John L. Paul
KOCHI
Soil leaching from beneath Kochi Metro’s pillar number 347 at Pathadipalam following the 2018 floods (when much of the NH 66 beneath Edappally-Aluva metro corridor was inundated for days) could have led to the settlement of foundations and subsequent misalignment of the tracks atop the pillar, says E. Sreedharan, former Principal Advisor to DMRC.
“The pillar might need reinforcement in the form of additional piles to transfer the load of the viaduct to overcome the problem. This might be too early to arrive at a solution though. I was informed by a KMRL official about the problem on Thursday night. I expressed my willingness to inspect the site, following which a plan of action could be formulated in tandem with KMRL. Many of the piles, as on either side of the 90-metre-long balanced-cantilever metro viaduct over tracks at Ernakulam Junction railway station, have piles that go as deep as 50 metres,” the Metroman said.
‘Pile cap sank by 20 mm’
It is reliably learnt that 20 mm of the pile cap beneath the pillar sank, which in turn was reflected in a 9-mm slant on the track. The KMRL did not confirm the extent of the sinking and slant. Trains are being driven at a speed of 20 kmph over the portion, as compared to the average speed of 35 kmph at which they used to operate, as a precautionary measure.
The KMRL had on Thursday said the incident, which came to light over a week ago during a routine inspection, could be on account of the changes in the properties of subsoil and bearing strata, which marginally affected the substructure and thus caused the misalignment of the track. It said that an expert agency would be engaged for geotechnical and geophysical investigation.
“Our in-house team frequently inspects the track and other components on the 25-km Aluva-Pettah metro viaduct. Nowhere else has such a problem been detected,” metro sources said.
‘Built to last 100 years’
Mr. Sreedharan had told The Hindu in an interview in 2018 that there was no cause for concern over the safety of metro pillars built through the city’s slushy terrain. The metro viaduct was built to last 100 years and all pillars were designed with a factor of safety of “three”, meaning they can support three times the design load. “Their design is to safely support two fully-loaded trains [each with 900 commuters] and operating parallel to each other at the top speed of 90 kmph,” he had said in the interview.
