• Title, Summary, Keyword: Excavation sequence

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Development of finite element analysis model for multi-step excavation problem (시공단계를 고려할 수 있는 유한요소 해석 모델 개발)

  • Lee, Youn-Kyou
    • Tunnel and Underground Space
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    • v.6 no.4
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    • pp.326-334
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    • 1996
  • In underground construction the multi-step excavation sequence is commonly adopted for the convenience of the underground work. A numerical simulation method which is capable of analyzing the effects of excavation sequence on the stability of the opening is greatly needed. In this study a two dimensional finite element code was developed based on the effective numerical algorithm for the multistep excavation. The practical applicability of the model was verified for the simplified excavation sequences.

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Elasto-Plastic Analysis of Underground Openings Considering the Effect of Excavation (굴착영향을 고려한 지하공동의 탄소성해석)

  • 최규섭;김대홍;황신일;심재구
    • The Journal of Engineering Geology
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    • v.8 no.3
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    • pp.225-234
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    • 1998
  • The behavior of the underground opening depends mainly on the magnitude of the initial stress existing before excavation and on the stress redistribution due to the excavation. In the case of elasto-plastic materials such as rock mass, as the structural behavior of surrounded opening due to excavation depends on the stress path, methods and sequence of excavation have influences on the results of numerical analysis. Therefore, in order to design underground openings with large cross-section such as underground nuclear power plants, radioactive waste disposal cavems, oil storage caverns, and so on more reasonably it is desirable to consider the effect of the excavation sequence in the analysis. In this paper, the underground structure is analyzed using the finite element method and the distinct element methods with a view to review the the effect of the excavation sequence. Based on the results of the analysis the followings are discussed : influence of excavation shape and sequence, effect of structural reinforcements, influence of multi caverns.

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A study on the excavation cycle by the drill-and-blast method for a room-and-pillar underground structure (주방식 지하구조물의 발파 굴착공정 분석 연구)

  • Lee, Chul-Ho;Hyun, Young-Hwan;Hwang, Je-Don;Choi, Soon-Wook;Kang, Tae-Ho;Chang, Soo-Ho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.18 no.6
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    • pp.511-524
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    • 2016
  • Since a room-and-pillar underground structure is characterized by its grid-type array of room and pillar, its economical efficiency can be governed by excavation sequence. In this study, the construction period by the drill-and-blast method as a excavation method for a room-and-pillar underground structure was examined. In addition, the parallel excavation sequence was considered as the main sequence of a room-and-pillar underground structure. Sequences of mucking and support installation were derived to estimate the total excavation cycle by taking the case of a road tunnel into consideration. From the excavation cycle of room-and-pillar underground structure, the relationship between available maximum and minimum numbers of jumbo drill machines depending on the number of faces in operation was suggested.

Modeling the Effect of Excavation Sequence and Reinforcement on the Response of Tunnels with Discontinuous Deformation Analysis Method (불연속 변형 해석법에 의한 굴착순서 및 지반보강이 터널의 거동에 미치는 영향 모델링)

  • 김용일;김영근
    • Tunnel and Underground Space
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    • v.10 no.1
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    • pp.25-32
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    • 2000
  • This paper presents two new extensions to the DDA method. The extensions consist of sequential loading or unloading and rock reinforcement by rockbolts, shotcrete or concrete lining. Examples of application of the DDA method with the new extensions are presented. Simulations of the underground excavation of the Unju Tunnel of Kyungbu High Speed Railway Project in Korea were carried out to evaluate the influence of excavation sequence and reinforcement on the tunnel stability. The results of the present study indicate that improper selection of excavation sequence could have a destabilizing effect on the tunnel stability. On the other hand, reinforcement by rockbolts and shotcrete can stabilize the tunnel. It is found that, in general, the DDA program with the three new extensions can now be used as d practical tool in the design of underground structures. In particular, phases of construction (excavation, reinforcement) can now be simulated more realistically.

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A preliminary study on the optimum excavation sequence of a room-and-pillar underground structure (주방식 지하구조물의 최적 굴착공정에 대한 예비 분석 연구)

  • Lee, Chulho;Choi, Soon-Wook;Hyun, Younghwan;Hwang, Jedon;Chang, Soo-Ho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.4
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    • pp.499-511
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    • 2015
  • A room-and-pillar underground structure is characterized by its grid-type array of galleries. As a result, its construction and economical efficiency can be governed by excavation sequence of galleries. Therefore, this study aims to study the optimum excavation scheme of a room-and-pillar underground structure by considering its various design factors such as ground conditions and excavation sequences. Drill-and-blast method is assumed as a excavation method for a room-and-pillar underground structure. In addition, two kinds of excavation patterns corresponding to a concurrent and a sequential excavation patterns are considered in this study. For the assumed conditions, the structural stability and the construction efficiency based on the number of faces and the travel distance of a jumbo drilling machine are analyzed for the two excavation patterns. Even though the two kinds of excavation patterns show almost the same structural stability as each other, the concurrent excavation pattern is relatively preferable to the sequential excavation pattern in terms of the number of faces in operation and travel distance of a drilling jumbo.

A Study on the Structural Behavior of Underground Openings Considering the Effect of Excavation (굴착영향을 고려한 지하공동의 구조거동연구)

  • 최규섭;김대홍
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.111-117
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    • 1992
  • In order to design and construct a safe and economic underground structure, it is essential to understand the structural behavior of underground openings considering the effect of the sequential excavation. Therefore, this paper includes the study of initial stress distribution before excavation and stress redistribution due to the sequential excavation. And discussion on numerical simulation techniques for the sequential excavation is also included. Then, the underground structure is analyzed using the finite element and distinct element methods of analysis considering the effect of the sequential excavation. Based on the results of the analysis, the followings are discussed: shape of the openings, effect and timing of structural reinforcements. methods and sequence of excavation.

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Modeling the Effect of Water, Excavation Sequence and Reinforcement on the Response of Tunnels

  • Kim, Yong-Il
    • Journal of the Korean Geotechnical Society
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    • v.15 no.3
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    • pp.161-176
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    • 1999
  • A powerful numerical method that can be used for modeling rock-structure interaction is the Discontinuous Deformation Analysis (D D A) method developed by Shi in 1988. In this method, rock masses are treated as systems of finite and deformable blocks. Large rock mass deformations and block movements are allowed. Although various extensions of the D D A method have been proposed in the literature, the method is not capable of modeling water-block interaction, sequential loading or unloading and rock reinforcement; three features that are needed when modeling surface or underground excavation in fractured rock. This paper presents three new extensions to the D D A method. The extensions consist of hydro-mechanical coupling between rock blocks and steady water flow in fractures, sequential loading or unloading, and rock reinforcement by rockbolts, shotcrete or concrete lining. Examples of application of the D D A method with the new extensions are presented. Simulations of the underground excavation of the \ulcornerUnju Tunnel\ulcorner in Korea were carried out to evaluate the influence of fracture flow, excavation sequence and reinforcement on the tunnel stability. The results of the present study indicate that fracture flow and improper selection of excavation sequence could have a destabilizing effect on the tunnel stability. On the other hand, reinforcement by rockbolts and shotcrete can stabilize the tunnel. It is found that, in general, the D D A program with the three new extensions can now be used as a practical tool in the design of underground structures. In particular, phases of construction (excavation, reinforcement) can now be simulated more realistically.

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A preliminary study on the excavation sequence of a room-and-pillar underground structure by the drill-and-blast method (발파 굴착에 의한 주방식 지하구조물의 굴착공기 분석 연구)

  • Lee, Chulho;Hyun, Younghwan;Song, Junho;Chang, Soo-Ho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.17 no.6
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    • pp.605-614
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    • 2015
  • A room-and-pillar underground structure is characterized by its grid-type array of room and pillar. As a result, its construction and economical efficiency can be governed by excavation sequence. In this study, the construction period by the drill and blast method which can be treated as a main sequence for excavation was examined by considering the regulation for blasting and construction standard of estimation in Korea. To evaluate the construction period for the room-and-pillar underground structure constructed in 4 kinds of square-type area ($30{\times}30{\sim}57{\times}57m$), the concurrent excavation pattern which was suggested in the previous researches was used. From the suggested condition, the total construction period by drill-and-blast method can be estimated with the consideration of the construction area, number of jumbo drill and faces in operation.

A Stability Case on the Deep Rock Excavation Site in Urban Area by Automatic Monitoring System (도심지 대심도 암반굴착공사에서의 자동계측 활용에 의한 붕괴방지 사례)

  • Kim, Tae-Seob;Jo, Nam-Shin;Jung, Chang-Won
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.1433-1437
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    • 2010
  • The deep excavation work in Korean downtown is almost excuted near by existing structures and utility lines because of the diminution of available yard for construction. So, it was required more and more that the accurate control of displacement on the earth retaining system for minimizing the popular complaint and the damage from constructional accident. Automatic monitoring system is adopted in fracture zone for real time monitoring. In addition, Face mapping is carried out on the face of fracture zone according to excavation sequence. As the result of automatic monitoring system and face mapping, we was able to take the necessary reinforcement and changing excavation method within suitable time. This paper is informed about a stability case on the deep rock excavation site with fracture zone in urban area by automatic monitoring system.

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An experimental study on the load transfer machanism of shallow 2-arch tunnel excavation sequence with vertical discontinuity planes in sandy ground (연직 불연속면이 존재하는 얕은 심도의 사질토 지반에서 2-arch 터널 단계별 굴착에 따른 하중전이에 관한 실험적연구)

  • Oh, Bum-Jin;Lee, Sang-Duk
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.13 no.3
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    • pp.215-231
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    • 2011
  • In this study, the behavior of a shallow 2-arch tunnel during the excavation in the sandy ground containing vertical discontinuity plane was experimentally studied. Load transfer mechanism in the pillar caused by a 2-arch tunnel excavation was observed. The position of the vertical discontinuity plane was varied. Model tests were carried out in the normal construction sequence of 2-arch tunnel. Test results-showed that the load transfer caused by the 2-arch tunnel excavation was concentrated in the discontinuity plane, and was cut by the discontinuity plane, so no load transfer took place above the discontinuity plane. It was also shown that the effect of adjacent tunnel excavation on the pillar load and the ground deformation was greater when excavating the upper half-face of the main tunnel, more than when excavating the lower half-face.