• Tunnel and Underground Space
• /
• v.8 no.3
• /
• pp.249-256
• /
• 1998

Pocheon, Keochang and Sangju granite samples of different granularity and mineralogical composition were thermally treated at pre-determined temperature of $600^{\circ}C$. Thermally-induced microcracks were characterized using an optical microscopy and their effects on the deformation behavior of thermally cycled samples were studied performing compressive mechanical tests. Optical observations shows that by $600^{\circ}C$ nearlly all crystal boundaries open and the new intracrystalline cracks form in the more grains. The intracrystalline cracks are most pronounced at thermally treated Pocheon and Keochang granite samples. Results from mechanical tests represents negative lateral strains, which give negative Poisson's ratios. It is the most probable that negative lateral strains are produced by residual stresses induced during cooling.

• The Journal of Engineering Geology
• /
• v.8 no.3
• /
• pp.275-284
• /
• 1998

Deformation behavior and microcrack development due to uniaxial compressive cyclic loading in the Pocheon granite were investigated using the ultrasonic velocity measurements and the differential strain analysis(DSA). Most microcracks were developed along the direction parallel to the loading axis. Microcracks developed at the early stage of cyclic loading were formed by propagation of pre-existing cracks. Ultrasonic velocity measurement, DSA and measurement of permanent deformation are good tools to represent microcrack development in rock. Since results from each method are slightly different, microcrack development should be interpreted from all three methods. The magnitude of microcracks developed at the early stage of cyclic loading under 80% loading level is twice compared with those under 70% loading level. The highest volumetric crack strain is about 3000, indicating that the Pocheon granite will fail with 0.3% occupation of microcrack in volume.

• Proceedings of the Mineralogical Society of Korea Conference
• /
• 2003.05a
• /
• pp.80-80
• /
• 2003

포천-기산리 일대에 분포하는 쥬라기의 대보화강암류의 변형정도를 결정하기 위해 석영의 파동소광의 강도(IWE : Intensity of Wavy Extinction)를 편광현미경, 디지털 카메라, NIH Image로 측정하였다. 파동소광이 나타나는 석영입자의 한 부분이 편광현미경 상에서 최대 소광이 될 때 IWE를 측정하고, 이 때 나타나는 파동소광의 아입자경계에 수직한 방향으로 측정을 시도하였다 본 연구에 사용된 NIH Image는 파동소광을 보여주는 각 부분의 광도를 256단계의 흑백 농담변화로 나타낼 수 있다. 이를 이용하여 측정 길이에 대한 농담변화로 IWE를 구하였다. 이렇게 획득한 IWE를 5$^{\circ}$ 단위로 묶어 돗수분포표로 처리하였으며, 자료의 분포특성상 히스토그램의 최빈값과 중간값 사이의 중간값을 그 암석의 대표 IWE로 정의하였다. 이를 다시 5단계의 변형대(무변형, 저변형, 중변형, 고변형, 최고변형)와 각각의 변형지수(D1, D2, D3, D4, D5)로 묶었다. 본 연구지역에 분포하는 화강암류는 흑운모화강암(Gb), 동부의 석류석흑운모화강암(Ggb) 그리고 북부의 복운모화강암(Gtm)으로 구성되어 있는 바 본 연구에는 크게 포천읍을 기준으로 서부에 분포하는 Gb와 동부에 분포하는 Ggb에서 파동소광의 강도 측정이 이루어 졌다. 연구결과 Gb는 D2 이하의 낮은 변형도가 나타났고, Ggb는 D3이상의 고변형이 나타나, 전반적으로 조사지역의 북서부에서 남동부로 갈수록 변형도가 증가하는 양상을 보여주었다.

• The Journal of Engineering Geology
• /
• v.24 no.3
• /
• pp.363-372
• /
• 2014

Granite rock is reported to have three orthogonal anistoropic planes i.e., rift, grain induced by microcrack characteristics and mineral arrangement. We investigated the influence of thus fabric anisotropy in granite on elastic wave properties using free-free resonance test to obtain unconstrained compression wave velocity, shear velocity, Poisson ratio and damping ratio. As a result, Rod wave velocity is more dependent on anisotropy of granite due to microcrack distribution than shear wave velocity. In addition, anisotropy of Poisson ratio and damping ratio is also observed with respect to three anisotropic planes.

• The Journal of the Petrological Society of Korea
• /
• v.12 no.3
• /
• pp.101-109
• /
• 2003

The wavy extinction of quartz can be used as a standard indicator showing the degree of rock deformation. In determine the degree of rock deformation, the intensity of wavy extinction (IWE) of quartz was measured using polarizing microscope, digital camera, and NIH Image program. This method was applied to the granite of Pocheon-Gisanri area, which are divided three type; biotite granite (Gb), garnet biotite granite (Ggb) and two mica granite (Gtm). In this study, measurement of wavy extinction was proceeded Ggb in eastern part and Gb in western part based on the Pocheoneup. The result was that Gb shows low deformation degree below D2, and Ggb represents high deformation degree above D3, generally showing that increasing deformation degree from northwest to southeast in the studied area. It is suggested that the fault which penetrated Ggb in 1/250,000 geological map affected the deformation degree of Ggb.

• Proceedings of the Petrological Society of Korea Conference
• /
• 2004.05a
• /
• pp.29-31
• /
• 2004

• Proceedings of the KSEEG Conference
• /
• 2005.04a
• /
• pp.290-291
• /
• 2005

• Proceedings of the KSEEG Conference
• /
• 2007.04a
• /
• pp.450-452
• /
• 2007

• Proceedings of the Mineralogical Society of Korea Conference
• /
• 2004.05a
• /
• pp.29-31
• /
• 2004

• Proceedings of the Mineralogical Society of Korea Conference
• /
• 2001.06a
• /
• pp.100-102
• /
• 2001