• Journal of the Korean GEO-environmental Society
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• v.12 no.9
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• pp.5-11
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• 2011

Recently, large and deep excavations are increasing. The damage of adjacent structures due to excavation has steadily increased with increasing construction demand. Especially in urban development and poor conditions, the excavation adjacent to the subway structures has caused a lot of problems. This paper was reviewed that the underground excavation and reinforcement of the status process through a case study on the field. And stability analysis through the case study evaluates applicability for reasonable reinforcement method by numerical analysis. As a result, the strata distribution condition of all 16 sites consisted of landfill from the top and distributed in the order of deposits, weathered soils, weak rock from the bottom. Also, when proceeding the excavation adjacent to structures, the location of site and layer conditions have highly effect on the results of the construction. Therefore, this study was applied reinforcement method to protect damage by excavation. Displacement and settlement were within allowable criterion and hence, stability of structure was analyzed as safe.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4C
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• pp.153-162
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• 2009

This paper investigates the effects of excavation-induced ground movements on nearby structures, considering soil-structure interactions of different soil and structural characteristics. The response of four and two-story block structures, which are subjected to excavation-induced advancing ground movements, are investigated in different soil conditions using numerical analysis. The structures for numerical analysis are modelled to have cracks when the shear and tensile stress exceed the maximum shear and tensile strength. The response of four and two-story block structures are investigated with advancing ground movement phases and compared with the response of structures which are subjected to excavation-induced total ground movement. The response of structures is compared among others in terms of the magnitude and shape of deformations and cracks in structures for different structure and ground conditions. The results of the comparison provide a background for better understandings for controlling and minimizing building damage on nearby structures due to excavation-induced ground movements.

• Geotechnical Engineering
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• v.11 no.2
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• pp.79-98
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• 1995

In the present study an analytical modeling was carried out to predict mobilized shear strength at the interface between the nail and surrounding soils by carefully examining the behavior characteristics of nailed boil excavated walls. Based on the developed model of mobilized shear strength, the method of overall stability analysis of nailed -soil walls was also developed using the Morgentern -Price limit -equilibrium slice method. The developed analytical procedure could predict the behaviors of nailed -soil excavated walls during the successive excavation stages, at the final stage of construction and post -construction stages. To verify the validity of the developed model and method of stability analysis, mobilized tensile forces of nails and overal stability estimated by the developed procedure were compared with test measurements from three nailed -soil experimental walls having different soil conditions. The effect of seepage pressures inside the soil mass was considered in the developed procedure.

• Journal of the Korean GEO-environmental Society
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• v.22 no.11
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• pp.39-47
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• 2021

Tunneling is widely increased in rail-road construction due to the large portion of mountainous regions in Korea as well as the improving running performance of train. Tunneling under poor rock condition, shallow overburden, or existing fault zone has high risk for collapse. Therefore, this study presents the stability of tunnel under unfavorable geological conditions using finite element methods.

• Journal of the Korean Geotechnical Society
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• v.32 no.4
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• pp.29-39
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• 2016

This paper presents the results of 2D and 3D finite element simulations conducted to analyze the effects of excavation depth (H), excavation width (L), and ground condition on the behavior of anchored earth retaining wall in inclined ground layers. The results of numerical analyses are compared with those of the site instrumentation analyses. Based on the results obtained, it appeared that 2D numerical analysis tends to overestimate the horizontal displacement of retaining wall compared to the 3D numerical analysis. When the excavation depth is deeper than 20m, it is found that 2D and 3D numerical analysis results of excavation work in soil ground condition are more different from the results in rock ground condition. For an accurate 3D numerical analysis, applying 3D mesh which has an excavation width twice longer than excavation depth is recommended. Consequently, 3D numerical analysis may be able to offer significantly better predictions of movement than 2D analysis.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.282-286
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• 2009

1979년 준공된 수도권 광역상수도 1단계 시설은 상당한 노후화가 진행되었을 것으로 예상되며, 또한 향후 한강하류권 용수공급계획이 예정되어 있어 내부부식 및 관로손상부 개량의 시급성이 제기되었다. 이에 따라 직경 2,800${\sim}$800mm의 초대구경 도수관 53.9km의 개량을 위한 사업이 추진되었으며 시공성, 환경성, 경제성 등의 여러 항목에 대한 검토 결과 신개념 녹색공법인 비굴착식 건식일체형 공법이 최종 선정되었다. 그동안 기존관 개량공사에서 주로 사용되었던 굴착공법이 굴착에 따른 공기지연, 소음 분진 악취 등의 환경오염, 전구간 굴착에 따른 공사비 증가 등 많은 문제점을 안고 있는 것에 반해, 동사업에서 채택된 비굴착공법은 관로내에서 작업이 이루어지므로 공기단축, 환경오염 최소화에 따른 민원발생 최소화, 작업구만 굴착함에서 오는 공사비 절감 등 상대적으로 훨씬 우수한 것으로 평가된다. 동공법에 따르면 관내부 갱생공사는 '배수 및 잔류토사 제거'${\to}$'관내건조'${\to}$'표면처리'${\to}$'프라이머도장'${\to}$'본도장'의 순으로 진행된다. 일체형 장비에 의한 이와 같은 초대형관의 자동화시공은 세계에서 처음 적용되는 것이다.

• Explosives and Blasting
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• v.20 no.1
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• pp.25-34
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• 2002

일반적으로 도심지에서 터널 시공을 위한 암반굴착 작업은 주변 보안물건에 대해 직접적인 피해를 유발시킬 수 있는 공해요소인 진동을 허용기준값 이하로 제어할 수 있으면서 상대적으로 시공성과 경제성이 뛰어난 공법으로 수행되어야 한다. 본 사례에서는 각내의 대표적인 문화시설인 예술의 전당 하부를 통과하는 우면산 터널 공사현장에서 암반굴착공법으로 고려한 TTM 장비를 이용한 기계굴착, 플라즈마 공법, 유압장비를 이용한 할암공법, 겔파쇄 공법, 미진동파쇄기를 이용한 공법, 진동제어발파공법에 대한 현장 적용성을 시험시공 등을 통해 평가한 내용과 결과를 제시하였다. 비록 각 도심지 터널의 현장 상황이나 주변 여건에 따라 이 현장에서의 시험시공 내용이나 적용 결과를 그대로 적용할 수는 없겠지만, 진동제어 암반굴착 공법에 대한 시험시공이나 선정 과정에 이 사례연구가 개략적인 참고자료로 활용될 수 있을 것이다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5D
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• pp.499-505
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• 2012

As the excavation depths during excavation works in urban sites are getting deeper and bigger, It is necessary to study for the improvements to solve the problems in the excavation processes. This research deals with the excavation method that can not only minimize the effect on the surrounding constructions, but also shorten the construction period of the excavation work. For this research, there have been an extensive literature review of the bibliographic data about Slurry Wall Method, which is recognized around the world, and the analysis of the major problems in the existing ineffective construction step. These efforts led to the technical improvements. Accordingly, a new construction method applied with the new technical factors has been suggested, and it was possible to compare Slurry Wall Method with the construction method and analyze them on the base of the examples using the suggested method. This new method decreased the excavation period by 15 days. It took only 33days to finish the excavation work, as compared to 48 days that can be seen on the pre-modification schedule. Furthermore, the suggested method in this research is safer, more economically feasible, and better for the environment than Slurry Wall Method. It will contribute to shortening the construction period of Slurry Wall Method in the end.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.622-640
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• 2009

원유 비축기지 저장공동과 같이 상하로 긴 형상의 대규모 공동에서 횡방향의 지압이 과도하게 작용하면 천정부의 응력집중과 측벽의 암반 변위가 과도하게 발생하여 저장공동의 불안정 요인이 된다. 특히 지압의 절대 크기가 암반 강도의 일정 비율 이상이 되면 응력 집중에 의한 암반의 취성 파괴를 유발하고, 이러한 현상은 터널 굴착 시 발생하는 파괴음(popping)과, 굴착면에 평행한 형태로 암편이 탈락하는 취성파괴(spalling) 현상을 동반한다. 이 글에서는 대규모 지하저장공동 굴착시 실제 발생한 과지압으로 인한 문제 사례에 대해 소개한다. 저장공동 굴착시 관찰된 암편 및 숏크리트 탈락과 균열 발생 현상을 관찰하고 암반 계측결과 분석을 통해 과지압의 현상을 진단하였다. 과지압 구간의 현재 상태 및 원안 설계안에 대해 연속체 및 불연속체 안정성 해석을 실시하여 문제의 심각성을 평가하였다. 이를 통해 굴착 형상 변경 및 특수 보강 방안을 제안하였으며 제안된 안의 보강효과에 대한 수치해석 평가 결과를 재검토 하였다. 이들 결과를 종합하여 과지압구간 보강안을 도출하였으며 상시 안정성 감시 대책으로 현장 암반의 미소파괴음 계측 방안을 제시하였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.4
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• pp.499-511
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• 2015

A room-and-pillar underground structure is characterized by its grid-type array of galleries. As a result, its construction and economical efficiency can be governed by excavation sequence of galleries. Therefore, this study aims to study the optimum excavation scheme of a room-and-pillar underground structure by considering its various design factors such as ground conditions and excavation sequences. Drill-and-blast method is assumed as a excavation method for a room-and-pillar underground structure. In addition, two kinds of excavation patterns corresponding to a concurrent and a sequential excavation patterns are considered in this study. For the assumed conditions, the structural stability and the construction efficiency based on the number of faces and the travel distance of a jumbo drilling machine are analyzed for the two excavation patterns. Even though the two kinds of excavation patterns show almost the same structural stability as each other, the concurrent excavation pattern is relatively preferable to the sequential excavation pattern in terms of the number of faces in operation and travel distance of a drilling jumbo.