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Zhu X.-R.,Zhejiang University | Wang S.-Z.,Zhejiang University | Ye J.-N.,Ningbo urban rail transit project construction headquarters | Wang W.-J.,Zhejiang University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

By analyzing the data of O-cell pile testing, new load transfer models before and after post grouting are proposed. The precise conversion method used to load-settlement curve transformation under the O-cell pile testing method is improved, and the influence of continuity of soil on the settlement is considered. The rationality of the proposed models is shown by the practical engineering. Further analysis shows that the the influence of continuity of soil on the settlement of super-long piles is strong, the ultimate bearing capacity with considering the continuity of soil is less than that without, and the improved method is safer.

Xu P.,Zhengzhou University | Tie Y.,Zhengzhou University | Chen B.,Ningbo urban rail transit project construction headquarters
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2015

The lengths of cylindrical cavities were considered as much larger than their diameters, so the isolation of incident plane P1 waves (fast compressive wave) by discontinuous barriers composed of several rows of cylindrical cavities was simplified as a two-dimensional plane problem. The conformal mapping method of complex functions and expansion method of wave functions were adopted, the cylindrical cavities were considered to be of free boundaries, where no stresses exist, and then the theoretical solutions about the complex coefficients of scattering wave potential functions were obtained. By studying the normalized displacement amplitudes, which are expressed as the ratios of displacement amplitudes of soils behind the barriers caused by both the incident and scattering waves to those only by the incident P1 waves, the isolation effects of the barriers composed of one, two and three rows of cylindrical cavities were compared. The results reveal that the isolation effects of barriers composed of several waterproof cylindrical cavities are better than those composed of permeable cylindrical cavities; the isolation effects of barriers composed of several rows of cylindrical cavities on incident P1 waves with higher frequencies are much better than on those with lower frequencies; with the increasing of row number of cylindrical cavities, the vibration isolation effects is obviously improved, and the effective isolation area is obviously increased; as the row number of cylindrical cavities reaches three, the isolation effects at some locations behind the barriers are much better and almost increase to 70%. ©, 2015, Chinese Vibration Engineering Society. All right reserved.

Junneng Y.,Ningbo urban rail transit project construction headquarters
15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability | Year: 2015

Ningbo is located in the southeast coast plain. There are thick, soft soil deposits lying in the sub-ground, which challenges the construction of urban rail transit in this area. A project of Ningbo Rail Transit Line 1 and the soil conditions for the construction site are firstly presented. Then, the excavation engineering designs for the project are summarized from four aspects: the design of building envelope, vertical and horizontal layout of supporting system, underground water dewatering and ground treatment. Simultaneously, the problems occurred in the design are also described. Lastly, the experiences gained from the project are summed up, so as to guide the further subway construction in the area and also provide a reference for the construction of similar project.

Ye J.,Ningbo urban rail transit project construction headquarters
Geotechnical Special Publication | Year: 2010

Due to the complicated construction condition, i.e. formidable natural conditions and complicated geological conditions and the large scale of bay bridges, the design and construction of Hangzhou bay bridge have inevitably encountered numerous obstacles, among which the construction of large scale pile foundation is a crucial one. In this paper, the key technology and countermeasures of construction of large scale pile foundation in rich shallow-buried gas in offshore zone of the south shore beach area are introduced. Deformation of the steel casing pipe and countermeasures project was studied in the pile construction of south and north channels bridge piers. In addition, such technologies as installation of cathode protection, large-sized pile-sinking barge performance and pile-sinking hammer model, are studied in steel-pipe pile foundation construction of water area. The results will serve as a theoretical foundation and guidance for successful construction, operation safety and sufficient durability of Hangzhou bay bridge, and also as a reference for design and construction of other bay bridges in China. © 2010 ASCE.

Ye J.-N.,Ningbo urban rail transit project construction headquarters
Yantu Lixue/Rock and Soil Mechanics | Year: 2010

Based on Biot's dynamic poroelastic theory, a system of rail pad, sleeper, ballast and double layers of transversely isotropic saturated subgrade is proposed, in which the system can be decomposed as a track system and a double layered soil system. Applying the double Fourier transformation technique to the track system and the soil layer system, the governing equation of track-layered transversely isotropic saturated subgrade system is simplified as an eigenvalue problem for solving a 6 order governing equation. The solutions of the dynamic response of track system-double layered transversely isotropic saturated subgrade to train loads are derived in the transformation domain. Numerical results are obtained by using the inverse fast Fourier transform(IFFT); and then the IFFT are used to analyze the influence of the modulus and Poisson ratio of the first and the second layer of soil on the displacement, pore pressure and shear stress. It is shown that there are great influence of the stiffness of soil layers on the dynamic response; and the influence of modulus are greater than that of Poisson ratio. The computational results can serve as a reference for determination of the reinforcement depth in the soft subgrade.

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