim, wherein at least one water storage tank for the building is located in one of the sub-caissons.
6. A flood-resistant building according to any preceding claim, wherein the sub-caissons are formed of waterproof concrete.
7. A flood-resistant building according to any preceding claim, wherein the caisson comprises six sub-caissons.
8. A method of constructing a flood-resistant building, comprising ex- cavating a recess in the ground and providing foundations in the base of the re-cess, constructing a plurality of sub-caissons, each having an area in plan less than that of the building and a depth substantially equal to that of the recess, positioning the sub-caissons to rest on the foundations side-by-side and secur-ing the sub-caissons together to form a caisson, and constructing a building on the caisson, whereby, in the event of a flood, the caisson, with the building thereon, floats with the upper edge thereof above the level of the water.
9. A method according to Claim 8, wherein the sides of the recess extend obliquely to a horizontal base surface in which the foundations are lo-cated.
10. A method according to Claim 9, wherein the foundations comprise piles driven into the base surface.
11. A method according to Claim 8, 9 or 10, comprising driving guide piles through opposed sides of the recess, and constructing deck members ex-tending horizontally from opposed sides of the building at the upper edge of the caisson such that the guide piles pass through apertures in the deck members, whereby the guide piles constrain horizontal movement of the building when the building floats.
12. A method according to any of Claims 8 to 11, comprising locating at least one water storage tank for the building in one of the sub-caissons.
13. A method according to any of Claims 8 to 12, comprising initially casting the sub-caissons in waterproof concrete.
14. A method according to any of Claims 8 to 13, comprising forming the caisson from six sub-caissons.
15. A flood-resistant building, substantially as described with refer-ence to, and/or as shown in, the drawings.
16. A method of constructing a flood-resistant building, substantially as described with reference to the drawings.