Current projects

• Lifting objects off seabed

  PhD student

  Mason (Sen) Mei

  Supervisors

  Assoc Prof Yinghui Tian, Prof Mark Cassidy

  Most of us have experienced the difficulty of lifting our shoes up from muddy ground (the quintessential ‘stuck in the mud’). This tells us that uplifting an object off the seabed requires much greater than its own submerged weight. This is termed as breakout phenomenon. The most significant component of the resistance force emanates from the ‘suction’ generated. During uplifting the ‘suction’ will dissipate and an abrupt and significant reduction in uplift resistance may occur.

  The research aims to improve the understanding of breakout process to enable offshore engineering operations, where a wide variety of applications, such as decommissioning of offshore infrastructures and securing offshore foundations, would require the knowledge of this problem.

• Behaviour of embedded anchor chains

  PhD student

  Wenlong Liu

  Supervisors

  Assoc Prof Yinghui Tian, Prof Mark Cassidy

  Offshore floating facilities are required to be secured through a mooring system, which comprises anchors and mooring lines. The segment of the mooring line, predominately using metallic chain, is embedded in the soil to connect the embedded anchor and takes a reversed catenary shape. The friction capacity of the anchor line itself can take up a major component of the overall anchor capacity. The bearing capacity of embedded anchors is controlled by the chain inclination and depth at the padeye. Most of existing research and current design practices consider the anchor line profile in a two-dimensional vertical plane. The friction and normal soil resistance to the anchor chain are not coupled in the existing analytical design method of embedded anchor line.

  The aim of this research is to gain in-depth knowledge about the soil resistance to the chain links and advance the fundamental understanding of three-dimensional performance of the embedded anchor line. This research mainly uses numerical simulation method to investigate the bearing capacity and combined yield surface of the chain link. A new numerical approach based on a force-resultant macroelement plasticity model will be developed to implement three-dimensional analysis of the anchor line.

• Securing submerged floating tunnels

  PhD student

  Wei Lin

  Supervisors

  Assoc Prof Yinghui Tian, Prof Mark Cassidy

  A submerged floating tunnel is a conceptual design of a tunnel that floats in water, supported by its buoyancy (specifically, by employing the hydrostatic thrust, or Archimedes' principle). Although the idea can be stemmed back to the late 19th century, none submerged floating tunnel has been built yet. One of the key barriers for this promising new infrastructure is how the tunnel can be securely moored to the seabed. This project aims to provide an efficient geotechnical solution through a loop of conceptual development, numerical modeling, centrifuge modelling and final verification using large scale model tests. Expected outcomes include a rigorously verified mooring system, quality first-hand observations and scientific knowledge advance, which are expected to pave the way for constructing the first submerged floating tunnel.

• Cyclic capacity of horizontal plate anchors in sand

  PhD student

  Rene Kurniadi

  Supervisors

  Dr Shiaohuey Chow, Prof Mark Cassidy

  The emergence of offshore floating renewable energy devices requires economic anchor solutions for sand. Plate anchors could represent such a solution due to their high efficiency in resisting tensile uplift loading. The monotonic capacity of plate anchors is relatively well investigated in sand. However their performance under realistic and long term offshore environmental or cyclic loading is not well understood. This project aims to investigate the performance of horizontal plate anchors under cyclic loading in sand. The project will involve numerical modelling using advanced constitutive model and model anchor tests using state-of-the-art centrifuge modelling. The outcomes of the project will be integrated into an accessible design tool to enable better predictability of the anchor cyclic capacity in practice.