• Geomechanics and Engineering
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• 제6권4호
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• pp.341-358
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• 2014

Uplift response of rectangular anchor plates has been investigated in physical model tests and numerical simulation using Plaxis. The behavior of rectangular plates during uplift test was studied by experimental data and finite element analyses in cohesionless soil. Validation of the analysis model was also carried out with 200 mm and 300 mm diameter of rectangular plates in sand. Agreement between the uplift responses from the physical model tests and finite element modeling using PLAXIS 2D, based on 200 mm and 300 mm computed maximum displacements were excellent for rectangular anchor plates. Numerical analysis using rectangular anchor plates was conducted based on hardening soil model (HSM). The research has showed that the finite element results gives higher than the experimental findings in dense and loose packing of cohesionless soil.

• 산업기술연구
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• 제18권
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• pp.7-16
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• 1998

This paper is an experimental study of investigating the reinforcing effect and the behavior of cohesionless slope installed with reticulated root pils. Reduced scale model tests with plane strain conditions were performed to study the behavior of the strip footing located on the surface of cohesionless slopes reinforced with root piles. Model tests were carried out with Jumunjin Standard Sand of 45% relative density prepared by raining method to have an uniform slope foundation during tests. Slope of model foundation was 1 : 1.5 and a rigid model slop. Parametric model tests were performed with changing location of model footing, arrangements of root piles and angles of pile installation. On the other hands, the technique with camera shooting was used to monitor sliding surface formed with discontinuty of dyed sand prepared during formation o foudation. From test results, parameters affecting the behavior of model footing were analyzed qualitatively to evaluate their effects on the characteristic of load - settlement, ultimate bearing capacity of model footing and failure mechanism based on the formation of failure surface.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
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• pp.98-106
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• 2001

The deformation characteristics of cohesionless soils in Korea were investigated using resonant column tests. Total 60 samples, which were sampled from sedimentary and residual soils and reconstituted using controlled particle-size distributions, were prepared. The confining pressure applied in the tests ranges from 20 kPa to 500 kPa. The test results ware categorized into 3 groups including clean sands, silt and silty sand, and residual soils. Based on test results, the small-strain shear modulus(G$_{max}$) and damping ratio(D$_{min}$) were determined and the effects of confinement on G$_{max}$ and D$_{max}$ were characterized. The empirical correlations predicting G$_{max}$ were suggested for 3 group soils. Nonlinear deformational characteristics of clean sands are significantly affected by confining pressure and the ranges and mean curves for G and D are suggested considering the range of confining Pressure. The silt and silty sand and residual soils were weakly affected by confining pressure, so the representative ranges and curves, independent of confining pressure, were proposed.d.posed.d.

• Interaction and multiscale mechanics
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• 제4권4호
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• pp.321-336
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• 2011

This paper presents the results of static vertical load tests carried out on a model building frame supported by pile groups embedded in cohesionless soil (sand). The effect of soil interaction on displacements and rotation at the column base and also the shears and bending moments in the columns of the building frame were investigated. The experimental results have been compared with those obtained from the finite element analysis and conventional method of analysis. Soil nonlinearity in the lateral direction is characterized by the p-y curves and in the axial direction by nonlinear vertical springs along the length of the piles (${\tau}-z$ curves) at their tips (Q-z curves). The results reveal that the conventional method gives the shear force in the column by about 40-60%, the bending moment at the column top about 20-30% and at the column base about 75-100% more than those from the experimental results. The response of the frame from the experimental results is in good agreement with that obtained by the nonlinear finite element analysis.

• 한국지반공학회논문집
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• 제17권5호
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• pp.115-128
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• 2001

본 논문에서는 반복하중이나 지진하중을 받는 지반-구조물 시스템의 설계에 필수적인 변수인 전단탄성계수와 감쇠비에 대한 연구를 국내에 존재하는 비점성토 지반에 대하여 수행하였다. 국내 퇴적토지반 및 풍화토지반에서 채취된 자연시료와 입도분포를 조정하여 제작한 시료를 포함하여 총 60개의 시료에 대하여 20kPa에서 500kPa의 구속응력 범위에서 공진주 시험을 수행하고, 이를 조립질 사질토, 실트 및 실트질 모래, 풍화토의 3개의 그룹으로 나누어 결과를 정리하였다. 저변형률 영역의 변형특성인 최대전단탄성계수와 최소감쇠비에 대하여 구속응력의 영향을 확인하였다. 최대전단탄성계수를 예측하는 경험식을 3개의 그룹별로 제안하였다. 최소감쇠비는 구속응력에 따른 분포영역을 제시하였다. 세립분이 적은 조립질 사질토의 경우, 비선형 변형특성이 구속응력의 영향을 뚜렷이 받고 있어 이를 주요한 변수로 고려하여 대표곡선과 분포영역을 제안하였다. 구속응력의 영향을 적게 받는 실트 및 실트질 모래와 풍화토는 구속응력에 관계없이 대표곡선과 분포영역을 제안하였다. 제안된 각 시료의 대표곡선과 기존의 Vucetic-Dobry와 Seed-Idriss가 제안한 곡선과 비교하였다. 본 논문의 연구결과는 국내지반의 비점성토 지반에 대한 지진해석이나 동하중을 받는 시스템의 해석시 유용하게 사용될 것으로 판단된다.

• Geomechanics and Engineering
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• 제13권4호
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• pp.701-714
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• 2017

The effect of nearby cohesionless sloping ground on the uplift capacity of horizontal strip plate anchor embedded in sand deposit with horizontal ground surface has been studied numerically. The numerical analysis has been carried out by using the lower bound theorem of limit analysis with finite elements and linear optimization. The results have been presented in the form of non-dimensional uplift capacity factor of anchor plate by changing its distance from the slope crest for different slope angles, embedment ratios and angles of soil internal friction. It has been found that the decrease in horizontal distance between the edge of the anchor plate and the slope crest causes a continuous decrease in uplift capacity of anchor plate. The optimum distance is that distance between slope crest and anchor plate below which uplift capacity of an anchor plate has been found to decrease with a decrease in normalized crest distance from the anchor plate in presence of nearby sloping ground. The normalized optimum distance between the slope crest and the anchor plate has been found to increase with an increase in slope angle, embedment ratio and soil internal friction angle.

• Geomechanics and Engineering
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• 제13권4호
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• pp.641-651
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• 2017

Ground improvement with use of geosynthetic products is globally accepted now. The present paper discusses the improvement in bearing capacity of square footing placed at surface of cohesionless soil reinforced with geocell. Mohr-Coulomb failure criterion has been used in the observations. To study effects of geocell with respect to planar geogrid, model tests were conducted on planar reinforcement also. A comparative study of unreinforced soil and soil reinforced with plane geogrid and geocell has also been made. Numerical analysis results obtained by PLaxis have been compared with those obtained from model tests and were found to be in good agreement. A parametric study revealed the role of length of reinforcement, spacing between layers, placement of reinforcement from top surface etc. on bearing capacity. A design example given in paper illustrates the savings in cost of construction of footing on reinforced sand. The study shows that there is improvement in bearing capacity with respect to unreinforced soil which is of the order of 86%. Similarly settlement reduction is 13.07% for single layer of geocell which for double layers of geocell is 693% and 86.48% respectively. The cost reduction in case of reinforced soil is 35% as compared to unreinforced soil.

• Geomechanics and Engineering
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• 제12권4호
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• pp.675-688
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• 2017

The anchor block is a specially designed concrete member intended to withstand pullout or thrust forces from backfill material of an internally stabilized anchored earth retaining wall by passive resistance of soil in front of the block. This study presents small-scale laboratory experimental works to investigate the pullout capacity of a concrete anchor block embedded in air dry sand and located at different distances from yielding boundary wall. The experimental setup consists of a large tank made of fiberglass sheets and steel framing system. A series of tests was carried out in the tank to investigate the load-displacement behavior of anchor block. Experimental results are then compared with the theoretical approaches suggested by different researchers and codes. The appropriate placement of an anchor block and the passive resistance coefficient, which is multiplied by the passive resistance in front of the anchor block to obtain the pullout capacity of the anchor, were also studied.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1994년도 가을 학술발표회 논문집
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• pp.265-272
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• 1994

The relative density seems to be important as a factor of controlling the physical properties in the case of cohesionless soil ground as sand. Therefore, the study is more important about the method for reappearing the same relative density when the specimen of shearing test is to be produced or the model test of ground is to be made. In this study, the apparatus making use of the multiple sieving pluviation method - one of the reappearance of relative density - could be made. Using this apparatus, tests were practiced varying the factors such as the size of sieve mesh and the number of sieve, the amount of falling discharge, the falling height etc. about the standard sand in Jumunjin and Hadong sand. When laboratory test is performed by the cohensionless soil , it presents the method for reappearing of the relative density in field.

• 한국지반공학회논문집
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• 제32권2호
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• pp.53-62
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• 2016

흙의 다짐 특성에 영향을 주는 주요인자 중 하나인 온도는 지역과 계절에 따라 다양하게 변화하는 특성을 가진다. 최근 동토지방에서 많은 토목공사가 시행되고 있지만, 온도와 관련된 흙의 다짐기준 및 지침을 정량화할 수 있는 문헌은 미비한 실정이다. 따라서 본 연구는 온도에 따른 흙의 다짐특성을 시험을 통해 평가하고자 하였다. 시험을 위해 러시아 시베리아, 캐나다 앨버타 주 오일 샌드 지역 등에서 자주 쓰이는 성토재료인 모래의 온도별 다짐특성을 나타낼 수 있는 주문진 모래를 사용하였으며, 표준다짐시험을 흙의 다양한 온도조건($-10^{\circ}C$에서 $17^{\circ}C$)에서 수행하였다. 시험 결과 영상 온도에서는 다짐 시 벌킹 효과로 인해 흙 공시체의 부피 팽창이 발생하였으며, 그 범위는 0%~6%이였다. $0^{\circ}C$에서 $17^{\circ}C$까지 온도가 증가하면서 최대 부피(최소 건조단위중량)에 해당하는 함수비는 감소하였고, 최소 부피(최대 건조단위중량)에 해당하는 함수비는 온도가 증가함에 따라 약간 증가하였다. 영하 온도의 경우 함수비가 추가됨에 따라 건조단위중량은 지속적으로 감소하였다. 영하 온도에서는 벌킹이 발생하지 않았으며 물의 단위부피보다 얼음의 단위부피가 더 크기 때문에 흙 공시체의 부피가 증가하였다.