• The Journal of the Petrological Society of Korea
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• v.14 no.1
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• pp.24-37
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• 2005

In this study we examined the geomorphological and geological characteristics of the granite landforms in the Iksan area. Moreover we investigated the source areas of stones which are used to build the Mieruksaji west stone pagoda. Joint is most identifiable geomorphological and geological structure in the Iksan area. Direction of J1 joint appears to be N71°E∼EW, and that of J2 joint ranges N20°W∼N20°E. Cross-pattern joint is predominant in the study area, and linen.-pattern vertical joint is also observed. Tor and corestone are easily found as geomorphological features in the study area. Corestones forming for are almost 2∼3 m across and 2∼3 m or over 5 m high. Their hardness is mainly of hammer bounce. Tower-type and castle-type of for are characteristic in the Mireuksan granites. Other geomorphological features such as tafoni, gnamma are also observed in the study area. Petrographical and geochemical features of the stones used for the Mireuksaji west stone pagoda are compared with those of the granites cropped out nearby, and indicate that the stones from the Mieruksaji west stone pagoda are quite similar to the Mireuksan granites. In the Mireuksan we can easily find lots of old traces for rock cutting.

• Journal of the Korean association of regional geographers
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• v.18 no.2
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• pp.129-140
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• 2012

In order to examine geomorphic characteristics such as form and retreat process of waterfalls in Jeju Island, 26 waterfalls were classified based upon materials forming a fall face. The waterfalls could be categorized into three types such as single unit, multiple units and basal soft-rock based upon the number and type of a lava flow. A block fall, composed of a pile of large blocks, could be added to the typology of waterfalls in Jeju Island. While the single unit fall is distributed in a region of trachyte or trachyandecite, the multiple units fall and basal soft-rock fall are largely developed in a region of basalt or trachybasalt. A retreat process of the single unit fall is an inclination or a replacement, but the basal soft-rock fall shows a parallel retreat. The multiple units fall exhibits three types of a retreat process according to the physical properties of a lava flow. The fall face is generally vertical due to well-developed vertical joints of a lava flow.

• Journal of the Korean Geographical Society
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• v.50 no.5
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• pp.459-472
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• 2015

Weathering hollows which develop on various rocks are the terrain whose lithological characteristics and formation of the bed rock is under active discussion. The shore in Dapyeong-ri, Sacheon-si has alternation of strata of pelite and sandstone, and the weathering hollows develop on the shore platform and the sea cliff where sandstone is exposed. To analyze the development characteristics of weathering hollows by development of joints, interpenetration of veins and physical and chemical features of the stone, the study conducted a topographic investigation, XRD analysis and an observation using a polarizing microscope. As the result of the investigation and analysis, tafoni and gnamma are spread in the same area and new tafoni is being formed as the existing weathering hollows are destroyed by the expansion and growth of the joint. The vein, which was found to be a quartz vein, may accelerate the development of weathering hollows combining with the joint but may also hamper their growth if the veins are penetrating perpendicularly. It is generally known that weathering hollows develop regardless of the type of rocks, however, the analysis on the lithological features show that the development is limited on the fractured and broken rocks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.3
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• pp.99-106
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• 1990

This study was aimed to see the effect of chemical grout on fresh granite joint shear strength. The grouting chemical used in this study was composed of 25% water glass. Direct shear tests were performed on the chemical filled joints, which had been made artificially with granite. The test results show that chemical grouted rock jonts have markedly reduced shear strength comparing with the ungrouted fresh joints and they sheared within chemical grout before the rock to rock contact had been established, while the ungrouted joint sheared between rock surfaces from the beginning of shear deformation. With chemical grouted joints the shear stress slowly reached its maximum without showing distinct peak shear strength. Therefore the shear stiffness of joints were decreased with increasing thickness of grout. but the shear strain at failure was increased with it.

• Korean Journal of Heritage: History & Science
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• v.51 no.2
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• pp.78-91
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• 2018

Sangjogam, located in Goseong, Gyeongsangnam-do, was designated as Natural Monument #411, because of its diverse geological heritage, such as fossils, ripple marks, dykes, and columnar joints. In the area, Byeongpungbawi, with its beautiful columnar joints vertical to the bedding plane of the underlying sedimentary rocks and spectacular coastal view, was named after its overall shape reminiscent of a huge folding screen. The purpose of this study was to investigate the formation process of the columnar joints using the anisotropy of magnetic susceptibility (AMS) method. AMS measurements showed that the k1 and k3 values representative of directions of the long and short axes of a magnetic particle at each point strongly clustered, and the oblate magnetic foliation structure in Byeongpungbawi developed during sill-type intrusion rather than lava flow. In summary, Byeongpungbawi was produced by sill-type intrusion along the bedding plane of the underlying sedimentary layer, and the subsequent formation of columnar joints was accompanied by the cooling and contraction of intruding rhyolite magma. This study potentially provides a basic research tool in understanding the formation mechanism of columnar joints which are widely distributed in southern Korea.

• Journal of Conservation Science
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• v.26 no.3
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• pp.277-294
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• 2010

The Seosanmaaesamjonbulsang (National Treasure No. 84) consists of light gray and coarse to mediumgrained biotite granite with partly developed pegmatite and quartz vein. The host rock is divided into dozens of rock blocks with various shape along irregular discontinuity plane. The evaluation results of discontinuity systems reveal that the host rock were exposed to instable sloping environments. Results of deterioration diagnosis show that the degree of damage has been made worse by physical weathering and surface discoloration laying stress on part that vertical and horizontal joints are massed. Generally, deterioration rate of the triad Buddha surface cover with 42.7%, however, the rate of physical weathering and surface discoloration are subdivided to 9.6% and 33.1%, respectively. Ultrasonic measurements indicate that the triad Buddha was reached highly weathered grade in general. And the rock material was weaken to show low velocity zone of 1,000m/s along irregular joint systems. Indoor and outdoor mean relative humidity of the shelter was recorded more than 70% during every season, and high frequency appears in high relative humidity range over 95%. Such environments seem to have produced dew condensation on the rock surface with rainfall and supply water, promoted physical, chemical and biological weathering along crack and joint, resulting in high permeation of water and percentage of water content. Therefore, it is judged that for scientific conservation of the triad Buddha it needs environment control through persistent preservation environment monitoring including water problem.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.5
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• pp.357-371
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• 2023

In cable tunnel construction using TBM, the vertical shaft is an essential structure for entrance and exit of TBM equipment and power lines. Since a shaft penetrates the ground vertically, it often encounters rock mass. Blasting or rock splitting methods, which are mainly used to the rock excavation, cause public complaints due to the noise, vibration and road occupation. Therefore, mechanical excavation using vertical shaft excavation machine are considered as an alternative to the conventional methods. However, at the current level of technology, the vertical excavation machine has limitation in its performance when applied for high strength rock with a compressive strength of more than 120 MPa. In this study, the potential utilization of waterjet technology as an excavation assistance method was investigated to improve mechanical excavation performance in the hard rock formations. Rock cutting experiments were conducted to verify the cutting performance of the abrasive waterjet. Based on the experimental result, it was found that ensuring excavation performance with respect to changing in ground conditions can be achieved by adjusting waterjet parameters such as standoff distance, traverse speed and water pressure. In addition, based on the relationship between excavation performance, uniaxial compressive strength and RQD, it was suggested that excavation performance could be improved by artificially creating joints using the abrasive waterjet. It is expected that these research results can be utilized as fundamental data for the introduction of vertical shaft excavation machines in the future.

• Tunnel and Underground Space
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• v.3 no.2
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• pp.142-151
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• 1993

In this study, the deformation characteristics of atrtificially fractured joints of granite under normal and shear loading were investigated. To obtain the characteristics of joint deformation, compression and shear tests were performed in the laboratory on three different sizes of rock specimens. The rock used in the experimens was Iksan granite. Joints were produced artificially by fracturing using the apparatus for generating extension-joint. Joint normal deformability was studied by conducting cyclic loading tests on the joints. Joint closure varied non-linearly with normal stress through cyclic loadings. As normal stress increased, the joints gradually reached a state of maximum joint closure. The relation between normal stress and joint closure for mated and unmated joints was well described by the hyperbolic and exponential function, respectively. Joint shear deformability was studied by performing direct shear tests under normal stresses on the joints. it was shown that the behaviour in the prepeak range was non-linear and joint shear stiffness depended on the size of specimen and the normal stress.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.83-88
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• 2004

제주도 서부지역에 위치한 2개 관측정을 대상으로 대수층별 대수성시험을 실시하구 지하수 산출능력을 평가하였다. 연구대상 관측정은 대수층이 수직적으로 서로 연결되어 있지 않을 뿐만 아니라, 대체로 해수면 하 10～20m 사이 구간에 제1대수층이 발달하고 있으며, 지하수 산출능력은 절리 또는 용암류 경계의 대수층(용수2호공)보다는 유리쇄설성 각력암층(무릉1호공)에서가 상대적으로 양호한 것으로 평가되었다. 서귀포층을 포함한 제2대수층은 수위하가 l0m 이상 발생하는 것으로 미루어 보아 제1대수층보다는 지하수 산출능력이 떨어지는 것으로 판단된다. 그러나, 제1대수층은 지표로부터 얕은 깊이에 위치하고 있어 질산성질소 농도가 전반적으로 높고, 양수에 의한 영향권이 취수정 주변 l00m까지 발생하고 있어 서부지역에서 제1대수층 개발은 세심한 주의가 요구되고 있다.

• Geophysics and Geophysical Exploration
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• v.2 no.1
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• pp.1-7
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• 1999

We investigated the weathering characteristics of On-Yang gneiss by means of geological survey and Ground Penetrating Radar(GPR). The results of geological survey and boring show the two sets of vertical joint and horizontal joint developed by foliation which is composed of salic and melanic layers. GPR section evidently shows foliation direction and differential weathering due to discontinuity and mineral composition of metamorphic rock. The GPR section for instantaneous phase attribute based on complex trace analysis evidently shows continuity and foliation direction of metamorphic rock. The strong reflection amplitude which is derived from the banded structure of weathered rock can be incorrectly interpreted as a reflection of bedrock. The depth of rock basement should be estimated from the overall exploration result such as boring, seismic method, and electrical resistivity method.