• Title, Summary, Keyword: 암반 절삭

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Effects of geometric parameters of a combined nozzle for rock cutting using an abrasive waterjet (연마재 워터젯 암석절삭을 위한 결합 노즐의 기하학적 변수 영향)

  • Oh, Tae-Min;Cho, Gye-Chun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.14 no.5
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    • pp.517-528
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    • 2012
  • Inserting a nozzle assembly into a removed cutting space during a continuous cutting operation is necessary in rock excavation using an abrasive waterjet. In this study, a combined two nozzle assembly is used to secure enough removal width. The shape of the cut space is affected by the geometric parameters (standoff distance, nozzle angle, and vertical distance between the nozzle tips) of the combined nozzle assembly. Abrasive waterjet cutting tests are performed with various geometric parameters for granite rock specimens. Optimized geometric parameters for the nozzle inserting process are determined and verified through the experimental tests.

Performance analysis of sand abrasives for economical rock cutting using waterjet (경제적인 워터젯 암반절삭을 위한 모래 연마재 성능 분석)

  • Oh, Tae-Min;Park, Dong-Yeup;Kong, Tae-Hyun
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.6
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    • pp.763-778
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    • 2019
  • Abrasive waterjet cutting technology has been used for rock excavation of tunnels and underground structures due to various advantages. In order to cut rocks by using the abrasive waterjet system, abrasive is essential to enhance impact energies for fracturing the target rock. Since garnet abrasives are not produced in Korea, alternative abrasives, instead of garnets, are needed to achieve the economical waterjet cutting. This study is to analyze cutting performance for rocks with sandy particles as alternative abrasive. Cutting tests were carried out on granite specimens at the constant waterjet energy (e.g., water pressure or water flow rate). The five kinds of sands, sampled by construction fields and natural sites, were prepared to perform the experimental tests. When sea sand was used as an alternative abrasive, cutting performance was secured to be 60~70% compared to the commercial garnet abrasive. Thus, it is expected that sand abrasives can be applied on the waterjet cutting process for the economical excavation construction.

Assessment of Cutting Performance of a TBM Disc Cutter for Anisotropic Rock by Linear Cutting Test (선형절삭시험에 의한 이방성 암석에 대한 TBM 디스크커터 절삭 성능 평가 연구)

  • Jeong, Ho-Young;Jeon, Seok-Won;Cho, Jung-Woo;Chang, Soo-Ho;Bae, Gyu-Jin
    • Tunnel and Underground Space
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    • v.21 no.6
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    • pp.508-517
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    • 2011
  • The linear cutting test is the most reliable and accurate approach to measuring cutting forces and cutting efficiency using full-size disc cutter in various rock types. The result of linear cutting tests can be used to obtain the key parameters of cutter-head design (i.e. optimum cutter spacing, cutter forces). In Korea, LCM (Linear Cutting Machine) tests have been performed for typical Korean rock types, but these studies focused on the isotropic rocktypes. For prediction of TBM (Tunnel Boring Machine) performances in complex geological conditions including a bedded and schistose rockmass, it is important to consider the effects of anisotropy of rockmass on cutting performances and cutting efficiency. This study discusses a series of LCM tests that were performed for Asan Gneiss having two types of anisotropy angles to assess the effect of the anisotropy angle on rock-cutting performances of TBM. The result shows that the rock-cutting performances and optimum cutting conditions are affected by anisotropy angle and the effect of anisotropy on rock strength should be considered in a prediction of the cutting performances and efficiency of TBM.

Study on a Wire Saw Rock Cutting Model for Tunnel Excavation and Cutting Performance Improvement (터널굴착용 와이어쏘 암반절삭 모델 구축 및 절삭성능 향상 연구)

  • Lee, Jin-Ho;Ahn, Sung-Kwon;Lee, Kyoung-Chan;Bang, Choon-Seok;Sagong, Myung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.10
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    • pp.1069-1077
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    • 2015
  • In tunnel excavation using blast, the wire saw rock cutting method generates a discontinuity perimeter around the center cut, and thus prevents blast vibration propagation to reduce vibration and noise. Therefore, the method is expected to be easy to use and economical compared with other methods. In this paper, the cutting mechanism of wire saw in tunnel excavation is investigated. A model describing the changes in cutting depth and wire saw shape inside a rock during cutting is established and validated for this purpose. Through a simulation using the model, the important characteristics of wire saw cut are investigated, and the influences of cutting conditions, such as wire saw tension, wire saw speed, feed speed, depth, and diameter of boring, on cutting performance are also examined. A method to improve the cutting performance is proposed based on the results.

Prediction of the optimum cutting condition of TBM disc cutter in Korean granite by the linear cutting test (선형절삭시험에 의한 TBM 디스크 커터의 최적 절삭조건 예측)

  • Park, Gwan-In;Jang, Su-Ho;Choe, Sun-Uk;Jeon, Seok-Won
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • pp.217-236
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    • 2006
  • In this study, the LCM was applied as the preliminary study for the cutterhead design of TBM and the drilling performance evaluation. The optimum cutting condition is obtained from the LCM tests and the effects of the design factors of IBM cutterhead, such as penetration depth and cutter spacing, on drilling performance are estimated. In this study, hence, to predict the accurate performance of TBM, instead of one-dimensional penetration depth applied in existing studies, three-dimensional cutting volume was quantified and measured. For this, the digital photogrammetry technique was applied to the LCM tests. Also, AUTODYN 2D was applied to investigate the applicability of the numerical analysis technique to simulate the cutting process of rock by the TBM disc cutter.

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Current Status of Rock Cutting Technique Using Undercutting Concept (언더커팅 개념을 적용한 암반절삭기술의 현황 분석)

  • Jeong, Hoyoung;Choi, Seungbeom;Jeon, Seokwon
    • Tunnel and Underground Space
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    • v.29 no.3
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    • pp.148-156
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    • 2019
  • In urban area, the use of mechanical excavators (e.g., TBM and roadheader) has been increasing in construction of tunnelling and underground space. The undercutting technology, which is modified from the conventional rock-cutting concept, has been developed by advanced countries. Therefore, research on the latest technology of mechanical excavation is required, and keeping carrying out research on conventional mechanical tunneling methods at the same time. In this study, as a fundamental study of the undercutting technique, the principle and concept of the undercutting were introduced, as well as the current status of the research of advanced countries. The undercutting is applicable as a full-face excavation method for the tunnels and underground spaces, as well as an auxiliary(partial-face excavation) method for extension of the existing tunnels.

Method for measuring 3-axis cutting force of a pick cutter using the single-axis load cell array (1축 로드셀 배열을 사용한 픽 커터의 3축 절삭력 측정방법)

  • Kang, Hoon;Jang, Jin-Seok;Park, Jin-Young;Cho, Jung-Woo;Jung, Myeong-Sik;Lee, Jae-Wook
    • Journal of Advanced Marine Engineering and Technology
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    • v.40 no.9
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    • pp.749-755
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    • 2016
  • A new method for measuring the 3-axis cutting forces of a pick cutter by substituting costly 3-D load cells is proposed in this paper. The proposed cutting force measurement method is capable of estimating the 3-axis cutting forces through mechanical constraints using four single-axis compressive load cells and shoulder bolts. The feasibility of the proposed method was verified by finite element analysis, and the accuracy of the force measurement of the developed force measurement device was investigated by conducting linear rock cutting tests. The tests showed that the new cutting force measurement method is able to measure 3-axis cutting forces with a relative error of approximately 6%. These results imply that the new method could be a suitable alternative to conventional 3-D load cells. In addition, it will allow a significant reduction of approximately 20-30% in the costs required for measuring the cutting force when compared to conventional 3-D load cells.