• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.61-70
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• 2008

Load settlement behaviors and load transfer characteristics of rock-socketed pile subjected bi-directional load at pile tip were investigated using bi-directional pile load tests (BD PLT) performed on ten large-diameter drilled shafts at four sites. Based on test results, additional pile-toe displacement ($w_{bs}$) by coupled soil resistance was analyzed, and thus equivalent top loaded load-settlement curve of pile subjected bi-directional load was proposed by taking into account the coupled soil resistance. Through comparisons with field case studies, it is found that for test piles there exists effect of coupled soil resistance, which is represented by wbs, and thus an equivalent curve obtained by existing uncoupled methods can overestimate bearing capacity of piles by BD PLT. On the other hand, the analysis by the proposed method with soil coupling effect has a considerably larger settlement when compared with the results by uncoupled load transfer method and estimates reasonable load-settlement behaviors of test piles. In case of pile socketed in high strength rocks, however, effects of coupled soil resistance can be neglected.

• Journal of the Korean GEO-environmental Society
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• v.2 no.4
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• pp.51-61
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• 2001

A series of model tests and analyses by load transfer function were performed to study load-settlement behaviour with relative compaction ratio of soil and embeded depth of pile. In the model tests, embeded depth ratio(L/D) of pile were installed 15, 20, 25 and relative compaction of soil(RC) is 85%, 95% and then cement were injected at around perimeter of pile. For analysis of embedded pile, the paper were compared results of model tests with analysis results by Vijayvergiya model and Castelli model, Gwizdala model of elastic plasticity-perfect plastic model and then the fitness load transfer mechanism was proposed to predict load-settlement behaviour of embeded pile. The analysis results of predicted bearing capacity by load transfer function, ultimate bearing capacity of embeded pile were approached to measured value and behaviour of initial load-settlement curve were estimated that load transfer function by Castelli were similar to measured value. The result of axial load analysis of bored pile shows that skin friction estimated by load transfer mechanism is investigated more a little than that of measured values.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1190-1193
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• 2010

본 연구에서는 점토층의 자중압밀을 시행하여 현장강도를 구현하기 위하여 1/70로 축소 모델링하여 원심모형실험을 수행하였으며, 점토구간에 PBD 타설시의 연약지반의 압밀침하거동을 분석하기 위하여서는 1/100로 축소모델링하여 원심모형실험과 전산해석을 실시하였다. 전산해석결과 성토체중심아래의 점토지반의 침하량은 1단계 성토제방하중 하에서 4.8개월 경과 후 최대 침하량은 41.1cm, 2단계 성토하중에서 4.2개월 경과 후의 최대침하량은 78.8, 3단계 성토하중에서 6개월 경과후의 침하량은 93.5cm의 침하가 발생하는 것으로 나타나 수치해석 결과와 원심모형실험결과 값의 유사한 경향을 확인하였다.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.25-34
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• 2008

An application of concrete track is being actively processed for the construction of Korean high speed railway. The concrete track has an advantage in decreasing the maintenance cost, whereas it has much difficulty controlling the long term settlement after settlement occurred. Therefore, the management and control of settlement are very important for the successful construction of concrete track. The purpose of this paper is to verify the allowable settlement between concrete track and ballast track, and piled raft foundation installation effects as settlement reducers for concrete track. Therefore, a series of 3D finite element analyses that take into account the allowable settlement were performed for major parameters such as soil condition, pile installation and loading type. Based on the analysis, it is shown that concrete track causes much smaller settlement than ballast track, and the effect of installation is necessary to effectively reduce the settlement of concrete track.

• Land and Housing Review
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• v.4 no.1
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• pp.125-131
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• 2013

To predict the real bearing capacity and settlement of the shallow foundation the plate load test results were used. But there is no field estimation method about igneous weathered soil and rock. Therefore, to predict the settlement equation, the plate load test about igneous weathered soil and rock was done in this study. To analyze the load ~ relative settlement curve by normalization, it did not use normal analysis method, but the load ~ relative settlement (s/B, s : settlement, B : breadth of plate) was used. As a result of normalization by load ~ relative settlement conception, the curve was regular regardless of plate diameter and it was suggested the relationship of in-situ soil condition and results.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.4
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• pp.413-420
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• 2008

Wave force is an important factor which gives a direct affect to stability of the rubble mound breakwater. Particularly wave force has been considered as the main cause of displacement for replaced rubble mound breakwater which permits a little displacement to some degree. But the effect on displacement by wave force has not been considered and reflected in design. Therefore in this study, we compared numerical analysis displacement with field measured displacement so that the effect of wave force on displacement can be reflected in design. Result of the numerical analysis displacement was well consistent with field measured displacement data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4C
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• pp.145-151
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• 2009

In general, a drilled shaft embedded in weathered rock has a large load bearing capacity. Therefore, most of the load tests are performed only up to the load level that confirms the pile design load capacity, and stopped much before the ultimate load of the pile is attained. If a reliable ultimate load value can be extracted from the premature load test data, it will be possible to greatly improve economic efficiency as well as pile design quality. The main purpose of this study is to propose a method for judging the reliability of the ultimate load of piles that is obtained from extrapolated load test data. To this aim, ten static load test data of load-displacement curves were obtained from testing of piles to their failures from 3 different field sites. For each load-displacement curve, loading was assumed as 25%, 50%, 60%, 70%, 80%, and 90% of the actual pile bearing capacity. The limited known data were then extrapolated using the hyperbolic function, and the ultimate capacity was re-determined for each extrapolated data by the Davisson method (1972). Statistical analysis was performed on the reliability of the re-evaluated ultimate loads. The results showed that if the ratio of the maximum-available displacement to the predicted displacement exceeds 0.6, the extrapolated ultimate load may be regarded as reliable, having less than a conservative 20% error on average. The applicability of the proposed method of judgment was also verified with static load test data of driven piles.

• Journal of the Korean GEO-environmental Society
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• v.9 no.2
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• pp.5-13
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• 2008

To identify the reclamation history formed by top dredged soil reclamation layer over the original ground, various field tests and laboratory tests were conducted. Especially when the original ground was not completely consolidated, CPTu test was carried out to calculate rational settlement due to the banking load. CPTu test results showed that the degree of consolidation of weak clay ground by dredged reclamation was on average 80%. As the research area was not completely consolidated by dredged reclamation in the past, the consolidation settlement should account for the residual settlement (20%) in the case of additional banking load. When the degree of consolidation of the original ground was not taken into account, the residual consolidation was expected in excessive settlement (up to 20%) and in such case PBD (Plastic Board Drain) was not effective in obtaining desired degree of consolidation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4C
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• pp.127-136
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• 2011

The settlement of a compaction plate resting on the surface of rubble-mound and subjected to a vibrating vertical load can be characterized by a transient amplitude and a plastic settlement. As long as the maximum imposed load does not exceed the bearing capacity of the rubble-mound, plastic settlement will approach an ultimate value and essentially steady-state vibration will ensue. For the settlement behavior by vibro-compaction, most laboratory experiments were conducted on laterally confined samples with loads over the full surface area or on samples placed on a vibrating table. In the field, the loads cover only a small fraction of the surface area. In this study, crushed stones are loaded with the same as field condition. According to the vibro-compaction experiments on crushed stone, it was found that approximately 90% of total settlement occur within 2 minutes and plastic settlement increases with increasing cyclic stress levels including static and dynamic stress. A compaction equation on which the number of load cycles, amplitude of plate, settlement, width of plate, and cyclic stress are related each other is proposed.

• Geotechnical Engineering
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• v.12 no.6
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• pp.79-86
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• 1996

This study develops a new method for interpreting the yield load from load tests on drilled shaft foundations ended on general soils, which is defined as a point where the maximum curvature on the hyperbolic-approximated load-settlement curve occurs. How ever, the point of maximum curvature is a variable depending on the units and scales of the load and settlement. Therefore, to obtain a unique maximum curvature point, both the load and settlement must be normalized by proper parameters, respectively, and be expressed on the same scaled arses(1:1). Normalization has been processed so that the yield load by the new interpretation is to be close to the average of yield loads interpreted by other methods investigated in this study. The quantitative comparison between the new criterion and other conventitonal methods is presented.