• Journal of the Korean Geophysical Society
• /
• v.9 no.1
• /
• pp.47-62
• /
• 2006

More than 70% of Korean Peninsula is consisted of mountains, so that lots of roads, rail-roads and tunnel,which play a pivotal role in the industry activity, are existed along the rock-slope and in the rock-mass. Thus,it is urgent that tegration of management system through the optimum survey and design of rock-slope excavation, proper stabilization method and database of rock-slope. However, conventional methods have shortcoming with the economy of survey time and human resources, and the overcome of difficulties of approach to the in-situ rock-slope. To overcome the limitation of conventional method, this paper proposed the development of remote measurement system using Terrestrial Laser Scanning System. The method using Terrestrial 3D Laser Scanning System, which can get 3D spatial information on the rock-slope and2)Dept. Geosystem Engineering, Kangwon National University, Korea tunnel, has an advantage of reduction of measurement time and the overcome of difficulties of approach to the in-situ rock-slope/dam/tunnel. In the case of rock-slope, through the analysis of 3D modeling of point-cloud by Terrestrial Laser Scanning System, orientation of discontinuity, roughness of joint surface, failure shape and volume were successively achieved. in the case of tunnel face, through reverse-engineering, monitoring of displacement was possible.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.17 no.3
• /
• pp.319-332
• /
• 2004

Due to their high strength to weight ratios and excellent durability, fiber reinforced polymer(FRP) is widely used in construction industries. In this paper, a shape optimum design of FRP bridge decks haying pultruded cellular cross-section is presented. In the problem formulation, an objective function is selected to minimize the volumes. The cross-sectional dimensions and material properties of the deck of FRP bridges are used as the design variables. On the other hand, deflection limits in the design code, material failure criteria, buckling load, minimum height, and stress are selected as the design constraints to enhance the structural performance of FRP decks. In order to efficiently treat the optimization process, the cross-sectional shape of bridge decks is assumed to be a tube shape. The optimization process utilizes an improved Genetic Algorithms incorporating indexing technique. For the structural analysis using a three-dimensional finite element, a commercial package(ABAQUS) is used. Using a computer program coded for this study, an example problem is solved and the results are presented with sensitivity analysis. The bridge consists of a deck width of 12.14m and is supported by five 40m long steel girders spaced at 2.5m. The bridge is designed to carry a standard DB-24 truck loading according to the Standard Specifications for Highway Bridges in Korea. Based on the optimum design, viable cross-sectional dimensions for FRP decks, suitable for pultrusion process are proposed.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.5
• /
• pp.717-732
• /
• 2017

Recently, the construction of underground structure such as a double-deck tunnel is increasing to manage rapid growth of roadway traffic volume. Double-deck tunnel includes middle slab to separate upper and lower road inside, and various sources affect the dynamic behaviour of middle slab due to dynamic loading of vehicle. Therefore, it is important to investigate the dynamic response of middle slab precisely to apply it to design and analysis of double-deck tunnel. In this study, dynamic analysis model of middle slab considering structural type, design velocity, vehicle load, and surface roughness, etc. is built. 3-dimensional dynamic analysis is performed to assess dynamic response of middle slab. Consequently, Dynamic Magnification Factor which represents dynamic response of middle slab shows maximum in case of elastomeric bearings (EB) and average roughness (Grade C). It is also expected that dynamic response can be reduced under the condition of good roughness (Grade B) and fixed bearings (FB).

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.21 no.1
• /
• pp.177-188
• /
• 2019

The purpose of the optimization of the installation of supply/exhaust ports for tunnels with transverse ventilation system is to supply fresh air from outside to inside of tunnels uniformly and exhaust pollutant from tunnels properly for creating safe and clean environment for tunnel users. For this purpose, a ventilation port area optimization program was developed to obtain a uniform supply or exhaust air volume inside a great depth double deck tunnel with transverse ventilation system. In order to area optimize the developed port sizing program, the wind velocity was measured in the duct of the currently operated tunnel with semi-transverse ventilation. Also 3D cfd was performed on the same tunnel and cfd results were compared to the measured value. As a result, the error rate between the predicted value from the program and measured value was 6.72%, while the error rate between the predicted value from the program and 3D cfd analysis value was 4.86%. Both of comparison results show less than 10% of error rate. Thus It is expected that supply/exhaust port optimization design of transverse ventilation tunnel can be possible with using this large exhaust port area optimization program.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.29 no.4D
• /
• pp.555-561
• /
• 2009

In lieu of section profile data, a fitting of the bored tunnel shape is more significant confirmation for maintenance of a tunnel. Before the permit on the completion of a tunnel, deformation of the completed tunnel with respect to the design model are considered. And deformation can be produced at continuously along the entire of the tunnel section. This study firstly includes an analysis of algebraic approach and test it with an observed field data. And then a number of methods, line search method, genetic algorithm, and pattern search methods, are compared with the 3D tunnel shape fitting. Algebraic methods can solve a simple circular cylinder type as like a railway tunnel. However, a more complex model (compound circular curve and non circular) as like a highway tunnel has to be solved with soft computing tools in the cause of conditional constraints. The genetic algorithm and pattern search methods are computationally more intensive, but they are more flexible at a complex condition. The line search method is fastest, but it needs a narrow bounds of the initial values.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.09a
• /
• pp.775-784
• /
• 2009

Weathered foliation could act as a critical failure plane because this type of plane tend to have low roughness and long extensions. A big constructed slope at $\bigcirc\bigcirc$ road construction site was failed due to the block movement along a fault zone which is parallel to foliation. Tectonic activity reactivated a fault zone parallel to foliation, and the fault clay within the shear zone metamorphosed retrogressively to chrolite. The failed block moved when the block weigh lost the balancing with the resisting force of the retrogressively metamorphosed chrolite. Evaluating the three dimensional distribution of the foliation was critical for establishing a plan for the stabilization of the slope. For this purpose, 10 boreholes were drilled as a lattice distribution, and the BIPS analyses are performed at each boreholes. The fractures measured in the boreholes are projected into 15 cross sections and their distributions are analysed, using Fracjection software. The projection analyse show that the strike of the foliation gets dipper towards left side of the slope. This geometry indicates that there are more failure block geometry at left side of the slope. Potential failure planes are searched using the projection method, and these information are provided for further support design.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.1 no.2
• /
• pp.17-29
• /
• 1997

Single-mode spectral analysis method is usually applied to a small-scale bridges with the simple geometric shape and uses only fundamental period to estimate the elastic earthquake forces and the displacements of the substructure. On the other hand, multi-mode spectral analysis method may be used instead if the possibilities of potential damage are developed when considering significance, scale, and geometric shape of briages. Since the dynamic responses of bridge can be significantly different depending on the modeling techniques for the restraint and support conditions etc, it may be misled to the unexpected results. In this study the dynamic analysis program which can model and analyze the bridge as a two- or three-dimensional framed structure is developed and verified with the results of other reliable program. Using this program together with the post processor, the designer can easily and readily obtain the reponses(moments, base shears, and displacements)of bridges necessary to design purpose. And further from the analysis results according to the variations of type, scale, and restraint and supprot conditions of bridges including sectional properties, applications of the effective and desirable seismic design are presented.

• Journal of the Society of Disaster Information
• /
• v.7 no.3
• /
• pp.206-219
• /
• 2011

The important elements in pavement design criteria are the stress and strain distributions. To obtain reasonable stress and strain distribution, tire contact area and tire pressures are very important. This study presents a viscoelastic characterization of flexible pavement subjected to moving loads. During the test, both longitudinal and lateral strains were measured at the bottom of asphalt layers and in-situ measurements were compared with the results of numerical analysis. A 3-dimension finite element model was used to simulate each test section and a step loading approximation has been adopted to analyze the effect of a moving vehicle on pavement behaviors. For viscoelastic analysis, relaxation moduli, E(t), of asphalt mixtures were obtained from laboratory test. Field responses reveal the strain anisotropy (i.e., discrepancy between longitudinal and lateral strains), and the amplitude of strain normally decreases as the vehicle speed increases. In most cases, lateral strain was smaller than longitudinal strain, and strain reduction was more significant in lateral direction.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.11 no.1
• /
• pp.14-23
• /
• 1997

In this paper, the results of the measurement and analysis of extremely low frequency(ELF) electric field in the vicinity of 154[kV] overhead transmission lines have been described. The planar-type electric field sensor has been fabricated by three dimensional structure with special consideration of taking the power frequency and lower components. The calibration experiments have been carried out according to the procedures of IEEE recommendation. The electric field measuring system has the frequency bandwidth of 7[Hz] to 2.7[MHz] and the response sensitivity of 0.094[mV/V/m]. Also the practical measurements of electric field under an 154[kV] double circuit overhead transmission lines have been made and analyzed. It was known that the lateral electric field profiles under an 154[kV] double circuit overhead transmission lines show the asymmetrical distributions owing to the environmental metal frame structures and their maximum electric field magnitude is less than 3[kV/m]. It can be concluded that the measured results of the electric fields satisfy with all limits or guidelines of the various authorized international institutes' recommendations.

• Journal of the Korean Geotechnical Society
• /
• v.38 no.7
• /
• pp.5-24
• /
• 2022

The current performance evaluation of slope anchors qualitatively determines the physical bonding between the anchor head and ground as well as cracks or breakage of the anchor head. However, such performance evaluation does not measure these primary factors quantitatively. Therefore, the time-dependent management of the anchors is almost impossible. This study is an evaluation of the 3D numerical model by SfM which combines UAS images with terrestrial LiDAR to collect numerical data on the damage factors. It also utilizes the data for the quantitative maintenance of the anchor system once it is installed on slopes. The UAS 3D model, which often shows relatively low precision in the z-coordinate for vertical objects such as slopes, is combined with terrestrial LiDAR scan data to improve the accuracy of the z-coordinate measurement. After validating the system, a field test is conducted with ten anchors installed on a slope with arbitrarily damaged heads. The damages (such as cracks, breakages, and rotational displacements) are detected and numerically evaluated through the orthogonal projection of the measurement system. The results show that the introduced system at the resolution of 8K can detect cracks less than 0.3 mm in any aperture with an error range of 0.05 mm. Also, the system can successfully detect the volume of the damaged part, showing that the maximum damage area of the anchor head was within 3% of the original design guideline. Originally, the ground adhesion to the anchor head, where the z-coordinate is highly relevant, was almost impossible to measure with the UAS 3D numerical model alone because of its blind spots. However, by applying the combined system, elevation differences between the anchor bottom and the irregular ground surface was identified so that the average value at 20 various locations was calculated for the ground adhesion. Additionally, rotation angle and displacement of the anchor head less than 1" were detected. From the observations, the validity of the 3D numerical model can obtain quantitative data on anchor damage. Such data collection can potentially create a database that could be used as a fundamental resource for quantitative anchor damage evaluation in the future.