• Journal of Ocean Engineering and Technology
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• v.31 no.6
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• pp.397-404
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• 2017

In this study, an anchor dragging simulation was performed using the CEL method to design a rock-berm, which is a protection method for submarine cables. In order to simulate an anchor drag, preliminary simulations were first performed to determine the initial anchor penetration depth, anchor drag velocity, drag angle, and distance between the anchor and rock-berm. Based on the preceding simulation results, a safe rock-berm design for protecting the submarine cables was simulated to calculate the anchor penetration depth by the anchor dragging. As a result, the penetration depth of the anchor was found to be shallower in a hard seabed, and the penetration depth was deeper in a soft seabed, the height of the rock-berm was determined according to the physical properties of the seabed.

• Geomechanics and Engineering
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• v.8 no.3
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• pp.391-414
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• 2015

In this paper, stabilities of a plane slide rock slope under different hydraulic distributions were studied based on the nonlinear Barton-Bandis (B-B) failure criterion. The influence of various parameters on the stability of rock slopes was analyzed. Parametric analysis indicated that studying the factor of safety (FS) of planar slide rock slopes using the B-B failure criterion is both simple and effective and that the effects of the basic friction angle of the joint (${\varphi}_b$), the joint roughness coefficient (JRC), and the joint compressive strength (JCS) on the FS of a planar slide rock slope are significant. Qualitatively, the influence of the JCS on the FS of a slope is small, whereas the influences of the ${\varphi}_b$ and the JRC are significant. The FS of the rock slope decreases as the water in a tension crack becomes deeper. This trend is more significant when the flow outlet is blocked, a situation that is particularly prevalent in regions with permafrost or seasonal frozen soil. Finally, the work is extended to study the reliability of the slope against plane failure according to the uncertainty from physical and mechanics parameters.

• Tunnel and Underground Space
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• v.21 no.6
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• pp.439-449
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• 2011

The characteristics of rock fractures for engineering rock classification are investigated by analyzing three dimensional point cloud generated from adjusted digital images of a tunnel face during construction and the tunnel is reinforced based on the supporting pattern suggested by the RMR and the Q system using parameters extracted from those images. As results, it is possible saving time required from face mapping to tunnel reinforcing work, enhancing safety during face mapping work in tunnels and reliability of both the mapping information and selecting supporting pattern by storing the files of digital images and related information which can be checked again, if necessary sometime in the future.

• Tunnel and Underground Space
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• v.30 no.4
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• pp.417-431
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• 2020

In this study, a fundamental investigation was made on how to use LiDAR technology to determine the degree of weathering and alteration of rock mass. The purpose of the study was to identify the affecting parameters to LiDAR intensity and to quantitatively assess the relations among them through laboratory-scale experiment. A few potential affecting parameters were selected including scanning distance, incidence angle, surface roughness, surface color, mineral composition, and water saturation. In the experiment, FARO LiDAR unit was used for twelve different types of specimen. It was observed that the intensity was affected by, in the order of importance, surface color, incidence angle, scanning distance, property of rock, water condition, and surface roughness.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.535-544
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• 2007

Discontinuities developed in a sedimentary rock mass are the most important factor to determine mechanical properties of the rock mass. Parameters described discontinuities in rock mass generally connote heterogeneity and uncertainty. In this study, probabilistic statistics method was used to determine parameters of discontinuities quantitatively and objectively. The field survey was conducted at 33 sedimentary rock slopes in Ulsan area, according to the suggested methods for the quantitative description of discontinuities in rock mass(ISRM, 1978). The engineering geological characteristics of the sedimentary rocks at Ulsan area was determined as probability distribution function deduced by analyzing parameters of discontinuities.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.946-956
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• 2008

Acoustic emission(AE) is low-energy seismic event associated with a sudden inelastic deformation such as the sudden movement of existing fractures, the generation of new fractures or the propagation of fractures. These events rapidly increase before major failure and happen within a given rock volume and radiate detectable seismic waves. Rock slopes are usually large in scale and there are many discontinuities in rock mass. AE waves are strongly attenuated when they propagate through joints. Thus we should resolve the attenuation problem to monitor large volume. In this study, we developed waveguide which is composed of two different materials, cement mortar and stainless steel rod. And several laboratory tests on developed waveguide are performed to obtain generalized AE parameters to predict the failure stage in rock slope. Comparing field data with experimental data in laboratory tests, failure stage of rock slope can be evaluated. To verify and optimize the developed monitoring method, we are now carrying out the field application at a rock slope.

• Geomechanics and Engineering
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• v.5 no.1
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• pp.71-86
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• 2013

For rock materials, a transversely isotropic failure criterion established through the extended Lade-Duncan failure criterion incorporating an anisotropic state scalar parameter, which is a joint invariant of deviatoric microstructure fabric tensor and normalized deviatoric stress tensor, is verified with the results of triaxial compressive data on Tournemire shale. For torsional shear mode with $0{\leq}b{\leq}0.75$, rock shear strengths decrease with ${\alpha}$ increasing until the rock shear strength approaches minimum value at ${\alpha}{\approx}40^{\circ}$, and after this point, the rock shear strengths increase as ${\alpha}$ increases further. For the torsional shear mode with b > 0.75, rock shear strengths are almost constant for ${\alpha}{\leq}40^{\circ}$, but it increases with increase in ${\alpha}$ afterwards. The rock shear strength variation against ${\alpha}$ agrees with shear strength changing tendency of heavily OCR natural London Clays tested before. Prediction results show that the transversely isotropic failure criterion proposed in the paper is reasonable.

• Journal of the Korean Geosynthetics Society
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• v.14 no.2
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• pp.81-88
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• 2015

This study assessed the behavior of rock pillar in tunnel diverging area by using a three dimensional numerical analysis. Based on parameters affecting the behavior of rock pillar, this study evaluated different safety factors according to pillar width, depth and rock conditions. It turned out that as the rock pillar width increases, the change curve of safety factors in accordance with depth and rock conditions shows more of the nonlinear behavior. By the assessment of the minimum safety factor, a safety factor chart on the behavior of rock pillar in tunnel diverging area was suggested.

• Economic and Environmental Geology
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• v.17 no.1
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• pp.57-78
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• 1984

The object of this study is to offer the standarized data for the design and calculating engineering cost of the rock excavation an the construction of the 3rd and 4th Seoul Subway lines From Jnauary to March in 1983, this study was carried out by the both methods of the field and laboratary studies. In the field, the geological survey in the entire area of Seoul City and sites on the subway lines were carried out and also a site measure of uniaxial compressional strength of rock masses by using Schmidt hammer was done. The labartory studies were carsied out by a study of preuions surveyes, microscopic studies of the mineral composition and degree of weathering of rocks, and measure of uniaxial compressional strengths Finally an engineering classification of each rock masses of South Africa council for Scientific and Industrial Research, CSIR, after Bieniawski, 1974. was done. In this method of classification 6 parameters such as strength of intact rock material, rock quality designation, spacing of fractures, condition of fractures, groundwater conditions, and the effect of fracture strike and dip orientation in tunnelling were used to evaluate rating of each rock mass.

• The Journal of Engineering Geology
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• v.13 no.3
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• pp.359-368
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• 2003

A quarry is operated for filling-up the New Busan Harbor which is under construction, but actual rock quality is something different from the primary design. Therefore, object of this study is to classify whole rock quality for the quarry through site investigation and laboratory analyses because unexpected large amount of wasted rock is produced. For this object, various analyses were performed such as surveying, Schimidt Hammer test. joint spacing investigation and laboratory analyses using DIPS & RockWorks programs for evaluating joint sets and sizes of rock fragments after blasting. As a result, it is expected that large amount of wasted rock under ${\Phi}100mm$ is produced after blasting because of high joint density.