Did pile foundation cavity have something to do with the collapse?

Jayant Tipnis’s office is a short distance away from Poonam Chambers. Though Tipnis, managing director of Jayant Tipnis Constructions -- a leading civil engineering firm in the city -- heard of the accident nearly two hours later, he spoke of the likely reasons for the collapse.

"Poonam Chambers was not a very sound building. The finish was not good and the building already had some reservations. The other buildings in the Shiv Sagar estate (the commercial complex which houses the ill-fated building) -- that were built before looked much more stronger. Poonam Chambers itself was not more than 20 years old."

Tipnis cites the reasons for a building collapse -- an earthquake, where the velocity of impact is not known and hits a structure suddenly. A weak foundation, or an improper cement-water ratio.

At Poonam Chambers, he feels, one wing of the building may have collapsed because of pile foundation cavity. In this a hole is drilled into the soil and concrete is poured into it. When concrete is poured, a cavity sometimes develops within this hole. The cavity, however, is not visible from above. Sometimes, the cavity can be around two feet wide. In due course, if the load of the column lying above this cavity increases, the column sinks in, collapses and brings the frame of the building down with it.

It is not necessary, says Tipnis, that prior indication of such a disaster would be available. Catastrophe can strike suddenly. Often, drilling and other construction work causes vibrations and damages the structure. Sometimes, repairs are done without adhering to the norms, taking precautions or following the right procedure.

Right now the first three floors of Poonam Chambers have collapsed. It is expected that the lower floors may shortly buckle under the impact from above. In a collapse of this scale, Tipnis feels the rescue operations will take at least three or four days.

--Archana Masih