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Xu Y.,Tianjin Research Institute of Building Science | Zhang J.-X.,Tianjin Research Institute of Building Science | He J.,Tianjin Research Institute of Building Science | Diao Y.,Tianjin University
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

Through theoretical calculation and finite element analysis, the feasibility of applying the planting reinforcing bar technique for static load test of foundation pile is researched. The experiment results show that the requirements of load force is satisfied and deformation of baseplate can be controlled after the planting-bar arranged in accordance with theoretical calculation. In the course of test, the baseplate rising of the edge of test pile side is maximum, farther from the edge of the test pile, the smaller uplift. The incidence of deformation in the test on the floor is the area away from the center of 7 m. Through adjusting the tightness degree of the reinforcing bar before the test, the stress of the reinforcing bar is uniform and the fracture of planting-bar is avoided. Application of planting reinforcing bar technique for static load test is feasible. The method has the advantages in the aspects of simplicity, safety and economy; which is the choice of static load test under special conditions as a new load force. Source


Xu J.,Civil Aviation University of China | He J.,Tianjin Research Institute of Building Science
Advanced Materials Research | Year: 2011

This paper are doing responsive and exploratory test of the pile bearing capacity for squeezing soil. In order to provide the basis for determining the ultimate bearing capacity of the pile foundation for the design and construction units. © (2011) Trans Tech Publications, Switzerland. Source


Xu J.,Civil Aviation University of China | Cheng G.,Civil Aviation University of China | Li B.,Tianjin Research Institute of Building Science | He J.,Tianjin Research Institute of Building Science
Applied Mechanics and Materials | Year: 2011

Pile grouting technology is widely used in engineering to effectively improve the vertical bearing capacity, in this paper; we made a comparative study on the bearing capacity of grouting pile and General pile in Wuqing district Tianjin City. And proving this method can improve the pile bearing capacity, with good effect, and significant economic benefits. © (2011) Trans Tech Publications. Source


Zhang X.,Hebei University of Technology | Li X.,Tianjin Research Institute of Building Science | Zhang M.,Tianjin Research Institute of Building Science | Zheng X.,Tianjin Research Institute of Building Science
Advanced Materials Research | Year: 2011

In foundation, crack width of uplift cast-in-place pile will exceed the limit of code. Reinforcement of piles has to be increased and sometimes the diameter of piles also needs to increase. Thus, reinforcement and crack control of uplift cast-in-place pile and prestressed uplift cast-in-place pile are analyzed by simulation design for the actual working condition. The calculation results show that prestressed uplift cast-in-place pile can not only decrease reinforcing area, but also control effectively the crack width of concrete in pile. © (2011) Trans Tech Publications, Switzerland. Source


Diao Y.,MOE Key Laboratory of Coast Civil Structure Safety | Diao Y.,Tianjin University | Zheng G.,MOE Key Laboratory of Coast Civil Structure Safety | Zheng G.,Tianjin University | And 3 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

For the static uplift pile load tests, the ideal tension condition is that only the tensile load is applied on the pile head. However, in the conventional uplift tests the reaction system can influence the soil surrounding piles. Also, the Osterberg cell test is also different from the ideal pushing condition where only the compressive force is applied on the pile toe, because the Osterber cell can influence the soil surrounding pile via contact soil or reaction pile beneath the pile toe. In this paper, the field pile load tests and FEM simulation are conducted to investigate the pile load tests under different loading conditions. It is found that the capacity of pile in the conventional uplift tests is closed to that in the Osterberg cell test, while the stiffness in the former is higher than that in the later. The Osterberg cell test, the ideal pushing test and ideal uplift test give similar results, which are regarded to be consistent with the characteristics of load transfer and settlement performance of real single tension piles. Therefore, the conventional uplift tests overestimate the stiffness of pile. It is due to the reaction system which transfers the reaction load to the soil surrounding the upper part of pile. On the one hand, the skin friction and the stiffness of the upper part of pile are increased. On the other hand, the reaction load increases the pile-soil relative displacement. For a given settlement of pile head, the practical tension tests can mobilize larger skin friction than the ideal tension tests and hence increases the stiffness of pile as well. Source

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