• Title/Summary/Keyword: underground empty space

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Effects of Underground Empty Spaces on the Geomagnetic Flux Density Distribution (지하의 빈 공간에 의한 지자기의 자속밀도분포)

  • Lee, Moon-Ho
    • Journal of the Korean Magnetics Society
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    • v.19 no.2
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    • pp.67-73
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    • 2009
  • The changes of geomagnetic flux density distribution on the ground surface by underground empty spaces had been investigated through the variations of the soil density and measuring heights. The geomagnetic flux density distributions were monitored for the surfaces of different density, sink-hole and tunnel by fluxgate-type magnetometer. The underground empty space and low soil density decreased the geomagnetic flux densities, which were decreased from the boundary of raw and low-density (empty) grounds, and showed the lowest value at the center of low-density (empty) ground. The decreases of geomagnetic flux density by underground empty spaces could be found at the surface with the tunnel located at 80 m underground. And, the underground defects of empty spaces, low density zone, fracture zone and sink holes could be monitored by the phenomena of this decreasing flux density.

Geomagnetic Anomalies by Underground Fracture Zones and Vacant Spaces (파쇄대와 지하의 빈 공간에 의한 지자기이상)

  • Lee, Moon-Ho
    • Journal of the Korean Magnetics Society
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    • v.20 no.2
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    • pp.52-60
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    • 2010
  • The changes of magnetic flux density distribution and the degree of magnetic anomaly on the ground surface by underground fracture zones and empty spaces had been investigated through the variations of the measuring heights. The magnetic flux density distributions were monitored for the ground surfaces of fracture zones, empty spaces and tunnels by fluxgate-type magnetometer. The fracture zones showed the magnetic anomaly with (+) and (-) peak-pairs in the magnetic flux distribution measured at 0.15 m height from the ground surface, and this anomaly disappeared at the height of 1.15 m. The underground empty spaces and tunnels showed the decrease of magnetic flux densities, where the degree of this density decrease diminished with the increase of the underground depth. And, the existence and size of underground empty spaces, such as tunnels and sink holes, could be monitored by the phenomena of this decreasing flux density.

A Study of Residents' Demand for External Space of Apartment Site (아파트 외부공간 실태와 조성기법)

  • 김한수
    • Journal of the Korean housing association
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    • v.11 no.3
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    • pp.87-98
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    • 2000
  • This study derives problems of external space utilization site from on-site observation and questionnaire survey in order to suggest solutions for the problems. The main results are follows. First, fences as visual boundaries of apartment site play some negative roles - separation of space and heterogeneity of circumstance. This study suggests green fences to cure this problem. Second, residents want to change space use - ground to be used as green space or space for relaxation in stead of parking lots, elevator hall as social space, and underground as bike parks or health centers. Third, rooftop space, used as empty space or machine storage space, should be designed to be utilized as relaxation space by making easy to enter and exit.

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Development and Application of Large-diameter Cut-hole Exploration System for Assessment of the Geological Condition beyond NATM Tunnel Face (NATM 터널의 굴착면 전방 지질 평가를 위한 대구경 심발공 탐사 시스템 개발 및 적용 사례)

  • Kim, Minseong;Jung, Jinhyeok;Lee, Jekyum;Park, Minsun;Bak, Jeonghyeon;Lee, Sean Seungwon
    • Tunnel and Underground Space
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    • v.31 no.1
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    • pp.1-9
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    • 2021
  • Recently, the development of underground space has been accelerated with rapid urbanization, and it is significantly important for safe construction to accurately understand the geological conditions of the section when excavating rocks. In this paper, a boring alignment tracking and geological exploration system have been developed to identify the geological conditions beyond the excavation face by utilizing a MSP method that bores a large empty hole to reduce blast-induced vibration. The major advantage of the proposed exploration system is that we can obtain the ground condition of 50 m ahead of the excavation face through exploration along blast cut-holes drilled for the NATM tunnel construction. In addition, we introduce several case histories regarding the assessment of the geological conditions beyond the tunnel face by monitoring the inside of large empty holes using the proposed hole exploration system.

A Study on the Volumetric Expansion Ratio of Rock Mass for Subsidence Behavior Analysis II (지반침하 거동특성 분석을 위한 암반의 부피팽창률에 관한 연구 II)

  • Lee, Seung-Joong;Jung, Yong-Bok;Choi, Sung-O.
    • Tunnel and Underground Space
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    • v.18 no.6
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    • pp.436-446
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    • 2008
  • The volumetric expansion ratio of rock mass on the subsidence occurrence area can explain why the depth of the surface subsidence is lower than the height of an opening; it is because the empty space of the gangway is filled with the broken rock. But, until now, when the surface subsidence mechanism is studied without consideration of the volumetric expansion ratio, it is usually overlooked that the amount of subsidence occurrence can be overestimated. Therefore, in this study, the authors researched the subsidence occurrence mechanism with a new theoretical approaching method. The volumetric expansion ratio obtained from this method has been applied to the numerical simulations. The authors adopted the UDEC(Universal Distinct Element Code) for their discontinuum numerical analysis, because this program has an advantage for analyzing the behavior of rock discontinuities.

The Circular Center Cut with Large Empty Hole & Pre-Splitting in Tunnel Blasting (터널에서 대구경 무장약공과 선균열을 이용한 심빼기 공법에 관한 연구)

  • 김재홍;임한욱
    • Tunnel and Underground Space
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    • v.11 no.3
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    • pp.248-256
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    • 2001
  • The cylindrical cut is most frequently used in tunnel blast regardless of their dimensions. In this study the new parallel cut is proposed to raise advance per round, which is considered to be an elevation of the traditional cylinder cuts. The general geometric pattern of a new cut with parallel blast holes is proposed. The detailed burden and spacing between the central blasthole and those of the four section are also given. The blast results between new cut and traditional cylinder cut are given. The main results of this study are as follows. 1) The average advances per rounds in new cuts can reach 99.5% of drilling length. That of traditional cylinder cuts are known approximately 90∼95% 2) Specific charge weight of new cut compare to that of cylinder cut is approximately reduced 5% from 1.363 to 1.297 kg/㎥ 3) Specific drilling rate is also reduced 8% from 2.393 to 2.130 m/㎥ 4) Vibrations, fly rock, and fragmentation produced by the new blast are to be proved superior to those of the traditional cylinder cuts.

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Analysis of the Influence of the Design Factors and Modeling for the 8inch Class Down-the-Hole Hammer (8인치급 다운더홀(DTH) 해머의 모델링 및 설계 인자에 따른 영향도 분석)

  • Lee, Chung No;Hong, Ki Chang;Jeong, Heon Sul
    • Journal of Drive and Control
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    • v.14 no.4
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    • pp.1-8
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    • 2017
  • The Down-the-Hole hammer is one of the pneumatic drill equipment used for grinding, drilling, and mining. One the advantages of which is that a reduction work efficiency at deep site are relatively small compared to other drilling methods. Due to the large vibration in the underground area, it is difficult to measure the performance of the hammer, and hammer testing requires substantial production cost and operating expenses so research on the development of the hammer is insufficient. Therefore, this study has developed a dynamic simulation model that apprehends the operating principles of an 8-inch DTH hammer and calculates performance data such as performance impact force, piston speed, and BPM. By using the simulation model, design factors related to strike force and BPM were selected, and the influence of each design factors on performance was analyzed through ANOVA analysis. As a result, be the most important for BPM and the strike force are position of upper port that push the piston in the direction of the bit and in BPM, the size of the empty space between the bits and the piston is the second most important design factor.