Concrete Pipe Piles Research Articles

Impact of Marine Chloride Ion Erosion Environment on the Durability of Deep Sea Pile Foundation

Yan, Y.; Tian, T., and Wang, B., 2019. Impact of marine chloride ion erosion environment on the durability of deep sea pile foundation. In: Li, L.; Wan, X., and Huang, X. (eds.), Recent Developments in Practices and Research on Coastal Regions: Transportation, Environment and Economy. Journal of Coastal Research, Special Issue No. 98, pp. 6–9. Coconut Creek (Florida), ISSN 0749-0208.Subject to the chloride-induced corrosion, pipe pile foundations will suffer losses of the cross-sectional area of the steel bar, the bond strength between the steel bar and the concrete, as well as its bearing capacity. Even worse, it will malfunction. It is of great engineering significance to explore the corrosion initiation time and evaluate the service life of steel bars in pipe pile foundations under a marine environment. Based on Fick's law, this paper investigates the bilateral diffusion of chloride ions in pipe pile foundations in coastal areas and analyzes how the chloride ion diffusion effect is subjected to some key parameters such as bilateral erosion from chloride ions, mortar and concrete stratification, and temperature. In the end, the service life of prestressed high-strength concrete (PHC) pipe piles withstanding the bilateral diffusion of chloride ions is discussed. The findings show that when the temperature difference between the inner and outer walls of the pipe pile foundations is greater than 15°C, the wall temperature correction factor is quite different. It should be corrected according to the actual service conditions of the pipe pile foundations. Based on the hollow structure of PHC pipe piles, one should consider the simultaneous diffusion of chloride ions from the inner and outer walls and the centrifugal stratification of the pipe pile foundations when designing its service life. The mortar layer thickness and the ambient temperature are dominant factors that the service life of PHC pipe piles will be subject to. If the service year of the pipe pile foundation is 50 years, given the impact of the mortar layer, the thickness of the pipe pile foundation should be greater than 95 mm, and the mortar layer should be less than 10 mm; given the temperature effect, the pipe wall thickness should be greater than 100 mm. If the service year is 100 years, given the impact of the mortar layer, the wall thickness should be greater than 145 mm, and the mortar layer should be less than 25 mm; given the temperature effect, the wall thickness should be greater than 150 mm.

Test study on the load transfer behavior of the composite foundation of pipe-pile with cap & holes

As the vertical reinforcement of composite foundation, the concrete pipe pile is suitable for the treatment of deep soft foundation engineering. In order to explore the working characteristics of the composite foundation of pipe-pile with cap & holes, the model tests have been carried out between the composite foundation of pipe-pile with cap & non-hole and the composite foundation of pipe-pile with cap & holes, which are three arrangements of holes. The working properties of settlement deformation, load transfer and the pile-soil stress ratio of the composite foundation of all piles have been analyzed. The test results show that: (1) the total settlement of composite foundation of pipe pile with cap & holes is smaller than that of the composite foundation of pipe pile with cap & non-holes, and its settlement curve is relatively gentle.(2)The pile axial force and the pile-soil stress ratio of the composite foundation of pipe-pile with holes is slightly less than that of pipe-pile. (3)The pile side frictional resistance and the soil pressure between two pile caps of the pipe-pile with holes is greater than the pipe-pile with cap & non-holes composite foundation.

Engineering Characteristics and Reinforcement Program of Inclined Pre-stressed Concrete Pipe Piles

When it comes to the deep soft soil foundation, improper construction, preloading, and excavation may result in the inclination of the pre-stressed concrete pipe (PCP) piles. Lack of understanding on deformation characteristics may lead to inaccurate reinforcement plan, thereby causing new engineering accidents. This study analyzes an engineering accident induced by the pile inclination, based on which the finite element method model is built. Deformation characteristics of the foundation incorporating inclined PCP piles are investigated, and the reinforcement program involving placement of the pile with opposite inclination is proposed and compared with the conventional reinforcement program using vertical piles. Findings of this study are two-folds: 1) A critical inclination angle affecting the vertical settlement exists, below which the pile inclination has limited effects upon the vertical load bearing capacity of the foundation. 2) The vertical subsidence, the lateral displacement and the bending moment of the reinforcement program based on the reversely inclined pile are all decreased, which helps bear the overburden load and improve stability. In the process of engineering accident treatment, the bearing capacity of PCP piles with small inclination angles can be first reduced according to their inclination angles, followed by judgement that whether these PCP piles meet the requirements on bearing capacity. The PCP piles with large inclination angles must be strengthened, and the reverse inclined PCP piles are recommended.

Model tests on open-ended concrete pipe piles jacked in sand

An experimental study of the performance of concrete pipe piles during installation under different penetration speeds and static load tests on the piles in sand is presented. The applied jacking force, the amount of pile penetration, length of soil plug formed and ultimate bearing capacity were measured during the model tests. The results showed that the concrete pipe piles were partially plugged and the behavior of the soil plug was significantly affected by the penetration speed. The lower the penetration speed, the larger the soil plug formed which in turn leads to a greater ultimate bearing capacity. The size of soil plug can be evaluated by the m value defined as the ratio of the volume of the soil plug to that of the penetrated pile wall. The relationship between the m value and the penetration speeds can be used to estimate the amount of soil plug and the depth of penetration for an open-ended concrete pipe pile jacked into sand.

Static load tests of driven concrete piles under CFRP confinement

ABSTRACT This paper describes compressive static load tests of concrete driven piles confined by Carbon Fibre Reinforced Polymer (CFRP). The tested piles include one concrete pipe pile and one concrete rectangular pile which are all partially confined by CFRP, and other two piles with the same dimensions without CFRP application. Tests program was performed to obtain the behaviours of these composite piles. Four Static Loading Tests (SLTs) were conducted and the results shown that those two types of composite pile demonstrate less vertical displacement with the same loading of traditional concrete piles. Furthermore, the traditional methods of Load-settlement (Q-s) curves, Settlement-lg (Load) (s-lgQ) curves and Settlement-lg (Time) curves are analysed. Due to un-plunging condition, the interpretation methods of Davisson’s, DeBeers, Double-Tangent as well as Chin’s methods are demonstrated for the ultimate bearing capacity of these four piles. It is concluded that the CFRP confinement increased the ultimate bearing capacity and this composite material can be perfectly applied in geotechnical condition.

Impact performance of new prestressed high-performance concrete pipe piles manufactured with an environmentally friendly technique

To satisfy the requirements of energy reduction, environmental protection, and cost reduction, a new environmentally friendly technique of prestressed high-performance concrete (PHC) pipe piles without the high temperature and pressure steam curing step was proposed in this paper. An impact performance test on four PHC pipe piles manufactured with the traditional and new processing techniques was conducted. Five impact levels with the hammer heights of 6.3 m, 4.2 m, 1.6 m, 1.1 m and 0.6 m were considered in the test. The failure modes were presented. The impact force, strain, and energy absorption capacity of two kinds of PHC pipe piles were measured and discussed. Finally, finite element simulations with non-linear code LS-DYNA were performed to further understand the impact response of the pile specimens. It is found that (1) the PHC pipe piles manufactured with traditional and new processing techniques had good impact performance; (2) the impact force and the maximum axial strain increased with the increase of the hammer height (or impact energy); (4) two kinds of pile specimens had similar energy absorption capabilities under impact loadings; and (5) the finite element model can fully simulate the impact performance of PHC pipe piles.

New method to calculate apparent phase velocity of open-ended pipe pile

The apparent phase velocity of open-ended pipe piles after installation is difficult to predict owing to the soil-plug effect. This paper derives an analytical solution to calculate the apparent phase velocity of a pipe pile segment with soil-plug filling inside (APVPSP) based on the additional mass model. The rationality and accuracy of the developed solution are confirmed through comparison with the solution derived using the soil-plug Winkler model and experimental results. A parameter combination of the additional mass model that can be applied to concrete pipe piles used most commonly is recommended. The attenuation mechanism of the soil plug on the APVPSP is clarified. The findings from this study demonstrate that the APVPSP decreases with the mass per unit length of the pile, but has nothing to do with the material longitudinal wave velocity of the pipe pile. The APVPSP decreases significantly as the impulse width increases; however, for pipe piles without soil-plug filling inside, the impulse width has negligible influence on the apparent phase velocity.

Durability and microstructure of steam cured and autoclaved PHC pipe piles

Effects of two different curing regimes (steam curing and autoclaved curing) on durability of pre-stressed high-strength concrete (PHC) pipe piles with fly ash (FA) had been investigated. The chloride penetration, salt and frost resistance performances of PHC pipe piles with these two curing regimes were tested. The results showed that the chloride ion permeability coefficient of steam cured sample at 85 °C for 4.5 h was decreased by 97.13% compared with that of autoclaved one, these steam cured sample could stand 150 times of salts (5% Na2SO4 + 3.5% NaCl solution) corrosion tests and 550 times freeze-thaw tests. The pore structural and micro-cracking analysis of samples with three water to binder ratios (0.21, 0.23, 0.25) revealed that the mean total porosity values of these steam cured sample were about 5%, which was less than half of that of autoclaved samples. The dipping dyeing test showed that the mean micro-cracks width, length and the density of the steam cured samples were less than that of the autoclaved samples. The results supported that by optimizing the mix ratio and curing regime the PHC pipe piles could be prepared with satisfied mechanical and durability performances. So a feasible low-carbon manufacturing technology for PHC pipe piles was provided.

Analysis of Influence of Sand Parameters on Seismic Performance of PHC Piles

In order to study the effect of sand parameters on the seismic behavior of prestressed high-strength concrete (PHC) pipe piles, using the general finite element software ABAQUS6.12, by applying horizontal reciprocating load on the top of the pile, the influence of sand parameters on the seismic behavior of PHC piles under horizontal load is studied. The results show that increasing the relative density of sand increases the degree of hysteresis of PHC pipe pile hysteresis curve and reduces the cumulative hysteresis energy of PHC pipe piles; Increasing the internal friction angle of the sand increases the hysteresis loop area of the PHC pipe pile, and the cumulative hysteresis energy consumption increases; Increasing the initial modulus of sand soil resistance makes the PHC pipe pile stagnation loop shrinkage, and the cumulative hysteresis energy consumption decreases slightly. Increasing the relative density of sand, internal friction angle and initial modulus of soil resistance can increase the overall stiffness of the pile-soil system, increase the horizontal ultimate bearing capacity of PHC piles and reduce the ultimate displacement of PHC piles.

EXPERIMENTAL STUDY ON SHEAR BEHAVIOR OF PRESTRESSED CONCRETE PIPE PILE WITH HYBRID REINFORCEMENT

A total of 7 prestressed concrete pipe piles with hybrid reinforcement (PRC pipe pile) and 3 prestressed concrete pipe piles (PHC pipe pile) were tested, hence the shear capacities of the two kinds of pipe piles were obtained. The influences of non-prestressed steel bars and axial compression were analyzed. It was indicated that introducing non-prestressed steel bars could increase the shear capacities and shear stiffness. Meanwhile, increasing the axial compression force would raise the shear capacities of pipe piles. The tests were simulated by finite element models and the numerical results were in a good agreement with the test results. Based on the obtained test and numerical data, a modified formula for calculating the shear capacities of PRC pipe piles has been proposed, which contributes to the establishment of the technical specification for the design of PRC pipe piles.

Field Performance of Open-Ended Prestressed High-Strength Concrete Pipe Piles Jacked into Clay.

The behavior of open-ended pipe piles is different from that of closed-ended pipe piles due to the soil plugging effect. In this study, a series of field tests were conducted to investigate the behavior of open-ended prestressed high-strength concrete (PHC) pipe piles installed into clay. Two open-ended PHC pipe piles were instrumented with Fiber Bragg Grating (FBG) sensors and jacked into clay for subsequent static loading tests. Soil plug length of the test piles was continuously measured during installation, allowing for calculation of the incremental filling ratio. The recorded data in static loading test were reported and analyzed. The distribution of residual forces after installation and the effect on the bearing capacity were also discussed in detail. The test piles were observed to be in partially plugged condition during installation. The measured ultimate shaft resistance and total resistance of the test piles were 639 and 1180 kN, respectively. The residual forces locked in the test piles after installation significantly affected the evaluation of the axial forces, and thus the shaft and end resistances. It tended to underestimate the end resistances and overestimate the shaft resistances if the residual forces were not considered in the loading test. However, the residual forces did not affect the total bearing capacity of open-ended PHC pipe piles in this study.

Probabilistic Lifetime Assessment of RC Pipe Piles Subjected to Chloride Environments

AbstractThis paper presents a probabilistic approach for evaluating the lifetime of reinforced concrete (RC) pipe piles subjected to chloride environments. A predictive model is developed for model...

Experiment and Numerical Study on Deformation Measurement of Cast-in-Place Concrete Large-Diameter Pipe Pile Using Optical Frequency Domain Reflectometer Technology

The Cast-in-place concrete large-diameter pipe (PCC) pile has been used as the foundation reinforcement and embankment in China due to its low cost and high bearing capacity. The deformation of PCC pile under different vertical loads is very important for the application of engineering. In order to study the deformation characteristics of PCC pile, a small-scale model test was carried out. The new distributed measuring technology, named Optical Frequency Domain Reflectometer (OFDR), was applied to measure the strain on the PCC pile. A single mode fiber (SMF) was used, and the methods of layout, packaging and protection of optical fiber are introduced in detail. The obtained data was dealt with by wavelet transform, and the strain curves were analyzed based on the experiments. The finite element (FE) analysis model was established by COMSOL Multiphysics, and the numerical results compared with the experiment results. It showed that the optical fiber sensor can measure the strain of PCC pile, and that the deformation of PCC pile can be successfully obtained by OFDR technology. The strain of the pile decreases with depth and increases with loading. The measured result agrees well with numerical simulation result. The potential application of OFDR technology to PCC pile in situ and PCC energy pile is discussed.

Investigation on the thermal response of full-scale PHC energy pile and ground temperature in multi-layer strata

A thermal response test (TRT) was conducted on a full-scale precast high strength concrete (PHC) pipe pile installed in multi-layered ground, in order to investigate the thermal response of the pile and soils in inhomogeneous ground. The thermal properties of each layer were tested in the laboratory and compared to the estimation from the TRT. The ground temperature evolution was monitored using 4 boreholes around the pile, and the pile temperature distribution was captured from transducers prefabricated in the pile wall. The system thermal conductivity estimated from TRT results was 2.11 W/(m K) which is about 2 times that from the lab test (1.15–1.71 W/(m K)). The comparison with other TRTs suggests that fitting time and heating power may influence the estimated results. The ground temperature response varied along the depth. Comparing the layers, more conductive soil was cooler near the pile but warmer at a distance. Up to 23% difference of temperature increment (1.1 °C) was found. The pile temperature was less influenced by soil stratification but was evidently affected by end effects, which caused a maximum difference of 16% (3.2 °C) from the average temperature increment. The average ground and pile temperature increased by 1.1 °C and 1.5 °C respectively at 37 days after heating. This suggests that an accumulated temperature increase could happen in a cooling-dominated district.

Pile load test of jacked open-ended prestressed high-strength concrete pipe pile in clay

The performance of open-ended piles can be different from that of closed piles due to the effect of soil plugging. This paper presents the results of a large-scale field pile load test conducted on an open-ended pile in clay under static compressive loads. A prestressed high-strength concrete pipe pile with an outer diameter of 400 mm and a wall thickness of 75 mm was instrumented with strain sensors and installed in a marine deposit for static load testing. The measured load-transfer data during pile installation and the pile load test results are reported and analysed. The data show that the pile was in a partially plugged condition during jacking and behaved in a fully plugged mode in the static load test. The measured ultimate shaft resistance and total resistance of the test pile were 659 and 1180 kN, respectively, which were smaller than the values calculated using a previously proposed method. The back-calculated α and β values (as used in the α and β methods) for axial pile capacity in marine deposits were 0·42 and 0·56, respectively.

Pseudo-static low cycle test on the mechanical behavior of PHC pipe piles with consideration of soil-pile interaction

Pre-stressed high-strength concrete (PHC) pipe piles have been widely used in the pile foundations of buildings and bridges which are usually designed elastic based on the capacity design principle. However, when the PHC pipe pile comes to the foundations of Integral Abutment Jointless Bridges (IAJBs), limited ductility might apply in order to accommodate the relatively large deformation demand under the effect of temperature fluctuations or earthquake. The conventional design methods for PHC pipe piles remain in doubt. This paper focuses on low cycle pseudo-static tests on 4 PHC pipe-pile models with various pre-stress levels to gain insight into their mechanical behaviors with consideration of soil-pile interaction. Medium sand was employed in the tests. The details of the experiments are introduced, including design of the models, instrumentation and loading scheme. The testing results indicate that the damages of the PHC pipe piles are mainly concentrated at 4D to 8D of embedded depths. Moreover, the pre-stress level and reinforcement ratio have a significant influence on the failure mode of PHC pipe piles, especially on the distribution of internal force and moment along piles. It is found that the interaction effect of pile-soil strengthens with the pre-stress level which is beneficial to the seismic performance. Furthermore, the backbone of the PHC pipe piles model has four stages: elastic, elastic-plastic, plastic hardening, and failure. It is concluded that PHC pipe piles perform favorably plastic and ductile behavior, and their failure modes are flexural (bending) not brittle (shear). Finally, the PHC pipe pile has an appreciable energy dissipation and deformation capacity, and hence can be used for pile foundations in IAJBs.

Study on Bearing Capacity of Prestressed Pipe Pile Foundation Under Horizontal Load

Background and Objective:Prestressed high strength concrete pipe pile (PHC) shows brittle fracture when subjected to more than its own bearing capacity. Therefore, the non-prestressed steel bar is added to the PHC pipe pile, that is, the mixed reinforced pipe pile (PRC). The mechanical behavior of PRC group piles and PHC group piles under horizontal force is studied, and the bending moment diagram and displacement diagram of the pile body are compared so as to find the weak parts.Material and Method:In this paper, Φ600 pipe piles are chosen, and the PRC pipe piles are made of non prestressed steel bars of the same number as the prestressing steel bars, and the two steel bars are spaced apart. Referring to a specific project of Binhai New Area, the geological parameters are used, and the force analysis of group piles under horizontal force is carried out by using the ANSYS software.Results:ANSYS simulation results show that, under the horizontal loading, when the number of piles in group piles is different, the locations of maximum bending moments are different. Increasing the number of the PRC pipe pile with non prestressed reinforcement can effectively reduce the maximum bending moment of the pile body.Conclusion:Under horizontal load, with the increase of pile number and the pile cap aggrandizement, the position of maximum moment of pile body is shifted from 5-8 times diameter of pile to the top of pile. When the pile number reaches a certain amount, the maximum bending moment will appear at the joint between the pile cap and the pile body. At the same time, increasing the non prestressed steel bar does not influence the bending moment, and the reinforcement of the pile cap and the pile top should be strengthened.

Time-dependent lateral bearing behaviour of corrosion-damaged RC pipe piles in marine environments

Chloride-induced steel corrosion is one of the major causes of the premature deterioration of reinforced concrete (RC) pipe piles in marine environments, inducing the degradation of the long-term resistance of RC pipe piles subjected to lateral loading. It is essential to conduct systematic research on the deterioration law of the lateral bearing behaviour of RC pipe piles in marine environments. In the present study, a mathematic model is developed to describe the chloride diffusion into an RC pipe pile. A time-dependent reinforcement corrosion model is adopted to simulate the reinforcement corrosion process in an RC pipe pile. In addition, the relationship between the degradation coefficient of the pile stiffness and the corrosion loss is established based on the experimental investigation. Based on the fitting relationship, the attenuation law of the pile stiffness of corrosion-damaged RC pipe piles in marine environments is investigated. The time-dependent lateral bearing behaviour of corrosion-damaged RC pipe piles in marine environments is investigated using the finite difference method. The analysis results demonstrate that the lateral bearing behaviour of RC pipe piles in marine environments has obvious time-varying characteristics. The pile stiffness decreases nonlinearly with the increase in exposure time. The degradation coefficient of the pile stiffness reduces to 0.32 and 0.30 for Ca=Cb=4.5kg/m3 and Ca=Cb=9.0kg/m3, respectively, for an exposure time of 90years. The maximum negative shear force and lateral deflection increase with the increase in exposure time, whereas the bending moment decreases with the increase in exposure time.

Reply to the discussion by Zhang et al. on “Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles”

Reply to the discussion by Zhang et al. on “Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles”

Discussion of “Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles”

Discussion of “Field study of residual forces developed in pre-stressed high-strength concrete (PHC) pipe piles”