Power Grid Corporation of India Ltd

Key Achievements

• Keller’s innovative solution by executing large diameter vibro stone columns (1.1  meters) helped in optimizing overall construction time and cost.
• The solution addressed settlement requirement and liquefaction mitigation.
• The vibro stone column solution has comparatively lower carbon footprint than the other possible solution.

 

The Project

Powergrid Corporation of India Ltd ( PGCIL ) proposed India’s 1st Ultra High Voltage   Direct Current (UHVDC) of 6,000MW capacity energy highway project to transmit the generated energy from Arunachal Pradesh in North East India and Bhutan to Agra ( Central India), a distance of 1,728km. Keller was commissioned by the main contractor to execute ground improvement work for a converter station in Assam which was spread over 1,000,000 m2 and consists of electrical equipment structures such as service building, valve control hall, P1, P2, AC transformers, tower foundations and other heavy structures.

The Challenge

The geotechnical investigation of the proposed site suggested that the subsoil comprised of poorly graded loose to medium fine sand followed by medium to stiff and then dense silt layer. This virgin soil condition was not suitable for the proposed structures as bearing capacity of soil was low and also susceptible to liquefaction, as the project site falls under seismic zone "V".

The Solution

Keller’s solution to address the associated challenge involved  ground improvement works using top feed vibro stone columns of diameter ranging from 0.8 meters to 1.1 meters. The selection of large diameter stone columns helped to reduce the construction time to a great extent.. Adequacy of the job was verified by performing stone column load test and real time monitoring of installation works by automated devices.

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Project Facts