• Geomechanics and Engineering
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• v.17 no.6
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• pp.573-581
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• 2019

Excavation of underground cavern and shaft was proposed for the construction of a ventilation facility in an urban area. A shaft connects the street-level air plenum to an underground cavern, which extends down approximately 46 m below the street surface. At the project site, the rock mass was relatively strong and well-defined joint sets were present. A kinematic block stability analysis was first performed to estimate the required reinforcement system. Then a 3-D discontinuum numerical analysis was conducted to evaluate the capacity of the initial support and the overall stability of the required excavation, followed by a 3-D continuum numerical analysis to complement the calculated result. This paper illustrates the application of detailed numerical analyses to the design of the required initial support system for the stability of underground hard rock mining at a relatively shallow depth.

• Geomechanics and Engineering
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• v.13 no.1
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• pp.173-194
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• 2017

Access shaft is of critical importance to the construction and operation of underground rock caverns. It usually has a relatively large cross-section and penetrates through fill materials, soil layers, and weathered rocks before reaching the caverns excavated in solid bedrock. In this paper, the design and construction of vertical shafts are reviewed in terms of diameter, depth, geological conditions, and support structure. Three shaft alternatives, namely alternative I: vertical shaft with spiral roads, alternative II: upper shaft with spiral roads & lower tunnels, alternative III: plain shaft, are proposed based on a simplified geological profile of the Jurong formation, Singapore. The advantages and limitations of the three types of shafts are discussed. The key issues relating to shaft design and construction, such as the shaft sinking, water control, support structure, are also discussed with a series of solutions provided, such as the sequential excavation, pre-grouting and diaphragm walls.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.574-584
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• 2006

Bi-directional loading test data are available to evaluate the design parameters which reflect the characteristics of a construction method and the variations of ground at the site where drilled shafts are installed. The method to obtain the design parameters of a real bridge by hi-directional loading test was introduced. The plans of multi-level testing and installation of measuring instruments should be made according to the rough estimation of axial bearing capacity, the length of pile, and the construction method. While the relationship between end bearing resistance and displacement was obtained directly from the hi-directional loading test, the relationship between unit side resistance and displacement was calculated through the measuring values. 1% displacement of pile diameter was adopted as the criteria of failure for ultimate resistance. As the settlement of pile head at the total ultimate bearing capacity obtained from these method was less than 1.5 % of pile diameter, this method was conservative to use in the field.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.49-83
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• 2005

ESCP Project showed an urban excavation case and introduced design method for case of Soil-Structure behavior in urban excavation. In this case, a retaining structures design to analysis the behavior of retaining wall and adjacent structures in urban excavations was applied by using a Elasto-plastic beam and limit Equilibrium analysis and soil-structure interaction analysis. Reliable design of earth retaining structures and the ground adjacent to braced wall in urban excavation are often difficult due to many variable factors. The ground settlement and the damage of adjacent structures in urban excavation has been an imprtant issue. Therefore, the stability of the adjacent structures must be secured with the excavation support and research on the protection of adjacent structure is necessary.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.601-612
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• 2005

In mountainous area, Two parallel tunnels have been usually recognized as a road tunnel which has benefits in aspects of cost and stability. However, Design and construction of 2-Arch road tunnel are growing recently due to environmental destruction, compensation of land and difficulty of route separation. As studies are mainly undergoing on only guaranteeing stability and developing a waterproofing-drainage system to avoid water leakage through comprehension for characteristics of 2-arch tunnel behaviors, there is a tendency to evaluate quantity of support by empirical method with a tunnel which has a complicated cross-section and lack of construction ability. In this study, therefore, we made a plan of tunnel cross-section which had shown good construction ability and developed the waterproofing-drainage system which is able to solve the water leakage problem fundamentally by analyzing precedented 2-arch tunnels and investigating their sites in and out of nation. We also determined fixed quantity of support by a large-scale model test and numerical analysis. We want to contribute to 2-arch tunnel design hereafter introducing design procedure and method applied here.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.862-870
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• 2010

This thesis has been researched on optimized design method for the total cross section of embankment considering the fact that the size of embankment cross section is directly related with economic efficiency when dam designing. In general, embankment cross section of fill dam is either determined by cohesion and angle of internal friction, a strength parameter of embankment materials or by permeability of embankment. Therefore the size of embankment cross section depending on strength parameter of embankment materials was determined by using MIDAS-GTS program through stress-seepage coupled analysis at the time of fill dam design. As a result, determination of embankment cross section was more affected by the size of central core and permeability rather than by slope stability by shear strength and it was revealed that in case of embankment height being over 20m, stability against infiltration and slope action could be secured only when embankment slope is at least over 1:2.5. In addition, it was also revealed that in case of making the size of central core exceeding specification standard, total cross section of embankment could be reduced considerably and at the time of embankment design, adequate size and appropriateness of embankment cross section could be determined with referring the table suggested by this study.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.78-89
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• 2007

Two design examples of deep foundations for high-rise buildings on soft ground are introduced in this paper. The first one is a 54-story building in Ho-Chi-Minh city, Vietnam, which was designed to be founded on $2.8m{\times}1.0m$ barrette foundations with approximately 60m to 75m depth. Based on a number of design guides and existing load test data from the construction sites in Ho-Chi-Minh city, the capacity of a barrette foundation in sand or clay layered ground was calculated to be 17.2MN to 27.8MN depending on the installing depth. The second one is a 40-story building in Baku city, Azerbaijan, which was designed to be supported by 2.0m diameter bored pile foundations with approximately 23m depth. As analytical or empirical guides for the local ground conditions were very limited, the design procedure from the SNiP Code, one of Russian specifications, was adopted and used to calculate the pile capacity. The capacity of bored pile foundation in highly weathered soil was expected to be 14.8MN to 15.5MN depending on the boring depth.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.938-945
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• 2004

In order to cope with ever growing traffic flow and complexity in the urban area, construction demands for expanding and realigning of existing urban roads and massive development of underground space within the urban area are in its increasing trend, it is fact that, mainly due to lack of statistical data accumulation through real construction, technology and construction practice to support such demands can hardly be said to have been established enough and leave many things still to be developed. These circumstances therefore came to motivate me to get into a study for a particular subject of "Design Basics for Closely Neighbored Twin Tunnel" among others, and also to put forward subjects required to be further studied in this connection in the future as follows: 1) To make a new economical design model for closely neighbored twin tunnel not only to make a drain for center perfect but also a tunnel construction safe. 2) Further efforts should be exerted for establishment of general standards for design and construction of various types of large cross-section tunnels including Twin structure.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.922-929
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• 2004

In some port construction, a case of reclamation with dredged soil for land use can be found. Even though this is not a new technology, there are some problems on the test method and analysis. The design parameters are still remained to be solved to get accurate prediction. Sedimentation of particle and self-weight consolidation are the most important design parameters in reclamation by dredged soils. The design parameters are influenced by properties of the physical and sedimentation of dredged soils. This influencing factors can be determined depend on the history of long term sedimentation and particle characteristics. Thus, properties of the sedimentation and consolidation are varies depend on the regional geologic formation. In this paper, three different sites with different regional soil properties will be compared in design parameters of sedimentation and self-weight consolidation.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.552-560
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• 2004

Stone column is a soil improvement method and can be applicable for loose sand or weak cohesive soil. Since the lack of sand in Korea, stone column seems one of the most adaptable approach for poor ground as a soil improvement method. However, this method was not studied for practical application. In this paper, the most effective design parameters for the being capacity of stone column were studied. The parametric study of major design factors for single stone column was carried out under the bulging and general shear failure condition, respectively. Especially, a test result of single stone column by static load was compared with the bearing capacity values of suggested formulas. The analysis result showed that the ultimate bearing capacity by the formula was much less than the measured value by the static load test. Especially, the result of the parametric study under general shear failure condition showed that the bearing capacity has apparent difference between each suggested formulas with the variation of the major design parameters. Therefore, the result of this study can be a suggestion which is applicable for the field test and the future research.