• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.105-116
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• 2011

No analytical solution exists for evaluating in-situ hydraulic conductivity of vertical cutoff walls by analyzing slug test results. Recently, an analytical solution to interpret slug tests has been proposed for a partially penetrated well in an aquifer. However, this analytical solution cannot be directly applied to the cutoff wall because the solution has been developed exclusively for an infinite aquifer instead of a narrow cutoff wall. To consider the cutoff wall boundary conditions, the analytical solution has been modified in this study to take into account the narrow boundaries by introducing the imaginary well theory. Two boundary conditions are considered according to the existence of filter cakes: constant head boundary and no flux boundary. Generalized steady-state shape factors are presented for each geometric condition, which can be used for evaluating the in-situ hydraulic conductivity of cutoff walls. The constant head boundary condition provides higher shape factors and no flux boundary condition provides lower shape factors than the infinite aquifer, which enables to adjust the in-situ hydraulic conductivity of the cutoff wall. The hydraulic conductivities calculated from the analytical solution in this paper give about 1.2~1.7 times higher than those from the Bouwer and Rice method, one of the semi-empirical formulas. Considering the compressibility of the backfill material, the analytical solution developed in this study was proved to correspond to the case of incompressible backfill materials.

• Journal of the KSME
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• v.16 no.4
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• pp.49-54
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• 1976

유한요소법이 처음 연구되기 시작할 때는 변위를 가변수로 하는 매트ㄹ스 변위법(Matrix Displacement Method) 과 외력을 자변수로 하는 매트ㄹ스 힘 방법(Matrix Force Method)외 두 길로 발전되어 갔었으나 경계 조건의 적용과 매트ㄹ스 분활(Partitioning)에 있어서 후자의 방법이 많은 번거로움을 갖는다는 것이 인정되어 오늘날은 전자의 방법 만이 사용되는 형편이다. 본 해 설에서는 유한요소의 기본성질을 모두 가지면서도 제일 간단한 보유한요소(Beam Finite Element )를 예로 다루며 유한 요소법의 기본이론과 응용방법을 설명코저 한다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.2
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• pp.183-204
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• 2007

When a tunnel is excavated below groundwater table, the groundwater flows into the excavated wall of tunnel and seepage forces are acting on the tunnel wall. Such seepage forces significantly affect the ground reaction curve which is defined as the relationship between internal pressure and radial displacement of tunnel wall. In this paper, seepage forces arising from the ground water flow into a tunnel were estimated quantitatively. Magnitude of seepage forces was decided based on hydraulic gradient distribution around tunnel. Using these results, the theoretical solutions of ground reaction curve with consideration of seepage forces under steady-state flow were derived. A no-support condition and a supported condition with grouted bolts and shotcrete lining were considered, respectively. The theoretical solution derived in this study was validated by numerical analysis. The changes in the ground reaction curve according to various cover depths and groundwater table conditions were investigated. Based on the results, the application limit of theoretical solutions was suggested.

• Computational Structural Engineering
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• v.8 no.4
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• pp.129-136
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• 1995

This paper presents a boundary element method for obtaining approximate solutions of 2-dimensional consolidation problems based on the Biot's linear theory. Laplace transform is applied to differential equation system in order to eliminate the time dependency. The boundary integral equations in transformed space are formulated and the fundamental solutions are shown in a closed form. In order to convert the transformed solutions to the ones in real space, the Hosono's numerical Laplace transform inversion method is applied. As a numerical example, a half-space consolidation problem subjected to a strip local load is selected and the applicability of the method is demonstrated through the comparison with the exact solutions.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.292-295
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• 2009

본 논문에서는 평판구조물의 정적 및 동적해석에 사용할 목적으로 성능이 향상된 평판유한요소를 제시하였다. 이 요소는 비적합변위형과 선택적 감차적분방법 그리고 대체전단변형률장을 복합적으로 적용하여 각각의 장점들을 포함하는 향상된 거동을 보여주고 있다. 또한 비적합변위형의 적용으로 발생되는 조각시험의 실패 문제점을 해결하기 위하여 직접수정법을 평판유한요소의 개선에 사용하였다. 대표적인 검증문제에 대한 수치해석작업을 통하여 본 연구에서 개발한 요소는 가상적인 제로에너지모드 및 전단잠김현상의 발생과 같은 문제를 나타내지 않음을 알 수 있었다. 특히 찌그러진 형상으로 모형화 한 경우에 있어서도 전단잠김현상이 발생하지 않았다. 본 연구에서 수행한 동적반응해석 시험에 있어서도 이론해와 잘 일치하는 결과를 보여주었다.

• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.2
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• pp.36-43
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• 2003

The analytic solution of radial displacements of thin cylindrical pressure vessel with carbon fiber T700/Epoxy orthotropic composites was obtained using equilibrium equations of the orthogonal curvilinear coordinate system. The governing equations with the simplified strain versus displacement relation of 3-dimensional curvilinear coordinate system were derived from the variational principle and the virtual work principle. Some theoretical analyses were presented and compared with the results of hydraulic tests for the pressure vessels with some various thicknesses. The results of the theoretical analysis and the hydraulic test were reasonably matched.

• Geotechnical Engineering
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• v.13 no.1
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• pp.101-110
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• 1997

This paper presents a two dimensional p-version static infinite element for analyzing $1/r^n$ displacement decay type problems in unbounded media. The proposed element is developed by using shape functions based on approximate expressions of an analytical solution. Numerical results are presented for an opening in a homogeneous elastic infinite medium and a rigid footing rested on a homogeneous elastic half-space. The numerical results show the effectiveness of the proposed infinite element.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.4
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• pp.93-99
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• 2022

Analytical solutions for regular waves generated by bottom wave makers in a 3-dimensional wave basin were derived in this study. Bottom wave makers which have triangular, rectangular and combination of two shapes were adopted. The 3-dimensional velocity potential was derived based on the linear wave theory with the bottom moving boundary condition, kinematic and dynamic free surface boundary conditions in a wave basin. Then, analytical solutions of 3-dimensional particle velocities and free surface displacement were derived from the velocity potential. The solutions showed physically valid results for regular waves generated by bottom wave makers in a wave basin. The analytical solution for obliquely propagating wave generation from bottom wave maker which works like a snake was also derived. Numerical results of the solution agree well with theoretically predicted results.

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.163-176
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• 2001

In this paper, the stress resultants and displacements of simply supported curved girder based on the flexural torsional theory considering torsional warping effects are analyzed. And elastic equations of continuous curved girder are obtained by using energy method. Also, bending moment warping torsional moment diagram, pure torsional moment diagram, shearing force diagram, and deflection diagram of continuos curved girder bridge subjecting to vertical loads and uniform loads are presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.6
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• pp.583-588
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• 2015

Asymptotic method has been often used to theoretically analyze the complete contact problem. The error of the asymptotic results increases as the distance from the contact edge increases. The singularity cannot be properly obtained from a finite element (FE) analysis owing to the finiteness of the element size. In the present work, the complete contact problem in bonded condition is analyzed using a combined experimental-numerical approach to assist and/or compare with the asymptotic results. Al and Cu alloys are used for the material combination of the punch and substrate. 120 and 135 degrees are used for the punch angle. The FE models are validated by comparison of displacement distributions obtained by the FE analysis and $moir{\acute{e}}$ experiment. Generalized stress intensity factors are evaluated using the validated FE models. Stress field in the vicinity of the sharp contact edges obtained from the FE and asymptotic analyses are compared. The discrepancies are also discussed.