• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1396-1404
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• 2012

A composite pile consisted of a concrete lower part with a steel tubular pile at upper part was installed by pre-drilling method. Seven pairs of strain gauges and inclinometer were attached on the pile in order to measure stresses and displacement along the pile during the lateral loading test. The results of instrumentation were analyzed using various theoretical approaches. The back analysis showed that the measured stresses were smaller than those of the calculated. The maximum stress is measured at the steel upper part and decreased rapidly with depth of the pile. The calculated lateral displacement along the pile provide very good agreement with the measured values if the coefficient of subgrade reaction is selected properly. The design concept of a composite pile is verified by the measured stresses and displacement which is within the tolerable limits of the pile.

• Geomechanics and Engineering
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• v.30 no.6
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• pp.579-586
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• 2022

Pile-supported structures are installed on saturated sloping grounds, where the ground stiffness may decrease due to liquefaction during earthquakes. Thus, it is important to consider saturated sloping ground and pile interactions. In this study, we conduct a centrifuge test of a pile-supported structure, and analyze the p-y_p loops, p-y_p loops provide the correlation between the lateral pile deflection (y_p) and lateral soil resistance (p). In the dry sand model (UV67), the p-y_p loops stiffness increased as ground depth increased, and the p-y_p loops stiffness was larger by approximately three times when the pile moved to the upslope direction, compared with when it moved to the downslope direction. In contrast, no significant difference was observed in the stiffness with the ground depth and pile moving direction in the saturated sand model (SV69). Furthermore, we identify the unstable zone based on the result of the lateral soil resistance (p). In the case of the SV69 model, the maximum depth of the unstable zone is five times larger than that of the dry sand model, and it was found that the saturated sand model was affected significantly by kinematic forces due to slope failure.

• Journal of the Korean Geosynthetics Society
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• v.20 no.4
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• pp.95-103
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• 2021

While the existing pile foundation had the role of supporting the superstructure or reducing the earth pressure, recently there are cases where it is integrated with the superstructure to increase the lateral resistance. This study aims to evaluate a lateral resistance of block-type breakwaters with group piles by modelling experiments. The lateral resistance and bending moments of the piles by penetrated depths for the piles were measured. As a result, it was found that the lateral resistance increased as the depth of embedment of the group piles. In particular, the lateral resistance was 1.52 times greater in the case where the pile embedded up to the riprap layer than the case where the pile was embedded into the block. For the bending moment, the rear piles ware larger than the front piles, and the outside piles were larger than the inside piles. The location of the maximum bending moment in the ground was shown at the interface between the riprap layer and the natural ground.

• Geomechanics and Engineering
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• v.31 no.5
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• pp.505-518
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• 2022

This study introduces soil resistance multipliers at locations encompassed by the zone of influence of the helix plate to consider the added lateral resistance provided to the helical pile. The zone of influence of a helix plate is a function of its diameter and serves as a boundary condition for the modified soil resistance springs. The concept is based on implementing p-multipliers as a reduction factor for piles in group action. The application of modified p-y springs in the analysis of helical piles allows for better characterization and understanding of the lateral behavior of helical piles, which will help further the development of design methods. To execute the proposed method, a finite difference program, HPCap (Helical Pile Capacity), was developed by the authors using Matlab. The program computes the deflection, shear force, bending moment, and soil resistance of the helical pile and allows the user to freely input the value of the zone of influence and Ω (a coefficient that affects the value of the p-multiplier). Results from ten full-scale lateral load tests on helical piles embedded at depths of 3.0 m with varying shaft diameters, shaft thicknesses, and helix configurations were analyzed to determine the zone of influence and the magnitude of the p-multipliers. The analysis determined that the value of the p-multipliers is influenced by the ratio between the pile embedment length and the shaft diameter (D_p), the effective helix diameter (D_h-D_p), and the zone of influence. Furthermore, the zone of influence is recommended to be 1.75 times the helix diameter (D_h). Using the numerical analysis method presented in this study, the predicted deflections of the various helical pile cases showed good agreement with the observed field test results.

• Journal of the Korean Geotechnical Society
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• v.25 no.11
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• pp.39-51
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• 2009

This is a study on rectangular-shaped passive row piles in inclined sand-ground by model tests. The experiment controlled the angle of inclination of ground and induced the ground destruction. We also measured the behavior of row piles, by adjusting the shape, position and spacing of piles. As a result, we confirmed the earth pressure, the lateral resistance, and the effect of depressing on the ground variation working on passive pile. The effect of B-type pile of which the front width is wide is bigger than that of H-type pile of which the side width is wide. We can find out the failure angle of slope, the shared force of pile and soil by using the lateral resistance graph based on slope angle.

• Journal of the Korean Geotechnical Society
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• v.33 no.5
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• pp.37-44
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• 2017

In this study, three dimensional numerical analyses were carried out to predict axial (pullout and compressive) and lateral behavior of rock-socketed steel pipe pile varying diameter, wall thickness, and length. As a result of the pile pullout analyses, it was confirmed that the pullout displacement was inversely proportional to the pile diameter for given pile length, thickness, pullout load. Load-settlement relationship of the compressive pile analyses revealed that the effect of pile thickness on pile resistance was more significant than that of pile diameter. In addition, laterally loaded pile analyses showed that pile lateral resistance is influenced above all else by pile diameter. This study showed that it is necessary to conduct numerical analyses to identify the effects of pile diameter, wall thickness, and pile length on the steel pipe pile behavior as a preliminary pile design under specified loading conditions.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.6
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• pp.427-436
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• 2009

In this study, new type of pile foundation was introduced for the better performance of lateral resistance than conventional piles by adopting enlarged upper section, because offshore structure design is subjected to the lateral loading. The numerical simulations were peformed in order to find out the lateral behaviour of the proposed pile. The economical efficiency of new pile system was also analyzed by considering the construction characteristics and material costs as well as the real field condition of harbor sites in Korea. From the study, it was revealed that the lateral resistance of piles with enlarged upper section is increased compared to conventional steel pile, and the construction costs would be reduced to about 62~80% of previous methods.

• Journal of the Korean Geotechnical Society
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• v.22 no.10
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• pp.165-172
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• 2006

This study describes a series of model tests on instrumented pile groups embedded in HAP-CHEN sand undergoing lateral movement. We tried to find the effect of group piles dependent on a number of factors, including the position of the pile in a group, the pile spacing, and the pile arrangement. The results of test are as follows. For the group piles, the bending moment profile for each pile is similar in shape to that of single pile, although the magnitude and the position of the maximum bending moment are different. $R_M$ (the ratio of maximum bending moment) and $R_F$ (the ratio of resistance to lateral soil movement) were found to increase with increasing pile spacing. When a pile is in a group under lateral soil movement, RM increased in the order of the middle row, front row, back row, according to the direction of lateral deformation, and the outer pile has a larger RM than the inner pile.

• Geomechanics and Engineering
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• v.19 no.1
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• pp.79-91
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• 2019

Renewed interest in the long-term pile foundations has been driven by the increase in offshore wind turbine installation to generate renewable energy. A monopile subjected to repetitive loads experiences an evolution of displacements, pile rotation, and stress redistribution along the embedded portion of the pile. However, it is not fully understood how the embedded pile interacts with the surrounding soil elements based on different pile geometries. This study investigates the long-term soil response around offshore monopiles using finite element method. The semi-empirical numerical approach is adopted to account for the fundamental features of volumetric strain (terminal void ratio) and shear strain (shakedown and ratcheting), the strain accumulation rate, and stress obliquity. The model is tested with different strain boundary conditions and stress obliquity by relaxing four model parameters. The parametric study includes pile diameter, embedded length, and moment arm distance from the surface. Numerical results indicate that different pile geometries produce a distinct evolution of lateral displacement and stress. In particular, the repetitive lateral load increases the global lateral load resistance. Further analysis provides insight into the propagation of the shear localization from the pile tip to the ground surface.

• Journal of the Korean Geotechnical Society
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• v.25 no.6
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• pp.59-72
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• 2009

The load distribution and deflection of offshore piles are investigated by lateral load-transfer curve method (p-y curve). Special attention is given to the soil-pile interaction and soil resistance of 3D wedge failure mode. A framework for determining a hyperbolic p-y curve is proposed based on theoretical analysis and experimental load test results. The methods for determining appropriate material parameters needed for constructing the proposed p-y curves are presented in this paper. Through comparisons with field case studies, it was found that the proposed method in the present study estimates reasonably the load transfer behavior of pile, and thus, the computed pile responses, such as bending moment and lateral displacement, agree well with the actual measured responses.