Geo System Research Group (GSR), founded in 2005, focuses on developing innovative and efficient solutions in the field of geotechnical engineering through state-of-the-art computational modeling, laboratory, and field testing. Our primary interests are 1) soil dynamics and earthquake engineering, 2) soil-structure interaction, 3) energy geotechnology, and 4) soil characterization via waves. We are currently actively participating in various government and industry funded projects including, but not limited to, development of new site response algorithms, probabilistic seismic hazard analysis and generation of synthetic ground motions, seismic design of geotechnical structures, soil-fluid-structure dynamic interaction modeling, simulation of geothermal heat pump systems and thermosyphons, elastic and electrical resistivity wave based soil characterization, and multi-scale modeling of soils. We are also involved in various real engineering projects.
We try to expose our members to the state-of-the-art research and practice oriented projects, maintain a closely mentored system, and provide a cooperative but challenging environment for learning. Our goal is to equip all members with a strong foundation in fundamental theories, research capabilities with an expertise in numerical modeling, practice-oriented knowledge, and efficient communication skills.
We welcome prospective students and postdoctoral researchers with innovative ideas and hard working ethics. International researchers and students are also welcomed. For more information about the research group and potential financial support, please contact us.
ENGINEERING at HANYANG UNIVERSITY
Design of Offshore structures
I am involved in several projects on the development of methods for design and analysis of offshore bucket foundations for wind turbines and spudcan foundations for jack-up barges. I have been funded by Korea Institute of Energy Technology Evaluation and Planning, Hyundai Heavy Industries, Korean Register, and Ministry of Trade, Industry, and Energy for a total of $764,017. I am using both physical and numerical modeling techniques. Funded by the projects, I built two soil chambers for testing foundations in clays and sands. The clay chamber has radius and height of 1 m and can be loaded up to 100 kN for consolidation. The sand chamber has a dimension of 1 x 1 x 1 m. The chambers are being used to investigate the suction installation process of bucket foundations and evaluate the capacities of both bucket and spudcan foundations. A series of physical tests revealed important findings on the installation characteristics and capacities of the offshore foundations.
2D and 3D numerical simulations were performed again to simulate the installation and to evaluate the bearing capacity of the offshore foundations. Predictive equations were proposed. The effect of cyclic loading on the degradation of stiffness and capacity of the foundations were investigated through finite element analyses. The results were reported in two journal papers published in Ocean Engineering and seven domestic journals.
Blast analysis
Because two thirds of Korea are covered with mountains, construction in Korea typically involves interaction with rocks. Blasting is frequently used for various purposes including tunneling and excavation. The vibration induced by blasting is a major source of public petitions and has resulted in critical delay of many major projects. Square or cube root empirical formulations are typically used to estimate the wave attenuation caused by blasting.
I have been funded by Korea Expressway Corporation to develop an efficient procedure to predict the blast induced vibration caused by tunnel blasting and its effect on adjacent road facilities. I have also been involved in various industry consulting projects. I performed a series of numerical simulations to unveil whether the tunnel blast has triggered a major landslide in Seoul, which caused serious property damage and even life losses. I performed projects to estimate the effect of blasting on the stability of cut slopes and influence on nearby existing tunnels.
I newly developed a novel procedure to predict the blast load from available test measurements, which is a critical input parameter in the numerical simulation of blasting. It allows accounting for the site specific load considering the energy dissipation caused during rock fracturing. This is done via an empirical residual function that is additive to the far-field attenuation relationship to account for the near-field attenuation. It was demonstrated that the near-field attenuation is important for cases of long wavelengths. The work is reported in a journal paper published in Rock Mechanics and Rock Engineering and two domestic papers. I am also currently involved in many consulting projects to estimate the level of vibration of adjacent buildings and vulnerability of historical structures to blasting. I have also participated in a research proposal to investigate the effect of underground structures and pipelines to surface enemy attack, where my work focuses on development of a numerical model to allow prediction of the damage in the underground facilities in real-time.
Use of Impact echo method to detect cavities around sewage pipelines
I am currently participating in a study to use of the impact echo method to detect cavities around sewage pipelines. In an impact-echo test, the reflected stress waves, generated at the surface of the target structural element through mechanically induced impact, is measured. The method has been utilized to detect flaws in concrete and to evaluate the state of grout bonding in tunnels. It is the first attempt to detect underground cavities formed by leakage of pipelines, which is becoming a major problem in many urban environments. Based on extensive model and field tests, I developed a new signal process procedure that uses the Fourier spectrum and the spectrogram to predict the presence of cavities. A quantitative index and guidelines to use this procedure in practice is in development as part of a 3-year project funded by Electronics and Telecommunications Research Institute. The work was published in Tunnelling and Underground Space Technology.
