• Tunnel and Underground Space
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• v.31 no.4
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• pp.211-220
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• 2021

Tunnel collapse often occurs during deep underground tunneling (> 40 m depth) in South Korea. Natural cavities as well as water supply pipes, sewer pipes, electric power cables, artificial cavities created by subway construction are complexly distributed in the artificial ground in the shallow depths of the urban area. For deep tunnel excavation, it is necessary to understand the properties of the ground which is characterized by porous elements and various geological structures, and their influence on the stability of the ground. This study analyzed geological factors for risk assessment in deep excavation in South Korea based on domestic and overseas case study. As a result, a total of 7 categories and 38 factors were derived. Factors with high weights were fault and fault clay, differential stress, rock type, groundwater and mud inrush, uniaxial compressive strength, cross-sectional area of tunnel, overburden thickness, karst and valley terrain, fold, limestone alternation, fluctuation of groundwater table, tunnel depth, dyke, RQD, joint characteristics, anisotropy, rockburst and so forth.

• Journal of the Korean Geotechnical Society
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• v.23 no.8
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• pp.87-95
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• 2007

This study analyzed ground settlement and ground stress depending on tunnel excavation and the ground reinforcing grouting methods for double line road tunnel through deep weathered zone. Diameter of double line road tunnel was approximately 12m and umbrella arch method and side wall reinforcing grouting were applied. The ring-cut split excavation method and CD-cut excavation method for excavation method were applied. Analyses of failure rate and vertical stress ratio show that the tunnel for which the height of the cover (H) was higher than four times the diameter, can be considered a deep tunnel. Comparisons of various excavation and ground reinforcement methods showed that CD-cut method results in lower surface and crown settlement, and lower failure rate than that obtained by Ring-cut split method. In addition, the side wall reinforcing grouting resulted in reduction of tunnel displacement and settlement.

• Explosives and Blasting
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• v.39 no.2
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• pp.15-26
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• 2021

Domestic electronic detonators are used widely in many quarry and construction sites since its launch at 2013. In the case of SOC projects conducted in the city, most of them are designed in high-depth to reduce complaints. The high-depth excavation needs a long construction period and huge cost for building shaft and ventilation hole. Mechanical excavation method is applied when safety things are located nearby the site. Solidity of rock and machine's performance affect on the method's efficiency. So as the efficiency is getting lower, the construction period is extended, and the cost is increases as well. This case study is about changing the machine excavation method to the blasting method which is electronic detonator applied at the shaft construction site in the city. This is an example of using electronic detonators on the construction site in reducing blast-noise and vibration while meeting environmental regulatory standards.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03a
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• pp.343-365
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• 2004

대도시 인구증가와 경제성장으로 인하여 제한된 공간을 효율적으로 사용하기 위한 노력이 계속되어 왔다. 도로의 확충, 지하철 건설, 대형구조물 건설 등 산업인프라의 확충과 더불어 지반굴착이 차지하는 비중이 점점 증대되고 있다. 또한 지상공간에 대한 제한으로 지하공간 활용에 대한 관심이 증대되었고 이에 따라 최근 대심도 굴착사례가 증가되고 있는 실정이다.(중략)

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.605-621
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• 2009

대심도 암반을 굴착함에 따라 암석강도 및 암반응력 등의 특성에 따라 Rockburst 등과 같은 취성파괴 및 Squeezing 등과 거동을 나타낼 수 있으며, 이러한 대심도 암반거동은 터널 및 지하 공동 시공중 위험요소로 작용하여 안정성에 심각한 영향을 줄 수 있다. 따라서 대심도 암반구간에 터널을 건설하는 경우에는 합리적인 설계 및 시공을 달성하기 위해서는 대심도 암반에 대한 지질 및 암반특성을 정확히 이해하는 것이 필요하며, 대심도 암반특성에 적합한 보강 및 시공대책을 수립하도록 하여야 한다. 본 고에서는 대심도 암반구간에서의 위험도 평가 및 터널 설계사례를 검토하여, 대심도 암반특성을 고려한 터널구조물 설계시 합리적인 방안을 도출하고자 하였다.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2005.03a
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• pp.121-134
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• 2005

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.93-105
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• 2001

해성토층(풍화토 및 모래질 충적토가 암반 위에 쌓인) 위에 준설매립된 수도권 해안매립지역에서 원형의 대심도 굴착공사로 인하여 발생하는 지중연속벽의 수평변위에 대한 현장계측을 중심으로 연구를 수행하였다. 현장측정으로는 지중연속벽의 8방향에서 벽체수평변위와 철근응력, 토압, 간극수압 등이 측정되었고, 정확한 측정결과를 얻기 위하여 합리적인 해석 및 보정방법이 연구되었다. 현장측정결과 굴착시공단계에 따라서 벽체수평변위가 증가하였으며, 일정깊이에 존재하는 점토층을 굴착함으로써 간극수압의 급격한 변화가 측정되었다. 한편, 굴착전후의 구속압감소에 따른 지반물성치의 변화를 정리하였다. 굴착전후의 탄성계수는 일정깊이까지 상당한 정도로 감소됨을 알 수 있었고 굴착전후 여러 가지 시험방법에 따른 탄성계수의 차이들을 비교하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1307-1316
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• 2009

In this case, powerfulness quorum of destruction side which we have expected are supposed general limit value for rock floor when retaining of earth on the section of rock floor in the urban area. For digging in the urban area, there are a lot of dislocations to be disadvantage for safety of digging ants. The displacement of the pondside didn't converged with the phase of the excavation. Also, the speed of displacement got higher than the percentages of risk in the construction. So, we put into operation Face mapping for checking special quality of dislocations which appear on the digging ants. This results were used to decide a destruction in the case of the final excavation by analyzing with other results. It was possible to know the unstable distribution of a fault line in Face Mapping and to get powerful lens of a surface of discontinuity by tests indoors and outdoors. The results were also used to make a solution. Therefore, It's a successful example using the Partial TopDown for stable digging. And it is important that Face Mapping have to be practiced for solving the uncertainty of ground organization when digging design in the urban city.

• Journal of the Korean GEO-environmental Society
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• v.6 no.4
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• pp.47-58
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• 2005

Development of underground space is conducted for various useful facility and underground structures and deep excavation technology for reclaimed area has been researched and developed. The seepage flow and behavior of phreatic line in reclaimed area was predominated by transient flow caused by tidal action. Also the soil-water characteristic relation is most important factor for transient flow analysis, therefore the research about the soil-water characteristic is strongly required. In this paper, laboratory tests (pressure cell, desiccator, and tensiometer test) and theoretical analysis were performed to investigate the soil-water characteristic such as air-entry value, metric suction, and residual water content. And the feasibility of prediction method for soil-water characteristic are presented by transient seepage analysis and comparison between analysis results and in-situ measured seepage flux in LNG TK-00 storage tank. Based on the result of laboratory and theoretical analysis, Fredlund and Xing's method provide to work out well for reclaimed ground soils. Also, the transient analysis result is more reasonable and effective for design of deep excavation work in coastal and reclaimed ground.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.107-115
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• 2001

해성토층 위에 준설매립된 수도권 해안매립지역에서 원형의 대심도 굴착공사로 인하여 발생하는 지중연속벽의 수평변위를 예측하기 위하여 수치해석을 수행하였고, 이러한 수치해석결과와 현장측정값을 비교하여 각각의 수치해석방법의 적용성을 평가하였다. 수치해석법으로는 지반반력해석, 선형 유한요소법 그리고 비선형 유한요소법이 수행되었다. 각각의 방법들에서는 미소변형률에서의 지반거동특성인 비선형성과 굴착으로 인한 구속압감소효과를 고려한 경우와 고려하지 않은 경우에 대하여 수치해석을 수행하여 각각 그 결과들을 비교.분석하였다. 이러한 분석결과 미소변형률에서의 비선형성과 굴착으로 인한 구속압감소 효과를 고려한 비선형 유한요소해석법이 가장 정확하게 수평변위를 예측할 수 있는 방법임을 알 수 있었다.