Supertech: Implosion may lead to new dimensions for future projects, says CBRI scientist - Hindustan Times
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Supertech: Implosion may lead to new dimensions for future projects, says CBRI scientist

Aug 27, 2022 03:14 AM IST

An expert in disaster management, Dr Debi Prasanna Kanungo, senior principal scientist at CBRI is leading a team of four young scientists who are geotechnical and structural experts

The Supreme Court-appointed body, Central Building Research Institute (CBRI), was the closest government body in the country fit to monitor the demolition of the 103-metre-tall Twin Towers in Noida’s Sector 93A. However, with extremely few demolitions undertaken in the country so far, there is little precedence or research available. When CBRI started asking questions, several questions remained unanswered initially. When it later submitted to the Supreme Court that the developer was not cooperating, Edifice Engineering, the demolition company, provided detailed voluminous data regarding the blast designs and the explosives that were analysed by CBRI. For this untiring effort to give priority to research, the apex court also praised the efforts of the team leader, Dr Debi Prasanna Kanungo, senior principal scientist at CBRI. An expert in disaster management, he is leading a team of four young scientists who are geotechnical and structural experts.

There are several old structures in India that require attention, and research from this project will help Dr Debi Prasanna Kanungo, senior principal scientist at CBRI, and his team work on them. (HT Photo)
There are several old structures in India that require attention, and research from this project will help Dr Debi Prasanna Kanungo, senior principal scientist at CBRI, and his team work on them. (HT Photo)

What is unique about the twin tower demolition?

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It is the first-of-its-kind demolition project in India and nothing of this scale has been done before. It is also uniquely challenging because heavy usage of concrete in the building makes it even more difficult to demolish than others of similar proportion. An extensive research is in the works as the implosion could lead to a new dimension for future projects. There are several old structures in India that require attention, and research from this project will help us work on them.

What were the major concerns with respect to structural safety?

Our most important concern was the satisfaction of residents and public safety. When we started, residents of Emerald Court were worried about the structural integrity of their existing buildings and how the vibrations from the blast would impact the closest towers. We inspected the site and focussed on Aster 2 and 3, the towers most at risk due to their proximity. We asked Supertech to conduct an authentic structural audit that we monitored as well. Both towers had 51 columns, five beams and three slabs. Of these,16 columns needed immediate attention. While the company repaired 10 by August 22, it was proposed to inject grouting and wrap carbon fibre reinforced polymer (CFRP) for the remaining six . Additionally, we suggested propping near the two towers as a second line of defence. We are glad that residents of Emerald Court are satisfied with our work.

More recently, we also discovered that a section close to Aster 2 and 3 was badly damaged due to water seepage caused by an open lawn over it. We suggested dismantling the entire section so that it can be reconstructed after the demolition. The dismantling will also be done by August 26.

What is being done for the GAIL gas pipeline that has been a major concern till now?

The closest distance at which the pipeline is laid is 16 metres at two points and even there, the debris will not fall directly during the blast but might spill over. GAIL appointed Engineers India Limited (EIL) as consultants to suggest next steps. They suggested impact cushions and bermswith debris along with 5x5 mm steel sheets that we approve. For additional safety, we suggested trapezoidal berms and old tyres to absorb impact on the top. GAIL will also supply gas at 70% pressure along this pipeline on the day of the blast and there are two valves on both sides as backup which can be closed immediately in case of danger.

What arrangements have been made to ensure that flying debris does not damage nearby buildings?

It cannot get any safer as 13 layers of protection in total are being used to wrap the columns and walls so that absolutely nothing manages to escape. For the primary blast floors, there are five layers of galvanized steel wire mesh sheets followed by five layers of geotextile fabric. For the secondary blast floors, the same sheets are used in 4+4 layers. This is aided by two layers of perimeter curtains covering the entire blast floors from the outside, followed by a layer of geotextile covering for the neighbouring buildings as well. This will ensure that all debris and broken pieces of concrete are contained inside the blast site.

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