Yonsei University · Engineering
Professor Tae Sup Yun's research lab specializes in the geomechanics and geophysics of gas hydrate-bearing sediments, with a focus on understanding the mechanical behavior, stiffness, permeability, and wave propagation characteristics of hydrate-bearing soils under various stress and hydrate saturation conditions. The lab employs advanced experimental techniques such as triaxial testing, instrumented pressure coring, and small-strain shear wave monitoring to investigate hydrate formation mechanisms, including pore-filling and frame-building, and their impact on sediment stability and geophysical properties. Research also extends to the effects of stress history, cementation, and k0 loading on soil stiffness and collapse behavior in natural and synthetic hydrate-bearing sediments.
Figures are computed from collected data and may differ slightly.
The mechanical behavior of hydrate‐bearing sediments subjected to large strains has relevance for the stability of the seafloor and submarine slopes, drilling and coring operations, and the analysis of certain small‐strain properties of these sediments (for example, seismic velocities). This study reports on the results of comprehensive axial compression triaxial tests conducted at up to 1 MPa confining pressure on sand, crushed silt, precipitated silt, and clay specimens with closely controlled
The competing hypotheses for gas hydrate formation at the particle scale in sediments describe processes of pore‐filling, frame‐building, or cementation. New measurements of compressional ( V P ) and shear wave ( V S ) velocities in fine‐grained sands subjected to low confinement and monitored during formation of tetrahydrofuran hydrate indicate that hydrate nucleates in the pore space (presumably at grain boundaries) and grows with limited impact on the sediment shear stiffness, V P , and V S u
Abstract A model for water permeability reduction in hydrate‐bearing sediments is presented by considering capillary effect in hydrate nucleation. Both grain‐coating and pore‐filling cases are considered. The model is developed from a series of lattice Boltzmann flow simulations. Results show that the permeability decreases quasi‐linearly with increasing hydrate saturation during grain‐coating nucleation and that the permeability tends to be higher than predicted by previous analytical models, i
The small-strain stiffness of freshly remolded soils is controlled by the state of stress. Diagenesis and cementation can significantly stiffen soils. However, these effects are lost at relatively low strain levels. Previous experimental results have shown the detrimental and irrecoverable effects of unloading on cementation. This study explores the effect of k0 loading on the small-strain stiffness of cemented specimens, with emphasis on the load-induced collapse and softening of cemented, loos
Gas hydrate-bearing sediments recovered by pressure coring from the Krishna−Godavari Basin offshore India during the 2006 National Gas Hydrate Program (NGHP) expedition were characterized using the instrumented pressure testing chamber (IPTC). The IPTC studies provided longitudinal profiles of P- and S-wave velocities, electrical conductivity, and undrained penetration resistance. The formation consisted of fine-grained clayey sediments of high specific surface and high plasticity. X-ray images
[1] The physical characteristics of hydrate-bearing sediments sampled by pressure coring from the Ulleung Basin in the Sea of Japan (East Sea) were investigated using an instrumented chamber capable of testing recovered natural sediments that have never left the methane hydrate stability field. The heterogeneous distribution of segregated hydrate veins and lens structures in sediments results in highly variable geophysical and geomechanical properties. The scaled production test was conducted by
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