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This paper presents the results of field tests performed to investigate the installation effects of pre-bored grouted planted (PGP) pile in deep clayey soil. The variation of horizontal soil displacements, excess pore water pressures and lateral soil pressures was measured in the PGP pile installation process. The test results show that the drilling and grouting process induced large horizontal soil displacements in the soil within a radial distance of 2 d (d is pile diameter), and the maximum horizontal soil displacements induced by the drilling and grouting process were smaller than 15.9 mm when the radial distance reached 4–5 d. Moreover, the horizontal soil displacements decreased along the soil layer depth, as the superficial soil layers were of small deformation modulus and lateral soil pressure. The drilling process brought large excess pore water pressures in the soil when the radial distance was less than 3 d, and the excess pore water pressures induced by the drilling stage were all less than 55 kPa when the radial distance reached 4–6 d. The drilling process also induced some lateral soil pressure increases in the soil within a radial distance of 3 d, while the measured maximum lateral soil pressure increases were smaller than 10.9 kPa when the radial distance increased to 4 d. On the whole, the excess pore water pressures and lateral soil pressure increases induced by the installation of PGP pile were much smaller than that induced by the installation of driven PHC pile. Moreover, the horizontal soil displacements, excess pore water pressures and lateral soil pressure increases induced by the installation of PGP pile all recovered rapidly after the installation of pile, as the cemented soil in the pile hole was in liquid state after the drilling and grouting stage. [ABSTRACT FROM AUTHOR]

This paper investigated the installation effects of a driven prestressed high-strength concrete (PHC) nodular pile in deep soft clay through full-scale tests, and the behavior of a driven PHC nodular pile is analyzed based on the field test results. The test results demonstrated that the driven PHC nodular pile installation process induced significant disturbance in the surrounding soil. The excess pore water pressures (Δu) that were induced by the installation of a driven PHC nodular pile were larger than the Δu that were induced by the installation of a driven PHC pipe pile. The driven PHC nodular pile installation caused significant Δu in the soil down to 2 m below the pile base, and the Δu became much smaller in the soil at 4 m below the pile base. The Δu dissipated slowly in the soft clay layers, and the Δu in the surficial soil layers dissipated faster than that in the deep soil layers. The nodules along the PHC nodular pile shaft could increase the pile shaft capacity. The measured shaft resistances of 350(400)-mm PHC nodular piles were 1.17–1.18 times the calculated shaft resistances of 350-mm PHC pipe piles in soft clay layers. [ABSTRACT FROM AUTHOR]

This paper presents a field study on the uplift bearing capacity of a pre-stressed high-strength concrete (PHC) pile embedded in clayey soil, and on the soil around the PHC pile that was treated with cement paste. The PHC pile was inserted into a pile hole filled with cemented soil by its own weight (by gravity), and the soil compaction effect of a conventionally driven pile induced by the installation process was avoided. The test results showed that: the pile head displacement needed to fully mobilize the uplift bearing capacity of the test piles was about 0.1 D (pile diameter); the ultimate skin friction of the PHC pile–cemented soil interface was much larger than that of the cemented soil–soil interface; the PHC pile and the cemented soil around the pile behaved as an integral pile in the load transfer process; and the measured ultimate bearing capacity of the test piles was 0.91–0.94 times the American Petroleum Institute (API)'s proposed values for piles under compression and 0.79–0.80 times the values calculated with the effective stress method for piles under compression. [ABSTRACT FROM AUTHOR]

In order to explore bearing characteristics of a new-type static drill rooted nodular pile foundation (SDRN), which is composed of PHC pile, bamboo joint pile, and cement soils, field tests of three piles were carried out by embedding internal rebar stress gauges to collect test data. The test results show that the SDRN piles were under elastic state and the load-settlement curves changed slowly before reaching the ultimate capacity. As pile head loads increased, the pile shaft frictions developed progressively, and axial forces gradually reduced along pile depths. Taking into account the interaction between the pile, the cement soils, and surrounding soils, a simplified method for calculating settlements and bearing capacity of SDRN piles was proposed. With corresponding parameters, the computing results obtained by the proposed method were compared with the field experimental data, which indicates acceptable agreements; thus, it is concluded that the applicability and predictive capability of the proposed method were verified. [ABSTRACT FROM AUTHOR]

The distribution of temperature in sand soils was measured through laboratory tests, and the temperature influence on friction resistances at the concrete-soil interface was analyzed. Based on the results of laboratory tests, the finite element model was established using the sequential thermal coupling method. The influences of temperature on the bearing characteristics of energy pile were analyzed. The analysis results show that the cyclic temperature will cause additional displacement along pile depth. It is pointed out that if applied vertical loads at energy pile head exceed the value from which nonlinear settlements would be initiated, irrecoverable additional settlement will occur at pile head. Based on the analysis results, a simplified approach was proposed to estimate the zero point of additional displacement along pile shaft and the additional axial pile force. The comparison between the calculated results obtained by the proposed method and that of ABAQUS on single energy pile was given to verify the accuracy of the proposed method. It is shown that reasonable predictions can be obtained without expensive and time-consuming analyses by the proposed method in this paper. [ABSTRACT FROM AUTHOR]

A series of unconfined compressive strength tests of cemented soil and a model test of a pre-bored grouted planted nodular (PGPN) pile were conducted to investigate the effect of cemented soil properties on the behavior of PGPN piles under compression. The load-displacement response, axial force, and tip resistance were measured during the loading process. Several conclusions could be drawn by comparing the results of the present model test with those of a previous test: the compressive bearing capacity of the PGPN pile was enhanced by increasing the cemented soil strength; the ultimate skin friction of the PGPN pile was increased to 1.06-1.36 times when the strength of the cemented soil along the pile shaft increased from 0.706 MPa to 1.21 MPa; the ultimate mobilized base load was increased to 1.42 times when the strength of the cemented soil at the enlarged base increased from 11.10 MPa to 16.02 MPa. [ABSTRACT FROM AUTHOR]

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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. [ABSTRACT FROM AUTHOR]