• Title/Summary/Keyword: 굴착 성능

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Estimation of design parameters of TBM using punch penetration and Cerchar abrasiveness test (압입시험 및 세르샤 마모시험에 의한 TBM의 설계변수 추정)

  • Jeong, Ho-Young;Lee, Sudeuk;Jeon, Seokwon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.16 no.2
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    • pp.237-248
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    • 2014
  • Linear cutting test is known to be very effective to determine machine parameters (i.e. thrust force and torque) and to estimate penetration rate of TBM and other operation conditions. Although the linear cutting test has significant advantages, the test is expensive and time-consuming because it requires large size specimen and high load capacity of the testing machine. Therefore, a few empirical prediction models (e.g. CSM, NTNU and QTBM) alternatively adopt laboratory index tests to estimate design parameters of TBM. This study discusses the estimation method of TBM machine parameters and disc cutter consumption using punch penetration test and Cerchar abrasion test of which the researches are rare. The cutter forces and cutter consumption can be estimated by the empirical models derived from the relationship between laboratory test result with field data and linear cutting test data. In addition, the estimation process was programmed through which the design parameters of TBM (e.g. thrust, torque, penetration rate, and cutter consumption) are automatically estimated using laboratory test results.

Analysis of inner parts in the disc cutters applied to the field tests (현장적용 디스크커터의 내부부품 분석)

  • Bae, Gyu-Jin;Choi, Soon-Wook;Chang, Soo-Ho;Lee, Gyu-Phil;Song, Bong-Chan;Kim, Kab-Boo
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.4
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    • pp.473-485
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    • 2015
  • The problems for non-rotating of a disc cutter proceed from the faults in inner parts of the disc cutter such as the leak of hydraulic fluid, the intrusion of tunnel mucks and water, overloading, overheating, poor assembly and substandard material. The rotating of a disc cutter is an indicator to show that the inner parts of disc cutter is operable, although the rotational torque depends on the extent of the damage. Therefore, the key in the problems for non-rotating of disc cutter is to maintain that the tapered roller bearings are working properly. This study aims to investigate the inner parts disassembled from disc cutters applied to the field tests in order to help decision for reuse of the disc cutters. As results, surface finishing to remove the scratch on the load zone of the hubs is needed, with the intent to reuse a hub. And the investigation of lapping surface by optical microscope of floating seals and the contamination test of oil need to be performed for reuse of a disc cutter. Especially, the analysis results show that the floating seals play a key role in the normal operation of bearings. There is nothing significant to report in the rest parts such as bearing, shaft, seal retainers.

Evaluation methods of shotcrete lining stresses considering steel rib capacities by two-dimensional numerical analysis (이차원 수치해석에 의한 강지보 성능을 고려한 숏크리트 라이닝의 부재력 평가 방법)

  • Ha, Tae-Wook;Kim, Dae-Young;Shin, Young-Wan;Yang, Hyung-Sik
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.10 no.3
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    • pp.269-282
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    • 2008
  • In general, the effects of steel ribs are not considered in the numerical analysis of tunnel design. However, attempts have been increased recently to consider these effects in the analysis of shallow tunnels in soft ground, based on the fact that the steel ribs embedded in the shotcrete take a role to support some portion of the redistributed load due to excavation. In such analyses, the steel ribs can be considered in four different methods: (1) a conventional method where the steel ribs are not considered, (2) a method using the equivalent composite cross section in which the bending moment of shotcrete is not considered, (3) a method using the equivalent composite cross section in which both the compressive stress and the bending moment for the shotcrete and steel rib are considered, and (4) a method using beam elements for the shotcrete and the steel rib, respectively. These methods are adopted in the numerical analysis using FLAC 2D to investigate stresses of both the shotcrete and the steel rib. The overall results show that the analyses are more practical and economical when the effects of steel rib are considered fer the methods (2), (3), and (4). Since the results of those analyses considering steel rib capacity may be different according to the ground condition, it will be necessary to consider the appropriate method among them in accordance with design conditions.

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Numerical Study on Vertical Stress Estimation for Panel Pillars at Room and Pillar Mines (주방식 광산의 패널 광주 수직응력 추정을 위한 수치해석 연구)

  • Yoon, Dong-Ho;Song, Jae-Joon
    • Tunnel and Underground Space
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    • v.30 no.5
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    • pp.473-483
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    • 2020
  • This paper examines the vertical stress change concentrated on mine pillar which occurs due to the stress disturbance from opening excavation at room and pillar mine by FLAC3D, a finite difference method (FDM) software. The mesh size combination is decided with a careful consideration of relative error and run-time, then its performance is verified. A series of numerical analyses is conducted and the vertical stress at central pillar was observed for the test cases of 1×1 to 11×11 mine pillars, 40 m to 320 m depth with 40 m difference. The results show that the vertical stress of pillar approaches to the similar value with the value estimated by tributary area theory(TAT) when the development area (NP) is increased or the height of overburden (HOB) is decreased, while it is overestimated in the opposite case. Furthermore, it also represents that the vertical stress factor (VSF) converges to a specific value when the depth is increased whille keeping the development area identical.

Fire Suppression Test using the Automatic Monitor System for Double-Deck Tunnel (복층터널 자동 모니터 소화설비를 이용한 화재진압 실험)

  • Park, Jin-Ouk;Yoo, Yong-Ho;Kim, Hwi-Seung;Park, Byoung-Jik;Kim, Yang-Kyun
    • Fire Science and Engineering
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    • v.31 no.6
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    • pp.40-46
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    • 2017
  • As one of the solutions to deal with economic loss caused by traffic congestion in metropolitan area, a deep underground road has been planned and implemented at home and abroad. The part of them has been pushed ahead with a double-deck scheme which has an advantage in constructability and cost efficiency comparing to traditional road tunnel. However, the double-deck tunnel has a lower floor height than the general road tunnel due to the special structure used as the upper and lower lines by installing the middle slab on one excavation section. Therefore, it is relatively weak against fire accidents and ventilation problems occurring in tunnels. Thus study to develop the life safety system optimized to a double-deck tunnel has been systematically carried out in order to overcome their weak point. In this study, automatic monitoring fire extinguisher (AMFE) is developed to suppress a fire and prevent its spread at early stage of tunnel fire, conducting the performance test through vehicle fire tests as verification. The tests were conducted with AMFE being 30 m apart from the vehicle and 10 m apart from engine room. As a results, it was confirmed that AMFE enables to suppress a fire and prevent its spread in both cases.

Evaluation of Allowable Bearing Capacity of 600 mm Diameter Preboring PHC Piles Using Dynamic Load Test (직경 600mm PHC 매입말뚝의 동재하시험을 통한 허용 지지력 평가)

  • Woo, Gyu-Seong;Park, Jong-Bae;Seo, Mi-Jeong;Lee, Jong-Sub
    • Journal of the Korean Geotechnical Society
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    • v.32 no.11
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    • pp.61-72
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    • 2016
  • For the construction of high-rise structures and the optimized foundation design, the use of the large-diameter PHC pile has increased. Especially, the use of the 600 mm diameter PHC pile has significantly increased. In this study, for the evaluation of the suitability of the current design practice, the 46 dynamic pile load tests, which were carried out in the 600 mm diameter preboring PHC pile, are analyzed. The end bearing capacity is obtained from the end of initial driving test and the shaft capacity is estimated from the restrike test. The allowable capacities estimated by the dynamic load test are compared with those based on the current design practice. The analyses show that the allowable end bearing capacity evaluated by the dynamic pile load test is greater than the design practice in most piles. The allowable shaft capacity, however, is smaller than the design practice in many piles. The higher end bearing capacity and the smaller shaft capacity may result from the improvement of the drilling equipment and the increase in the penetration depth. Thus, the portion of the end bearing capacity in the total capacity increases.

The Effect of Ground Heterogeneity on the GPR Signal: Numerical Analysis (지반의 불균질성이 GPR탐사 신호에 미치는 영향에 대한 수치해석적 분석)

  • Lee, Sangyun;Song, Ki-il;Ryu, Heehwan;Kang, Kyungnam
    • Journal of the Korean GEO-environmental Society
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    • v.23 no.8
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    • pp.29-36
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    • 2022
  • The importance of subsurface information is becoming crucial in urban area due to increase of underground construction. The position of underground facilities should be identified precisely before excavation work. Geophyiscal exporation method such as ground penetration radar (GPR) can be useful to investigate the subsurface facilities. GPR transmits electromagnetic waves to the ground and analyzes the reflected signals to determine the location and depth of subsurface facilities. Unfortunately, the readability of GPR signal is not favorable. To overcome this deficiency and automate the GPR signal processing, deep learning technique has been introduced recently. The accuracy of deep learning model can be improved with abundant training data. The ground is inherently heteorogeneous and the spacially variable ground properties can affact on the GPR signal. However, the effect of ground heterogeneity on the GPR signal has yet to be fully investigated. In this study, ground heterogeneity is simulated based on the fractal theory and GPR simulation is carried out by using gprMax. It is found that as the fractal dimension increases exceed 2.0, the error of fitting parameter reduces significantly. And the range of water content should be less than 0.14 to secure the validity of analysis.

Standard Procedures and Field Application Case of Constant Pressure Injection Test for Evaluating Hydrogeological Characteristics in Deep Fractured Rock Aquifer (고심도 균열암반대수층 수리지질특성 평가를 위한 정압주입시험 조사절차 및 현장적용사례 연구)

  • Hangbok Lee;Chan Park;Eui-Seob Park;Yong-Bok Jung;Dae-Sung Cheon;SeongHo Bae;Hyung-Mok Kim;Ki Seog Kim
    • Tunnel and Underground Space
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    • v.33 no.5
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    • pp.348-372
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    • 2023
  • In relation to the high-level radioactive waste disposal project in deep fractured rock aquifer environments, it is essential to evaluate hydrogeological characteristics for evaluating the suitability of the site and operational stability. Such subsurface hydrogeological data is obtained through in-situ tests using boreholes excavated at the target site. The accuracy and reliability of the investigation results are directly related to the selection of appropriate test methods, the performance of the investigation system, standardization of the investigation procedure. In this report, we introduce the detailed procedures for the representative test method, the constant pressure injection test (CPIT), which is used to determine the key hydrogeological parameters of the subsurface fractured rock aquifer, namely hydraulic conductivity and storativity. This report further refines the standard test method suggested by the KSRM in 2022 and includes practical field application case conducted in volcanic rock aquifers where this investigation procedure has been applied.

Evaluation of Low-temperature Compaction Characteristics According to Organic Matter Content through Laboratory Compaction Tests (실내 다짐시험을 통한 유기물 함량에 따른 저온 다짐 특성 분석)

  • Choi, Hyun-Jun;Kim, Sewon;Lee, Seungjoo;Park, Hyeontae;Choi, Hangseok;Kim, YoungSeok
    • Journal of the Korean Geotechnical Society
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    • v.40 no.3
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    • pp.93-100
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    • 2024
  • Pore water freezes in low-temperature compaction, which leads to different compaction characteristics compared to room temperature conditions. In regions like Alberta, Canada, where organic soils are prevalent, compaction performance is influenced by the high water retention and compressibility of organic soils, as well as their sensitivity to freezing and thawing. Alberta's strict environmental regulations demand the reuse of excavated soil for backfill, and the long winter season creates challenging conditions for civil engineering projects. In this study, a laboratory compaction test was conducted to evaluate the low-temperature compaction characteristics of organic soils with varying organic content. The results indicate that the optimum moisture content increases as the organic content increases, and the maximum dry unit weight decreases by up to 21.9%. In addition, under temperature conditions below -4℃, no optimum moisture content was observed, and the dry unit weight decreased as the moisture content increased.

Case Study of Shield Tunnel Construction : Incheon Metro Line 1 Geomdan Extension Phase 1 Project (쉴드TBM 터널 시공 사례 : 인천도시철도1호선 검단연장선 1공구)

  • Byungkwan Park;Chaeman Joo;Dohak Huh;Hyunsup Song;Gwangsu Joo;Dohoon Kim;Minsang Lee
    • Tunnel and Underground Space
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    • v.34 no.3
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    • pp.185-195
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    • 2024
  • The Incheon Metro Line 1 Geomdan Extension Phase 1 is the first project in South Korea where both a roadheader and TBM (Tunnel Boring Machine) are being used together. The shield TBM tunnel section is 1,057 m long, and is mostly composed of rock, including the section beneath the Airport Railroad and the Gyeongin Ara Waterway. A 7.8 m earth pressure balance shield TBM was used for tunnel excavation. The average monthly advance rate for both the North and South tracks is 239.1 m, with a maximum monthly advance rate of 334.5 m. This technical article comprehensively evaluates the productivity of the shield TBM, focusing on the TBM excavation performance. Above all, it aims to provide useful reference material for the successful execution of shield TBM tunnel construction.