The Journal of Engineering GeologyISSN:1226-5268(Print) 2287-7169(Online)대한지질공학회

This study is to examine the engineering characteristics of colunmar joints in Mudeugsan National Park, a global geopark. For these purposes, physical and mechanical properties of Mudeungsan Tuff, evaluation for the weathering degree of columnar joints, and crack behavior monitoring in columnar joints were conducted. The physical properties of Mudeungsan tuff were 1.02% for the average porosity, 0.38% for the average absorption, 2.69 g/cm³ for the average specific gravity, and 4,948 m/s for the average elastic wave velocity. Its mechanical properties were 337 MPa for the average uniaxial compressive strength, 68 GPa for the average elastic modulus, 0.29 for the average Poisson’s ratio, 41.3 MPa for the average cohesion strength, and 62.8° for the average friction angle. the average rebound Q-value of the silver Schmidt hammer for the three columnar joint blocks at the Ipseok-dae was shown as 49.3. when this value is converted into uniaxial compressive strength, it becomes 70.5 MPa, which is about 21% of the uniaxial compression strength of Mudeungsan tuff. In addition, according to the results of crack monitoring measurements for the three columnar joint blocks at the Ipseok-dae, the crack behavior is less than 1 mm, so it is believed that its behavior in Ipseak-dae columnar joints has hardly occured to date.