• Tunnel and Underground Space
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• v.8 no.3
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• pp.226-233
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• 1998

Microcracks in rock materials, whether natural or induced, provide useful information on the engineering performance of in situ rockmasses. A population of preferentially oriented microcracks has observable effects on the physical properties of a rockmass, but their effects may not be evident if the rock material is highly anisotropic due to other causes. An experimental program was undertaken to investigate the effect of rock fabrics on the physical properties of rock materials. In this study, anisotropy in the circumferential wave velocity and the direction of induced fractures under axial point loading were measured. Rock specimens (NX-size) of the leucocractic Pocheon granite were cored from rock blocks, retaining the relative directions of each specimen. Another set of specimens was prepared from the rock cores of the same meterial, obtained in the field. The master orientation line (MOL) was set to be the representative direction of the microcracks in the specimen. Variation of the circumferential wave velocity of each specimen was then measured along the core, keeping the MOL as reference. The direction of the minimum wave velocity was nearly perpendicular to the direction of the MOL. Coring of smaller-sized (EX-size), concentric specimens from the NX specimens were then followed, and axial point loading was applied. The direction of induced fractures due to axial point loading was closely related to the MOL direction, confirming the prior test result.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.3
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• pp.136-144
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• 2001

Two organic materials, peat and rock wool were used for removal of $H_2S$ by a biofilter inoculated with night soil sludge. By gradually increasing the inlet load of $H_2S$, the complete removal capacity, which was defined as the inlet load of $H_2S$ that was complete removed, and the maximum removal capacity of $H_2S$, which was the value when the removal capacity leveled off for organic materials, were estimated. Both values for Rock wool are larger than peat, based on a unit dry weight of material. By using kinetic analysis, the maximum removal rate of $H_2S$, $V_m$, and the saturation constant, $K_s$, were determined for all packing materials and the values of $V_m$ for rock wool was found to be larger. By using the kinetic parameters, the removal rates for $H_2S$ were compared both packing materials, and rock wool showed better performance for the removal of $H_2S$ in the inlet concentration range of 0~200ppm.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.1
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• pp.9-15
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• 2014

It is not easy to analyze the behavior of a structural body composed of particles such as rocks using the finite element method facilitating typical element meshes because we cannot ignore the interactions among particles. In the study, we investigated the applicability of smooth particle hydrodynamics (SPH) element method for collision analysis of rock-berm by comparison with the conventional Lagrange method. As the result, SPH technique is expected to be capable of realistic simulation under collision analysis of material composed of particles.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1166-1171
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• 2008

Despite of the increasing number of the application of drilled shaft piles in construction site, most studies on pile capacity have been focused on the side shear resistance. But it is common that the drilled shaft is socketed on the rock so as to use its bearing resistance. The prediction of the end movement and characteristics of the bearing capacity of the pile is great important as well. Therefore, a series of scaled model tests were carried out in order to study the characteristics of the bearing capacity on rock mass. The material of the test block was cement mortar which was mixed with sand, cement and water, and the size of a test block size was $240{\times}240{\times}240mm$. The axial load was applied by a miniaturized pile of 45mm in diameter and flat jacks and steel plate were used for confinement to simulate the real underground loading conditions. The relation of load-displacement was measured in various different conditions of rock mass such as strength, discontinuity of the rock mass and in-situ stress, so q-w curves of the end of the pile were presented for each condition.

• Computers and Concrete
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• v.21 no.4
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• pp.399-406
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• 2018

The present study focuses on the performance of basalt fiber reinforced concrete (BFRC) lining in tunnel situated in sandstone rock when subjected to internal blast loading. The blast analysis of the lined tunnel is carried out using the three-dimensional (3-D) nonlinear finite element (FE) method. The stress-strain response of the sandstone rock is simulated using a crushable plasticity model which can simulate the brittle behavior of rock and that of BFRC lining is analyzed using a damaged plasticity model for concrete capturing damage response. The strain rate dependent material properties of BFRC are collected from the literature and that of rock are taken from the authors' previous work using split Hopkinson pressure bar (SHPB). The constitutive model performance is validated through the FE simulation of SHPB test and the comparison of simulation results with the experimental data. Further, blast loading in the tunnel is simulated for 10 kg and 50 kg Trinitrotoluene (TNT) charge weights using the equivalent pressure-time curves obtained through hydrocode simulations. The analysis results are studied for the stress and displacement response of rock and tunnel lining. Blast performance of BFRC lining is compared with that of plain concrete (PC) and steel fiber reinforced concrete (SFRC) lining materials. It is observed that the BFRC lining exhibits almost 65% lesser displacement as compared to PC and 30% lesser displacement as compared to SFRC tunnel linings.

• The Research Journal of the Costume Culture
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• v.16 no.6
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• pp.1156-1168
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• 2008

This study investigated the preceding studies and concept of Glam Rock style, modernistically reinterpreted its aesthetic function and symbolism and connected them to design. It analyzed according to the standards for classification the Glam Rock style appearing mainly in the collections from 2002 S/S to 2007 S/S and presented four pieces of design through the analysis. Its findings are synthesized as follows. First, unstructured design constitutes mule stressing gold cubic overall. It takes an unstable form by the placement of unshapely front ball of foot from transforming Chopin and a relatively poor heel. Second, over trimming constitutes separated pumps in the form of over trimming irregularly a piece of broken glass, metal and thumb tack. Third, Mix & Match combines Boot body of flexible knit material with an acrylic wedge sandal. Fourth, a platform sandal has the structure of color contrast between yellow and bronze in calf fur of tiger-skin pattern. I hope that this study will be developed by reflecting Glam Rock spirit and style as cultural phenomena through analyzing Glam Rock style and presenting design according to selected standards for classification, inferring plastic beauty of fashion shoes from them, investigating the change and feature of age-specific shoe design and making a new attempt possible.

• Tunnel and Underground Space
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• v.11 no.1
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• pp.59-63
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• 2001

The total number of elastic constants of an anisotropic body is 9 and thus it is very difficult to measure these constants experimentally. The number of elastic constants can be reduced if a rock or rock mass is regarded as isotropic or transversely isotropic material. Since only 4 stress-strain relationships can be obtained, it is theoretically impossible to determine all 5 constants from a single uniaxial compression teat. Lekhnitskii overcame this problem by suggesting the fifth equation based on laboratory tests. But his equation is theoretically wrong and does not agree with experimental results. This paper describes the stress-strain relationships and the independent/dependent elastic constants of an anisotropic mass and suggests a testing mothed to determine 5 independent elastic constants for a transversely isotropic rock.

• Geomechanics and Engineering
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• v.27 no.5
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• pp.511-525
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• 2021

In the design of underground excavation, the shear strength (SS) is a key characteristic. It describes the way the rock material resists the shear stress-induced deformations. In general, the measurement of the parameters related to rock shear strength is done through laboratory experiments, which are costly, damaging, and time-consuming. Add to this the difficulty of preparing core samples of acceptable quality, particularly in case of highly weathered and fractured rock. This study applies rock index test to the indirect measurement of the SS parameters of shale. For this aim, two efficient artificial intelligence methods, namely (1) adaptive neuro-fuzzy inference system (ANFIS) implemented by subtractive clustering method (SCM) and (2) support vector regression (SVR) optimized by Harmony Search (HS) algorithm, are proposed. Note that, it is the first work that predicts the SS parameters of shale through ANFIS-SCM and SVR-HS hybrid models. In modeling processes of ANFIS-SCM and SVR-HS, the results obtained from the rock index tests were set as inputs, while the SS parameters were set as outputs. By reviewing the obtained results, it was found that both ANFIS-SCM and SVR-HS models can provide acceptable predictions for interlocking and friction angle parameters, however, ANFIS-SCM showed a better generalization capability.

• Geomechanics and Engineering
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• v.30 no.2
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• pp.123-138
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• 2022

Present study computes the ultimate bearing capacity of an embedded strip footing situated on the rock slope subjected to seismic loading. Influences of embedment depth of strip footing, horizontal seismic acceleration coefficient, rock slope angle, Geological Strength Index, normalized uniaxial compressive strength of rock mass, disturbance factor, and Hoek-Brown material constant are studied in detail. To perform the analysis, the lower bound finite element limit analysis method in combination with the semidefinite programming is utilized. From the results of the present study, it can be found that the magnitude of the bearing capacity factor reduces quite substantially with an increment in the seismic loading. In addition, with the increment in slope angle, further reduction in the value of the bearing capacity factor is observed. On the other hand, with an increment in the embedment depth, an increment in the value of the bearing capacity factor is found. Stress contours are presented to describe the combined failure mechanism of the footing-rock slope system in the presence of static as well as seismic loadings for the different embedment depths.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1358-1365
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• 2010

A case study deals with Squeezing behavior under tunneling. Squeezing stands for large time-dependent convergence during tunnel excavation. Squeezing can occur in both rock and soil as long as the particular combination of induced stresses and material properties pushes some zone around the tunnel beyond the limiting shear stress at which creep starts. Under squeezing rock conditions, If the support installation is delayed the rock mass moves into the tunnel and a stress redistribution takes place around it. On the contrary, if deformation is restrained, squeezing will lead to long-term load build-up of rock support. This paper shows analysis case mutually with monitoring and numerical analysis result of squeezing behavior of Pinglin tunnel in Taiwan.