• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.4
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• pp.863-874
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• 2015

The use of pile reinforcement is considered as one of the most promising techniques for improving load carrying capacity of piles in offshore area. In this study, to consider the horizontal and uplift bearing capacity of submerged breakwater bearing pile, exclusive analysis on load-transfer behaviour of pile was conducted. First of all, check the reinforcing effect from the three-dimensional finite element method, and estimate load transfer curve (ground reaction force). Based on these results, the reinforcing effect was quantified by estimating the coefficients of horizontal and uplift reinforcement of reinforced piles. Load transfer function with consideration of the reinforcing effect was proposed from estimated coefficients. A comparison of the analysis using the proposed load transfer function with three-dimensional finite element analysis has resulted that the proposed load transfer function is displaying good accuracy of predicting behavior of the load transfer between the pile and soil reinforcement. Interpretation of the submerged structure by applying a load transfer function considering the reinforcing effect, has shown that the reinforced pile's shear, bending moment and displacement are less than that of non-reinforced piles, while the subgrade reaction modulus arises greater. Thus, it is expected to be relatively cost effective in terms of design.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.61-70
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• 2008

In this research, load-transfer-function method was selected, because that is widely used in geotechnical engineering among the analysis methods to verify the behavior of load-lateral displacement. Lateral loading test of field scale was conducted, this measured data was analyzed. From the analysis, the model of load-lateral displacement was suggested. The test results were studied and compared to the commercial programs, 'LPILE', which contain the load transfer functions proposed before. By analysis of measure data of load-lateral displacement that expressed to several functions, $y=ae^{bx}$ model was the simplest and applicable to the field. In that case a value converged about 1.3, b value had a tendency to converge about 0.02. From the comparison analysis between measured data and load transfer function by 'LPILE', it is examined that if the lateral load is small, calculated displacements of them show a similar value compared to measured values. Furthermore, the bigger lateral loads, the bigger calculated values compared to the measured data. If the results are compared by Matlock-Reese method and Matlock-API method, Matlock-Reese method shows result of safe side because lateral displacement is calculated greatly relatively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6C
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• pp.359-366
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• 2008

The load distribution and deformation of pile subjected to axial loads are evaluated by a load-transfer method. The emphasis is on quantifying the effect of coupled soil resistance that is closely related to the ratio of pile diameter to soil modulus $(D/E_s)$ and the ratio of total shaft resistance against total applied load $(R_s/Q)$, in rock-socketed drilled shafts using the coupled load-transfer method. The proposed analytical method that takes into account the soil coupling effect was developed using a modified Mindlin's point load solution. Through comparisons with field case studies, it was found that the proposed method in the present study estimated reasonable load transfer behavior of pile and coupling effects due to the transfer of shaft shear loading, and thus represents a significant improvement in the prediction of load deflections of drilled shafts.

• Journal of the Korean Geotechnical Society
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• v.27 no.2
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• pp.35-42
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• 2011

The residual stress on drilled shafts is often neglected. Neglect of the existence of locked-in loads in the shaft is the main reason for conclusions of instrumented tests which suggest that shaft resistance is smaller when the shaft is loaded in tension than when it is loaded in compression. A few researchers studied the residual stress and mentioned that the residual stress is influenced by either the physical expansion/contraction of concrete during the curing or site stratigraphy. In this study, field measurements of residual stress on test shafts were conducted and the factors influencing the residual stress were figured out.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.10a
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• pp.399-408
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• 1997

• Journal of the Korean Geotechnical Society
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• v.22 no.7
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• pp.23-35
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• 2006

Shear load transfer characteristics of rock-socketed drilled shafts were analyzed. The constant normal stiffness (CNS) direct shear tests were performed to identify the major influencing factors of shaft resistance, i.e., unconfined compressive strength, borehole roughness, normal stiffness, initial confining stress, and material properties. Based on the CNS tests, shear load transfer function of drilled shafts in rocks is proposed using borehole roughness and the geological strength index (GSI), which indicates discontinuity and surface condition of rock mass in Hoek-Brown criterion (1997). The proposed load-transfer function was verified by the load test results of seven rock-socketed drilled test shafts subjected to axial loads. Through comparisons of the results of load tests, it is found that the load-transfer function by the present study is in good agreement with the general trend observed by in situ measurements, and thus represents a significant improvement in the prediction of load transfer of drilled shafts.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5C
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• pp.163-170
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• 2011

Perimeter load transfer functions were developed by an analysis of the static pile load test results of the 7 large diameter drilled shafts constructed in domestic areas. Using the pile axial load distributions obtained from the static pile load tests of large diameter drilled shafts, the unit skin frictions were analyzed and, based on unit skin friction test data, perimeter load transfer functions could be suggested. The load transfer distributions calculated by suggested functions and the load transfer functions obtained from the bi-directional pile load tests were compared. As a result, the 2 load transfer distributions were coincided, respectively.

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

• Journal of the Korean GEO-environmental Society
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• v.9 no.1
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• pp.41-46
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• 2008

In this study, the analysis of load transition of PHC pile was performed with the static load test, which was driven in deep soft clay layer of MyungJi site in the western area of Pusan. The results of test showed that the range of unit side resistance of pile in sand layer were $7.4t/m^2$ to $23.3t/m^2$ and $6.4t/m^2$ in the soft clay layer, while the unit base resistance was $955t/m^2$ in dense silty sand layer. To select the most reasonable static bearing capacity formular, the field measured values are compared with the calculated ones from the suggested various formular. In the case of side resistance in sand layer, the suggest formular in the Structural Foundation Design Manual by KGS was most reasonable, while in clay layer Railroad Design Manual.

• Journal of the Korean Geotechnical Society
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• v.32 no.12
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• pp.79-91
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• 2016

Geosynthetic-reinforced and Pile-supported (GRPS) embankment method is widely used to construct structures on soft ground due to restraining residual settlement and their rapid construction. However, effect of cyclic loading has not been established although some countries suggest design methods through many studies. In this paper, cyclic loading tests were conducted to analyze dynamic load transfer characteristics of pile-supported embankment reinforced with geosynthetics. A series of 3 case full scale model tests which were non-reinforced, one-layer-reinforced, two-layer reinforced with geosynthetics were performed on piled embankments. In these series of tests, the height of embankment and pile spacing were selected according to EBGEO (2010) standard in Germany. As a result of the vertical load parts on the pile and on the geosynthetic reinforcement measured separately, cyclic loads transferred by only arching effect decreased with strength geosynthetic-reinforced case. However, final loads on the pile showed no differences among the cases. These results conflict with previous studies that reinforcement with geosynthetics increases transfer load concentrated on piles. In addition, it is observed that the load transferred to pile decreases at the beginning of cycle number due to reduction of arching effected by cyclic loading. Based on these results, transferred mechanism for cyclic load on GRPS system has been presented.