• Tunnel and Underground Space
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• v.12 no.4
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• pp.259-267
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• 2002

Recently, Umbrella Arch Method(UAM) is commonly used in order to enhance the stability of tunnel itself and stabilize the adjacent surface structure. But quantitative estimation of reinforcement effect is needed because UAM is designed and constructed only on the basis of empirical experience. By using 3-dimensional finite element method, parametric study is performed for elastic modulus of ground and overburden, and reinforcement effect is analyzed quantitatively. From the results, surface settlement decreases about 9%∼27% in soil tunnel, about 4%∼24% in weathered rock tunnel and 4%∼17% in soft rock tunnel when applied with UAM. The prediction equation for final surface settlement is suggested through regression analysis and the equation is expressed as exponential function which has variable Smax, unknown coefficient i and k.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.3
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• pp.229-242
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• 2009

Numerical analysis has been performed to estimate maximum settlement, maximum horizontal displacement and total settlement volume at the ground surface due to tunnel excavation varying ground condition, tunnel depth and diameter, and construction condition (volume loss at excavation face). The maximum surface settlement from the numerical analysis has been compared with the maximum settlement at tunnel crown considering ground condition, tunnel depth and diameter, and construction condition, and it has been also compared with the maximum horizontal displacement. In addition, the volume loss ($V_L$) at tunnel excavation face has been compared with the total surface settlement volume ($V_s$) with the variation of ground condition, tunnel depth, and tunnel diameter. The results from the numerical analysis have been compared with field measurements to confirm the applicability and validity of the results and by this comparison it is believed that the numerical results in this study can be utilized practically in analyzing the ground movements due to tunnel excavation.

• Journal of the Korean Geotechnical Society
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• v.18 no.6
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• pp.117-127
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• 2002

A deterministic approach of slope stability, which is generally corresponding to the model of a simple non-linear function for slopes, is problematic in that it does not account the versatile characteristics of ground layers in an effective way. To resolve this problem, this study proposes a new way of analyzing slope stability, so-called “genetic algorithm method, ” so as to reflect some particular conditions pertaining to the grounds under concern. Similarities and differences in slope stability that may exist between homogeneous and multiple ground layers are examined in a competitive manner, Overall, though similarities deemed a little bit salient, the algorithm method turned out to be very applicable to estimating the validity of slope stability. Furthermore, an additional effort to consider long-standing sequential and dynamic changes in both the amount of rainfall and the underground water level is made in order to improve the results.

• Spatial Information Research
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• v.8 no.2
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• pp.301-315
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• 2000

Every, year, a great amount of site investigation data is collected on site to obtain sufficient conditions. Investigation of subsurface conditions is prerequisite to the design and construction of structures and also provides information on ground properties such as geologic formation and types of soil. This data set, which portrays real representation of ground conditions over the existing geologic and soil maps, could be further utilized for analyzing the subsurface conditions. It is therefore necessary to develope a subsurface exploration analysis system which is able to extract the valuable information from the heterogeneous, non-normalized subsurface investigation data. This paper presents the overall design scheme and implementation on a subsurface exploration analysis system. The analysis system employs one of data set such as bore-hole data. The clustering technique employed in the developed system makes a large volume of bore-hole data into several groups in terms of ground formation and geographical vicinity. As a result of clustering, each group or cluster consists of bore-hole data with similar characteristics of subsurface and geographical vicinity. In addition, each clustered data is displayed on digital topographical map with different color so that the analysis of site investigation data could be performed in more sensible ways.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4C
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• pp.109-116
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• 2011

In this study, dynamic response of a vertical shaft subjected to seismic loads was evaluated by three-dimensional Finite Element (FE) approach. The emphasis was on quantifying the ground conditions, input motions and direction of motions. A series of parametric analyses were carried out. From the results of FE analysis, more than 1.7 times increase in shear force and bending moment is obtained when the stiff layer was thinker than the soft layer. And all of the maximum values were occurred near the interface between the soil layers. The dynamic behavior of vertical shaft was significantly influenced by the different frequencies of the input motion, and normalized acceleration of surrounding soil was 3 times larger than vertical shaft.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.2
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• pp.37-46
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• 2000

본 논문에서는 부지특성을 고려한 설계지반운동의 산정방법을 연구하였으며 그 해석결과를 지반 구조물의 내진설계에 적용하는 방법을 제안하였다 지진응답 해석시 사용되는 설계응답스펙트럼과 설계시간 이력등의 입력운동의 통제점 위치가 지반구조물 내진설동 지층내 암반운동 그리고 노두운동을 사용하는 방법으로 나눌 수 있고 이에 따라 작용 설계지진운동이 변화하므로 지반구조물의 경계조건에 적합한 방법을 사용하여야 한다.

• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.21-34
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• 2021

In this study, to solve a problem that cannot consider the contribution effect of each layers when the apparent earth pressure in homogeneous ground is applied to multi-layered ground, the measured earth pressures at World were investigated and analyzed. It has been confirmed that the apparent earth pressure in mulit-layered ground is different from single ground and that the extra layer's contribution to the earth pressure cannot be considered. The conventional method of calculating the apparent earth pressure for single ground was extended to mulit-layered ground, and proposed and verified the applicable method for both single and mulit-layered ground. The proposed methods predicted the earth pressure closer to the measurements at the excavation depth of 0.1Z/H or below, and the prediction reliability was evaluated to be better than the conventional method. Among the proposed methods, the method of considering the area ratio of the active failure has a geotechnical validity and predicts the most similar results to the actual earth pressure. To confirm the applicability of the proposed methods, it was presented by comparing and analyzing the results of the proposed methods with the conventional method for the actual case.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.253-256
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• 2008

지하 토사 조건 및 지질 구조는 지진 시 지반 운동의 증폭에 관련된 부지 효과에 매우 큰 영향을 미친다. 본 연구에서는 국내 홍성 지역을 대상으로 시추 조사와 현장 탄성파 시험을 포함한 현장 조사 및 지표 부근지질 정보를 획득하기 위한 부지 답사를 통해 부지 효과를 확인하였다. 홍성 지역은 1978년 계기 지진이 발생한 지역으로서 기반암 상부에 최대 약 50 m 두께의 풍화대 지층이 분포한다. 연구 대상 지역의 공간 지층 구조를 효율적으로 확인하기 위하여 지리정보시스템(GIS) 기법 기반의 지반 정보 시스템(GTIS)의 구축하였으며, 홍성 지역은 분지는 얕고 넓은 형상임을 확인하였다. 홍성 지역의 부지 지진 응답을 평가하기 위하여 대표 단면에 대한 2차원 유한 요소 해석을 수행하였다. 도출된 지진 응답으로부터 지반 운동이 기반암 상부 토사층을 통해 전단파가 전파되면서 증폭되고 분지 형상에 따른 전단파의 상호 작용으로 생성된 표면파로 인해 분지 경계 부근 진동 지속 시간이 증가됨을 확인하였다. 뿐만 아니라, 분지 내의 선정된 토사 부지들에 대해서 추가적인 1차원 유한 요소 지진 응답 해석을 수행하였으며, 본 연구 대상 분지가 매우 얕고 넓음에 따라 분지 경계 부근을 제외하고는 분지 내 대부분의 위치에서 2차원 지진 응답과 유사한 결과를 보였다.

• Journal of the Korean Association of Geographic Information Studies
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• v.10 no.4
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• pp.142-152
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• 2007

Geotechnical information database, foundation of underground geographic information system in 2nd NGIS plan, had been developing by Ministry of Construction and Transportation since 2000. This database contains not only soil condition, such as depth, type and color of layer, and ground water level, but also engineering properties used for foundation design and construction, for instance, standard penetration test, compression test. But, it is difficult to apply this database for analyzing and designing geotechnical works, because report document is only offered. In this paper, we have developed web-based geospatial information system for the effective uses. First, underground cross-section model is generated by location, layer, and engineering properties of geotechnical information database at the realtime process. Second, earth volume, bearing capacity, and settlement is calculated and potentials of soft ground, liquefaction are evaluated through pre-defined empirical formula. This process is operated by web-based client. We wish to strengthen the application capacity through this system in construction planning and design works.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2001.11a
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• pp.61-69
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• 2001