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Dai Q.,Hefei University of Technology | Qian D.,Hefei University of Technology | Zhang Z.,Hefei University of Technology | Tong G.,Hefei University of Technology | And 2 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering

Shaking table test on the interaction between the pile group and super highrise building system on liquefiable foundation was conducted to reproduce the liquefaction-induced large deformation of the system in saturated sandy ground. The excess pore water pressure(EPWP) of ground, the natural frequency, the damping ratio, the strain of pile group, the contact pressure at the bottom of pile and the displacement at pile top was calculated and analyzed before and after large deformation. It was shown that the EPWP response in and out of pile group was different. The sand layer liquefied, the natural frequency of pile group decreased and the damping ratio of pile group increased with the raise of peak acceleration. The dynamic response of piles was relevant to both the peak acceleration and the spectral characteristic of earthquake wave. Besides, the peak strain of pile increased upward along pile body so that there were more cracks on the top of pile. The displacement of pile head varied with the seismic behavior. The primary cause of the large deformation of the system was revealed through the phenomenon which two corner piles were pulled up and pressed down alternately under excitation. Consequently, it is effective to improve the anti-seismic capacity of super highrise building-pile group system by strengthening compressive and tensile resistant property of pile and improving the liquefaction conditions of ground. © 2015, Science Press. All right reserved. Source

Liu Y.,Anhui University of Architecture | Liu Y.,Hefei University of Technology | Ding K.,Anhui University of Architecture | Wu Z.,Anhui Institute of Building Research and Design | Ye X.,Hefei University of Technology
2011 International Conference on Multimedia Technology, ICMT 2011

The exhibition hall of Hefei lakeside international convention center is shaped surface space grid and tube truss structure.in order to balance the horizontal force caused by the long span steel roof, the foundation beam with a span of 76.3m adopts bonded prestressed concrete beam, which is the longest span in China. In order to meet the design requirements to ensure the prestressed beams, using strain monitoring system to track and monitor the Strain rate of the prestressed beams and the steel strand. The results show that: For the similar design of prestressed concrete beams in this project, the need to consider calculating the Bearing capacity of the beam and crack computation of the tension before imposing beams prestressed tension; ordinary one end of tensioning prestressed concrete beam method is not suitable for the long prestressed girder which must be used at both ends of tension; the rule of the stress losses is not the same as the conventional prestressed concrete beam, it is necessary to revise the formula to adapt for calculating such long prestressed beams. © 2011 IEEE. Source

Ou X.,Guangxi University | Tang Y.,Guangxi University | Cui W.,Guangxi University | Cui W.,Anhui Institute of Building Research and Design | And 2 more authors.
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering

Indoor experiments were carried out on models with geometric similarity of 1:20 to study h-shaped anti-sliding piles mechanism. The load was applied in steps by a jack, and the moment and deformation patterns of three h-shaped anti-sliding piles with different row spacings and different beam positions were obtained. The pile-soil interaction model of h-shaped anti-sliding pile was established by finite element software ABAQUS; and several design parameters of pile were analyzed and optimized. The results show that the optimal pile row spacing is 5 times pile diameter; the optimal stiffness of connecting beam is 1.5 times of pile; the optimal embedded depth of pile is 3/8 of the length of front row pile. Finally, the conclusions were successfully applied to treatment of an actual landslide in Nanning. Source

Liu H.-X.,Hefei University of Technology | Liu H.-X.,Anhui Institute of Building Research and Design | Liu D.-J.,Hefei University of Technology | Lu Z.-T.,Tongji University | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering

To improve the computational efficiency of low-strain numerical simulation of piles, the variable step staggered grid finite difference method is introduced into the calculation of three-dimensional pile-soil model based on the traditional difference method. By differentiating three-dimensional elastic wave equation and introducing absorbing boundary conditions on the computational model interface, the low-strain numerical simulation of the response of piles is calculated under transient vertical excitating force. The results show that the computational accuracy is guaranteed and the computational process is more flexible and simple because of varied difference grids. The process can also reduce the memory requirements and the computational time. The absorbing boundary which absorbs the incident waves reaching the computational model interface is effective. The proposed method has achieved good effects on fitting low-strain measured curve and numerical simulation of asymmetric defective piles. Source

Zhang J.,Hefei University of Technology | Liu D.-J.,Hefei University of Technology | Geng X.,Hefei University of Technology | Gao Z.-J.,Shenzhen Traffic Construction Engineering Test & Detection Center | And 2 more authors.
Indian Geotechnical Journal

In order to study the low strain numerical simulation of piles, a three-dimensional axisymmetric viscoelastic model is established. The velocity response for transient vibration is obtained by solving the 3-D wave equations. A MATLAB program is compiled via using finite difference method. The correctness and rationality of the numerical calculation are verified by comparing theoretical result with measured curve. The characteristics of velocity response at pile top are shown through analyzing the simulated results with different viscoelastic parameters. A kind of under-reamed pile (named DX pile in China) is calculated numerically while combining with the engineering practice. And the characteristics of wave propagation in DX pile are reflected intuitively in axial plane wave field diagrams. The results have a certain guiding significance for engineering practice. © 2015, Indian Geotechnical Society. Source

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