Sliding Mudmats Design - Current State of Practice and Realistic 3D Simulations-Paper

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The paper reviews the design and behavior of subsea mudmats that slide directly over soft clay seabeds to accommodate thermal expansion and contraction of high-pressure, high-temperature pipelines. This approach can avoid the large, heavy foundations or complex sliding mechanisms required to resist pipeline forces, but repeated movement may cause settlement, rotation, soil berm formation, and excessive loads on pipeline and jumper connections.<br /><br />Earlier studies have improved understanding of sliding resistance, cyclic soil behavior, and settlement. However, many rely on simplified two-dimensional analyses, small-deformation models, or tests with restricted rotation and loading conditions. The authors argue that these assumptions can miss important three-dimensional interactions and lead to unreliable estimates of foundation movement and connection stresses.<br /><br />They propose an integrated, large-deformation 3D simulation of the entire system: mudmat, seabed, flowline, and jumper. Using ABAQUS’s coupled Eulerian–Lagrangian method, their model can represent severe soil deformation and repeated sliding without mesh distortion. Initial simulations reproduced key features of centrifuge-test behavior, including settlement and berm development. Further simulations showed that jumper restraint can cause mudmat yaw and that slanted mudmat sides can reduce vertical displacement compared with blunt sides.<br /><br />The authors conclude that dependable design requires assessing all six degrees of freedom and modeling the interacting system as a whole. Mudmat geometry must balance competing needs: low sliding resistance, limited settlement and rotation, and reduced digging into the seabed. They present their simulations as evidence that full-system 3D analysis can better predict foundation performance and protect connected components, while noting that the approach remains under development.

Keywords

subsea mudmats

soft clay seabed

pipeline thermal expansion

large-deformation 3D simulation

coupled Eulerian-Lagrangian method

sliding resistance

soil berm formation

settlement and rotation

jumper restraint

mudmat geometry