This paper describes an investigation into the performance and pullout capacity of an inflatable anchor system embedded in soft clay soil. A series of scaled physical model tests have been used to study anchor performance and pullout capacity. The anchor behaviour during pullout has been interpreted using finite element analysis that accounts for the non-linear soil behaviour with different undrained shear strengths, inflation pressures and anchor-soil interaction. The scaled model tests and interpretations indicate that the soil strength, inflation pressure and the degree of consolidation were the dominant mechanisms affecting the pullout capacity of the inflatable anchor system in soft clay. The results of back calculation obtained from the finite element analysis indicate that local drainage occurred during placement of the anchors and subsequent inflation (cavity expansion) leading to increase of the undrained shear strength of the soft clay.
Anchor systems can be advantageous when used with remotely operated offshore vehicles (ROV). Significant reaction loads are sometimes required to prevent movement and/or to assist with controlling the vehicle. Previous attempts to employ ‘classical’ anchor systems, such as helical screws, duckbill or plate anchors, have had variable success and an alternative form of inflatable anchor has been developed. This paper describes an investigation into the performance and pullout capacity of this inflatable anchor system embedded in soft clay. The anchor system comprises of a hydraulically inflated rubber membrane or packer that may be bored or jetted into place and inflated to provide pullout resistance. A series of scaled physical model tests have been used to study anchor performance and pullout capacity (Newson and Brunning, 2001). The model tests were done in a calibration chamber using an artificial soft clayey soil with various undrained shear strengths. The finite element program PLAXIS has been used to analyze the anchor behaviour during pullout.
