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Liu K.,Zhejiang Sci-Tech University | Xie X.,Zhejiang University | Liu H.,Hanjia Design Group of China
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2010

Rigid-flexible-pile composite foundations are a newly developed method for resisting vertical load in deep soft soil. Flexible piles are used to strengthen shallow soft soil, and rigid piles are used to reduce settlement of the foundation. A cushion below the foundation caps is used to redistribute and adjust stresses on the piles and subsoil. The soft soil can also share part of the applied load in the foundation system. This enables the rigid-flexible-pile composite foundation to resist much larger load with less settlement. This paper examines the performance of such a foundation under vertical load. The results show that the stress and load-sharing ratio of the two kinds of pile and subsoil varies with the applied loading, but most of the applied load is shared by the rigid and flexible piles. Settlement of the composite foundation is controlled well, and can satisfy the performance requirements of buildings on deep soft soil. Source

Xie X.-Y.,Zhejiang University | Wu Y.-H.,Hanjia Design Group of China | Jiang W.-D.,Hanjia Design Group of China | Wu J.,Hanjia Design Group of China | Liu K.-F.,Zhejiang Sci-Tech University
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2011

Based on the design practice of a super-tall building crossing metro tunnel, a three-dimensional, elasto-plastic numerical simulation was conducted by using software ABAQUS to investigate the deformation and internal forces of piled raft foundation due to the passage of a metro tunnel. The mohr-coulmb yield criterion was adopted for soil. According to the numerical results, the experiential design was optimized. The numerical results indicate that bending moment of the raft increases due to tunnel excavation. Adjacent piles are bending towards tunnel, and the horizontal deformation of piles in front row is lager than those of rear row. In the same row, deformation of the side pile is larger than that of the middle pile. Furthermore, the variation of internal force and horizontal deformation of piles mainly occur in the zone of three times of embedded depth of tunnel along piles. With the increment of the force of shield construction, the horizontal deformation of piles decreases. Source

Jiang J.,Zhejiang University | Xu Z.-H.,Zhejiang University | Xu L.-F.,Hanjia Design Group of China
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2010

A meso-constitutive model was established in order to analyze the load and the deformation feature of granular material. The core of the model was the stability of the force chain and the kinetics. A force chain composed of three particles of different radiuses was chosen as study object. The relative tangential displacements between the particles and their rotation angles were obtained from the conditions for motor coordination and bending equilibrium by defining the displacement model between particles. Then the expression representing the load and the displacement on force chain was deduced from the energy equation of its buckling deformation according to the thermodynamic theory. Given three particles of same radiuses, the model can match the experimental results obtained by the discrete element method after contrasting and analyzing the reasonability of the model. The changes of each variable were analyzed with the changes of the radiuses of two groups of particles. Results demonstrate that the changing radiuses of particles can greatly influence the force load and the deformation feature. Source

Shen G.-H.,Zhejiang University | Zhang C.-S.,Hanjia Design Group of China | Sun B.-N.,Zhejiang University | Lou W.-J.,Zhejiang University
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2011

The computational fluid dynamics (CFD) methodology is employed to obtain the wind pressures on the inner surface of large hyperbolic cooling towers. The wind pressures on the inner surface of cooling tower, which are induced by the action of outer wind field and self-circulating system due to air temperature difference, are calculated numerically with the k-ε turbulence model and multiphase model, respectively. The distributions of these two parts of wind pressure with respect to height and latitude are then investigated. The resultant wind pressures on inner surface on cooling tower are obtained and their suggestive values are given. Results from this study show that the wind pressures on inner surface induced by the action of outer wind field vary significantly with heights and latitudes, whereas those induced by self-circulating system keep almost unchanged with respect to latitude. If the velocity of outer wind field is small, the wind pressure on inner surface induced by self-circulating system will occupy a certain proportion of the resultant wind pressures, while if the velocity is large, it can be neglected. Source

Sun X.-Y.,Zhejiang University | Xu C.,Hanjia Design Group of China | Wang H.-L.,Zhejiang University | Chu J.-F.,China State Construction Co.
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2012

In order to realize accurate evaluation of the fatigue damage and failure risk for existing bridges which suffering vehicle overloading, fatigue experiments of bridge component with and without carbon fiber reinforced plastics (CFRP) reinforcement were carried out based on vehicle load survey. Three overloading states were simulated, which were general state, serious state and combine state. The capacity after overloading was tested, and the performance parameters, such as section strain, crack pattern, maximum crack width, deflection, were monitored, then the development law of above parameters versus the number of fatigue cycles under overloading were investigated. The experimental results indicate that the capacity cannot be used to refer the service performance of bridge, and a better way to reflect the overloading effect is fatigue damage, which affects the deformation capacity of the bridge structure. The section strain increases with the number of fatigue cycles under low cycle fatigue load. The plane-section assumption is still satisfied approximatively till the end of the fatigue cycle. The fatigue performance of bridge component under overloading should be evaluated using steel rebar strain and mid-span deflection as the main control indexes. Source

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