• Land and Housing Review
• /
• v.2 no.3
• /
• pp.277-285
• /
• 2011

To reinforce bearing capacity-changed section or different foundation in the same building, empirical or simple tools have been used. To solve this problem, an analytical solution which can evaluate and reinforce the stability of foundation is introduced. To suggest a clue for the problems, current foundation reinforcing method is studied through recent literature studies and the structural analyses of foundation slab are performed on the pile foundation of 49$m^2$, 59$m^2$ and 84$m^2$ I type apartments in 15 story building. The analyses are conducted with SAP 2000, a computer program for ordinary structural analysis. To predict the moments of slab by ground non-uniformity, the structural analysis results for the foundation slab of 3 types 15 story apartment buildings in 49$m^2$, 59$m^2$ and 84$m^2$ I type on non-uniformity ground are shown in the diagrams.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.16 no.1
• /
• pp.18-26
• /
• 2004

In order to accelerate the rate of consolidation settlement, to reduce settlement, and to increase bearing capacity for soft ground under quay, sand compaction pile method (SCP) has usually been applied. SCP-reinforced ground is composite soil which consists of the sand pile and the surrounding soft soil. One of main important considerations in design and analysis for SCP-reinforced soils is stress concentration ratio according to area replacement ratio. In this paper, the numerical analysis was conducted to investigate characteristics of stress concentration ratio in composite ground. It was found that stress concentration ratio of composite ground is not constant as well as depends on several factors such as area replacement ratio, depth of soft soil, and consolidation process. The values of stress concentration ratio increase during loading stage due to stress transfer of composite soil, and reach up to 2.5∼12 according to area replacement ratio at the end of construction. After the end of consolidation, however, these values are converged to 2.5 to 6.0 irrespective of area replacement ratio due to increase in effective stress of soft soil during consolidation process.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.6
• /
• pp.1031-1034
• /
• 2007

Electric transmission lines pass through a variety of area. Foundation supporting the conductors and tower are selected properly in accordance with external load, for example dead load, wind load, snow load, construction load etc, and topography and geology condition. Typical types of foundation are as follows: pad foundation for small load and hard soil or rock in mountainous area, pile foundation for medium or large load and soft soil in plain field area. This paper introduced cylindrical foundation design & construction for large load and mountainous area. This foundation failure mode against pulling-out show splitting failure by tensile force toward circumferential direction.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.512-517
• /
• 2009

Resistance factors for static bearing capacity of driven steel pipe piles were calibrated in the framework of reliability theory. A comprehensive foundation design case study on an actual bridge was performed using resistance factors developed in this study. Comparing with Allowable Stress Design (ASD), LRFD design method provides quantitative evaluation of safety level of designed foundation and exhibits considerable potential economy in design.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.6
• /
• pp.5-13
• /
• 2000

모래지반의 상대밀도, 말뚝의 시공방법, 일정근입깊이에 따른 소요향타 에너지 그리고 지하수 조건에 따라 말뚝의 지지력과 하중전이를 연구하기 위하여 강관말뚝을 이용한 모형실험을 수행하였다. 매입말뚝은 말뚝을 미리 설치한후에 지반성형을 실시하였고, 타입말뚝은 매입말뚝과 같은 깊이까지 항타높이를 5, 10, 15cm로 달리하여 말뚝을 관입하였다. 그 뒤 정적하중을 단계적으로 가하여 하중-침하 곡선에 의한 모형 말뚝의 지지력과ㅏ 말뚝내의 등간격으로 설치된 변형 게이지를 이용하여 타입말뚝 의 하중전이에 대해 살펴보았다. 타입말뚝의 하중전이시험에서는 항타 전과 항타 후 말뚝내 하중전의 소효항타 에너지에 따른 변화를 관찰하였다. 매입말뚝의 시험결과는 현재 가장 많이 사용하고 있는 대표적인 정적 지지력 공식들에 의하여 계산되어진 값들과 비교 분석하였다. 그 결과 상대밀도가 작은 느슨한모래지반에서는 Vesic 공식이 그리고 상대밀도가 큰 조밀한 모래지반에서는 Hanbu 공식이 가장 근접한 평가를 나타내었다. 하중전이시험에 의한 항타시 잔류응력은 모든 경우에서 지표면과 선단부위에서 아주 큰 잔류응력이 나타났고. 말뚝의 선단 지지력비는 상대밀도에 비례하게 증가하였다.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2000.10a
• /
• pp.438-443
• /
• 2000

A wide range of problems geotechnical engineering have been analyzed by using the finite element method. In order to establish confidence in a numerical procedure, it is desirable that numerical solution be verified against field or laboratory observations, or both, and in order to aid the user in applying the method to practical problems, it is necessary to examine effects of various parameters that influence the behavior of engineering structures. Often it can be profitable to translate numerical solutions in formats that can be used readily for design analysis. The allowable bearing capacity of concrete piles is mainly governed by settlement rather than by strength of soil. Therefore, the load-displacement behavior of piles should be well understood at the design stage. This paper deals with some of these goals by considering the problem of load-displacement behavior of axially-loaded pile foundations.

• Structural Engineering and Mechanics
• /
• v.12 no.6
• /
• pp.615-632
• /
• 2001

Ductility of open piled wharves under reversed cyclic loads has been investigated. Experimental testing of five wharf models having a scale of about 1:4 was conducted under the application of horizontal reversed cyclic loading. The experiments were designed to focus on the horizontal ultimate load, ductility and failure mode of the considered wharf models. Nonlinear numerical analyses using the finite element method were also performed on numerical models representing the experimentally tested wharves. The results of the experimental tests showed that open piled wharves possessed favourable ductile behaviour and that their load bearing capacity did not depreciate until a ductility factor of 3 to 4 was reached. The numerical analysis showed that the relative rotation that took place at the joints between the steel piles and the R.C. beam was responsible for a considerable portion of the total horizontal deformation of the wharves. Therefore, it was concluded that introducing the joint stiffness in calculating the deformations of open piled wharves was important to achieve reasonable accuracy.

• Journal of the Korean Geotechnical Society
• /
• v.30 no.1
• /
• pp.75-91
• /
• 2014

In this study the analysis is performed for influencing factors on the behavior of rigid piles (short pile) by research papers and case study. The results indicated that the point of virtual fixity should be calculated considering the relative stiffness of soil and pile, and Chang (1937) and P-Y method estimated the similar fixity. The values of ultimate resistances of a vertical pile to a lateral load are different for laboratory and field tests in cohesive soils and its ultimate values in laboratory tests are underestimated and in field tests are under or overestimated. The estimated resistance by Hansen (1961)'s method is similar to the value of field tests. The horizontal resistances to laterally loaded pile in cohesionless soils are overestimated in laboratory tests and generally overestimated in field tests. The ultimate resistances by Zhang (2005)'s method, used to the empirical distribution of the resistance, are similar to the test results. In the paper the calculating method and distribution of the ultimate resistance in cohesive soils are proposed. The estimated value by the proposed method is closer to the test results than any other method of calculating ultimate resistance of the piles embedded into cohesive soils.

• Journal of the Korean Geotechnical Society
• /
• v.40 no.1
• /
• pp.5-14
• /
• 2024

PHC piles demonstrate superior resistance to compression and bending moments, and their factory-based production enhances quality assurance and management processes. Despite these advantages that have resulted in widespread use in civil engineering and construction projects, the design process frequently relies on empirical formulas or N-values to estimate the soil-pile friction, which is crucial for bearing capacity, and this reliance underscores a significant lack of experimental validation. In addition, environmental factors, e.g., the pH levels in groundwater and the effects of seawater, are commonly not considered. Thus, this study investigates the influence of vibrating machine foundations on PHC pile models in consideration of the effects of varying pH conditions. Concrete model piles were subjected to a one-month conditioning period in different pH environments (acidic, neutral, and alkaline) and under the influence of seawater. Subsequent repeated direct shear tests were performed on the pile-soil interface, and the disturbed state concept was employed to derive parameters that effectively quantify the dynamic behavior of this interface. The results revealed a descending order of shear stress in neutral, acidic, and alkaline conditions, with the pH-influenced samples exhibiting a more pronounced reduction in shear stress than those affected by seawater.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.1
• /
• pp.81-91
• /
• 2005

This paper is the results of experimental and numerical works on the investigating design factors influencing the bearing capacity, the ratio of stress concentration, and the failure mechanism of the clay ground improved with sand compaction piles (SCP). In order to find the behavior of the clay ground improved with SCP, extensive centrifuge model experiments were carried out for each of the SCP replacement ratio of 20, 40, and $70\%$, the non-plastic fine contents in sand of 5, 10, and $15\%$, and the ratio of the improved width to the loaded area (W/B) of 1, 2, and 3. The commertially available software of FEM, CRISP, was used to analyze test results by performing numerical estimations. In these numerical analyses the sand compaction piles and the clay ground were simulated as a linear elastic and plastic constitutive model and the modified Cam-clay model, based on Critical State Soil Mechanics, respectively.