• Tunnel and Underground Space
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• v.20 no.5
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• pp.318-324
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• 2010

Dynamic properties of materials by shock loads such as rock blasting and earthquake are recently attracted in the design of aboveground and underground structures. The advance of measuring devices enables to obtain the whole histories of stress and strain in rock specimen of which the failure is completed in several hundred microseconds. The SHPB has been a popular and promising technique to study the dynamic behavior of rock. And the dynamic compressive, tensile and other test with this experiment system are planned to be Suggested Methods of ISRM. This technical paper is to introduced one study article which focuses the design of 3S (special shaped striker) to produce the half-sine wave to eliminate the problems of the rectangular wave. This article is also describing the advantage of half-sine incident wave and size effect of rock dynamic strength.

• Tunnel and Underground Space
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• v.23 no.3
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• pp.161-168
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• 2013

Recently, the application of High-Power mechanized tunnelling technology has been expended around the world. Especially, High-power Modern TBM machines are used in a successful results. Essential for the great success of this modern TBM in difficult rock conditions are based on the development of machine power, suitable better cutter developments, and also developed assesment technology regards on the extensive site investigations. OPP (Owner Procurement Process) system is a proven alternative contract delivery method that is potentially applicable to many tunnel projects. Using the OPP, the owner specifies and procures the TBMs and tunnel lining in advance of the tunnel contract procurement and provides TBM to a tunnel contractor with a goals of reducing project risks and accelerating project schedule. Depending on the blasting vibrations and noises, mechanized tunnelling will be more important particularly in city areas.

• Korean Journal of Construction Engineering and Management
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• v.11 no.3
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• pp.55-63
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• 2010

Although the environmental conflicts regarding noise and vibration are continually increasing during construction, noise and vibration occurring in construction are only managed in construction phase. Noise and Vibration occurring in construction are considered to be insufficient, so we find that noise and vibration management in design phase has to be operated for reducing. The objective of this paper is to present noise and vibration management lists to consider in design phase for enhancing efficiency in noise and vibration management and to develop the appraisal sheets for designers to evaluate and the manuals to easily use management lists. To achieve this, we identify the noise and vibration management lists to consider in design phase through analyzing the previous literatures and confirm the 9 lists through conducting a research with experts in environmental area for verifying the propriety of lists. Also, this study applies to AHP technique to identify the priority and the weight evaluation among the lists. Through this study, we identify the most efficient lists, including from the low noise and low vibration methods, the noise and vibration reduction by blasting works, the installment and the arrangement of noise and vibration control equipments, for noise and vibration management in design phase. The achievement of this study will help to prevent the environmental disputes and conflicts in advance and will consider utilizing for the successful construction project.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.101-107
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• 2017

Over-break, which is excavated larger than planned line at tunnel excavation, is inevitable due to the nature of blasting. But regarding the bottom of the foundation, most of the domestic ordering organizations pay only 10 cm thick filled concrete when pouring concrete due to over-break. In accordance, the construction cost will increase greatly if all the depths of the designed over-break are filled only with concrete. When tunnel excavation occurs, concrete filling of 18 MPa(T = 100 mm) and 150 mm~237 mm auxiliary concrete layer and 240 mm concrete track(TCL) are applied to the upper part. The concrete is installed in an excessive amount of about 600 mm between the lower part of the rail and the tunnel rock bed. Therefore, in this study, it is necessary to analyze the concrete crack structure according to the depth of the existing tunnel and the modified tunnel section, and to evaluate the adequacy of the required thickness of the tunnel floor concrete for securing the crack stability of the concrete.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.545-553
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• 2008

Face mapping and displacement monitoring during tunnel construction are the most influential information for the stability assessment of ground and around structures. Especially, the result of face mapping and displacement analysis is essential to the excavation and support design in NATM which is based on the drilling and blasting. However, there have not been so many studies to put those useful information into practice for decision-making process during construction. The study reviewed the tunnel behaviour based on the RMR rating and displacement monitoring when the geological condition of rock mass varies inevitably. The study analysed the crown settlement using convergence equation in order to compensate the disparity induced by the location and time of measurement and found a distinct relation between the geological condition and the line of influence. As a result of analysing the various parameters related to the tunnel convergence according to the geological condition, the study suggested the basic knowledge about the relation between face mapping and displacement behaviour of tunnel.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.299-306
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• 2016

In this research, influence of low quality aggregate on engineering properties of concrete was evaluated experimentally. From the experiment, the fresh properties of slump and air content were controlled with unit water and AE dosage and all mixture were designed to have similar fresh properties of slump and air content with various quality of aggregate. Under this conditions, comparing with the mixture with high quality aggregate, the mixture with low quality aggregate showed the unit water and AE dosage were increased about 18 and 98%, respectively, because of poor grading and quantity of fines. For compressive strength, the low quality aggregate, specifically, exploded debris, clay sand, and sea sand contributed on decreasing compressive strength about 20~35%. Additionally, the concrete mixture including low quality fine and coarse aggregate showed adverse quality in not only compressive strength but also durability of freeze-thawing resistance, drying shrinkage, carbonation, and chloride ingression. Therefore, it is considered that for low quality aggregate, extra treatment processes such as washing or controlling gradation, and regulation to limit the use of low quality aggregate are needed.

• Explosives and Blasting
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• v.41 no.4
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• pp.9-16
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• 2023

To compare the global warming impact of the TBM and NATM method, which are representative tunnel excavation methods, a life cycle assessment was performed for each method. Life cycle assessment should compare the sum of carbon emissions by considering the pre-manufacturing stage, product manufacturing stage, usage stage, and disposal stage. However, access to TBM (Tunnel Boring Machine) manufacturing and disposal data is limited, so I had no choice but to focus on the analysis for the usage stage. In general, carbon emissions during the pre-product manufacturing stage and product manufacturing stage often exceed 90% of carbon emissions throughout the entire process. Therefore, since it is difficult to achieve the analysis goal only by comparing the usage stage, the analysis scope was expanded, and carbon emissions for the process were calculated for the NATM method with access to manufacturing data. As a result of comparing the relative impact on global warming, the carbon emissions of the TBM method were found to be higher than those of the NATM method even though TBM method was only considered for the usage stage. So there it is, the NATM method can be seen as environmentally friendly in the future when considering the impact of climate change (global warming), which has recently attracted attention among environmental impact fields.

• Tunnel and Underground Space
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• v.16 no.6 s.65
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• pp.506-525
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• 2006

For the design of large scale rock slope which has complex formations and geological structures, generally, insufficiency of geotechnical investigations and laboratory tests are the main factors of slope failures doling construction. In such case, remedial measures to stabilize slope should be selected and applied through reliable investigations and analysis considering the geotechnical characteristics. The rock slope of this study, one of the largest cut slopes in Korea with a length of 520.0 m and maximum height of 122.0 m consists of metasedimentary rocks. And a case study on the causes of large-scale rock slope failure was carried out by analysis of landslides history and site investigations during construction. When the slope with the original design slope of 0.7: 1.0 (H:V) was partially constructed, the slope failure was occurred due to the factors such as poor conditions of rocks (weathered zone, coaly shale and fault shear zone), various discontinuities (joints, foliations and faults), severe rain storm and so on. The types of failures were rockfall, circular failure, wedge failure and the combination of these types. So, the design of slope was changed three times to ensure long-term slope stability. This paper is intended to be a useful reference for analyzing and estimating the stability of rock slopes whose site conditions are similar to those of this study site such as geological structures and geotechnical properties.

• Tunnel and Underground Space
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• v.22 no.5
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• pp.297-309
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• 2012

The stability assessment of abandoned gangway for the purpose of services was performed. Among the many factors that affect the stability of openings, the span of the opening in a given rock mass condition provides an important element of design. In this paper, the stability of gangway was assessed by the critical span curves proposed by Lang, the modified Mathews'stability graph method and using support measures of the Q system. In the evaluation of stability as a whole the gangway is considered as stable. But the rockfalls of wedge-shaped blocks were expected in the area in which the horizontal joints of low angle appear. The support measures such as local rock bolts are required to use for commercial purposes of the abandoned gangway. And entrance section may require the particular attention as unstable section. Since there are so many spalling due to bad blasting in the roof and sidewall of gangway, the scaling operations should be followed primarily.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.4
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• pp.305-311
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• 2005

Shotcrete adhesive strength in large section tunnels in jointed rock masses plays an important role in preventing rock block from falling and shotcrete debonding due to blasting vibration. Nevertheless, it has not been considered as a major factor such as shotcrete compressive strength in design and construction. For this reason, the purpose of this study is to analyze the effect on shotcrete adhesive strength for large-sectioned tunnels. First, the parametric study using numerical model similar to Holmgren's punch-loaded test was executed for various range of adhesive strength. It shows that the shotcrete bearing capacity is linearly proportioned to the adhesive strength between shotcrete layer and blocks. And then, distinct element analysis of a jointed rock tunnel for an adhesive strength of 1 MPa and a conventional fully-bonded condition between the shotcrete layer and the excavation face was compared in order to evaluate the effect of the shotcrete adhesive strength.