There are four fundamental aspects that need to be considered for construction near the coast in India.
Florida partial building collapse: Last week, the Champlain South Towers condominium in Florida’s Surfside partially collapsed, in a reminder of the vulnerability of structures built near the coast. According to a report in IE, engineering firm Thomas E Henz had said in October 2018 that the 40-year-old apartment block needed substantial repairs, finding that the pool deck and the entrance driveway were not adequately waterproofed, while the 12-storey oceanfront building’s parking lot had cracking and spalling in varying degrees in the columns, beams and walls.
Irregular or unplanned building of structures near the coast, or “marine urban sprawl” plays a big role in the rising of water levels and in land subsidence because excessive groundwater is extracted, the report cited University of New South Wales Dean of Science Emma Johnston as saying. So far, the exact cause of the collapse has not yet been established, but there are certain factors that need to be considered while building structures close to the sea. The report added that there are four fundamental aspects that need to be considered for construction near the coast in India.
The first and foremost of these is the soil and the foundation. Coastal areas are lined with a sandy strata that goes considerably deep below which is a layer of hard rock or maybe sometimes, marine clay. Structures are therefore built on a pile of foundation in such locations, in which piles of concrete are driven to rest on a stratum that is suitable and deep into the ground. These piles can live longer if materials that can withstand the hostile marine environment are carefully selected, according to Principal Consultant in Design Spectrum Santosh K. Chemical additives can be included in this to improve the performance of sulphate-resistant cement or concrete. Moreover, so that the hard strata supports the foundation, the engineers also ensure that non-corrosive steel is used and the area of the concrete is increased. The concrete is also made dense so that it becomes watertight.
The second fundamental point to keep in mind is the material interaction. Saltwater seeping into the concrete – called spalling – can be a major concern in structures built close to the sea, since this can cause support beams to rust and gradually weaken. Coastal buildings also often see corrosion and the cover of steel can affect the erosion. Carbonation is also an issue, since it can cause the cement slurry surrounding the structure to lose its protective properties.
Structural audits are also key to ensure that buildings near large water bodies are well-maintained. The report said that in 2019, the Brihanmumbai Municipal Corporation had called for conducting structural audits of buildings that are older than 30 years old. Timely interventions like these can help in preventing building collapses, even as the implementation of such measures continue to be a challenge.
Last of the points to consider is the sea level. Santosh said that when humans encroach into the territory of the sea, the sea does get back elsewhere. He added that all over the world, instances of rising water levels have been reported which is why there needs to be more research in this area so that decisions can be made accordingly.