The frequent floods witnessed around the world (as this is being written, a third of Pakistan is under water) are seen as a direct manifestation of climate change. As people literally struggle to stay afloat amid the rising waters, ‘adaptation’ is the new watchword.
Researchers MV Varkey and Philbin M Philip of the APJ Abdul Kalam Technological University in Thiruvananthapuram, Kerala, have come up with an interesting proposition — houses that float.
Such ‘amphibious architecture’ — a growing area of interest in flood mitigation — enables a standard structure to float in floodwater, instead of being submerged.
The amphibious structure rests on earth but is designed to rise during a flood through a floatation mechanism underneath the house. It will stay afloat at one spot, supported chiefly by floodwater.
This also serves as a water conservation solution that works with the region’s natural flood cycle, rather than attempting to prevent it.
It is ideal for regions with indefinite inundation rates, as also delicate geographic conditions that make drastic remedies unviable.
The ‘floating house’ concept developed by Varkey and Philip is based on the fundamental law of floatation — if an object is lighter that the liquid it displaces, then it will float. Also, weight depends on the density of a material — the lesser the density, the lighter the object.
The researchers designed the house using waterproof material and sustainable architecture. A stainless-steel frame and a sub-frame made of fibreglass act as a buoy; perpendicular guide poles connected to the barge provide resistance to lateral wind and water pressures. The buoyant force upon a submerged object equals the weight of the fluid displaced by it, according to Archimedes Principle. The hybrid home is constructed in such a way that its load is equal to or less than the uplift force of water, allowing it to float, the designers explain.
Since the house is fixed down with vertical guideposts, it can only rise and fall as needed. Since the density of the hollow fibreglass base structure is less than that of water, it floats. The forces created by buoyancy might result in an uplift force, which keeps the house on the water’s surface.
The materials used in the construction should be appropriate as they will otherwise deteriorate in the saltwater, the researchers say. “EPS [expanded polystyrene] blocks, GFRC [glass fibre reinforced concrete] coating, GFRG [glass fibre reinforced gypsum] panels, concrete barges, ferro cement, fibreglass, and bamboo are some of the materials examined,” they say in a study authored by them.
The structure is 3 metres tall and made of 12.4-cm thick GFRG panels on a base of fibreglass hollow cylinders to keep the building afloat. Fibreglass has a low corrosive rate and does not affect the water.
The GFRG panels and fibreglass cylinder arrangement help lower the house’s centre of gravity, thereby improving its stability. The roof is made of lightweight steel. The building contains two bedrooms, a kitchen, and a dining/living area. Overall, the built-up area is 36.77 sq m.
The foundation can be a driven pile, with a floating section made of fibreglass cylinders. When loading exceeds the limit, a pile foundation can be installed under the four guide poles attached to the base truss. If the weight of the proposed construction appears to be more, soil stabilising processes can be used.
The design has some limitations. The structure can disintegrate in saline water, while flowing water will gather sludge. Over time, the sludge can cause the utility connection to deteriorate and the steel to corrode. However, these are engineering issues, for which solutions may be found over time.
“It’s time to establish a new connection with water, to push the boundaries of design and construction, and to start looking forward to a flooded era with more joy and inventiveness,” Varkey and Philip conclude in their study.
September 04, 2022