• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03b
• /
• pp.151-158
• /
• 2000

The lateral deformation of one row pile groups was investigated based on analytical study and a numerical analysis. The emphasis was on quantifing the load transfer of pile groups subjected to lateral soil movement. An analytical method to consider pile-soil interaction in weathered soil was developed using load-transfer curve methods. Through the comparative study, it is found that the prediction by present approach is in good agreement with the general trend observed by in-situ measurements.

• Geomechanics and Engineering
• /
• v.21 no.5
• /
• pp.401-411
• /
• 2020

The paper describes the influence of pile reinforcement on the stability of the slope behaviour, and the exploitation of the results of in situ measurements will be conducted. In the second part, a 2D numerical modelling will be conducted by using the finite element code PLAXIS2D; in order to validate the proposed modelling approach by comparing the numerical results with the measurements results carried out on the slides studied; to study the effect of positioning of piles as a function of the shear parameters of the supported soil on the behaviour of the soil. For various shear strength of the soil a row of pile position is found, at which the piles offer the maximum contribution to slope stability. The position of piles is found to influence the safety factor in granular soil whereas it shows a slight influence on the safety factor in coherent soil. The results also indicate that the ideal position for such stabilizing piles is in the middle height of the slope. Comparison of results of present study with literature from publication: indicated that to reach the maximum stability of slope, the pile must be installed with L_x/L ratio (0.37 to 0.62) and the inclination must be between 30° to 60°. Even, after a certain length of the pile, the increasing will be useless. The application of the present approach to such a problem is located at the section of PK 210+480 to 210+800 of the Algerian East-West Highway.

• The Journal of Engineering Geology
• /
• v.16 no.2 s.48
• /
• pp.189-199
• /
• 2006

This paper presents a field study of the stability of slope collapsed during road construction and proposes a reasonable countermeasure if the current slope is unstable. As a result of slope investigation, it was found that the slope includes five tension cracks and the sliding surface is started from the tension crack and propagated the surface soil layer through weathered rock layer. The slope stability analyses are conducted in case of dry and rainfall seasons. The results indicate that the slope is unstable status. A reinforcement method of slope failure should be selected according to the scale of failure. That is, the scale of slope failure, which is classified small, middle and large size determines the reinforcement method of slope. Since the slope interested in this study is large size failure slope, the reinforcement method to control slope failure is selected stabilizing piles, and seed spray and drainage of surface waterare also selected to remain the factor of safety. The SLOPILE (Ver. 3.0) program is applied in order to do stability analysis of slope reinforced by piles. As the result of analysis, the slope reinforced by a row of piles shows the stable state. It is clearly confirmed that the stabilizing of piles can improve the stability of slope.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.1
• /
• pp.117-129
• /
• 2000

This paper discusses the lateral behavior of group pile in homogeneous and non- homogeneous (two layered) soil. In the group pile, the model tests were to investigate the effects on spacing-to-diameter ratio of pile, pile array, ratio of pile spacing, constraint condition of pile tip, eccentric load and ground condition. The group efficiency and lateral deflection induced in active piles were found to be highly dependent on the spacing-to-diameter ratio of pile, number of pile. Lateral bearing capacities in the group piles of fixed tip, in the case of 6D spacing and $3\times3$ array, were 40-100% higher than those in the group pile of free tip. Based on the results obtained, a spacing-to-diameter of 6.0 seems to be large enough to eliminate the group effect for the case of relative density of 61.8% and 32.8%, and then each pile in such a case behaves essentially the same as a single pile. However, in the case of dense sand, it can be estimated that a spacing-to-diameter of 8.0 seems to be large enough to eliminate the group effect. In this study the group efficiency is illustrated in experimental function with spacing-to-diameter, S/D, relative density and number of pile. The distribution of shear force in lead row piles, in the case of 3$\times$3 array group pile, was 41.6-52.4% for 3D spacing and 34-40% for 6D spacing, respectively. The shadowing effect for the parallel direction of lateral loading appears to be more significant than the one for the perpendicular direction of lateral loading.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.4
• /
• pp.109-118
• /
• 2018

Two-row overlap pile wall, currently under development for use in deep excavations, is a novel retaining structure designed to perform itself as a cutoff wall as well as a high-stiffness wall by constructing four overlapping piles arranged in zigzag manner at a time using a tetra-axis auger. This wall has a relatively complex cross-section, compared with other types of pile wall, which would make it difficult to determine design parameters related to cross-section. In this study, a flexural rigidity equation has been derived by analyzing both theoretically and statistically various wall cross-sections with different pile diameters and overlap lengths. The flexural rigidity equation was found to show the maximum error rate of 3%.

• Journal of the Korean Geotechnical Society
• /
• v.36 no.11
• /
• pp.35-49
• /
• 2020

The lateral bearing capacity of the micropile depends on the installed conditions such as number, installation angle and spacing of the pile. Existing research on micropile has been limited to the evaluation of vertical bearing characteristics and suggestion of effective installation methods, and there are few studies on failure mechanisms such as failure mode. And most of the studies on the lateral bearing capacity of micropile are also on the 1-row micropile. Therefore, in this study, a model test was performed to evaluate the behavior and lateral bearing characteristics of a 2-row micropile when the installed conditions such as the installation length, angle, and spacing of the pile were different. As a result of the model test, when the installation angle is θ > 0° (Not cross installation), the lateral bearing capacity of 2-row micropile depends on the spacing of the piles, and the installation angle θ = +30° was the most effective for increasing the bearing capacity. In addition, when the installation angle is θ < 0° (Overlap installation), it depends on the spacing and angle of the pile, and the condition of installation angle θ = -15° was found to be the most effective for increasing the bearing capacity.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.4
• /
• pp.171-181
• /
• 2000

A series of model tests were performed both to investigate the load transfer by soil acrching in fills above embankment pils and to verify of the theoretical analysis. In the model tests, the piles were installed in a row below the embankment and the cap beams were placed on the pile heads perpendicular to the longitudinal axias of the embankment. The space between pile cap beams and the embankment height was focused as the major factors affecting the load transfer in embankment fill. When the embankment fill was higher than the minimum required height, which was about 33% higher than the radius of the soil arch proposed by theoretical discussion in the previous study, not only the soil arching could be developed completely but also the experimental results showed good agreement with theoretical predictions. The portion of the embankment load carried by model pile cap beams decreased with increment of the space between pile cap beams, while it increased with increment of the embankment height. Therefore, to maximize the effect of embankment load transfer by piles on design, the interval ratio of pile cap beams should be decreased under considerably high embankments by reducing the space between cap beams and/or enlarging the width of pile cap beams.

• Journal of the Korean Geotechnical Society
• /
• v.17 no.6
• /
• pp.5-14
• /
• 2001

This paper describes a simplified design method of stabilizing piles based on an experimental tests and an analytical study which can take into account the safety factor of slope and pile spacing. The nonlinear characteristics of the soil-pile interaction for stabilizing piles are modeled by using load transfer method. The interaction factors due to pile spacing and cap rigidity were estimated by using a three dimensional nonlinear finite element approach and laboratory tests. Based on the results obtained, the interaction factors are proposed quantitatively for one-row pile groups with spacing-to-diameter ratios varying far 2.5 to 7.0. The Bishop's simplified method of slope stability analysis is extended to incorporate the soil-pile interaction and determine the safety factor of the reinforced slope. Through the comparative study, it is found that the prediction by present approach is in relatively good agreement with the results of centrifuge tests and field tests and three dimensional finite element analyses.

• Journal of the Korean Geotechnical Society
• /
• v.27 no.7
• /
• pp.47-57
• /
• 2011

The p-y curve has been used to design pile foundations subjected to lateral loading. Although the p-y curve has a large influence on the pile lateral behavior, p-y curves have not been clearly suggested. In this study, the p-y curve of clay was evaluated for drilled shafts in marine deposits by using 3-dimensional numerical analyses. First, the optimization study was performed to properly determine boundary extent, mesh size, and interface stiffness. The numerical modeling in the study was verified by comparing the calculated and the pile loading test results. Then, the p-y curves of single and group piles were evaluated from the parametric study. The selected parameters were pile diameter, pile Young's modulus and pile head fixed condition for a single pile, and pile spacing for group piles. Finally, the p-multiplier was evaluated by comparing the p-y curves of a single pile and group piles. As a result, the p-multiplier at pile spacing of 3D was 0.83, 0.67 and 0.78 for the front, middle, and back row piles, respectively, and showed values similar to those of O'Neill and Reese (1999). For the pile group with pile spacing larger than 60, the group effect can be ignorable.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.1
• /
• pp.131-143
• /
• 2000

Several theoretical analyses are performed to predict the vertical load on embankment piles with cap beams. The piles are installed in a row in soft ground below the embankment and the cap beams are placed perpendicular to the longitudinal axis of the embankment. Two failure mechanisms such as the soil arching failure and the punching shear failure are investigated according to the failure pattern in embankment on soft ground supported by piles with cap beams. The soil arching can be developed when the space between cap beams is narrow and/or the embankment is high enough. In the investigation of the soil arching failure, the stability in the crown of the arch is compared with that above the cap beams. The factors affecting the load transfer in the embankment fill by soil arching are the space between cap beams, the width of cap beams and the soil parameters of the embankment fill. The portion of the embankment load carried by cap beams decreases with increment of the space between cap beams, while it increases with the embankment height, the width of cap beams, the internal friction angle and cohesion of the embankment fill. Thus, the factors affecting load transfer in embankment should be appropriately decided in order to maximize the effect of embankment load transfer by piles.