• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.53-67
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• 2003

In this paper, a new systematic method will be introduced, in which a Rock-mass Prediction System(RPS) predicts the geological conditions and rock mass movements before tunnel excavation and the appropriate counter-measures are taken in the expected weak zones during tunnel construction. The Rock-mass Prediction System(RPS) consists of the LIM, a horizontal con drilling and a seismic exploration method (TSP/HSP). In the Rock-mass Prediction System(RPS), the seismic exploration method (TSP/HSP) gives information on the locations of the weak zones such as major faults and voids in wide-range, and the horizontal core drillings are utilized to find exact location and widths of the faults or voids near the weak zones which was predicted by the seismic exploration method (TSP/HSP). The LIM is used to find the hardness of the rock mass and small weak zones near the excavation face. The Rock-mass Prediction System(RPS) was successfully applied to the Sol-An Tunnel and the effectiveness of the system was verified.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2003년도 춘계학술발표회 논문집
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• pp.13-30
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• 2003

본 고에서는 터널 굴착전 대상지반의 지질상태 및 암반거동을 암반예측시스템(RPS)을 통해 사전에 예측하고, 시공중 취약구간에 대해 적절한 대응을 하는 새로운 종합적인 방법을 소개하고자 한다. 암반예측시스템(RPS)은 선진보링(LIM), 선진수평시추, 탄성파탐사(TSP/HSP)로 구성되어 있다. 암반예측시스템에서 탄성파탐사(TSP/HSP)는 주요 단층과 공동등 연약대의 위치에 대한 개략적인 정보를 제공하며, 선진수평시추는 탄성파탐사(TSP/HSP)에 의해 예측된 연약대 전방에서 단층 또는 공동의 위치와 폭을 확인하는 데 활용된다. 선진보링(LIM)은 암반의 연경도와 굴착면 부근의 작은 연약대를 발견하는 데 활용된다. 암반예측시스템(RPS)은 영동선 철도현장의 솔안터널에 성공적으로 적용되어 그 효용성이 입증되었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.939-948
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• 2006

The structural anisotropy and heterogeneity of rock mass, caused by discontinuities and weak zones, have a great influence on the deformation behavior of tunnel. Tunnel construction in these complex ground conditions is very difficult. No matter how excellent a geological investigation is, local uncertainties of rock mass conditions still remain. Under these uncertain circumstances, an accurate forecast of the ground conditions ahead of the advancing tunnel face is indispensable to safe and economic tunnel construction. This paper presents the effect of anisotropy and heterogeneity of the rock masses to be excavated by numerical analysis. The influences of distance from weak zone, the size or dimension, the different stiffness and the orientation of weak zones are analysedby 2-D and 3-D finite element analysis. By analysing these numerical results, the tunnel behavior due to excavation can be well understood and the prediction of rock mass condition ahead of tunnel face can be possible.

• 화약ㆍ발파
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• 제21권4호
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• pp.1-10
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• 2003

연암평가는 굴착난이도 평가와 관계가 많은 것을 고려할 때 굴착과 관련되는 발파와 연관 지울 수 있다. 따라서 현장에서 소량의 화약을 사용하여 누두공시험에 의해 구해진 누두지수와 발파계수를 연암의 분류요소로 사용하기 위한 시도가 이루어 졌다. 또한 현지 지반의 탄성파속도와 암석의 파쇄에 대한 저항성 나타내는 Protodyakonov의 계수도 분류요소로 사용하여 연암의 분류를 실시하였다.

• Geomechanics and Engineering
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• 제30권3호
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• pp.281-291
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• 2022

Complex rock masses include various joint planes, bedding planes and other weak structural planes. The existence of these structural planes affects the mechanical properties, deformation rules and failure modes of jointed rock masses. To study the influence of the parameters of a nonpersistent joint network on the mechanical properties and failure modes of jointed rock masses, synthetic rock mass (SRM) technology based on discrete elements is introduced. The results show that as the size of the joints in the rock mass increases, the compressive strength and the discreteness of the rock mass first increase and then decrease. Among them, the joints that are characterized by "small but many" joints and "large and clustered" joints have the most significant impact on the strength of the rock mass. With the increase in joint density in the rock mass, the compressive strength of rock mass decreases monotonically, but the rate of decrease gradually decreases. With the increase in the joint dip angle in rock mass, the strength of the rock mass first decreases and then increases, forming a U-shaped change rule. In the analysis of the failure mode and deformation of a jointed rock mass, the type of plastic zone formed after rock mass failure is closely related to the macroscopic displacement deformation of the rock mass and the parameters of the joints, which generally shows that the location and density of the joints greatly affect the failure mode and displacement degree of the jointed rock mass. The instability mechanism of jointed surrounding rock is revealed.

• 한국터널지하공간학회 논문집
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• 제8권2호
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• pp.115-128
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• 2006

불연속면 또는 연약대로 인해 야기되는 암반의 구조적 이방성과 비균질성은 터널의 변형 거동에 큰 영향을 미친다. 아무리 우수한 지반조사가 이루어진다 하더라도, 지역적 불확실성은 여전히 남아 있으므로 복잡한 지반 조건에서의 터널 굴착은 매우 어려운 작업이다. 이러한 불확실한 환경에서 터널 막장 전방의 지반 상태를 정확히 예측하는 것은 안전하고 경제적인 터널 건설에 필요불가결하다 할 수 있다. 따라서 본 논문은 3차원 수치해석을 통하여 암반의 이방성 및 비균질성의 영향을 평가하였다. 즉 터널 굴착으로 인해 야기되는 지반 거동을 분석하고 이에 대한 연약대의 폭과 강성 그리고 방향성의 영향을 정량적으로 평가하였다.

• 터널과지하공간
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• 제3권2호
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• pp.132-141
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• 1993

Laboratory and field tests were performed to find out the effectiveness of ground improvement by grouting for an urban subway tunnel that was excavated in weak rock by the NATM. Field measurements were carried out to monitor the behavior of rock mass around the tunnel and to ensure the validity of the current design of the distance form the measuring points to the tunnel face. The final converged displacement and the peroid were predicted using the gamma function. It was found that the ground improvement in terms of reduced permeability and increased stength in the self-supportability of the excavation face enabled the NATM applied in poor gorund. As the result of applying the gamma function to the predicting of displacement, the final displacement including the preceding one and the converged period could be approximately predicted at the early excavation stage.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.255-261
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• 2003

Tunnelling in poor and heterogeneous ground is a difficult task. Even with a good geological investigation, uncertainties with respect to the local rock mass structure will remain. Especially for such conditions, a reliable short-term prediction of the conditions ahead and outside the tunnel profile are of paramount importance for the choice of appropriate excavation and support methods. The information contained in the absolute displacement monitoring data allows a comprehensive evaluation of the displacements and the determination of the behaviour and influence of an anisotropic rock mass. Case histories and with numerical simulations show, that changes in the displacement vector orientation can indicate changing rock mass conditions ahead of the tunnel face (Schubert & Budil 1995, Steindorfer & Schubert 1997). Further research has been conducted to quantify the influence of weak zones on stresses and displacements (Grossauer 2001). Sellner (2000) developed software, which allows predicting displacements (GeoFit$\circledR$). The function parameters describe the time and advance dependent deformation of a tunnel. Routinely applying this method at each measuring section allows determining trends of those parameters. It shows, that the trends of parameter sets indicate changes in the stiffness of the rock mass outside the tunnel in a similar way, as the displacement vector orientation does. Three-dimensional Finite Element simulations of different weakness zone properties, thicknesses, and orientations relative to the tunnel axis were carried out and the function parameters evaluated from the results. The results are compared to monitoring results from alpine tunnels in heterogeneous rock. The good qualitative correlation between trends observed on site and numerical results gives hope that by a routine determination of the function parameters during excavation the prediction of rock mass conditions ahead of the tunnel face can be improved. Implementing the rules developed from experience and simulations into the monitoring data evaluation program allows to automatically issuing information on the expected rock mass quality ahead of the tunnel.

• 한국터널지하공간학회 논문집
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• 제6권4호
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• pp.327-343
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• 2004

터널 시공 도중이나 터널 굴착 직후 주지보재에 의한 보강 전에 터널막장 전방에 존재하는 연약암반 혹은 단층파쇄대로 인해 유발되는 터널막장의 붕괴사고가 빈번이 일어나고 있다. 기존의 지반탐사방법으로는 터널막장부근에 있는 연약암반이나 단층파쇄대를 찾기 어렵다. 본 연구에서는 이러한 문제점들을 극복하고 기존의 탐사방법들을 보완하기 위해 전자기파를 이용한 터널전방 예측방법을 제안하였다. 전기장의 특성을 고려한 Coulomb 및 Gauss 법칙을 이용하여 절리를 가지는 암반에서의 전기장을 해석하였다. 이를 바탕으로 터널막장 전방에 구형연약암반과 단층파쇄대가 존재하는 경우에 대하여 각각 전기장해석을 수행하여 이론식을 도출하였다. 또한 개발된 해석기법을 작용하여 터널 전방에 구형연약이역과 단층파쇄대가 존재하는 경우에 대하여 예제해석을 수행하였다. 해석결과는 터널 전방에 부착된 몇 개의 전극에서 측정된 암반의 저항으로부터 역함수기법을 이용하여 터널 전방에 존재하는 연약지역의 등가 크기, 위치 및 성질을 정확하게 예측할 수 있음을 보여주었다. 암반에서의 전기저항 가탐심도는 터널막장의 크기, 자연전위 및 기타 전기적 신호에 의해 영향을 받음을 알 수 있었다. 제시된 해석기법은 실내시험을 통하여 검증하였다. 가로, 세로, 높이가 각각 5cm인 콘크리트 블록 1800여 개를 가지고서 3방향 절리를 가진 암반상태를 구현하였고 터널 전방에 전기전도도가 콘크리트 블록보다 상대적으로 높은 물질을 이용하여 연약지반을 구현하였다. 모델링을 통한 실험결과는 해석결과와 거의 일치함을 보여주었다.

• Geomechanics and Engineering
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• 제31권5호
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• pp.529-543
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• 2022

The lattice-spring-based synthetic rock mass model (LS-SRM) technique has been extensively employed in large open-pit mining and underground projects in the last decade. Since the LS-SRM requires a complex and time-consuming calibration process, a robust approach was developed using the Response Surface Methodology (RSM) to optimize the calibration procedure. For this purpose, numerical models were designed using the Box-Behnken Design technique, and numerical simulations were performed under uniaxial and triaxial stress states. The model input parameters represented the models' micro-mechanical (lattice) properties and the macro-scale properties, including uniaxial compressive strength (UCS), elastic modulus, cohesion, and friction angle constitute the output parameters of the model. The results from RSM models indicate that the lattice UCS and lattice friction angle are the most influential parameters on the macro-scale UCS of the specimen. Moreover, lattice UCS and elastic modulus mainly control macro-scale cohesion. Lattice friction angle (flat joint fiction angle) and lattice elastic modulus affect the macro-scale friction angle. Model validation was performed using physical laboratory experiment results, ranging from weak to hard rock. The results indicated that the RSM model could be employed to calibrate LS-SRM numerical models without a trial-and-error process.