• Tunnel and Underground Space
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• v.17 no.6
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• pp.453-463
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• 2007

Terzaghi's tunnel pressure theory is generally used to estimate primary design pressures on tunnel support for shield and urban NATM tunnels until now. A trial is made in this paper to investigate the interaction between the ground deformation behavior and Terzaghi's tunnel pressure, which assumes pound's limit (or critical) state, by considering results of 'Terzaghi's tunnel pressure theory. two-dimensional reduced-scale model tunnel tests and nonlinear numerical analysis based on strain softening modeling. A full understanding between tunnel pressure and ground deformation behavior under the tunnel excavation and an effective utilization of this interaction lead to an economical tunnel support design and a safe construction of tunnel.

• Economic and Environmental Geology
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• v.31 no.5
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• pp.415-424
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• 1998

In order to investigate soil-gas $^{222}Rn$ concentrations, Kwanak Campus (Seoul National University), Boeun (Choong-buk) and Gapyung (Kyonggi) areas were selected and classified depending on their base rock types. Radon risk indices of these study areas decrease in the order of Gapyung>Kwanak Campus>Boeun areas, and in the order of rock type as banded gneiss>granite gneiss>granite>black slate-shale>mica schist>shale-lirnestone>phyllite-schist. Radon emanating trends with water content and grain size of soils were assessed by modified Morse 3 min. method. Radon emanation increases with the increase of water content in soils which is lower than 6~16 wt.%, and decreases in the range of higher than 6-16 wt. %. It shows that Rn emanation increases with the decrease of soil grain size. Radioactivity analysis of radionuclides of 238U series in some soil samples shows that radioactive disequilibrium state between $^{226}Ra$ and $^{238}U$ exists owing to different geochemical behavior of each radionuclide, and, it is necessary to carry out radioactive isotope geochemical approach for soil-gas $^{222}Rn$ study.

• Land and Housing Review
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• v.4 no.1
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• pp.125-131
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• 2013

To predict the real bearing capacity and settlement of the shallow foundation the plate load test results were used. But there is no field estimation method about igneous weathered soil and rock. Therefore, to predict the settlement equation, the plate load test about igneous weathered soil and rock was done in this study. To analyze the load ~ relative settlement curve by normalization, it did not use normal analysis method, but the load ~ relative settlement (s/B, s : settlement, B : breadth of plate) was used. As a result of normalization by load ~ relative settlement conception, the curve was regular regardless of plate diameter and it was suggested the relationship of in-situ soil condition and results.

• Journal of the Economic Geographical Society of Korea
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• v.19 no.4
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• pp.583-596
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• 2016

Since the 1970s, advanced industrial economies have been suffering from rapid de-industrialization. While the impacts were more serious in the areas specialized in heavy industries, these old industrial areas are struggling with problems of high unemployment, environmental contamination and destruction of urban landscape. To tackle such problems and rebuild urban economies, some authors, such as Richard Florida and Charles Lanrdry, have suggested a new economy centered on "creativity." Adopting this suggestion, many countries have been attempting to create creative cities. Authors of this paper individually conducted a case study research on a few selected cities of England, France, Australia, Japan and Korea. This paper synthesizes the results of such research to compare and analyse the processes and mechanisms contributed to developing the creative cities in each country and draw theoretical and policy implications from the individual research.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.472-472
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• 2004

Numerous studies on urban groundwater have been carried out in many other countries. Urban groundwater shows a unique hydrologic system because of complex urban characteristics such as road pavement, sewers and public water supply systems. These urban facilities may change the characteristics of groundwater recharge but contaminate its quality as well. There have been several researches on urban groundwater in Seoul. Seoul has been industrialized very rapidly so that the city has large population. The recent population in Seoul amounts to more than ten millions, corresponding to a very high density of about 17, 000 people/km$^2$. Therefore, many factors affect the groundwater quality and quantity in Seoul. Nowadays, groundwater in Seoul is being extracted for construction, industrial use, and drinking and so on. There are 15, 714 wells in Seoul and its annual usage is 41, 425, 977m$^3$(in 2001). Therefore, systematic studies are needed to properly manage and use the groundwater in Seoul. The purposes of this study in progress are to identify geochemical characteristics of groundwater in Seoul and to determine the extent of groundwater contamination and its relationship with urban characteristics. For this study, groundwater was sampled from more than 400 preexisting wells that were randomly selected throughout the Seoul area. For all samples, major cations together with Si, Al, Fe, Pb, Hg For 200 samples among them, TCE, PCE, BTEX were also analyzed by GC. Our study shows that groundwater types of Seoul are distributed broadly from Ca-HCO$_3$ type to Ca-Cl＋NO$_3$ type. The latter type indicates anthropogenic contamination. Among cations, Ca is generally high in most samples. In some samples, Na and K are dominant. The dominant anions change widely from HCO$_3$ to Cl＋NO$_3$. The anion composition is considered to effectively indicate the contribution of distinct anthropogenic sources. In addition, major ions are positively proportional to total dissolved solid (TDS) except K and NO$_3$. Thus, we consider that TDS may be used as an effective indicator of the extent of pollution. However, the increase of TDS may result from increased water-rock interaction. To determine the extent of groundwater contamination, it is needed to figure out the baseline water quality in Seoul. Furthermore, detailed geochemical studies are required to find out pollution sources and their corresponding hydrochemical parameters.

• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.157-164
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• 2005

Urban conditions such as underground facilities and ambient noises due to cultural activity restrict the application of conventional geophysical techniques in general. We used the refraction microtremor (REMI) technique as an alternative way to get the geotechnical information, in particular shear-wave (S-wave) velocity information, at a site along an existing rail road. The REMI method uses ambient noises recorded using standard refraction equipment to derived shear-wave velocity information at a site. It does a wavefield transformation on the recorded wavefield to produce Rayleigh wave dispersion curve, which are then picked and modeled to get the shear-wave velocity structure. At this site the vibrations from the running trains provided strong noise sources that allowed REMI to be very effective. REMI was performed along the planned new underground rail tunnel. In addition, Suspension PS logging (SPS) were carried out at selected boreholes along the profile in order to draw out the quantitative relation between the shear wave velocity from the PS logging and the rock mass rating (RMR) determined from the inspection of the cores recovered from the same boreholes, These correlations were then used to relate the shear-wave velocity derived from REMI to RMR along the entire profile. The correlation between shear wave velocity and RMR was very good and so it was possible to estimate the RMR of the total zone of interest for the design of underground tunnel,

• Explosives and Blasting
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• v.34 no.1
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• pp.11-18
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• 2016

It is necessary to minimize ground vibration and noise due to blasting work in urban environment. The blast induced ground vibration and noise are generally generated by a portion of detonation energy, where most of the energy is utilized for rock breakage and movement of rock mass. Recently a blast method utilizing U-shaped steel charge holder was suggested to reduce the ground vibration without decreasing destructive power toward the free surface. In this study, single hole blasting utilizing U-shaped steel charge holder were simulated and the stress waves caused by the detonation of explosives were monitored using AUTODYN software. In order to examine the fragmentation efficiency of the U-shaped steel charge holder, one free face blasting models which adapt the blast induced stress waves were simulated by dynamic fracture process analysis (DFPA) code. In addition, the general blasting models were also simulated to investigate the fragmentation effectiveness of the U-shaped steel charge holder in rock blasting.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.1
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• pp.49-57
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• 2013

The conventional blasting method generates serious blasting vibration and underbreak/overbreak in spite of its high efficiency for rock excavation. To overcome these disadvantages, this paper introduces an alternative excavation method that combines the conventional blasting process with the free surface on the perimeter of the tunnel face using waterjet cutting technology. This proposed excavation method has advantages of (1) reducing vibration and noise level; (2) minimizing underbreak and overbreak; and (3) maximizing excavation efficiency. To verify the effects of the proposed excavation method, field tests were performed with a smooth blasting method at the same excavation conditions. Test results show that the vibration is reduced by up to 55% and little underbreak/overbreak is generated compared with the smooth blasting method. In addition, the excavation efficiency of the proposed method is greater than that of the smooth blasting method. The proposed blasting method with a free surface using waterjet cutting can be applied to urban excavation construction as well as to underground structure construction.

• Journal of the Korean Geosynthetics Society
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• v.15 no.1
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• pp.1-10
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• 2016

Recently, offshore wind farms are increasingly expected, because there are huge resource and large site in offshore. Jeju island has optimum condition for constructing a wind energy farm. Unlike the mainland, Jeju island has stratified structure distribution between rock layers sediments due to volcanic activation. In these case, it can be occur engineering problems in whole structures as well as the safety of foundation as the thickness and distribution of sediment under top rock layer can not support sufficiently the structure. In this study, field lateral load test of the pile for analyzing lateral behavior of the offshore wind turbine which is embedded in basalt. After calculating the subgrade resistance and the horizontal deflection from the measured strain to derive p-y curve from the lateral load test results, the subgrade resistance amplifies the error in the process of differentiation and the error of piecewise polynomial curve fitting is the smallest. In order to calculate the horizontal deflection from the measured strain, the six-order polynomial was used.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.869-886
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• 2018

Rockbolt is one of the most common supports used to reinforce discontinuous rock during underground excavation. Extra drain pipes are installed to improve excavation workability and the anchorage of rockbolts in water bearing ground. The drain pipe is effective in improving the workability by providing drainage path, but it is difficult to expect the reinforcement effect, increasing disturbance of the discontinuous rock mass and the construction cost. To solve this problem, dual purpose rockbolt (DPR) has been developed for the reinforcement of rock and the drainage of ground water. DPR was able to improve the mechanical and hydraulic stability of the rocks quickly and economically. Two kinds of DPRs using FRP (Fiber Reinforced Plastic) and steel were investigated for the mechanical and hydraulic performance. Also, the workability and stability of DPR were analyzed.