• International Journal of Railway
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• 제6권2호
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• pp.69-77
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• 2013

In this study, numerical analysis and model experiments were conducted to analyze behavioral characteristics acting on the track roadbed with excavation through steel pipe injection, a non-exclusive method of crossing construction under railroad as primary target. In model experiments that simulate injection excavation behaviors with an increase in the depth of soil cover, the upper displacement was measured by construction of the first and the second pipes in order to predict actual behaviors, and the behavior characteristics were verified through numerical analysis. The investigation results showed that surface displacement was smaller under the condition of higher soil cover. In the case of injecting two pipes, when the first pipe was injected, deformation of the surface increased linearly in both settlement and uplift experiments. However, when the second pipe was injected, the amount of change was found to be very small due to the relaxation and plastic zones around the first pipe. In addition, the results of numerical analysis on the same cross section with the model experiment found that the results of investigation into settlement ratio and volume loss were in very good agreement with those obtained by the model experiment.

• Geomechanics and Engineering
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• 제37권1호
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• pp.31-48
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• 2024

To stabilize the excavations in urban area, soil anchorage is among the very common methods in geotechnical engineering. A more efficient deformation analysis can potentially lead to cost-effective and safer designs. To this end, a total of 116 three-dimensional (3D) finite element (FE) models of a deep excavation supported by tie-back wall system were analyzed in this study. An initial validation was conducted through examination of the results against the Texas A&M excavation cases. After the validation step, an extensive parametric study was carried out to cover significant design parameters of tie-back wall system in deep excavations. The numerical results indicated that the maximum horizontal displacement values of the wall (δ_hm) and maximum surface settlement (δ_vm) increase by an increase in the value of ground anchors inclination relative to the horizon. Additionally, a change in the wall embedment depth was found to be contributing more to δ_vm than to δ_hm. Based on the 3D FE analysis results, two simple equations are proposed to estimate excavation deformations for different scenarios in which the geometric configuration parameters are taken into account. The model proposed in this study can help the engineers to have a better understanding of the behavior of such systems.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1991년도 추계학술발표회 논문집 지반공학에서의 컴퓨터 활용 COMPUTER UTILIZATION IN GEOTECHNICAL ENGINEERING
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• pp.289-311
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• 1991

Analysis of supported excavation system by Elasto-Plastic Isoparametric Finite Element Method and Elasto-Plastic Beam Method have been conducted for the simulation of stepwise underground excavation. Conventional methods, fixed Supported Beam and Spring Supported Beam method, also have been examined and compared with the results of elasto-plastic beam method and field data. Except unavoidable result of upward ground settlement near the top of retaining wall and relatively high bending moment of wall at each excavation level, satisfactory results have been derived using elasto-plastic isopara metric finite element method. The results from elasto-plastic beam analysis program, developed by the author, are proved to be fit field data in acceptable variance as shown in the paper. Displacement and bending moment, of the wall by conventional methods, both fixed supported beam and spring supported beam, are always underestimated than field data, and attention must be given that the diffence increases with deeper excavation depth and lower horizontal subgrade reaction of the ground.

• 한국지반공학회논문집
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• 제33권10호
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• pp.33-47
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• 2017

지주식 흙막이 공법(Inclined Earth Retaining Wall; 이하 IER)은 지반 조건과 상재하중 등의 영향에 따라 다르지만 일반적으로 6.0~7.0m의 굴착 심도에서 자립이 가능하다. 하지만 더 깊은 심도의 굴착과 이에 따른 안정성을 확보하기 위해서 다른 공법과 병행하여 적용 할 필요가 있다. 따라서 본 연구에서는 IER에 소일네일링 공법을 적용한 복합형 IER의 안정성을 확인하고 효율적인 설치방법을 제안하고자 실내모형실험과 3차원 유한요소해석을 실시하였다. 실내 모형실험 결과 소일네일을 설치하였을 때가 설치하지 않았을 때와 비교하여 수평변위가 약 92% 감소하는 것으로 분석되었고, 3차원 유한요소해석 결과 소일네일 간격은 수평방향${\times}$수직방향 간격이 $1.5m{\times}0.75m$이고, 길이는 굴착 심도의 86%일 때 경제성과 안정성이 최적인 결과가 나타나는 것으로 분석되었다. 또한, IER의 변위가 크게 증가하는 굴착 심도 이전의 굴착 단계에 소일네일을 설치하였을 때 최대 1.71배 더 굴착이 가능한 것으로 분석되었다.

• 한국지반신소재학회논문집
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• 제14권4호
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• pp.23-33
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• 2015

소단은 굴착 후 지지구조물이 설치되기 전 벽체의 강성과 더불어 가설벽체의 안정성을 좌우하는 역할을 한다. 특히 굴착지반이 느슨하거나 연약한 경우 소단의 역할은 매우 중요하다. 본 연구에서는 소단을 이용한 도심지 버팀굴착현장의 계측결과와 수치해석을 사용하여 가설벽체의 최대수평변위에 미치는 소단의 규모(폭과 경사) 및 굴착깊이, 지반물성의 영향을 분석하였다. 계측결과 소단 폭이 짧아질수록 벽체의 수평변위는 증가하는 경향을 보였다. 수치해석 결과 소단의 경사가 급해질수록, 소단폭이 짧아질수록 최대수평변위량은 크게 나타나 소단이 벽체의 변위를 억제하는데 효과가 있음을 알 수 있었다. 또한 굴착심도가 깊어질수록 소단폭과 경사의 영향을 크게 받는 것으로 나타났다. 동일한 소단 조건에서 지반물성이 높을수록 벽체의 최대수평변위를 억제하는 것으로 나타났다.

• 터널과지하공간
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• 제14권4호
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• pp.295-303
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• 2004

연약층과 견고한 암반층이 습곡형태로 혼재된 지질조건의 지하 심부 채굴 현장을 대상으로, 심부 급경사 연약층의 단계적 굴착 진행에 따른 갱도 및 주변 암반의 거동 양상을 전산해석과 현장계측을 통하여 비교 분석하였다. 전산해석에서는 Hoek ＆ Brown의 경험적 파괴기준 및 변형률연화모델을 적용한 탄소성 해석 기법을 이용하였다. 현장계측에서는 유압캡슐, 지중변위계, 내공변위계를 갱도 및 주변 암반에 설치하여 응력과 변위를 계측하였다. 경험적 파괴조건 및 변형률연화모델을 이용한 탄소성 해석은, 현장 지질조건 및 채굴과정의 복잡함에도 불구하고 현장계측결과와 유사한 양상을 보여주어 타당성을 검증할 수 있었다. 이러한 전산해석 및 현장계측의 비교를 통해 지하 굴착 갱도의 변형 거동 과정을 예측하고 이후의 굴착 및 지보보강 설계의 지침을 제공할 수 있을 것이다.

• Geomechanics and Engineering
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• 제9권4호
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• pp.513-530
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• 2015

Commonly, the base stability of sheeted excavation pits against seepage failure by heave is evaluated by using two-dimensional groundwater flow models and Terzaghi's failure criterion. The objective of the present study is to investigate the effect of three-dimensional groundwater flow on the heave for sheeted excavation pits with various dimensions. For this purpose, the steady-state groundwater flow analyses are performed by using the finite element program ABAQUS 6.12. It has been shown that, in homogeneous soils depending on the ratio of half of excavation width to embedment depth b/D, the ratio of safety factor obtained from 3D analyses to that obtained from 2D analyses $FS_{(3D)}/FS_{(2D)}$ can reach up to 1.56 and 1.34 for square and circular shaped excavations, respectively. As failure body, both an infinitesimal soil column adjacent to the wall (Baumgart & Davidenkoff's criterion) and a three-dimensional failure body with the width suggested by Terzaghi for two-dimensional cases are used. It has been shown that the ratio of $FS_{(Terzaghi)}/FS_{(Davidenkoff)}$ varies between 0.75 and 0.94 depending on the ratio of b/D. Additionally, the effects of model size, the shape of excavation pit and anisotropic permeability on the heave are studied. Finally, the problem is investigated for excavation pits in stratified soils, and important points are emphasized.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.643-650
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• 2009

The necessary consequence by the rapid economic growth in large-scale urban excavation is increasing. If the site is the congested in downtown, the scale of excavation will get the large-scale and the extreme depth. We have achieved a high level technology internationally by the design and construction of underground excavation since 1980's. But the accidents during excavation are frequently occurring. So, this demage instigates the human life loss as well as economical loss. The recent accident is come about the damage for public facilities such as the railroad, subway and etc. in addition to the loss of life and property. For these reasons, the recent accident is being caused the damage of copious social overhead capital. The reasons of collapse during excavation can be classified roughly into the administrative part(sanction, permission), the investigation and design, the construction and management and etc. In this study the close check for the cases of the recent collapse is performed and the improvement course for the prevention of collapse is found.

• Geomechanics and Engineering
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• 제19권3호
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• pp.283-293
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• 2019

Evaluating the stability of the excavation face of the cross-river shield tunnel with good accuracy is considered as a nonlinear and multivariable complex issue. Understanding the stability evaluation method of the shield tunnel excavation face is vital to operate and control the shield machine during shield tunneling. Considering the instability mechanism of the excavation face of the cross-river shield and the characteristics of this engineering, seven evaluation indexes of the stability of the excavation face were selected, i.e., the over-span ratio, buried depth of the tunnel, groundwater condition, soil permeability, internal friction angle, soil cohesion and advancing speed. The weight of each evaluation index was obtained by using the analytic hierarchy process and the entropy weight method. The evaluation model of the cross-river shield construction excavation face stability is established based on the idea point method. The feasibility of the evaluation model was verified by the engineering application in a cross-river shield tunnel project in China. Results obtained via the evaluation model are in good agreement with the actual construction situation. The proposed evaluation method is demonstrated as a promising and innovative method for the stability evaluation and safety construction of the cross-river shield tunnel engineerings.

• 드라이브 ㆍ 컨트롤
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• 제18권2호
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• pp.20-31
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• 2021

An excavator is a construction machine that can perform various tasks such as trenching, piping, excavating, slope cutting, grading, and rock demolishing. In the 2010s, unmanned construction equipment using ICT technology was continuously developed. In this paper, the path design process was studied to implement the output data of the decision stage, and the path design algorithm was developed. For example, the output data of the decision stage were terrain data around the excavator, excavator mechanism information, excavator hydraulic information, the position and posture of the bucket at key points, the speed of the desired bucket path, and the required excavation volume. The result of the path design was the movement of the hydraulic cylinder, boom arm, bucket, and bucket edge. The core functions of the path design algorithm are the function of avoiding impact during the excavation process, the function to calculate the excavation depth that satisfies the required excavation volume, and the function that allows the bucket to pass through the main points of the excavation process while maintaining the speed of the desired path. In particular, in the process of developing the last function, the node tracking method expressed in the path design table was newly developed. The path design algorithm was verified as this path design satisfied the JCMAS H02 requirement.