29th IGS Annual Lecture READ FULL LENGTH PAPER IN PDF

Prof. S.  Narasimha Rao

PULLOUT BEHAVIOUR OF SCREW AND SUCTION ANCHORS IN
SOFT MARINE CLAYS

Dr. S. Narasimha Rao
Professor [Retd.],
Department of Ocean Engineering,I.I.T. Madras, Chennai – 600036, India.


AS2 Veena Apartments, No.70, 2nd Main Road, Gandhi Nagar Chennai – 600020
Email: snarasimharao@hotmail.com

ABSTRACT:  In the foundations of some marine structures, it is common to use anchors. It has been proposed that screw and suctions types of anchors can be used in soft marine clay formations. If the water depths are quite large with poor subsoil conditions as encountered in some of the Indian Offshore areas, some innovative types of offshore structure have to be planned. The pullout capacities of screw suction types of anchors are brought out.

Screw types of anchors can be easily installed in Marine environment. An attempt has been made to predict the pullout capacities in terms of pile sizes, spacing of screw plates and soil strength and based on the embedment depths, the screw anchors are divided into shallow and deep anchors. The capacities are verified for both static and cyclic loading conditions. Further, the lateral capacities are estimated.

For foundations of complaint structures, it is proposed that suction pile/ caisson type of anchors can be conveniently used. Formulations for pullout capacities are suggested in terms of the various components which helps in the easy installation of anchors and contributes to the uplift capacity. The capacities are verified for both static and cyclic loads.
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