• 터널과지하공간
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• 제7권1호
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• pp.1-12
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• 1997

Engineering rock mass classification is extensively used to determine the reasonable support system throughout the tunneling process in the field. Selection of support system based on the results of engineering rock mass classification is simple and straight-forward. However, this method cannot consider the effect of in-situ stresses, mechanical properties of support material, and support installation time on the behavior or rock-support system To handle the various conditions encountered in the underground excavation sites rock-support system. To handle the various conditions encountered in th eunderground excavation sites rock-support interaction program has been developed. This program can analyze the interaction between rock mass and support materials and also can simulate the tunnel excavation-support insstallation process by controlling the support installation time and the stiffness of support system. Practical applicability of this program was verfied by comparing the results of support design to those from rock mass classification for virtual underground excavation at the drilling site KD-06 in Geoje island.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 춘계 학술발표회
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• pp.811-818
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• 2010

This paper presents the results of a numerical investigation on behavior of deep excavation wall system supported by steel pipe struts. A series of three-dimensional finite element analyses were carried out on a deep excavation project site which adopted steel pipe struts. The results indicated that the mechanical behavior of steel pipe supported deep excavation is comparable to that of a conventional H-pile supported deep excavation, although the steel pipe supported system is required less number of struts than the conventional H-pile strut system. Also shown is that the sectional stresses of the steel pipe support system are within the allowable values implying that the steel pipe support system can be effectively used as an alternative to conventional H-pile support system.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.336-343
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• 2005

In the braced excavations, careful consideration must be given to the risks of progressive collapse of the entire support system due to failure of a single member. The existing connection methods of the excavation support system results in many problems during construction. To overcome these, simple joint method is proposed in this study. The full scale test and the numerical analysis using finite element method were performed to verify the safety of them. As results, simple joint method was good effective to increase strength. And it was good effective to decrease in numbers of bolt. Also, new method is cheaper than existing connection methods and a good construction as well.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1991년도 추계학술발표회 논문집 지반공학에서의 컴퓨터 활용 COMPUTER UTILIZATION IN GEOTECHNICAL ENGINEERING
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• pp.123-132
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• 1991

The GEOKST program was used to solve the tunnel example problem. The package can solve such geotechnical problem as excavation, embankment, foundations, etc., in which the soil can be modeled by various elastoplastic geomaterial models. The main objective was to consider the effects of excavation depth to the face of the tunnel on the stability of the ground and support system. Depended on the strength of the ground materials, the limit excavation depth without any support system could be established by analyzing three-dimensional excavation problem. In this given example problem, the strengths of the ground materials were enough for the stability of the tunnel without any support system up to fairly deep excavation and the maximum tunnel section displacement was stabilized as the excavation proceed. The asymptotic value was approximately the same as that of the plane strain analysis. Thus, assuming the plain strain condition and simulation the actual excavation procedure, the maximum tunnel section displacement was caculated after final step. The maximum calculated displacement occured at the top section of the tunnel geometry and was about 8mm.

• Geomechanics and Engineering
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• 제33권5호
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• pp.507-518
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• 2023

The effects of various supporting arrangements have been investigated on an excavation support system using a numerical tool. The purpose of providing different supporting arrangements was to limit the pile wall deflection in the range of 0.5% to 1% of the excavation depth. Firstly, a deep excavation supported by sheet pile wall was modeled and the effects of sheet pile wall thickness, excavation depth and distance to adjacent footings from sheet pile wall face were explored on the soil deformation and wall deflection. Further analysis was performed considering six different arrangements of tieback anchors and struts in order to limit the wall deflections. Case-01 represents the basic excavation geometry supported by sheet pile wall only. In Case-02, sheet pile wall was supported by struts. Case-03 is a sheet pile wall supported by tieback anchors. Likewise, for the Cases 04, 05 and 06, different arrangements of struts and tieback anchors were used. Finally, the effects of different supporting arrangements on soil deformation, sheet pile wall deflection, bending moments and anchor forces have been presented.

• 한국지반공학회논문집
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• 제26권6호
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• pp.45-56
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• 2010

본 논문에서는 강관버팀보로 지지되는 흙막이 굴착 시스템의 거동에 관한 수치해석 연구내용을 다루었다. 최근 들어 적용성이 점차 늘고 있는 강관버팀보로 지지되는 흙막이 시스템의 거동특성에 관한 이해 증진의 일환으로 본 연구에서는 강관버팀보가 적용된 실제 현장 단면에 대한 3차원 해석을 수행하였으며 그 결과를 토대로 흙막이 벽체 및 버팀보, 브레이싱 시스템에 대한 3차원 거동 메카니즘을 고찰하였다. 이와 아울러 동일한 굴착단면에 대해 H-형강 버팀보 적용 조건에 추가해석을 통해 강관버팀보 적용 단면과의 직접적인 비교를 시도하였다. 그 결과 강관버팀보 적용단면의 경우 H-형강 단면과 비교하여 수평간격이 넓음에도 불구하고 거의 대등한 거동을 보이는 것으로 나타났다.

• 한국지반공학회논문집
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• 제20권2호
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• pp.107-113
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• 2004

본 논문에서는 강선의 선행하중을 이용한 새로운 흙막이 공법의 원리와 적용 사례를 다루고자 한다. IPS(Innovative Prestressed Earth Retention System) 흙막이 공법은 띠장에 강선의 인장력을 적용한 선행하중 공법이다. IPS 흙막이 공법은 강선, H-Beam 받침대, 띠장으로 구성된 띠장에 강선의 긴장력을 도입하여 굴착 지반에 선행하중을 가하고 지반의 추가 굴착으로 인한 토압의 증가를 IPS 띠장과 트러스 버팀보 또는 코너 스트럿으로 지지하는 개념을 가지고 있다. IPS 흙막이 공법은 경제성, 시공성, 안정성을 제공하며 휨 강성이 큰 IPS 띠장을 이용하여 지지 간격을 획기적으로 증대시킨 특징을 가지고 있다. 본 논문에서는 IPS 흙막이 공법의 기본 원리 및 메커니즘을 설명하고 IPS 흙막이 공법의 특징, 적용 범위와 설계 방법을 언급하였다. IPS 흙막이 공법의 현장시험을 수행하여 현장 적용성과 안정성을 확인하고 현장 계측결과를 분석하여 IPS 흙막이의 거동을 파악하였다.

• Geomechanics and Engineering
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• 제17권6호
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• pp.573-581
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• 2019

Excavation of underground cavern and shaft was proposed for the construction of a ventilation facility in an urban area. A shaft connects the street-level air plenum to an underground cavern, which extends down approximately 46 m below the street surface. At the project site, the rock mass was relatively strong and well-defined joint sets were present. A kinematic block stability analysis was first performed to estimate the required reinforcement system. Then a 3-D discontinuum numerical analysis was conducted to evaluate the capacity of the initial support and the overall stability of the required excavation, followed by a 3-D continuum numerical analysis to complement the calculated result. This paper illustrates the application of detailed numerical analyses to the design of the required initial support system for the stability of underground hard rock mining at a relatively shallow depth.

• Geomechanics and Engineering
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• 제28권3호
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• pp.265-281
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• 2022

A set of slurry shield test system capable of cutter cutting and slurry automatic circulation is used to investigate the deformation characteristics, the evolution characteristics of support resistance and the distribution and evolution process of earth pressure during excavating and collapsing of slurry shield tunneling in circular-gravel layer. The influence of cover-span ratio on surface subsidence, support resistance and failure mode of excavation face is also discussed. Three-dimensional numerical calculations are performed to verify the reliability of the test results. The results show that, with the decrease of the supporting force of the excavation face, the surface subsidence goes through four stages: insensitivity, slow growth, rapid growth and stability. The influence of shield excavation on the axial earth pressure of the front soil is greater than that of the vertical earth pressure. When the support resistance of the excavation face decreases to the critical value, the soil in front of the excavation face collapses. The shape of the collapse is similar to that of a bucket. The ultimate support resistance increase with the increase of the cover-span ratio, however, the angle between the bottom of the collapsed body and the direction of the tunnel excavation axis when the excavation face is damaged increase first and then becomes stable. The surface settlement value and the range of settlement trough decrease with the increase of cover-span ratio. The numerical results are basically consistent with the model test results.

• 터널과지하공간
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• 제8권2호
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• pp.130-138
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• 1998

Comprehensive monitoring system for the safe and economical excavation of underground opening has been established by employing the 3 independent models each of which can i) predict the ultimate convergence, ii) assess the in-situ stresses and the elastic modulus of excavating rock, iii) calculate the time-dependent opening behavior with respect to the face advance rate and support pressure at the equilibrium state. Accuracy of each model has been verified through illustrative examples. The step-by-step procedures of comprehensive monitoring system for analyzing the rock behavior and the optimum support installation has been explained. The capability and applicability of this system to the practical excavation also has been discussed.