• Geomechanics and Engineering
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• v.29 no.4
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• pp.407-420
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• 2022

Embedded piles, which are typically used in Korea, are precast piles inserted into prebored ground with cement paste. Dynamic pile tests tend to underestimate the bearing capacity of embedded piles because of the undeveloped shaft resistance prior to the curing of the cement paste and the insufficient energy transferred after the curing. In this study, a resistance combination method using the base resistance before the cement paste is cured and the shaft resistance after the cement paste is cured is proposed to obtain a combined load-settlement curve from dynamic pile tests. Two pairs of embedded piles with diameters of 600 and 500 mm are installed. Each pair comprises one pile for the dynamic pile test and another pile for the static load test. The shape of the load-settlement curve obtained using the proposed method is similar to that obtained from the static load test. Thus, the resistances evaluated using the proposed method at selected settlements are similar to those obtained from the static load test. This study shows that the resistance combination method may be used effectively in dynamic pile tests to accurately evaluate the bearing capacity of embedded piles.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.435-440
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• 2002

The free vibration of partially embedded piles is investigated. The pile model is based on the Bernoulli-Euler beam theory and the soil is idealized as a Winkler model for mathematical simplicity. The governing differential equation for the free vibrations of such members is solved numerically The piles with one typical end constraint (clamped/hinged/free) and the other hinged end with rotational spring are applied in numerical examples. The lowest three natural frequencies are calculated over a range of non-dimensional system parameters: the rotational spring parameter, the relative stiffness and the embedded ratio.

• Structural Engineering and Mechanics
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• v.28 no.2
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• pp.221-238
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• 2008

Numerical solution to buckling analysis of beams and columns are obtained by the method of differential quadrature (DQ) and harmonic differential quadrature (HDQ) for various support conditions considering the variation of flexural rigidity. The solution technique is applied to find the buckling load of fully or partially embedded columns such as piles. A simple semi- inverse method of DQ or HDQ is proposed for determining the flexural rigidities at various sections of non-prismatic column ( pile) partially and fully embedded given the buckling load, buckled shape and sub-grade reaction of the soil. The obtained results are compared with the existing solutions available from other numerical methods and analytical results. In addition, this paper also uses a recently developed technique, known as the differential transformation (DT) to determine the critical buckling load of fully or partially supported heavy prismatic piles as well as fully supported non-prismatic piles. In solving the problem, governing differential equation is converted to algebraic equations using differential transformation methods (DT) which must be solved together with applied boundary conditions. The symbolic programming package, Mathematica is ideally suitable to solve such recursive equations by considering fairly large number of terms.

• Journal of the Korean Geotechnical Society
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• v.31 no.11
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• pp.5-13
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• 2015

For the bearing capacity evaluation, dynamic pile tests instead of static pile tests have been commonly used in embedded piles, which are known to have low noise and low vibration construction method. The objective of this study is to analyze the bearing capacity and penetration behaviors of embedded piles, which are constructed in different ground conditions, by using force and velocity signals obtained in the final blows during construction of embedded piles. For the dynamic pile analyses, the CAse Pile Wave Analysis Program (CAPWAP) and Wave Equation Analysis of Piles (WEAP) have been commonly used. In this study, the CAPWAP and WEAP are used for the analyses of the dynamic pile tests, which are conducted on embedded piles. The input values, output values, and force-velocity graphs of CAPWAP determined by analyzing the measured force-velocity signals are investigated. In addition, similar force-velocity singals are obtained from the WEAP by analyzing the input values of the WEAP. Considering the subsurface investigation results around the pile tips, if the N-value increases exponentially along the depth, toe quake value should be small, and therefore large bearing capacity is identified. On the contrary, if the N-value increases linearly, the bearing capacity is small because of large toe quake value. Furthermore, the stiffness of hammer cushion and pile cushion, which is difficult to find correct values, is recommended lower than 500 kN/mm. This study demonstrates that the results of WEAP may be similar to those of CAPWAP and the WEAP can be used to estimate the bearing capacity of embedded piles.

• Geomechanics and Engineering
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• v.2 no.1
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• pp.45-56
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• 2010

The current study presents a mathematical model and numerical method for free vibration of tapered piles embedded in two-parameter elastic foundations. The method of Discrete Singular Convolution (DSC) is used for numerical simulation. Bernoulli-Euler beam theory is considered. Various numerical applications demonstrate the validity and applicability of the proposed method for free vibration analysis. The results prove that the proposed method is quite easy to implement, accurate and highly efficient for free vibration analysis of tapered beam-columns embedded in Winkler- Pasternak elastic foundations.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.6
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• pp.155-163
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• 2023

A two-dimensional numerical analysis was performed on the depth of pile embedment, the magnitude of the residual water level, and the condition of the presence or absence of cap concrete to understand the behavior of the block-type quay wall with piles. The results showed the control effect of the lateral displacement of the quay wall depending on the embedment of the pile. When the piles were not embedded, the lateral displacement of the quay wall increased proportionally as the residual water level difference increased. In contrast, when the piles were embedded into the ground, the control of the lateral displacement of the quay wall was greatly exerted even if the residual water level difference increased. There was little difference in the lateral displacement of the block-type quay wall regardless of the presence or absence of cap concrete. Under the condition where the piles were embedded down to the rubble mound layer, the piles exhibited the rotational behavior seen in the short piles. As the embedment depth of the piles increased, the piles showed the same bending behavior as the intermediate piles. Thus, the piles significantly contribute to the control of lateral displacement in the block-type quay wall with piles.

• Journal of Industrial Technology
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• v.26 no.B
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• pp.93-99
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• 2006

Centrifuge model experiments were performed to investigate the confining effects of the sheet piles, installed to the sides of soft clay ground treated with sand compaction piles, on the bearing capacity and concentration ratio of composite ground. For the given g-level in the centrifuge model tests, replacement ratio of SCP and the width of surcharge loads on the surface of ground with SCP, the confining effects of installing the sheet piles on the edges of SCP ground on the bearing capacity, change of stress concentration ratio and failure mechanism were investigated. Kaolin, one of typical clay mineral, and Jumunjin standard sand were used as a soft clay ground and sand compaction pile irrespectively. As results of experiments, lateral confining effect by inserting the model sheet piles fixed to the loading plate was observed. For the strip surcharge loading condition, the yielding stress intensity in the form of the strip surcharge loads tends to increase with increasing the embedded depth of sheet piles. The stress concentration ratio was found not to be influenced consistently with the embedded depth of sheet piles whereas the effect of stress intensity on stress concentration ratio shows the general trend that values of stress concentration ratio are relatively high at the initial stage of loading and tend to decrease and converge to the certain values. For the failure mechanism in the case of reinforced with sheet piles, displacement behavior related to the punching failure, settlement right beneath the loading plate occurred since the soil was confined with sheet piles, was observed.

• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.832-835
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• 2005

The free vibration of tapered piles embedded in soil is investigated. The pile model is based on the Bernoulli-Euler beam theory and the soil is idealized as a Winkler model for mathematical simplicity. The governing differential equations for the free vibrations of such members are solved numerically. The square tapered piles with one free and the other hinged end with rotational spring are applied in numerical examples. The lowest two natural frequencies are obtained over a range of non-dimensional system parameters: the rotational spring parameter, the embedded ratio, the foundation parameter, the width ratio of the contact area and the section ratio.

• Computers and Concrete
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• v.31 no.4
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• pp.359-370
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• 2023

Slime is produced by excavation during the installation of embedded piles, and it tends to mix with the cement paste injected into the pile shafts. The objective of this study is to investigate the strength and stiffness characteristics of cement pasteslime mixtures. Mixtures with different slime ratios are prepared and cured for 28 days. Uniaxial compression tests and elastic wave measurements are conducted to obtain the static and dynamic properties, respectively. The uniaxial compressive strengths and static elastic moduli of the mixtures are evaluated according to the curing period, slime ratio, and water-cement ratio. In addition, dynamic properties, e.g., the constrained, shear, and elastic moduli, are estimated from the compressional and shear wave velocities. The experimental results show that the static and dynamic properties increase under an increase in the curing period but decrease under an increase in the slime and water-cement ratios. The cement paste-slime mixtures show several exponential relationships between their static and dynamic properties, depending on the slime ratio. The bearing mechanisms of embedded piles can be better understood by examining the strength and stiffness characteristics of cement paste-slime mixtures.