• 한국터널지하공간학회 논문집
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• 제11권3호
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• pp.229-242
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• 2009

본 논문에서는 터널굴착으로 발생한 지표면에서의 최대 침하 및 수평변위와 총 침하부피량을 추정하기 위하여 서로 상이한 지층에서 다양한 깊이 및 직경, 서로 다른 시공조건(지반손실량)을 가진 터널에 대해 수치해석을 수행하였다. 수치해석 결과로부터 얻어진 지표면에서의 최대 침하량은 터널 굴착부 천단에서의 최대 침하량과 지층별, 터널직경 및 깊이, 시공조건(지반손실량)별로 비교되었으며, 또한 지표면에서의 최대 침하량은 지표면에서의 최대 수평변위량과도 비교하였다. 뿐만 아니라, 터널굴착부에서 발생한 지반손실량($V_L$)과 지표면에서 형성된 총 침하부피량($V_s$)을 지층 및 터널깊이와 직경을 달리하여 상호 비교하였다. 수치해석을 통해 얻어진 결과는 그 적용성과 타당성을 검증하기 위하여 기존 현장계측자료와의 비교가 수행되었으며, 이를 통해 본 연구의 수치해석 결과가 향후 터널굴착으로 발생된 주변 지반의 거동을 파악하고 분석하는 실무자료로서 활용될 수 있다는 것을 파악하였다.

• 문화기술의 융합
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• 제10권6호
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• pp.751-758
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• 2024

국내에서는 지하철 터널구조물과 인접한 위치에서 공사 시 자동화계측 시스템을 도입하여 실시간으로 지하철 터널구조물의 안전성을 관리하고 있는 실정이다. 그러나 현재 자동화계측 시스템의 모니터링결과는 일정 기간 내에 측정된 결과 중 최댓값을 안전관리기준치와 비교하여 평가하는 실정이다. 또한 측정결과의 활용도가 매우 낮으며, 믿을수 있는 기준 및 평가 방법에 대한 연구가 미흡한 실정이다. 본 연구에서는 인접굴착공사 시 장기간 터널구조물 변위거동 모니터링결과를 이용하여 거동에 영향을 미치는 시공단계를 분석하였다. 현장측정에서는 지하철 터널구조물에 내공변위계를 설치한 후 총 24개월 동안 공사에 따른 변위거동 모니터링 데이터를 수집하였다. 또한 지하철 터널구조물 손상에 직접적인 영향을 미칠 수 있는 수직방향 변위데이터를 수집하였다. 본 연구에서는 장기간 측정된 데이터를 이용하여 인접굴착공사 시 지하철 터널구조물에 영향을 미치는 공정을 파악하고 취약부 및 안전성을 평가하였다.

• 한국도로학회논문집
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• 제17권6호
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• pp.27-32
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• 2015

PURPOSES : It is difficult to estimate tunnel stability because of lack of timely information during tunnel excavation. Tunnel deformability refers to the capacity of rock to strain under applied loads or unloads during tunnel excavation. This study was conducted to analyze a methods of pre-evaluation of stability during tunnel construction using the critical strain concept, which is applied to the results of tunnel settlement data and unconfined compression strength of intact rock or rock mass at the tunnel construction site. METHODS : Based on the critical strain concept, the pre-evaluation of stability of a tunnel was performed in the Daegu region, at a tunnel through andesite and granite rock. The critical strain concept is a method of predicting tunnel behavior from tunnel crown settlement data using the critical strain chart that is obtained from the relationship between strain and the unconfined compression strength of intact rock in a laboratory. RESULTS : In a pre-evaluation of stability of a tunnel, only actually measured crown settlement data is plotted on the lower position of the critical strain chart, to be compared with the total displacement of crown settlement, including precedent settlement and displacement data from before the settlement measurement. However, both cases show almost the same tunnel behavior. In an evaluation using rock mass instead of intact rock, the data for the rock mass strength is plotted on the lower portion of the critical strain chart, as a way to compare to the data for intact rock strength. CONCLUSIONS : From the results of the pre-evaluation of stability of the tunnel using the critical strain chart, we reaffirmed that it is possible to promptly evaluate the stability of a tunnel under construction. Moreover, this research shows that a safety evaluation using the actual instrumented crown settlement data with the unconfined compression strength of intact rock, rather than with the unconfined compression strength of a rock mass in the tunnel working face, is more conservative.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.257-264
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• 2003

Tunnelling in water bearing soils influences the ground water regime. It has been indicated in the literature that the existence of ground water above a tunnel influences tunnel stability and the settlement profile. Only limited research, however, has been done on ground water movements around tunnels and their influence on tunnel performance. Time dependent soil behaviour can be caused by the changes of pore water pressure and/or the viscous properties of soil(creep) under the stress change resulting from the advance of the tunnel face. De Moor(1989) demonstrated that the time dependent deformations due to tunnelling are mainly the results of pore pressure dissipation and should be interpreted in terms of effective stress changes. Drainage into tunnels is governed by the permeability of the soil, the length of the drainage path and the hydraulic boundary conditions. The potential effect of lime dependent settlement in a shallow tunnel is likely to occur rapidly due to the short drainage path and possibly high coefficient of consolidation. Existing 2D modelling methods are not applicable to these tunnelling problems, as it is difficult to define empirical parameters. In this paper the time-based 2D modelling method is adopted to account for the three dimensional effect and time dependent behaviour during tunnel construction. The effect of coupling between the unloading procedure and consolidation during excavation is profoundly investigated with the method. It is pointed out that realistic modelling can be achieved by defining a proper permeability at the excavation boundary and prescribing appropriate time for excavation Some guidelines for the numerical modelling of drained and undrained excavation has been suggested using characteristic time factor. It is highlighted that certain range of the factor shows combined effect between the unloading procedure due to excavation and consolidation during construction.

• Geomechanics and Engineering
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• 제35권4호
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• pp.395-409
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• 2023

Long-span suspension bridges have tunnel anchor systems to maintain stable cables. More investigations are required to determine how closely tunnel excavation beneath the tunnel anchor impacts the stability of the tunnel anchor. In order to investigate the impact of the adjacent tunnel's excavation on the stability of the tunnel anchor, a large-span suspension bridge tunnel anchor is utilised as an example in a three-dimensional numerical simulation approach. In order to explore the deformation control mechanism, orthogonal tests are employed to pinpoint the major impacting elements. The construction of an advanced pipe shed, strengthening the primary support. Moreover, according to the findings the grouting reinforcement of the surrounding rock, have a significant control effect on the settlement of the tunnel vault and plug body. However, reducing the lag distance of the secondary lining does not have such big influence. The greatest way to control tunnel vault settling is to use the grout reinforcement, which increases the bearing capacity and strength of the surrounding rock. This greatly minimizes the size of the tunnel excavation disturbance area. Advanced pipe shed can not only increase the surrounding rock's bearing capacity at the pipe shed, but can also prevent the tunnel vault from connecting with the disturbance area at the bottom of the anchorage tunnel, reduce the range of shear failure area outside the anchorage tunnel, and have the best impact on the plug body's settlement control.

• 터널과지하공간
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• 제21권4호
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• pp.251-263
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• 2011

대단면 터널의 안전한 시공을 달성하기 위해서는 굴착암반의 공학적 특성 및 단층 등과 같은 구조지질적인 특성에 대한 파악이 무엇보다 중요하다. 본 현장은 운모 편암내에 대규모 스러스트 단층이 존재하고 있어, 대단면 터널 굴착시 터널의 안정성에 매우 심각한 영향을 미치는 지질공학적 리스크가 특히 큰 현장이라고 할 수 있다. 본 연구에서는 스러스트 단층의 구조지질적 분포 특성 및 단층암의 공학적 특성에 대한 지반조사결과를 바탕으로 터널낙반의 원인과 메카니즘을 분석하고, 이를 바탕으로 대단면 터널의 안전한 재시공을 위한 합리적인 보강대책을 수립하였다.

• 한국터널지하공간학회 논문집
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• 제21권2호
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• pp.257-266
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• 2019

터널 굴착 중 발생하는 지하수는 터널 시공성 및 안정성에 중요한 영향을 끼친다. 따라서 터널의 굴착 중 발생하는 지하수의 유입을 감소시키기 위한 적절한 차수그라우팅이 필요하다. 대부분 터널 설계단계에서는 Pre Grouting을 적용하고 있으나 그라우팅 재료 및 차수효과의 적정성에 대한 분석은 미미하다. 본 연구에서는 현장의 차수 그라우팅 시공사례를 분석하고, 실측된 시공자료를 바탕으로 시공개선사항 및 그라우팅 영역의 투수계수 감소를 고려한 수치해석을 통해 차수효과를 분석하였다.

• Geomechanics and Engineering
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• 제28권6호
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• pp.573-584
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• 2022

Water inrush may occur during seaside urban tunnel excavation. Various factors affect the water inrush, and the water inrush mechanism is complex. In this study, nine evaluation indices having potential effects on water inrush were analysed. Specifically, the geographic and geomorphic conditions, unfavourable geology, distance from the tunnel to sea, strength of the surrounding rock, groundwater level, tidal action, cyclical footage, grouting pressure, and grouting reinforced region were analysed. Furthermore, a two-step interval risk assessment method for water inrush management during seaside urban tunnel excavation was developed by a multi-index system and interval risk assessment comprised of an interval analytic hierarchy process, fuzzy comprehensive evaluation, and relative superiority analysis. The novel assessment method was applied to the Haicang Tunnel successfully. A preliminary interval risk assessment method for water inrush was performed based on engineering geological conditions. As a result, the risk level fell into a risk level IV, which represents a section with high risk. Subsequently, a secondary interval risk assessment method was performed based on engineering geological conditions and construction conditions. The risk level of water inrush is reduced to a risk level II. The results agreed with the current tunnel situation, which verified the reliability of this approach.

• 한국터널지하공간학회 논문집
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• 제4권3호
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• pp.185-193
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• 2002

본 연구에서는 풍화토층에 굴착된 지하철 터널의 변형거동과 종방향 지보재의 보강효과가 3차원 유한차분해석에 의해 조사되었다. 굴착방법이 터널 변형거동에 미치는 영향을 조사하기 위해서 반단면 및 전단면의 2가지 굴착방법이 고려되었다. 또한, 우산형 막장보강법 (RPUM) 및 유리섬유 파이프의 보강효과가 비교되었다. 터널 변형거동을 분석하기 위해 막장변위, 내공변위, 선행변위 및 측벽변위가 조사되었고, 굴착방법 및 종방향 지보재의 효과가 지표침하량를 사용하여 분석되었다. 해석 결과, 반단면 굴착이 전단면 굴착 보다 더 큰 내공변위, 선행변위, 측벽변위를 야기시키며, 반면 막장변위는 전단면 굴착이 반단면 굴착에 비해 더 크게 발생됨을 알았다. 또한, 같은 굴착방법에서는 RPUM만이 사용되었을 때가 RPUM이 유리섬유 파이프와 같이 사용되었을 때 보다 모든 변위가 더 켜졌다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(II)
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• pp.460-465
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• 2003

In this paper, we have studied the expected problems when tunnel is excavated under the wetland, and described the measure to maintain the wetland's ecosystem environment. Firstly, we investigated the wetland's ecosystem such as plants and animals, and executed ground investigation including in-situ tests and geophysical survey. And we analyzed the foreign similar cases for tunnel excavation near the wetland. We also evaluated the runoff and infiltration quantity of groundwater and hydraulic behaviour of rock mass and wetland by numerical analysis. Finally, we established the effective measure to minimize the ecosystem's influence by tunnel excavation.