Whilst many remotely operated vehicles (ROVs) have the necessary hydraulic control systems to employ anchors, previous attempts to develop seabed fixity have had variable success. This project aimed to determine whether a flexible, inflatible anchor system would provide sufficient uplift capacity to fix ROVs during offshore activities. A series of scaled physical model tests were used to assess the performance of the proposed system. A limited range of anchor designs and operating conditions were investigated for a sandy soil. The experimental data showed that the pullout capacity increased for larger, more deeply embedded anchors and denser, stiffer soil samples. Improvements in pullout capacity were also seen for stiffer and rougher membranes. The pullout capacity of the anchors in sand compares favourably to enlarged base piles of similar dimensions described in the literature. The performance of the inflatible anchor was found to be much better than helical screw or plate anchors of equivalent geometry. The mobilisation distance for peak load was found to be higher than enlarged base piles and was found to be a function of membrane stiffness. Based on the data shown in this study, the inflatible anchor system shows considerable promise for offshore use in sandy soils.
Since many remotely operated vehicles (ROVs) are neutrally or positively bouyant, any activities that require any significant reaction load, e.g. in situ soil testing, are not possible without additional anchoring or clump weights. Whilst the majority of ROVs used by the offshore oil and gas industries have the necessary hydraulic and pneumatic control systems to employ anchors, previous attempts to develop seabed fixity have had variable success. This project had the aim of determining whether a flexible, inflatible anchor system may provide sufficient uplift capacity to fix ROVs during offshore activities.
