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Zhou J.-J.,Zhejiang University | Gong X.-N.,Zhejiang University | Wang K.-H.,Zhejiang University | Zhang R.-H.,ZDOON Building Materials Group
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2015

A series of field tests on static drill rooted nodular piles are conducted to investigate their behavior under tension. A group of destructive field tests are conducted to investigate the load-displacement response of the static drill rooted nodular piles under tension. Moreover, the power function, hyperbolic function and exponential function are used to fit the load-displacement curves of the test piles, respectively. Field tests on the static drill rooted nodular piles instrumented with strain gauges are conducted to investigate their skin friction and mobilized tip resistance. The test results show that the load-displacement curves of the static drill rooted nodular piles under tension are relatively flat, and that the exponential function can be used to fit the curves well. The frictional capacity of the static drill rooted nodular piles is better than that of the bored piles, and the skin friction of the static drill rooted nodular piles is about 1.47~2.11 times that of the bored piles. The existence of the enlarged cemented soil base of the static drill rooted piles can improve the capacity of the tip resistance as well as the frictional capacity of the pile-soil interface close to the enlarged base. ©, 2015, Chinese Society of Civil Engineering. All right reserved. Source


Zhou J.-J.,Zhejiang University | Gong X.-N.,Zhejiang University | Wang K.-H.,Zhejiang University | Zhang R.-H.,ZDOON Building Materials Group | Yan T.-L.,ZDOON Building Materials Group
Marine Georesources and Geotechnology | Year: 2016

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. © 2016, Copyright © Taylor & Francis Group, LLC. Source


Zhou J.-J.,Zhejiang University | Gong X.-N.,Zhejiang University | Wang K.-H.,Zhejiang University | Zhang R.-H.,ZDOON Building Materials Group | Yan T.-L.,ZDOON Building Materials Group
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2015

For investigating the load transfer mechanism of the nodular pile, a model test of the pile was conducted in the model box. The axial force of the nodular pile and the mobilized base load were measured by the strain gauges attached on the pile shaft and the soil pressure sensors underneath the pile base respectively, while the stress in the cemented soil was measured with the help of the Polyvinylchlorid (PVC) pipe on which the strain gauges were attached. The experimental results show that: the function of the cemented soil along the shaft is different from that of the cemented soil at the enlarged pile base; the stress in the cemented soil along the shaft is enlarged suddenly when approaching the pile base, thus the cemented soil at this area should be strengthened in actual projects; the ultimate skin friction of the model pile is larger than the skin friction in the field test, thus the skin friction should be improved by increasing the homogeneity of the cemented soil in actual projects; the theoretical tip displacement-tip load curves of traditional pile foundation can be applied for the nodular pile. ©, 2015, Zhejiang University. All right reserved. Source


Zhou J.-J.,Zhejiang University | Wang K.-H.,Zhejiang University | Gong X.-N.,Zhejiang University | Zhang R.-H.,ZDOON Building Materials Group | And 2 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2014

The static drill rooted nodular pile is a new type of composite pile foundation which consists of precast nodular pile and the cemented soil along the pile shaft. This kind of composite pile has a good bearing capacity, and the mud pollution will largely be reduced in its construction process. A group of experiments were conducted to provide a comparison between this composite pile and the bored pile. The axial force of the nodular pile was measured by the strain gauges attached on the pile shaft to analyze the distribution of the axial force and the skin friction along the shaft; and then a three-dimensional model was built by using the ABAQUS finite element program to investigate the load transfer mechanism of this composite pile in detail. The results of the field tests and ABAQUS simulation showed that: the bearing capacity of the static drill rooted nodular pile is better than that of the bored pile in soft soil area. The settlement of the composite pile is controlled by the precast pile, and the deformation of the precast pile and the cemented soil can be considered as deformation compatibility. The nodes on the nodular pile play an important role during the load transfer process; and the skin friction of the static drill rooted nodular pile is about 1.05-1.10 times of the skin friction of the bored pile in the same soil layer. Source

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