The National Highways Authority of India (NHAI) has launched a large-scale geotechnical investigation across the entire NH-66 expansion project in Kerala following the recent collapse of a reinforced soil (RS) wall at Mylakkadu in Kollam.
In order to address concerns over structural integrity, the NHAI has employed 18 geotechnical agencies to perform rigorous soil sampling and testing at a total of 378 RS wall locations across 18 different highway projects in Kerala. This comprehensive audit will cover sites that are already constructed, currently in progress, and those yet to begin.
The appointed agencies are required to deploy multiple drilling rigs within the next 7 to 10 days, with the goal of completing tests at 100 locations within the first month and finalising the entire assessment within a three-month time frame, aiming to quickly ascertain the safety and stability of all reinforced soil structures along the corridor.
The collapse of the RS wall at Mylakkadu, which was part of the approach structure to a vehicular underpass on the Kollam–Kadambattukonam NH-66 project, is linked to a fundamental geotechnical problem. Preliminary assessments of the NHAI indicate the collapse of the 9.4-metre-high wall was due to a deep-seated shear or bearing capacity failure. Essentially, the soil beneath the foundation was critically weak and unable to support the heavy load imposed by the RS wall and the massive earth fill behind it.
