Field and numerical study of vibration on existing berthing structure due to pile driving

The tremendous inflow of goods from different parts of the world to ports in India has created an increased demand for renovation of existing berthing structure and also extension of the port. The ports have to be extended so as to harbour large number of incoming vessels. The extension will have to be near the existing berth in order to get proper connectivity to other port facilities and also to obtain the pros of site like the water depth requirement and water area protection. The new berthing structure construction involves several vibratory processes like chiselling and pile driving. These construction activities cause vibration on adjacent berthing structure which may lead to non-serviceability of those. Hence, it is essential to find that these lie much below the permissible limits. The field test was done at Tuticorin where the chiselling process was going on adjacent to an existing berthing structure. The site predominantly had weathered basalt rock, and this has to be bored using chisel before concreting. The vibration measurement was taken at the deck of adjacent existing berthing structure. This was repeated by placing instrument at various distances from pile on deck. The geophone, a vibration-measuring instrument, records vibration and peak particle velocity along all the three perpendicular directions, i.e. transverse, longitudinal and vertical directions. The vibration measurements were found to be much lesser than permissible limits, and hence, the structure is safe. The site details, pile details and pile hammer details were collected and are modelled in Plaxis to confirm that the field measurements taken were proper.