• Geomechanics and Engineering
• /
• 제7권1호
• /
• pp.75-85
• /
• 2014

The application of the mechanized tunnelling has been extended in recent years. There are at present different approaches that are used in the design of segmental tunnel linings supported in mechanized tunnels. Even though segmental lining is utilized for mechanized tunnels, its behaviour is still quite unclear under in situ stress and there is a lack of data regarding the distribution of stresses inside segmental linings. So far no single effective calculation method exists for segmental lining design. The lack of clear solutions makes the use of segmental lining to be more expensive due to the adoption of greater safety factors. Therefore, a particular attention must be given in order to obtain data from monitored tunnels which permits to validate design methods. In this study, strain measurements, which were conducted during the construction of twin tunnels in the Bologna-Florence railway line, have been presented. The behaviour of segmental lining during the excavation and the influence of a new tunnel excavation on an existing tunnel have been shown through the measured data. The data are then compared with the results obtained with Einstein and Schwartz's method and Duddeck and Erdmann's method, which permits to highlight the fact that the two analytical methods underestimate structural forces induced in the segmental lining and then must be used with caution.

• Steel and Composite Structures
• /
• 제19권2호
• /
• pp.405-416
• /
• 2015

We proposed the concept of nominal rigidity of a long-span V-shaped rigid frame composite arch bridge, analyzed the effects of structural parameters on nominal rigidity, and derived a theoretical nominal rigidity equation. In addition, we discussed the selection of the arch-to-beam rigidity ratio and its effect on the distribution of internal forces, and analyzed the influence of the ratio on the internal forces. We determined the delimitation value between rigid arch-flexible beam and flexible arch-rigid beam. We summarized the nominal rigidity and arch to beam rigidity ratios of existing bridges. The results show that (1) rigid arch-flexible beam and flexible arch-rigid beam can be defined by the arch-to-beam rigidity ratio; (2) nominal rigidities have no obvious differences among the continuous rigid frame composite arch bridge, V-shaped rigid frame bridge, and arch bridge, which shows that nominal rigidity can reflect the global stiffness of a structure.

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

• Structural Monitoring and Maintenance
• /
• 제5권3호
• /
• pp.363-377
• /
• 2018

The proper functioning of critical points on transport infrastructure is decisive for the entire network. Tunnels and bridges certainly belong to the critical points of the surface transport network, both road and rail. Risk management should be a holistic and dynamic process throughout the entire life cycle. However, the level of risk is usually determined only during the design stage mainly due to the fact that it is a time-consuming and costly process. This paper presents a simplified quantitative risk analysis method that can be used any time during the decades of a tunnel's lifetime and can estimate the changing risks on a continuous basis and thus uncover hidden safety threats. The presented method is a decision support system for tunnel managers designed to preserve or even increase tunnel safety. The CAPITA method is a deterministic scenario-oriented risk analysis approach for assessment of mortality risks in road tunnels in case of the most dangerous situation - a fire. It is implemented through an advanced risk analysis CAPITA SW. Both, the method as well as the resulting software were developed by the authors' team. Unlike existing analyzes requiring specialized microsimulation tools for traffic flow, smoke propagation and evacuation modeling, the CAPITA contains comprehensive database with the results of thousands of simulations performed in advance for various combinations of variables. This approach significantly simplifies the overall complexity and thus enhances the usability of the resulting risk analysis. Additionally, it provides the decision makers with holistic view by providing not only on the expected risk but also on the risk's sensitivity to different variables. This allows the tunnel manager or another decision maker to estimate the primary change of risk whenever traffic conditions in the tunnel change and to see the dependencies to particular input variables.

• 지질공학
• /
• 제24권3호
• /
• pp.343-351
• /
• 2014

터널 시공 중 막장 매핑은 터널의 위험도 판단과 향후 지보패턴 결정에 중요한 역할을 한다. 본 연구에서는 막장관찰기록지를 이용한 기존의 수기 매핑 방식을 탈피하여 모바일을 이용한 디지털 매핑 시스템을 제시하였다. 현장에서 디바이스를 기반으로 작성된 매핑 자료는 메인서버와 연동되어 자동으로 데이터베이스화가 되며 담당자 및 관련전문가들 사이에서 실시간 피드백이 가능하도록 구현하였다. 매핑의 정밀한 표현 방식 및 다량의 데이터 누적에 의한 속도 저하 문제는 Douglas-Peucker 알고리즘 등을 이용하여 해결하고자 하였다. 본 시스템은 향후 다양한 현장 검증 및 추가적인 기능 개선 등을 통해 완성도가 높아질 것으로 기대된다.

• Geomechanics and Engineering
• /
• 제15권2호
• /
• pp.745-754
• /
• 2018

In the analysis of the effects of rock tunnel blasting vibration on adjacent existing buildings, the model of simplified equivalent load produces higher calculation result of vibration, due to the lack of consideration of the millisecond delay effect. This paper, based on the static force equivalence principle of blasting load, proposes a new determination method of equivalent load of blasting vibration. The proposed method, based on the elastic-static force equivalence principle of stress wave, equals the blasting loads of several single blastholes in the same section of millisecond blasting to the triangle blasting load curve of the exploded equivalent elastic boundary surface. According to the attenuation law of stress wave, the attenuated equivalent triangle blasting load curve of the equivalent elastic boundary is applied on the tunnel excavation contour surface, obtaining the final applied equivalent load. Taking the millisecond delay time of different sections into account, the time-history curve of equivalent load of the whole section applied on the tunnel excavation contour surface can be obtained. Based on Sailing Tunnel with small spacing on Sanmenxia-Xichuan Expressway, an analysis on the blasting vibration response of the later and early stages of the tunnel construction is carried out through numerical simulation using the proposed equivalent load model considering millisecond delay effect and the simplified equivalent triangle load curve model respectively. The analysis of the numerical results comparing with the field monitoring ones shows that the calculation results obtained from the proposed equivalent load model are closer to the measured ones and more feasible.

• 한국터널지하공간학회 논문집
• /
• 제8권3호
• /
• pp.227-235
• /
• 2006

최근 터널에서 균열, 누수 등과 같은 변상이 많이 발생하고 있어 터널의 안정성에 큰 문제가 되고 있으며, 기존 터널의 효율적인 안전 및 유지관리를 위해서는 터널 콘크리트 라이닝의 역학적 건전도를 평가하는 것이 필수적이라 할 수 있다. 본 연구에서 사용된 콘크리트 라이닝 모형 시험체는 실제 도로터널의 축소모형으로서 단일라이닝으로 구성되어 있으며, 하중조건, 라이닝 두께, 천단부 배면 공동 유무 및 강섬유 혼입률 등과 같은 라이닝 조건에 따른 모형실험을 실시하였다. 이러한 모형실험으로부터 터널 콘크리트 라이닝의 균열발생하중과 파괴하중, 처짐과 균열발생 형태를 조사하여 터널 콘크리트 라이닝의 변형 및 역학적 특성을 평가하였다.

• 대한토목학회논문집
• /
• 제35권2호
• /
• pp.387-396
• /
• 2015

기존 쉴드터널은 일률적으로 비배수 개념이 적용되고 있지만 시공 및 운영 과정에서 고질적인 누수 발생이 문제가 되고 있으며, 쉴드 세그먼트의 경우 토압 및 수압까지 고려한 설계로 인해 단면이 과다하게 증가되고 세그먼트 재료비 상승을 유발하고 있다. 이러한 문제점들을 개선하기 위해 쉴드터널에 배수 개념을 적용한 부분배수형 쉴드터널에 대한 연구가 진행되고 있다. 본 연구에서는 부분배수 쉴드터널의 적용 가능성을 평가하기 위해 축소모형실험을 통해 배수 및 비배수 조건에서의 토압 및 수압 변화를 측정하였다. 실험 결과를 통해 도출된 수압 저감 효과를 바탕으로 지하수위 아래 위치한 쉴드터널 설계사례에 적용하여 구조 안정성을 검토하였고, 수압 저감을 통한 세그먼트 단면 축소 효과에 대해 평가하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.53-54
• /
• 2006

The main purpose of tunnel ventilation system is to maintain CO pollutant and VI (visibility index) under an adequate level to provide drivers with safe driving condition. Moreover, it is necessary to minimize power consumption used to operate ventilation system. To achieve the objectives, the control algorithm used in this research is reinforcement teaming (RL) method. RL is a goal-directed teaming of a mapping from situations to actions. The goal of RL is to maximize a reward which is an evaluative feedback from the environment. Constructing the reward of the tunnel ventilation system, two objectives listed above are included. RL algorithm based on actor-critic architecture and natural gradient method is adopted to the system. Also, the recursive least-squares (RLS) is employed to the learning process to improve the efficiency of the use of data. The simulation results performed with real data collected from existing tunnel are provided in this paper. It is confirmed that with the suggested controller, the pollutant level inside the tunnel was well maintained under allowable limit and the performance of energy consumption was improved compared to conventional control scheme.

• 한국방재학회 논문집
• /
• 제9권5호
• /
• pp.69-78
• /
• 2009

발파 시 폭약의 폭발로 발생되는 발파진동은 발파지역 인근의 기존 구조물에 피해를 유발시킬 수도 있으며, 이러한 경우 구조물의 안정성 검토를 필요로 한다. 본 연구에서는 기설 터널의 상부 지층 발파 시 터널의 안정성을 구조물의 허용진동속도가 아닌 콘크리트 구조설계기준에 제시된 구조물의 허용응력을 기준으로 수치해석 프로그램인 $FLAC^{2D}$를 이용하여 구조물의 발파 진동이 터널 지보재인 콘크리트 라이닝의 응력 및 록볼트의 축력에 미치는 영향을 검토하였다. 터널에 근접하여 발파가 이루어지는 경우에는 발파진동속도와 콘크리트 라이닝의 휨 압축응력과 전단응력, 록볼트의 축력은 급격히 증가하는 것으로 나타났다.