The fault in construction and lack of precautionary measures led to tunnel cave-in in Bilaspur district that has put the life of three labourers at risk. Former Director of the Geological Survey of India (GSI) LN Aggarwal said this while talking to The Tribune here today.
He said debris blocked a 100-metre patch in the tunnel which is being constructed by Himalayan Construction Company on the Kiratpur-Ner Chowk sector.
He said the company carrying the construction had done shot creating at entrance of the tunnel. In shot creating, an iron mesh is put on the surface of the tunnel and it is concretised. However, the strata, in which construction was being carried out, was that of Shivalik hills that was loose. In such cases as per the load factor of hill, wood or iron lining is erected to support the tunnel entrance. Had such precautionary measures been taken, the accident could have been averted, former director of the GSI said.
He further said it appeared that construction engineers had not taken into consideration the geological set-up of the area. The first and foremost geological requirement for the excavation of a tunnel is to understand the lithological and structural setup.
As per information, the area is occupied by the fluviatile sediments comprising mudstones, sandstones, siltstones, conglomerates, etc belonging to the Shivalik formation. The rocks are jointed, fractured, weathered and tectonically bound by faults on the North and the South, Aggarwal said.
When tunnelling in the hills is done, the stresses in the rock mass get redistributed and equilibrium of the strata is disturbed. Therefore, before commencing the construction of a tunnel, full precaution has to be taken.
The geotechnical details, including geological longitudinal and cross sections of the tunnel, revealing the lithological details of the strata to be encountered during excavation should have been taken. This would have given the company possibilities of rock fall, rock flow, rock burst, rock loads in the cavities.
He said debris blocked a 100-metre patch in the tunnel which is being constructed by Himalayan Construction Company on the Kiratpur-Ner Chowk sector.
He said the company carrying the construction had done shot creating at entrance of the tunnel. In shot creating, an iron mesh is put on the surface of the tunnel and it is concretised. However, the strata, in which construction was being carried out, was that of Shivalik hills that was loose. In such cases as per the load factor of hill, wood or iron lining is erected to support the tunnel entrance. Had such precautionary measures been taken, the accident could have been averted, former director of the GSI said.
He further said it appeared that construction engineers had not taken into consideration the geological set-up of the area. The first and foremost geological requirement for the excavation of a tunnel is to understand the lithological and structural setup.
As per information, the area is occupied by the fluviatile sediments comprising mudstones, sandstones, siltstones, conglomerates, etc belonging to the Shivalik formation. The rocks are jointed, fractured, weathered and tectonically bound by faults on the North and the South, Aggarwal said.
When tunnelling in the hills is done, the stresses in the rock mass get redistributed and equilibrium of the strata is disturbed. Therefore, before commencing the construction of a tunnel, full precaution has to be taken.
The geotechnical details, including geological longitudinal and cross sections of the tunnel, revealing the lithological details of the strata to be encountered during excavation should have been taken. This would have given the company possibilities of rock fall, rock flow, rock burst, rock loads in the cavities.
