Kolkata: Engineers have overcome a technical challenge that will pave the way for reconstruction of houses that had collapsed following multiple cave-in incidents at Bowbazar in 2019 and 2022 during the East-West Metro construction.With deep foundation ruled out due to the presence of the twin metro tunnels that lie directly beneath Durga Pituri Lane and Syakrapara Lane in Bowbazar, engineers conducted a ‘plate load test’ to check the load bearing capacity and settlement behavior of the soil at Durga Pituri Lane recently. Following satisfactory results of the crucial soil test, the agency can now go ahead and construct houses using a design that does not require deep foundation.TOI on July 15 reported that some displaced families have started moving in after Kolkata Metro Rail Corporation (KMRC), implementing agency of the Howrah Maidan-Sector V Green Line or East-West Metro, completed construction of four new houses that had collapsed due to the subsidence on Aug 31, 2019.However, the agency has been facing construction challenges for building homes directly over the two underground tunnels.The twin underground tunnels pass through this northern part of the open space where a cluster of century-old buildings stood in the pre-subsidence era.“It is not possible to build piles (deep foundations) near the tunnels, which are 15 m deep. The buildings above the tunnels will be built with alternative modern techniques adopted to construct houses on soft soil,” said an engineer.The plate load test involved placing rows of sandbags on a square steel plate to measuring the resulting settlement. The tolerance limit for the test is 75 mm. The results were less than 60mm.Now, plain cement concrete will be cast above the rows of sandbags placed over the twin tunnels. And a new building – 6A Sykrapara Lane – will be constructed there. It was one of 25 century-old structures that fell when the tunnel borer digging the westbound tunnel hit a sand aquifer, and water started gushing out from below the soil.
