Indian Experience of Refurbishment of Tower Foundation Located in Water Bodies Kunte Chaitanya1, Jain Kunal1, Gore Santosh1, Ambardekar Mahesh1, Sharma Arvind Kumar1 1Adani Electricity Mumbai Limited, Mumbai, India Online Published on 05 February, 2022. Abstract Transmission sector plays a vital role in transmitting bulk power to load centers. It is a link between power generation & distribution utilities. At generating station, the transmitting voltage is stepped up for transmitting power over long distances using extra high voltage (EHV) transmission lines to reduce the technical losses. Thus, transmission system becomes very crucial element of power sector. Therefore, uninterrupted availability of transmission system becomes a critical factor. In order to maintain the healthiness of transmission lines, routine maintenance activities are carried out during the Operation & Maintenance. However, more focus is given for superstructure elements & less emphasis is given to the foundations. Due to cross country nature of the lines themselves, the towers are located at different geographical arena & ensuring healthiness of tower foundations becomes difficult & critical; failure of tower due to deterioration of foundation would lead to disruptions affecting the end consumers. Therefore, specialized efforts are required to keep healthiness of foundation of towers located on land or in water bodies (partly or fully submerged). Mumbai city being the financial capital of India & a state capital of Maharashtra, demands 100% availability of its major infrastructures like rail, road, electricity etc. to meet need of city for smooth operation of the major facilities. This requires uninterrupted 24 X 7 power supply to the city. To meet this need; Adani Electricity Mumbai Limited (AEML) have commissioned 2 nos. of 220 kV double circuit transmission lines from Dahanu generation plant to Mumbai in year 1995, which helps to ensure uninterrupted power supply to Mumbai distribution utilities. This transmission network consists of total 813 numbers of transmission towers. Out of these, 4 numbers of towers are situated inside creek water bodies (2 numbers at Marve creek & other 2 at Vasai/Ghodbunder Creek). Foundation for each leg comprises of RCC piles, pile cap & chimney. Considering criticality of these transmission lines, after 25 years of operation, AEML decided to carry out residual life assessment study of foundations of these mid-stream towers to investigate healthiness & to take remedial measures required, if any. As the name suggest, these midstream towers are continuously present in saline water of creek. The upper part of foundation i.e. chimney and pile cap alongwith part piles are subject to splash zone. This induces chemical & mechanical corrosion inside the concrete structures. Structures falling under splash zone are also prone to shell formation having tough hardness & firm attachment with liner/steel plates covering structures. For residual life assessment of these mid-stream tower foundations, we jointly worked with a prominent technical institute of India. The assessment of both visible & completely submerged foundation parts was carried out with the help of professionals specialised in under water structure assessment. Subsequent to inputs from this assessment, a methodology was finalized to further strengthen the foundations for life extension. It was found that the corrosion is one of the major causes of deterioration of concrete structures and is considered a big threat to the durability of the structures especially for structures in continuous contact with saline water. Concrete structures located in aggressive environment where high temperatures and high chloride levels exist in both onshore & offshore, are subject to premature deterioration from corrosion of the reinforcement. The paper covers pre execution and execution challenges & safety measures taken during execution adhering field quality. The paper will be a guide for executing the refurbishment activities for the civil foundations situated inside water bodies for Transmission towers. Residual life assessment of foundations for towers situated inside water bodies is always challenging. This refurbishment would further strengthen the civil foundations to withstand adverse saline atmosphere thus ensuring no damage to superstructure which carries electricity from generating station to load centres, thus committing uninterrupted reliable power supply to distribution utilities. Top Keywords Mid- Stream Towers, Corrosion, Foundation, Splash zone, Submerge, Saline – water, Rebound hammer, UPV, Shore. Top |