• Geotechnical Engineering
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• v.9 no.3
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• pp.77-90
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• 1993

In the settlement analysis of shallow foundation soil properties, loads and soil strata involve many uncertainties so it is necessary to do analysis of settlement that considers the probabilistic properties of each variable. This study is performed to probabilistic analysis for settlement of shallow foundation consisted of individual footings by using Monte Carlo Method. To consider the uncertainty of variables, both the soil properties and loads are assumed to be normal distribution random variables and get settlement mean and coefficient of variation of individual footing. And the settlement of each individual footing is also assumed to be normal distribution. Settlement of each individual footing which considers the probability of soft soil pockets in soil strata follows Markov process. Then it is performed to do sensitivity analysis which is involved to excess probability of allowable criteria of maxi mum settlement and differential settlement according to varity of each variable. It is thought to be proper that the settlement analysis of shallow foundation should be analyzed considering uncertainty of variables and soil stratum conditions.

• Journal of the Korean GEO-environmental Society
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• v.19 no.9
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• pp.21-28
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• 2018

In this study, a standard consolidation test (Oedometer) was performed on the relative density of sand in the south coast to evaluate long-term creep settlement characteristics. Experimental results show that the cumulative settlement at the final loading stage decreases as the relative density increases and the variation of the void ratio decreases. As a result of analyzing the settlement rate of long-term creep of sand, creep settlement of 4.7~11.0% occurred depending on relative density with respect to total settlement. The creep parameter, Beta, of Schmertmann et al. (1978) was estimated to be 0.17~0.40 (average 0.21), and it tended to converge to a certain value when the load step becomes more than a certain level. It was found that there is no significant difference in the creep parameter depending on the layer thickness, and it was confirmed that the creep parameter could be applied regardless of the field layer thickness.

• 도로교통
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• s.84
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• pp.54-70
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• 2001

• Journal of the Korean GEO-environmental Society
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• v.5 no.3
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• pp.17-30
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• 2004

In this study, a new formula of settlement at the head of IGM was suggested and the applicability of suggested formula was verified with field test results. This suggested formula was the function of the settlement at the shaft head and the elastic compression of shaft. The applicability of suggested formula was verified with the result of in-situ load test. Also, the bearing capacity of drilled shaft with the IGM's theory was compared with those of classical theories. The results showed that classical method showed smaller values of bearing capacity than those of field load test data. The results of analysis also showed that the suggested formula and IGM's theory were applicable for the estimation of bearing capacity with the increase of shaft settlement. Especially, settlement correction factor($k_m$), which reflects ground condition and load transfer characteristics, increases as the applying load and shaft deformation increase. This suggested formula was applicable for medium density or higher density of soil condition and $k_m=1$ means yielding load for firm soil condition.

• Journal of the Korean Geosynthetics Society
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• v.19 no.3
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• pp.35-44
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• 2020

This study described the result of laboratory model tests, in order to compare the improvement effect of the DCM column installed on the soft ground according to DCM column type. In the laboratory model test, the non-reinforced type and the 3 types of DCM column were applied, and the behavior (settlement, lateral flow) of soft ground was evaluated under the surcharge load condition for each type. The settlement evaluation result showed that the settlement of soft ground without DCM column occurred rapidly under the low load condition, but the settlement of the soft ground with the DCM column had relatively small settlement. The evaluation result of lateral flow in the soft ground showed that the soft ground with DCM column had lower lateral displacement than the soft ground without DCM column. Especially, the lateral displacement under the same load condition decreased in the order of pile type, wall type, and grid type. Therefore, it confirmed that the improvement effect of soft ground was excellent when the DCM of grid type was applied for settlement and lateral flow.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.99-110
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• 1999

Settlement and consolidation time were predicted through systematic soil investigation at the delta of Nakdong river where the preloading method was applied. Field measurements were executed with well-selected instruments. As the results of the comparison, the predicted settlement on the sand layer of about 20m thick underestimated the observed one by 20%. This underestimation was due to the effects of vibration during installation of PBD, creep, the overestimated deformation modulus, and so on. For the clay layer of about 20m in thickness under the sand layer, an ID analysis for underconsolidated soil initially overestimated the observed settlement by 240%. However, when the laboratory compression curve was reconstructed and a conventional ID analysis for NC clay was applied, the re-calculated settlement of the clay layer was relatively similar with the observed one. And the predicted consolidation time was about 45% less than the observed one, because of different influencing factors.

• Journal of the Korean GEO-environmental Society
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• v.13 no.6
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• pp.67-72
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• 2012

Finite element method was used to compare un-piled and piled raft foundation behaviors on sandy soils in this study. The soil parameters were estimated from SPT tests of 25 boreholes. Based on these soil parameters, a finite element analysis was conducted on un-piled and piled raft foundations. For the un-piled raft, the normalized settlement parameter for raft sizes of $8m{\times}8m$ and $15m{\times}15m$ ranged from 1.02~1.15 and 0.64~0.81, respectively. The raft thickness affects differential settlement and bending moments, but has little effect on load sharing or maximum settlement. Pile spacing greatly affected the maximum settlement, the differential settlement, the bending moment in the raft, and the load shared by the piles, while the differential settlement, the maximum bending moment and the load sharing are not affected very much by increasing the pile lengths.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.7-14
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• 2001

구조물 하중에 의한 점성토 지반의 침하량을 보다 정확하게 평가하기 위해서는 지반 내의 흙요소가 경험하는 실제적인 응력경로와 이에 따른 변형양상이 적절하게 고려되어야만 한다. 따라서 본 연구에서는 축대칭 조건의 다양한 응력경로를 따라 발생하는 정규압밀 점성토의 변형 거동을 고찰한 기존의 실험적 연구결과를 바탕으로 응력경로법에 근거한 보다 간편하고 합리적인 침하량 평가기법을 제시하였다. 또한 본 연구에서는 제시된 평가기법을 기존의 1차원적인 침하량 평가기법들과 함께 실제와 유사한 조건을 가지는 가상지반의 침하량 산정에 적용해 보았으며, 동일한 조건에 대해 소성모델(MCC 모델)과 혼합압밀이론에 바탕을 둔 유한요소해석을 실시하였다. 그리고 이를 통해 얻어진 결과들을 비교.분석함으로써 기존 평가기법들의 문제점과 한계를 명확히 제시하였으며, 응력증분 평가방법이 침하량 평가에 미치는 영향을 분석하였다.

• Journal of the Korean Geotechnical Society
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• v.36 no.7
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• pp.15-28
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• 2020

As the skin friction of an embedded pile is produced by the cement paste injected into the borehole, the skin friction cannot be evaluated by the end of initial driving test, which is conducted before the cement paste is cured. In addition, the total resistance of an embedded pile may not be properly evaluated during the restrike test if the base resistance is not fully mobilized because of the insufficient driven energy. The objective of this study is to suggest a new load-settlement curve of embedded piles by combining the results of the end of initial driving and restrike tests. Test piles are installed at fields by using the embedded pile method, and the results of the dynamic pile tests are analyzed using CAse Pile Wave Analysis Program (CAPWAP) after the end of initial driving and restrike tests are conducted. A new load transfer curve, which combines the behaviors of the pile base at the end of initial driving and of the pile shaft at the restrike, is suggested, and a new load-settlement curve is obtained. Subsequently, the resistances of the test piles are evaluated using the combined load-settlement curve, and compared with the results from the end of initial driving and restrike tests. The results showed that the resistances, which are evaluated using the combined load-settlement curve, may overcome the underestimation of the resistance because of the insufficient driven energy. In addition, the resistance resulted from the combined load-settlement curve may be more similar to that from the static load test because the suggested load transfer curve is closer to the behavior of the embedded pile compared to the results of end of initial driving and restrike tests. Therefore, this study demonstrates that the combined load-settlement curve may be effectively used for the evaluation of the bearing capacity of embedded piles.

• Journal of the Korean GEO-environmental Society
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• v.24 no.1
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• pp.5-14
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• 2023

In this study, the load transfer characteristics of the base and skin of drilled shafts were analyzed and the load sharing ratio was calculated by performing a load transfer large-scale model test and three-dimensional numerical analysis considering the similarity of drilled shafts, which is the design target. From the linear behavior of drilled shafts shown in the large-scale model test and 3D numerical analysis results, the skin load transition curve for the design conditions of this study was proposed by Baquelin et al., and the base load transition curve was proposed by Baquelin et al. For the horizontal load transition curve, the formula proposed by Reese et al. was confirmed to be appropriate. The test value was slightly larger than the numerical analysis value for the axial load at the rock socketing, but the load sharing ratio at the rock socketing increased, on average, about 27.8% as the vertical load increased. The analysis value of the vertical settlement of the pile head under the vertical load was evaluated to be slightly smaller than the test value, and the maximum vertical settlement of the pile head in the model test and analysis maximum vertical load was 10.6 mm in the test value and 10.0 mm in the analysis value, and the maximum vertical settlement value at the base of the pile was found to be a test value of 2.0 mm and an analysis value of 1.9 mm. The horizontal displacement at the head of the column (ground surface) and the head of the pile during the horizontal load was found to agree relatively well with the test value and the analysis value. As a result of the model soil test, the horizontal load measured at the maximum horizontal displacement of 38.0 mm was evaluated to be 24,713 kN, and the horizontal load in the numerical analysis was evaluated to be 26,073 kN.