• 터널과지하공간
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• 제26권6호
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• pp.475-483
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• 2016

지하공동 굴착현장에서 관찰되는 절리분포 양상에 대한 자료를 기반으로 굴착과정에서 형성될 수 있는 사면체 블록의 형상, 규모 및 붕락 가능성을 절리 영속성을 고려하여 예측하는 수치해석 기법을 개발하였다. 절리 영속성 분석결과를 이용하여 절리면의 확장성에 따른 개착면에서의 표출정도 및 블록형성 가능성 해석을 수행하는 기능을 고안하여 기존에 개발된 결정론적 3차원 블록해석모델에 접목시켰다. 개선된 수치해석모델의 신뢰성을 고찰하기 위하여 실제 블록 붕락이 발생된 굴착현장에 대한 해석을 수행하였다. 조사된 절리분포 양상에 의거하여 대표 방향성을 설정하고 잠재적 블록 형성을 분석하여 붕락된 블록 형상에 부합된 해석 결과를 도출하였으며, 이에 근거하여 굴착과정에서의 붕락 진행 미캐니즘을 블록형상을 고려하여 고찰하였다.

• 한국터널지하공간학회 논문집
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• 제12권2호
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• pp.117-127
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• 2010

대부분의 지하구조물들은 불포화 지반에 건설되어있는 경우가 많으므로, 본 논문에서는 불포화토의 겉보기 점착력이 지반 굴착시 거동에 미치는 영향에 관하여 연구하였다. 이를 위해 압력판 추출시험, 불포화 삼축압축시험, Trap-door 시험을 수행하여 다양한 범위의 겉보기 점착력에서 지반의 거동이 어떻게 변화하는지 관찰하였다. 그 결과 완전 포화와 완전 건조 상태일 때는 지반이 거의 같은 거동을 보이고, 불포화 상태일 때는 함수비의 증가에 따라 그 거동이 매우 달라짐을 알 수 있었다. 이를 통해 겉보기 점착력이 지하 구조물 굴착 시 매우 중요한 역할을 한다는 것을 알 수 있었다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.344-351
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• 2005

In this paper, a reliability-groundwater flow program is developed by coupling the 2-D finite element numerical groundwater flow program with first and second order reliability program. From the parametric study of hydraulic conductivity of soil layers, the increase of both mean and variance of hydraulic conductivity results in the increase of probability of exceeding the threshold hydraulic head. The probability of failure was more sensitive to parameters of weathered granitic soil and rock located at the middle and bottom of the excavation than those at the other locations. It can be recommended from this study that the reliability method, which can include the uncertainty of soil parameters, should be performed together with the deterministic analysis to compensate the weakness of the latter analysis for the groundwater flow problem of underground excavations.

• 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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.65-84
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• 2002

The Observational Method proposed by Terzaghi can be applied for the safe and economic construction projects where the exact prediction of the behavior of the structures is difficult as in the underground excavation. The method consists of measuring lateral displacement, ground settlement and axial force of supports in the earlier stage of the construction and back analysis technique to find the best fit design parameters such as earth pressure coefficient, subgrade reaction etc, which will minimize the gap between calculated displacement and measured displacement. With the results, more reliable prediction of the later stage can be obtained. In this study, back analysis programs using the Direct Method, based on the Hill Climbing Method were made and evaluated, and to overcome the limits of the method, Genetic Algorithm(GA) was applied and tested for the actual construction cases.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1996년도 봄 학술발표회 논문집
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• pp.103-110
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• 1996

In this paper, behaviour of underground structural systems due to excavation and change of groundwater level is analyzed using finite elements. Equilibrium equations based on the effective pressure theory and transient flow equations considering the groundwater level are derived. Integration equations are derived using Galerkin's approximation and time dependent analysis is employed to compute groundwater level change and pore pressures. This computed pore pressures are employed in equilibrium equations and then finally displacements and stresses are computed. The developed program is applied to analyze the behaviour of ground excavation below the groundwater level. The program is also applied to multi-step excavation at the same model. The results show that the displacements of the ground surface are much influenced by the change of the groundwater level. Therefore, it is concluded that the change of the groundwater level should be considered in order to analyze the behaviour of the underground structural systems accurately

• 한국건축시공학회지
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• 제6권4호
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• pp.45-52
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• 2006

Top Down method is more widely used in downtown construction, recently. As underground construction constitutes a significant portion of the total construction cost and time in Top Down construction, it is important to develop a construction method to reduce the time required in underground works. The purpose of this study is to analyze load carrying capacity of Top Down prefounded columns on different excavation schedule. When several floors are excavated, the valid buckling length of prefounded column is increased and allowable buckling stress is decreased. The result shows that all columns are safe in buckling down to B3 story whether 2 or 3 stories are excavated. However, several columns are not safe from B4 story when 2 or 3 stories are excavated straightly. With these results, a process can be designed that the first three stories in the basement are excavated, and then excavate B4 story after placing concrete on B1 and B2 floor.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.49-83
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• 2005

ESCP Project showed an urban excavation case and introduced design method for case of Soil-Structure behavior in urban excavation. In this case, a retaining structures design to analysis the behavior of retaining wall and adjacent structures in urban excavations was applied by using a Elasto-plastic beam and limit Equilibrium analysis and soil-structure interaction analysis. Reliable design of earth retaining structures and the ground adjacent to braced wall in urban excavation are often difficult due to many variable factors. The ground settlement and the damage of adjacent structures in urban excavation has been an imprtant issue. Therefore, the stability of the adjacent structures must be secured with the excavation support and research on the protection of adjacent structure is necessary.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2008년도 춘계 학술논문 발표대회
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• pp.7-10
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• 2008

As the land price in the downtown area increases, buildings are becoming bigger, deeper and higher. Consequently, the importance of underground construction has increased. Although construction engineers make every effort to complete underground construction without any problem, construction failures like landslides and the collapse of a retaining wall occur because of the uncertainty of the soil conditions as well as the unexpected risks of excavation work. In order to prevent potential excavation accidents, it is essential to understand the causes and impacts of such accidents. However, there are only a few examples of construction failures, which show the economic impact on accidents during excavation because of the sensibility of the information. This paper presents two cases of excavation accidents, which were investigated by construction insurance company. The compensation for the accidents paid by the insurance company was compared with the estimated costs calculated based on the estimation method for excavation accidents proposed by our previous study. The comparison results showed that the estimate calculated by our method was much less than the actual compensation because the estimate solely focused on the construction costs whereas the compensation included other external factors.

• 한국터널지하공간학회 논문집
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• 제4권2호
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• pp.167-174
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• 2002

본 연구에서는 시공순서를 고려한 대단면 터널의 안정성 평가를 수치해석에 의해 수행하였다. 일반적으로 터널의 안정성은 최종 굴착 후의 안정성에 의해 판단하는 것이 보통이나, 본 연구에서는 굴착단계별 안정성을 비교·검토하였다. 해석결과를 종합하면, 터널의 안정성에는 별 문제가 없을 것으로 판단되며, 이곳을 시공할 때 계측을 철저히 하는 등의 각별한 주의가 요구된다. 또한, 굴착단계별 안정성을 비교한 결과, 우측 본선터널 상부 반단면 굴착시 (5 단계)의 안정성이 오히려 최종굴착 후의 안정성보다 취약한 것으로 나타났다.