Composite Pile Research Articles

Influence of cement-fly ash-gravel pile-supported approach embankment on abutment piles in soft ground

Abutment piles in soft ground may be subjected to both vertical and horizontal soil movements resulting from approach embankment loads. To constrain the soil movements, the soft soil ground beneath the approach embankment is often improved using composite pile foundations, which aim at mitigating the bump induced by high-speed trains passing through the bridge. So far, there is limited literature on exploring the influence of the degree of ground improvement on abutment piles installed in soft soil grounds. In this paper, a series of three-dimensional (3D) centrifuge model tests was performed on an approach embankment over a silty clay deposit improved by cement-fly ash-gravel (CFG) piles combined with geogrid. Emphasis is placed on the effects of ground replacement ratio (m) on the responses of the abutment piles induced by embankment loads. Meanwhile, a numerical study was conducted with varying ground replacement ratio of the pile-reinforced grounds. Results show that the performance of the abutment piles is significantly improved when reinforcing the ground with CFG piles beneath the approach embankment. Interestingly, there is a threshold value of the replacement ratio of around 4.9% above which the effect of CFG pile foundations is limited. This implies that it is essential to optimize the ground improvement for having a cost-effective design while minimizing the risk of the bump at the end of bridge.

Numerical evaluation of pile group effect of a composite group

Pile group effects of a composite pile group that consists of a group of subgroups are investigated based on a series of static pushover analysis with the help of the nonlinear three-dimensional finite element method (FEM). The numerical result suggests that there is an interaction between subgroups as well as an interaction within each subgroup; the former interaction effect is very similar to the latter if the distance between subgroups is normalized with respect to an equivalent pile diameter of each subgroup. A simplified method to estimate pile group effects of a composite pile group is then proposed in which the interaction effects within and between the subgroups are both accounted for using the same P-multiplier approach commonly employed for a pile group. The P-multipliers estimated by the proposed method show a fairly good agreement with those estimated from the FEM analyses.

Lateral Load Analysis of a Composite Pile

Based on the results of full-scale experiments, specifics of the behavior of a single-pile foundation in the form of a pyramidal-prismatic composite pile subject to lateral load have been established. Both "rigid" and "flexible" behavioral schemes were considered. A lateral load analysis procedure for a single-pile foundation in the form of a pyramidal-prismatic composite pile is presented. The calculation accuracy was evaluated by comparing the calculated and experimental data.

Shaft capacity of the pre-bored grouted planted pile in dense sand

The pre-bored grouted planted pile is a new type of composite pile foundation that consists of a precast concrete pile and the surrounding cemented soil. A series of shear tests were conducted in a specific shear test apparatus to investigate the shaft capacity of the different pile–soil interfaces. The test results show that the frictional capacity of the cemented soil–sand interface is controlled mainly by the sand properties, while the strength of the cemented soil slightly influences the interface properties by affecting the normalized roughness coefficient Rn. The frictional capacity of the concrete–sand interface is similar to the frictional capacity of the cemented soil–sand interface, and the existence of mud cake layer virtually hampers the frictional properties of the interface. The maximum skin friction of the concrete–cemented soil interface increases approximately linearly with the increasing cemented soil strength, and the value of the maximum skin friction is much larger than that of the cemented soil–sand interface of identical cemented soil strength, which demonstrates the integrity of the pre-bored grouted planted pile in the load transfer process.

Укрепление береговой линии реки Смоленки с помощью композитных шпунтовых свай

Укрепление береговой линии реки Смоленки с помощью композитных шпунтовых свай

Strength Characteristics of Hollow Prestressed Concrete Filled Steel Tube Piles for Hybrid Composite Piles

Strength Characteristics of Hollow Prestressed Concrete Filled Steel Tube Piles for Hybrid Composite Piles

A simplified nonlinear calculation method to describe the settlement of pre-bored grouting planted nodular piles

The pre-bored grouting planted nodular (PGPN) pile is a type of composite pile foundation that is considered to be environmentally friendly and economical. A simplified approach, which considers the two interfaces of the pile shaft, was proposed to analyze the load-displacement response of a single PGPN pile. An elastic-failure model, based on the shear test results, was used to simulate the shearing behavior of the concrete-cemented soil interface. A hyperbolic nonlinear model, considering the influence of cement paste injection, was created to simulate the behavior between the skin friction and the relative displacement developed along the cemented soil-soil interface. A linear model and a nonlinear model that considers the reduction in the shearing stiffness were used to simulate the PGPN pile base load-displacement responses in a field test and in a model test, respectively. Comparisons between the calculated and measured load-displacement responses revealed relatively good agreement. The proposed approach is thus shown to be efficient and suitable for the analysis of a single PGPN pile embedded in layered soils, and is used to analyze the factors influencing its behavior. Enlarged cemented soil base is considered to be effective in promoting the behavior of a short PGPN pile, while increasing the diameter of cemented soil along the shaft is efficient in promoting the compressive bearing capacity of a long PGPN pile.

Open-face tunnelling effects on non-displacement piles in clay – part 1: centrifuge modelling techniques

A research programme conducted at the University of Cambridge geotechnical centrifuge provided high-quality data on the interaction effects of open-faced tunnelling beneath non-displacement piles in clay. This paper presents details of the novel centrifuge package, including the reinforced composite piles used to measure loads during the centrifuge tests. Attention is particularly drawn to the importance of temperature compensation and the corresponding effect on the model piles. Results from maintained pile load tests conducted in the centrifuge are presented; through photogrammetric techniques, these are compared with data from pile load cells. The results, also compared with analytical t–z power-law modelling of the soil stress–strain behaviour based on triaxial tests, illustrate the importance of modelling the full history of both soil and piles prior to any subsequent tunnelling-induced loading. The experimental results of the simulated tunnelling tests on piles are presented and compared with simple analytical solutions in a companion paper.

Application of extended end composite pile design in pile foundation work

Pre-tensioned, spun, high-strength concrete (PHC) piles are the most commonly used type of pile in South Korea. Approximately 60% of the pile's strength is used in the design bearing capacity, and the rest is simply residing in the ground. Increasing the ground bearing capacity is crucial to reduce waste of the pile strength and to improve efficiency. Extended end (Ext) piles are a new kind of composite pile that can overcome the weakness of PHC piles. This study investigates the behaviour of Ext piles. Through field testing, it is confirmed that the bearing capacity of Ext piles is better than PHC piles by about 35% to 50%. Based on the study findings, the Ext pile design reduces the number of piles by around 38% compared to the PHC pile design through application in a selected construction site. The increased bearing capacity of Ext piles affects both work duration and project cost, which are 25% and 14% decreased, respectively.

Structural Applications of Fiber-Reinforced Polymer (FRP) Composites in Australia and Philippines

Fiber-reinforced polymer (FRP) composites are considered viable alternatives due to their inherent advantages over traditional materials. Their advantages include light weight, high specific strength, high durability, corrosion resistance, chemical and environmental resistance, and low maintenance cost. This innovative material has been globally applied into civil infrastructure. In Australia, the applications include composite pile system and rehabilitation, marine structures, bridge structures and electrical cross-arms. On the other hand, strengthening of bridge and building structures are the common application of fiber composites in the Philippines. This paper presents the recent developments on the application of FRP composites in Australia and in the Philippines. Challenges in the implementation of this material are also presented. It is hoped that with the information revealed in this study, it will gain further application of this innovative material into civil infrastructure here in the Philippines.

Simulation of Vertical Bearing Capacity for PHC-Steel Composite Pile

PHC-Steel Composite Pile is a new kind of piles combined by PHC pile in the upper part and Steel pile in the lower part. PHC-Steel composite pile has the advantages of corrosion resistance and good penetration properties over the traditional piles. However, one of the problem of PHC-Steel composite pile is the determination and computation of the vertical bearing capacity, which is very important for the safety of construction based on the piles. The traditional method can not be applied directly to calculate the vertical bearing capacity and the load transfer mechanisms were not investigated. Therefore, the design of composite pile is lack of mechanism basis. This paper performed simulation research on the PHC-Steel composite pile withe the software FLAC3D, based on geological conditions of the Yangtze River region of Zhenjiang Yangzhong. The vertical distribution of displacement field, the ultimate bearing capacity of pile, the micro strain were simulated by using the FLAC3D finite difference software. The contact between pile and soil were simulated by establishing contact surfaces. The ultimate bearing capacity of PHC- pipe piles was discussed, which provides the basis for design and analysis of PHC- steel pipe composite pile project.

Flexural Performance Evaluation of Hybrid Concrete Filled Fiber Reinforced Polymer Plastic (FRP) Tube Connection

In the construction industries, in order to compensate material disadvantages of existing construction material (concrete, steel, wood, etc.) and satisfy requirements of the structural performance, research on durable and outstanding corrosion resistant fiber reinforced polymeric plastic (FRP) is actively underway. In general, a pile cannot be produced with unlimited lengths because of the size of the manufacturing machine and transportation to construction site. Therefore, the connection of pile and structural integrity of connection should be considered in the pile design. In this paper, hybrid FRP-concrete composite pile (HCFFT) was investigated by focusing on the connection of HCFFT members. The connection capacity of HCFFT was evaluated by the experiment and the finite element analysis. From the results appropriate connection method of HCFFT is discussed.

Bearing Capacity Characteristics of Steel Pipe Piles with Wings installed in Soil Cement Column

The steel pipe piles with wings installed in soil cement developed in Japan and Vietnam are composite foundation piles made of steel pipes with wings with foundation improvement pillars in soil cement and spiral wings attached to the shaft intermittently. This composite pile has large vertical and horizontal bearing capacities and is a construction method of foundation piles with consideration of environments with little surplus soil, using steel pipes with small diameters. In this study, several full scale loading tests on steel pipe pile with wings installed in soil cement column are presented, and bearing capacity of the composite pile is studied. Especially, combination effect of soil cement column and steel pipe with wings on bearing capacity performance are discussed. Threedimensional elasto-plastic finite element analysis based on the results of loading tests to help understand this composite pile’s mechanical characteristics is also performed.

単純梁方式曲げ試験によるSC杭の中空部に中詰めした効果の検討

The objective of this study is to examine the concrete filled effect in the hollow part of SC pile in order to improve the deformation performance of pile. In the pile foundation structure, the improvement is prompted, assuming secondary seismic design. But, Study on the deformation capacity of precast concrete pile is not sufficiently advanced. The bending tests of plie are carried out on a daily basis for performance assessment. The purposes of the test is the confirmation of the flexural strength. Therefore, the test data accumulation is not enough to discuss the deformation performance of pile. This study focuses on the SC pile in precast concrete pile. The SC pile is a cylindrically shaped member manufactured by centrifugal casting with concrete placed in the hollow section of a steel pipe. The SC pile is a composite pile that utilizes the merits of concrete with good resistance against compressive forces and steel shell with good resistance to tensile forces. Concrete prevents local buckling of the steel pipe, while the steel pipe constrains concrete; therefore, the SC pile has excellent flexural bearing capacity and deformation capacity. This study examined effects of some parameters for deformation performance of the SC pile by the simple beam bending test. Four parameters are set for the test. The parameters are 1) Loading method, 2) Steel pipe thickness, 3) Axial force, 4) Infilled material. We observed the failure conditions, relations between the load and the displacement, and relations between the bending moment and the curvature. The knowledge obtained from this study are shown below. 1) Reinforced by infilling the hollow part of the pile with material, the following effects can be expected: prevention of depression of the steel pipe, prevention of flaking or crush of the pile body concrete, and improvement of the bending deformation performance of the pile. It is more effective to use infilled material with high Compressive strength and high Elastic modulus. 2) The results of bending tests of piles, maximum flexural strength and maximum curvature, are influenced by loading method. The results obtained by the one-way cyclic loading are greater than those obtained by the peak-to-peak alternate cyclic loading. Test value obtained by the one-way cyclic loading is on dangerous side as the evaluation of the deformation performance of the pile. Therefore, it is desirable to adopt the peak-to-peak alternate cyclic loading for appropriate evaluation of the deformation performance of the pile. 3) It is effective to increase the thickness of the steel pipe for the improvement of the flexural strength of the pile. But, it is not effective to increase the thickness of the steel pipe for the improvement of the deformation performance of the pile. 4) With respect to the maximum value of curvature, the test value of the standard specimens is not more than the analysis value. The test value of the test specimen that was reinforced with soil cement is about equivalent to the analysis value. The test value of the test specimen that was reinforced with concrete is greater than or equal to the analysis value.

鋼コンクリート複合杭を用いた橋梁拡幅部既設杭基礎の耐震補強

鋼コンクリート複合杭を用いた橋梁拡幅部既設杭基礎の耐震補強

A field study on the behavior of static drill rooted nodular piles with caps under compression

The static drill rooted nodular (SDRN) pile is a new type of composite pile that consists of a precast pile and surrounding cemented soil. Its cost advantages and environmentally friendly construction have been proven in applications in Southeast China. Moreover, the composition of pipe pile and nodular pile is based on the load transfer mechanisms of a pile foundation, which is effective in optimal design. This paper presents a field study on the behavior of SDRN piles under compression. The load-displacement response, axial force, mobilized load of pile cap, skin friction, and tip resistance of the composite pile are discussed. Here, the bilinear base load-displacement model was adopted to analyze the test results. It is found that providing caps on the static drill rooted piles takes full advantage of the static drill rooted method, and drilling and grouting into the soil beneath the cap, which can be considered a type of ground improvement treatment, can increase the bearing capacity of the pile cap; thus, setting a pile cap for this type of piles is recommended. The existence of the caps in the field tests decreased the skin friction of the upper part of pile shaft because of the additional settlement of the surrounding soil, which developed owing to the pressure from the caps. The frictional capacity of the concrete-cemented soil interface was much higher than that of the cemented soil-soil interface. The skin friction of the lower part of the pile shaft was about 1.25 times in clayey soil and 2.0 times in sandy soil compared with the bored pile. It can be concluded that the cemented soil-soil interface of the SDRN pile was probably better than the concrete-soil interface of the bored pile. The test results fitted the first stage curve of the bilinear model well, and it can be supposed that the base soil was strengthened because of the permeation of the cement paste.

Study of Vibration Characteristics about Two-Layered Composite Pile

In this study, two-layered composite piles are made based on the multi-mode coupling principle. The relationship between the bandwidths of 1–3 composites with different thicknesses and those of two-layered composite piles are analyzed by finite element simulation and experimental measurement. The simulation results agree well with the results of the experiment. Change rules for the resonance frequency difference and for the bandwidth of the composite pile are obtained by adjusting the thickness difference of the two composites, and the errors between the simulation and experiment are analyzed.

Erratum: Wave equation analyses of fiber reinforced polymer composite piling (Journal of Composites for Construction (May 2002) 6:2 (88-96))

Erratum: Wave equation analyses of fiber reinforced polymer composite piling (Journal of Composites for Construction (May 2002) 6:2 (88-96))

A Model Test on the Behavior of a Static Drill Rooted Nodular Pile Under Compression

A static drill rooted nodular pile is a new type of composite pile foundation with high bearing capacity, and mud emissions can be largely reduced using the static drill rooted method. This report presents a model test on the behavior of this composite pile in a test box. The load-displacement response, axial force, skin friction, and mobilized base load are discussed in the report; in particular, the force in the cemented soil was investigated based on the measured data. Moreover, the finite element software ABAQUS was used to help investigate this behavior more thoroughly. It was determined that the function of the cemented soil around the pile shaft was different from that at the enlarged pile base; the stress in the cemented soil around the shaft increased suddenly when nearing the pile base; the ultimate skin friction obtained in the model test was larger than that estimated in the field test; and the relative displacement between the precast nodular pile and the cemented soil could be ignored during the loading process, which corresponded to the result of the field test and demonstrated that the nodular pile and cemented soil act as one entity during the loading process.

Research on Integrative Construction Technology of Pile Peripheral Cemented Soil Reinforced Cast <i>In Situ</i> Concrete Stiffness Core Pile

the construction method of the ordinary cemented soil stiffness core composite pile is that the pile peripheral cemented soil and the core pile are constructed at different time, which might lead to the situations as the pile body is broken due to the forced inserting of the core pile into the cemented soil mixed pile after the initial setting time, the neighboring finished pile is damaged due to the compacting effect caused by the reaming construction of the core pile and the failure of effectively transferring the load due to the loose joining of stiffness core pile and the cemented soil whose construction is completed after the initial setting time. This paper aims to overcome the defects of the conventional construction method by introducing a new construction technology, and the construction technology is verified to be reliable through the application in the actual engineering projects and has the advantages that the peripheral soil body is significantly strengthened, the composite pile foundation can effectively overcome the harm as uneven settlement of buildings, so as to ensure the normal usage of the buildings, and the construction technology has excellent economic benefits and is significant for the later construction technology for treating the soft soil foundation.