• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.45-51
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• 2003

Grouting materials in rock is grouted as vein type along the fault surface by the other way for soil and allow a change of characteristics in rock faults as a result of that. Therefore the deformation characteristics of rock faults after grouting differ as a direction and characteristic of grouted fault and stress condition of field rock. Thereby it must be analyzed the effect for deformation of rock according to characteristics of rock faults and characteristics of grouting materials to accurately evaluate the reinforced effect by grouting. But grouting method used in field until present depends on experience of workers, and inspection for those effects are evaluated by measurement of elastic wave velocity, permeability tests and etc. in field. In this study, it was investigated that the effects for shear characteristics of maximum shear strength, residual shear strength and etc. by comparison and analysis of test results which were worked by direct shear tests of rock faults with changing a type of grouting materials and the grouting depth(t) for average width(a) of fault surface roughness when OPC(Ordinary Portland Cement) and Micro cement was grouted in fault surface of field rock to evaluate characteristicsof the shear deformation for rock fault surface of dam by grouting.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.111-122
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• 2005

The data on the pile load tests performed on 35 large drilled shafts are analyzed to investigate the load-settlement characteristics of large drilled shafts embedded in bed rocks. Generally, the settlement of large drilled shafts embedded in bed rocks is too small to determine the ultimated load with application of the regulation in design code for either the total settlement or the residual settlement. Therefore, to determine the yield load of large drilled shafts embedded in bed rocks, p(load)-logS (settlement) curve method, which has been proposed originally for the driven pile, was applied to the investigation on the data of the pile load tests. This technique shows that the yield load can be determined accurately and easily rather than other conventional techniques such as P-S, logp-logS, S-logt, and P-S curve methods. An empirical equation is proposed to represent the relationship between pile load and settlement before the yield loading condition. And the settlement of piles was related with the depth embedded in rock as well as rock properties. Based on the investigation on the data of pile load tests, the resonable regulations f3r both the total settlement and the residual settlement are proposed to determine the yield load of large drilled shafts embedded in bed rocks.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.3
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• pp.239-247
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• 2005

A new railway line of about 17km length was planned between Dongbaeksan and the neighboring town Dokye to improve the existing decrepit railway system. New line about 17km of the distance will almost be in circular alignment tunnels owing to the difference of elevation about 380m. Since the geology of the area is rather unusual compared to the normal in South Korea, extensive geological investigations have been carried out to prepare geological maps and profiles along the planned tunnel routes. The tunnel will almost be in sedimentary rock formations, such as limestone, sandstone, shale, coal etc and be near abandoned mines Various rock formations have the complicated, alter ed those rocks, but are well developed with laminated formations. Each rock formations have been classified using the Q-system and the cost of tunnel excavation, support has been estimated and compared for three alternative routes in the design stage. Based on these estimates, the final route of t he railway line was chosen.

• Tunnel and Underground Space
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• v.12 no.4
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• pp.237-247
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• 2002

A total of 18 stress measurements were performed in the rock and rock-like blocks in the laboratory to estimate the influence of anisotropy in rock. Full scale overcoring equipment, which consists of a coring machine and a biaxial loading system by flat jacks, was developed to simulate the in-situ rock stress condition in the laboratory By comparing the isotropic analysis with the anisotropic analysis in measuring the stress, conclusions have been drawn as to the influence of anisotropy. The maximum difference between the isotropic and the anisotropic analysis was 34% and it was shown that the stress measurement considering the anisotropy was needed. To confirm the validity of the observed data, a diagnostic analysis of stress relief curve by overcoring was conducted using the three dimensional finite difference program, FLAC 3D.

• Journal of the Korean Geophysical Society
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• v.7 no.4
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• pp.255-267
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• 2004

Analysis of fracture system in a stone quarry mine is a critical importance in assessing the recoverable amounts of building stones as well as in establishing the systematic and efficient development plan. Rock formation comprising vein structure, degree of weathering, and compositon of minerals, is a critical factor of estimating the stone quality. The aim of this study is to provide desirable informations about both fracture pattern and rock formation by using Televiewer and Color-corescanner. Televiewer measurement were conducted at 7 boreholes in the gneiss quarry mine, Hadong, Kyeongsangnamdo province and the corresponding cores were scanned using Color-corescanner at the same place. In Televiewer images, all kinds of fractures were clearly observed and a better discrimination of stone quality can be identified. Meanwhile, the core images with high resolution (max. 20 pixels/mm) provided detailed informations on rock formation such as features of particles and fissures that can be nearly undetected by Televiewer.

• Journal of the Korean Geotechnical Society
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• v.35 no.5
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• pp.5-19
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• 2019

Considering the natural phenomenon in which steep slopes ($65^{\circ}{\sim}85^{\circ}$) consisting of rock mass remain stable for decades, slopes steeper than 1:0.5 (the standard of slope angle for blast rock) may be applied in geotechnical conditions which are similar to those above at the design and initial construction stages. In the process of analysing the stability of a good to fair continuum rock slope that can be designed as a steep slope, a general method of estimating rock mass strength properties from design practice perspective was required. Practical and genealized engineering methods of determining the properties of a rock mass are important for a good continuum rock slope that can be designed as a steep slope. The Genealized Hoek-Brown (H-B) failure criterion and GSI (Geological Strength Index), which were revised and supplemented by Hoek et al. (2002), were assessed as rock mass characterization systems fully taking into account the effects of discontinuities, and were widely utilized as a method for calculating equivalent Mohr-Coulomb shear strength (balancing the areas) according to stress changes. The concept of calculating equivalent M-C shear strength according to the change of confining stress range was proposed, and on a slope, the equivalent shear strength changes sensitively with changes in the maximum confining stress (${{\sigma}^{\prime}}_{3max}$ or normal stress), making it difficult to use it in practical design. In this study, the method of estimating the strength properties (an iso-angle division method) that can be applied universally within the maximum confining stress range for a good to fair continuum rock mass slope is proposed by applying the H-B failure criterion. In order to assess the validity and applicability of the proposed method of estimating the shear strength (A), the rock slope, which is a study object, was selected as the type of rock (igneous, metamorphic, sedimentary) on the steep slope near the existing working design site. It is compared and analyzed with the equivalent M-C shear strength (balancing the areas) proposed by Hoek. The equivalent M-C shear strength of the balancing the areas method and iso-angle division method was estimated using the RocLab program (geotechnical properties calculation software based on the H-B failure criterion (2002)) by using the basic data of the laboratory rock triaxial compression test at the existing working design site and the face mapping of discontinuities on the rock slope of study area. The calculated equivalent M-C shear strength of the balancing the areas method was interlinked to show very large or small cohesion and internal friction angles (generally, greater than $45^{\circ}$). The equivalent M-C shear strength of the iso-angle division is in-between the equivalent M-C shear properties of the balancing the areas, and the internal friction angles show a range of $30^{\circ}$ to $42^{\circ}$. We compared and analyzed the shear strength (A) of the iso-angle division method at the study area with the shear strength (B) of the existing working design site with similar or the same grade RMR each other. The application of the proposed iso-angle division method was indirectly evaluated through the results of the stability analysis (limit equilibrium analysis and finite element analysis) applied with these the strength properties. The difference between A and B of the shear strength is about 10%. LEM results (in wet condition) showed that Fs (A) = 14.08~58.22 (average 32.9) and Fs (B) = 18.39~60.04 (average 32.2), which were similar in accordance with the same rock types. As a result of FEM, displacement (A) = 0.13~0.65 mm (average 0.27 mm) and displacement (B) = 0.14~1.07 mm (average 0.37 mm). Using the GSI and Hoek-Brown failure criterion, the significant result could be identified in the application evaluation. Therefore, the strength properties of rock mass estimated by the iso-angle division method could be applied with practical shear strength.

• Proceedings of the KSEG Conference
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• 2004.03a
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• pp.22001-22109
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• 2004

사면 파괴의 분류에 대하여는 여러 학자들(Hutchinson, 1968; Varnes, 1978; Hoek and Bray, 1981)에 의하여 시도되어 왔으며, 일반적으로 파괴면의 기하학적 형상, 물질의 이동 형태와 이동 물질의 종류 등에 따라 분류한다. 현재 널리 사용되는 사면 파괴에 대한 분류로는 Varnes(1978)와 Hoek and Bray(1981)의 분류법이다. 이외 일본 지반 공학회에서는 파괴 두께와 관련된 사면 붕괴 유형을 구분하였다. 여기서는 각각의 분류에 대해 기술하고, 일반적으로 암반 사면에 대한 붕괴 유형 분류를 제시한다. (중략)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.197-198
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• 2001

일반적으로 해조류가 번무하고 있던 암초지대에서 무엇인가의 원인으로 해조류가 고사ㆍ소멸하고, 그 공간을 석회조류로 불리는 여러 종류의 산호말류 (coralline algae)이 점유하여 암반이 백색 또는 황색, 분홍색을 나타내는 현상을 ‘백화현상’ 이 라고 한다. 현재 추측되는 백화현상의 원인으로는 해양생태계 내에서의 환경변화 - 대기중 이산화탄소의 증가, 지구 온난화에 의한 수온상승, 그리고 연안역의 오염 -와 군집의 동태와 생물학적 작용-엽상형 해조류와 무절석회조류간의 경쟁과 성게를 포함한 초식동물의 초식작용, 질소, 인등의 결핍이 불러오는 빈(貧)영양화 - 에 의해 일어난다고 추측된다 (analysis.cheju.ac.kr.). (중략)

• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.115-124
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• 2004

According to Sagong and Paik (2003), the side resistance of rock socketed drilled shafts is affected by rock quality, types, uniaxial compressive strength, and confining stress. Their approach based upon the Hoek-Brown criterion provides reasonable predictions of the side resistance. In this study, we propose an equation to calculate the side resistance considering size effects of the shafts and investigate the influence of drilled shaft diameter on the side resistance. A new method employs the modified Hoek-Brown criterion together with an empirical size effect of rock core. From the previous field tests, 12 pile load test results were collected and compared with prediction calculated from the equation proposed in this study. In a given condition, similar results between measurement and estimate are observed. From the parametric study on the GSI, confining stress, uniaxial compressive of intact rock and pile size, it is shown that uniaxial compressive strength is the most influential parameter on the side resistance. Though pile size shows the least influence on the resistance, the size effect is apparent as rock quality increases.

• Tunnel and Underground Space
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• v.9 no.1
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• pp.20-26
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• 1999

The completion of the Bakun Diversion Tunnel is subsequently to the Main Dam construction. Therefore, the completion date is very important for the Bakun Hydroelectric Project. Generally, the tunnel lining work as a finishing phase of the tunnelling project occupies a important portion as well as an excavation and a support work of the tunnels in respect to the construction cost and period. Internal section of Bakun Diversion Tunnel is designed circular shape to reduce the roughness of the water flow with 12 meters in diameter of total length 4314.6 meters of 3 tunnels. The lining thickness is varied between 500 mm and 700 mm depending on the structural condition. From the original Tender design of the Bakun tunnels, the required quantity of steel bars was 5,985 ton designed by Reinforced Concrete (RC) through the entire tunnel linings. During the detail design stage by the consideration of the rock conditions and various load conditions, we could suggest five kinds of RC lining type including plain concrete lining type. Through the detail design modification, we could reduce the required amount of steel bars to 2,178 ton, as a half of original Bill of Quantity. Finally, this design modification give us the time and cost saving effect to catch up the construction progress in time.