Bearing capacity failure, soil quality led to collapse of RS wall at NH-66 in Kollam, says NHAI

Kollam (Kerala), Dec 11 (PTI) NHAI has said that the collapse of the Reinforced Soil wall at Mylakkadu, part of the NH-66 development work here, was due to poor bearing capacity and quality of the soil used, and action has been initiated against the contractor and the engineering firm.

In a statement, the National Highways Authority of India (NHAI) said its preliminary assessment indicates the cause to be a deep-seated shear or bearing capacity failure, meaning the soil at the foundation was too weak to support the fill.

The collapse occurred on December 5 at a 9.4-metre-high reinforced soil wall that serves as an approach to a vehicular underpass at Mylakkadu on the Kollam-Kadambattukonam route while it was under construction.

"Concessionaire and its promoters (M/s Shivalaya) and the Independent Engineer (M/s Feedback - Satra JV) have been temporarily suspended from bidding for future projects. They have also been issued show cause notices for potential debarment (up to 3 years for the concessionaire and up to 2 years for the IE), along with monetary penalties," the statement said.

The project manager of the Concessionaire and the resident engineer have also been removed from the project site, NHAI said.

According to the agency, while RS wall technology is proven, the failures raise serious concerns about the bearing capacity and quality of the soil used in the design and construction of such structures along NH-66.

To address this, NHAI is launching multiple initiatives. A high-level expert committee comprising Jimmy Thomas (IIT-Kanpur) and TK Sudheesh (IIT-Palakkad) visited the site on December 6 to investigate the failure and recommend corrective measures.

The findings of an earlier expert committee, constituted after the Kooriyad NH collapse, are also being implemented.

NHAI has further appointed 18 geotechnical agencies to conduct soil sampling and testing at 378 structures and RS wall locations across 18 projects on NH-66 in Kerala. This includes sites already built, under construction, or yet to start, officials said.

Agencies will deploy multiple rigs within 7 to 10 days, aiming to complete tests at 100 locations within one month and the rest within three months.

NHAI said the design and construction of every RS wall will be reassessed based on the field and laboratory reports.

"Remedial actions, including dismantling and reconstruction of walls, will be taken where necessary. RS walls will only be accepted after this process is complete and quality is confirmed. Accountability will be fixed for all lapses found during this review," the statement said.

Following a separate incident involving the falling of girders on the Aroor-Thuravoor Elevated Road Project in November, NHAI has already engaged RITES to conduct a safety audit.

This audit will now be expanded to other NH-66 projects to proactively identify and rectify safety concerns, the agency added. PTI TBA TBA KH