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

Kou, Hai‐lei; Chu, Jian; Guo, Wei Dong; Zhang, Mingyi

doi:10.1139/cgj-2015-0177

Cited by 40 publications

(16 citation statements)

References 31 publications

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We thank the Discussers for their interest in our paper (Kou et al 2016). We agree that the jacking of adjacent piles could cause a tensile effect when the center-to-center distance between two adjacent piles is small.

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confidence: 56%

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

et al. 2017

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We thank the Discussers for their interest in our paper (Kou et al. 2016). We agree that the jacking of adjacent piles could cause a tensile effect when the center-to-center distance between two adjacent piles is small. However, as this is not the case for our study as pointed out by the Discussers (Zhang et al. 2017), this question is irrelevant. As explained in the paper, residual forces are usually caused by pile compression, rebound of the soil at the pile base, and the soil strength recovery after installation. If the distance between adjacent piles is small, the tensile effect caused by the installation of adjacent piles will push the pile upward and reduce the residual forces in the pile.We were well aware of the temperature effect on the wavelength of fiber Brag grating (FBG) strain sensors during monitoring. It was for this reason that the field tests presented in the paper were conducted in June and July where the temperature variation was small during the day.In the paper, residual force refers to the compressive force caused by the elastic compression of the pile. This elastic compression is mainly caused by jacking force, shaft resistance, and base resistance. The jacking force plays a key role during the process. After installation, the pile recovers from the elastic deformation. There are two types of forces preventing the pile recovering from the elastic deformation after installation. One is the shear force between the soil and pile, which is enhanced due to the dissipation of excess pore-water pressures. The other is the additional downward force caused by the settlement of the ground, which is also caused by the dissipation of pore-water pressures. Note that the additional downward force can prevent the pile from recovering from the elastic deformation. If the additional downward force causes the residual forces to increase, it means that the deformation caused by the additional downward force is larger than the initial elastic deformation. However, this is almost impossible because the force that caused the initial elastic deformation is larger than the additional downward force. Therefore, for a pile after installation, residual forces would decrease until the recovering force, shear force, and additional downward force reach an equilibrium state.The measured base resistance presented in the paper included both annulus resistance of the pile base and soil plug resistance. Figure 4 in the paper shows the arrangement of strain sensors along the test pile. Note that the inner diameter of the test pile was only 250 mm and thus it was difficult to install strain gauges inside the pile. To measure the annulus resistance of the pile base and the soil plug resistance separately, double-walled pile systems have been used for open-ended steel pipe piles in calibration chambers (e.g., Lehane and Gavin 2001;Paik et al. 2003) and in the field (e.g., Ko and Jeong 2015). However, the double-walled pile method is not applicable to concrete piles as the wall thickness is significantly larger than steel pipe ...

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

et al. 2017

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“…With the development of marine economy and high-speed traffic engineering in the 21st century, offshore engineering and high-speed railways and expressways, which can bear complicated loads such as wind, wave, and traffic for a long time, have put forward higher requirements for pile foundations [5][6][7][8]. Prestressed high-strength concrete (PHC) pipe pile has been widely used for its advantages of convenient construction, high bearing capacity, reliable quality, and short molding and curing time [9,10]. Plie jacking produces less noise and vibration, less air pollution, and does not affect the surrounding environment.…”

Section: Introductionmentioning

confidence: 99%

Field Test of Excess Pore Water Pressure at Pile–Soil Interface Caused by PHC Pipe Pile Penetration Based on Silicon Piezoresistive Sensor

Wang

Liu

Zhang

et al. 2020

Sensors

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Prestressed high-strength concrete (PHC) pipe pile with the static press-in method has been widely used in recent years. The generation and dissipation of excess pore water pressure at the pile–soil interface during pile jacking have an important influence on the pile’s mechanical characteristics and bearing capacity. In addition, this can cause uncontrolled concrete damage. Monitoring the change in excess pore water pressure at the pile–soil interface during pile jacking is a plan that many researchers hope to implement. In this paper, field tests of two full-footjacked piles were carried out in a viscous soil foundation, the laws of generation and dissipation of excess pore water pressure at the pile–soil interface during pile jacking were monitored in real time, and the laws of variation in excess pore water pressure at the pile–soil interface with the burial depth and time were analyzed. As can be seen from the test results, the excess pore water pressure at the pile–soil interface increased to the peak and then began to decline, but the excess pore water pressure after the decline was still relatively large. Test pile S1 decreased from 201.4 to 86.3 kPa, while test pile S2 decreased from 374.1 to 114.3 kPa after pile jacking. The excess pore water pressure at the pile–soil interface rose first at the initial stage of consolidation and dissipated only after the hydraulic gradient between the pile–soil interface and the soil surrounding the pile disappeared. The dissipation degree of excess pore water pressure reached about 75–85%. The excess pore water pressure at the pile–soil interface increased with the increase in buried depth and finally tended to stabilize.

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“…A number of field and model tests were conducted to study the effect of soil plugging on the behaviour of open-ended piles jacked into sand [12]. Kou et al [13,14] revealed that the loading-settlement behavior was closely related to the development of soil plugs. Yu and Yang [15] compared major open-ended pipe pile design methods and proposed the Hong Kong University (HKU) method to estimate the end bearing capacity of open-ended steel piles in sand based on the Imperial College Pile (ICP) and the University of Western Australia (UWA) methods [16,17].…”

Section: Introductionmentioning

confidence: 99%

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

Kou

Diao

Liu

et al. 2018

Sensors

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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.

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

Cited by 40 publications

References 31 publications

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”

Field Test of Excess Pore Water Pressure at Pile–Soil Interface Caused by PHC Pipe Pile Penetration Based on Silicon Piezoresistive Sensor

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

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