• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.708-712
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• 2008

Piles and pile foundations have been in common use since very early times. Usually function of piles is to carry load to a depth at which adequate support is available. Another important use of piles is to furnish lateral support and nowadays it is getting highlighted due to the wind load, lateral action of earthquake, and so on. After Broms (1964), many researchers have been suggested methods for estimating lateral capacity of pile. But each method assumes different earth pressure distribution and lateral earth pressure coefficient and it gives confusion to pile designers. Lateral earth pressure, essential in lateral capacity estimation, influenced by pile's behavior under lateral load. Prasad and Chari (1999) assumed the rotation point of pile and suggested an equation of ultimate lateral load capacity. In this study, we investigate the depth of rotation point in both homogeneous soil and multi layered soil, and compare to the estimation value by previous research. To model the pile set up in the sand, we use the chamber and small scale steel pile, and rain drop method. Test results show the rotation point is formed where the Prasad and Chari's estimation value, and they also show multi layered condition affects to location of rotation point to be scattered.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.744-747
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• 2008

In this study, to analyze the rotation point of piles, the laboratory lateral load test was performed. The lateral load bearing capacity is one of the important factor related with structure failure directly. Analyzing rotation point in different soil condition, relative density and stress condition, leads more accurate ultimate lateral bearing capacity. Also, reliability was analyzed about established 예측식 as applying to tapered pile. As a result, the established prediction was suitable to cylider pile, but not to tapered pile.

• Journal of the Korean Geotechnical Society
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• v.25 no.1
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• pp.55-64
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• 2009

One of the important use of piles is to furnish lateral support and nowadays it is getting highlighted due to the increase of skyscrapers, transmission towers, wind turbines, and other lateral action dependent structures. After Broms (1964), many researchers have suggested methods for estimating lateral capacity of pile. But each method assumes different earth pressure distribution and lateral earth pressure coefficient causing confusion on the part of pile designers. Lateral earth pressure, essential in lateral capacity estimation, is influenced by pile's rotational behavior under lateral load. Prasad and Chari (1999) assumed the rotation point of pile and suggested an equation of ultimate lateral load capacity. In this study, we investigate the depth of rotation point in both homogeneous soil and multi layered soil, and compare with the estimation value by previous research. Test results show that measured rotation point and estimated value by Prasad and Chari's equation show good agreement and multi layered condition affects the location of rotation point to be changed.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.104-110
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• 2010

In this study, a series of two-dimensional model test and numerical analysis was carried out to investigate the pile movement due to tunnelling in soft ground. The model test consists of 21 cases according to locations of the pile tip over the centre position of model tunnel. To identify both the pile and ground movements a close-range photogrammetric technique was adopted in the model test. The results from the model test were compared to the two-dimensional finite element analysis using the CRISP program. It was found that the rotation point on the pile was significantly affected by factors such as the offset distance from the model tunnel and the volume loss that occurred during the tunnelling operation.

• Journal of the Korean Geotechnical Society
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• v.32 no.1
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• pp.5-18
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• 2016

In this study, we grasped the resistance state of the back ground which had a notable influence on computing the lateral resistance of the laterally loaded pile group in the homogeneous ground by the model test. Resistance state was grasped as the depth of rotation-point, wedge failure angle, and wedge wing angle. The model experiment is performed by varying the width, spacing and number of piles and the relative density of sand in this study. According to the observation of the rear ground surface deformation of the piles in lateral load, rotation point ratio, wedge failure angle, and wedge wing angle of the front row were similar to those of the middle row; however, those of the back row were relatively smaller. The rotation point ratio, wedge failure angle and wedge wing angle of the piles in parallel were the same as those of a single pile. Based on the model test results, equations for estimation of the rotation-point, wedge failure angle, and wedge wing angle are proposed.

• Journal of the Korean Geotechnical Society
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• v.24 no.8
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• pp.53-60
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• 2008

In this study, various kinds of behavior characteristics such as deformation area zone of back ground, failure angle and rotation point are examined on the laterally loaded single pile in the homogeneous ground through a model test. The main obtained conclusions are summarized as follows; In the back ground of single pile to which the lateral load is applied, failure surface shows almost linear movement characteristics and it is inclined to converge to constant values no matter how the length of pile and the pile head displacement.

• Journal of the Korean Geosynthetics Society
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• v.22 no.3
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• pp.97-103
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• 2023

Recently, research on the lateral resistance of pile foundations has been actively conducted. In experimental studies on the lateral resistance of pile foundations, displacement control or load control methods are used. However, in the case of the displacement control method, the lateral resistance of the pile varies depending on the rate of the load applied to the pile. Therefore, this study seeks to determine the change in lateral resistance of pile foundations according to lateral loading rate through model experiments. The experimental results showed that the lateral resistance of the pile tended to decrease as the lateral loading rate applied to the pile head increased. In order to confirm this, a model experiment of the side change of the ground and pile according to the loading rate was additionally conducted. Through inverse analysis, the change in the depth of the rotation point according to the lateral loading rate was identified. Through the change in the lateral resistance of the pile foundation and the depth of the rotating point according to the lateral loading rate, it was proposed to test the loading rate within 1.5 mm/min during the lateral loading test of the pile.

• Journal of the Korean Geotechnical Society
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• v.33 no.8
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• pp.5-16
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• 2017

When a lateral load is applied to a short pile whose embedded depth is relatively smaller than its diameter, an overturning failure occurs. To investigate the behavior of laterally loaded short piles, several model tests in laboratory scales had been carried out, however the behavior of large moment carrying piles for electric poles, traffic sign and road lamp, etc. have not been revealed yet. This paper deals with the real-scale load tests for 750 mm diameter short piles. To simulate the actual loading condition, very large moment was mobilized by applying lateral loads to the location 8 m away from the pile head. Three load tests changing the pile embedded lengths to 2.0 m, 2.5 m, and 3.0 m were carried out. The test piles overturned abruptly with very small displacement and rotation before the failures. These brittle failures are in contrast with the ductile failures shown in the former model tests with the relatively smaller moment to lateral load ratio. Comparisons of the test results with three existing methods for the estimation of the ultimate lateral capacity show that the method assuming the rotation point at pile tip matches well when the embedded depth is small, however, as the embedded depth increases the other two methods assuming the inversion of soil pressure with respect to rotation points in pile length match better.

• Journal of the Korean Geotechnical Society
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• v.19 no.3
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• pp.53-64
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• 2003

Many transmission towers, high-rise buildings and bridges are constructed near steep slopes and are supported by large-diameter piles. These structures may be subjected to large lateral loads, such as violent winds and earthquakes. Widely used types of foundations for these structures are pier foundations, which have large-diameters with high stiffness. The behavior of a pier foundation subjected to lateral loads is similar to that of a short rigid pile because both elements seem to fail by rotation developing passive resistance on opposite faces above and below the rotation point, unlike the behavior of a long flexible pile. This paper describes the results of several numerical studies performed with a three-dimensional finite element method (FEM) of model tests of a laterally loaded short pile located near slopes, respectively. In this paper, the results of model tests of single piles and pile groups subjected to lateral loading, in homogeneous sand with 30$^{\circ}$ slopes and horizontal ground were analyzed by the 3-D FE analyses. The pile was assumed to be linearly elastic. The sand was assumed to have non-associative characteristics, following the MC-DP model. The failure criterion is governed by the Mohr-Coulomb equation and the plastic potential is given by the Drucker-Prager equation. The main purpose of this paper is the validation of the 3-D elasto-plastic FEM by comparisons with the experimental data.

• Journal of the Korean Geotechnical Society
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• v.25 no.11
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• pp.61-73
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• 2009

In this study, we grasped the resistance state of the back ground which had a notable influence on computing the lateral resistance of the laterally loaded single pile in the homogeneous ground by the model test. In order to grasp a resistance behavior, we have to know the deformation area of the back ground and the side failure angle other than the rotation point of pile and vertical failure angle of back ground which were proposed by Bae & Kim in 2008. We found out in this test the characteristics of the behavior of the back ground in accordance with the shape and size of the pile and ground density. We examined the interrelationship of the relative density of sand, the size and the sectional shape of the pile as well.