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, Volume 6 Issue 3 Previous Issue    Next Issue
Civil Engineering
Nonlinear analysis of consolidation with variable compressibility and permeability
ZHUANG Ying-chun, XIE Kang-he, LI Xi-bin
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6(3): 181-187.   https://doi.org/10.1631/jzus.2005.A0181
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Terzaghi gave a theory of soil consolidation based on the effective stress principle, which was derived on several ideal assumptions to get a simplified theory. To avoid the limitations involved in Terzaghi’s theory, many efforts are being made by scholars to solve the problems in practical engineering situations. This paper presents a generalized theory for one dimensional consolidation of saturated soft clay with variable compressibility and permeability. The semi-analytical solution presented here takes into account the well known empirical e-logk and e-logp′(σ′) relations under instantaneous loading. Study of the consolidation behaviors showed that the ratio of Cc and Ck (the slope of e-logp and e-logk respectively) govern the ratio of consolidation. A simulative laboratory investigation with GDS advanced consolidation system was made to analyze the clay consolidation process and compare the results with the semi-analytical solution.
Solution of a rigid disk on saturated soil considering consolidation and rheology
GAO Shao-wu, WANG Jian-hua, ZHOU Xiang-lian
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6(3): 222-228.   https://doi.org/10.1631/jzus.2005.A0222
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The problem of a rigid disk acting with normal force on saturated soil was studied using Biot consolidation theory and integral equation method and the Merchant model to describe the saturated soil rheology. Using integral transform techniques, general solutions of Biot consolidation functions and the dual integral equations of a rigid disk on saturated soil were established based on the boundary conditions. These equations can be simplified using Laplace-Hankel and Abel transform methods. The numerical solutions of the integral equations, and the corresponding inversion transform were used to obtain the settlement and contact stresses of the rigid disk. Numerical examples showed that the soil settlement is small if only consolidation is considered, so the soil rheology must be taken into account to calculate the soil settlement. Numerical solution of Hankel inverse transform is also given in this paper.
Design and research of gymnasium structure in Zhejiang University
WU Kai-cheng, ZHUANG Yi-zhou
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6(3): 237-242.   https://doi.org/10.1631/jzus.2005.A0237
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This paper deals with the issues involved during the design of a complex gymnasium located at the new campus of Zhejiang University. The complexity comes from the gymnasium’s being of three parts: long-span membrane structure, prestressed concrete structure and extraordinarily long tubular steel structure without seams. The paper first presents considerations of the prestress design, followed by analyses of the stress states due to temperature changes and concrete shrinkage. Buckling and postbuckling analyses were performed to determine the load-carrying capacity of the perfect and imperfect tubular steel structure of the inclined arch system, while dynamic relaxation method and general nonlinear finite element analysis were used to carry out shape-finding and stress analyses of the membrane structure respectively. Finally, collated monitoring date was applied to control the construction quality and verify the design parameters. Some useful conclusions are available at the end of the paper.
Physical modelling and scale effects of air-water flows on stepped spillways
CHANSON Hubert, GONZALEZ Carlos A.
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2005, 6(3): 243-250.   https://doi.org/10.1631/jzus.2005.A0243
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During the last three decades, the introduction of new construction materials (e.g. RCC (Roller Compacted Concrete), strengthened gabions) has increased the interest for stepped channels and spillways. However stepped chute hydraulics is not simple, because of different flow regimes and importantly because of very-strong interactions between entrained air and turbulence. In this study, new air-water flow measurements were conducted in two large-size stepped chute facilities with two step heights in each facility to study experimental distortion caused by scale effects and the soundness of result extrapolation to prototypes. Experimental data included distributions of air concentration, air-water flow velocity, bubble frequency, bubble chord length and air-water flow turbulence intensity. For a Froude similitude, the results implied that scale effects were observed in both facilities, although the geometric scaling ratio was only Lr=2 in each case. The selection of the criterion for scale effects is a critical issue. For example, major differences (i.e. scale effects) were observed in terms of bubble chord sizes and turbulence levels although little scale effects were seen in terms of void fraction and velocity distributions. Overall the findings emphasize that physical modelling of stepped chutes based upon a Froude similitude is more sensitive to scale effects than classical smooth-invert chute studies, and this is consistent with basic dimensional analysis developed herein.
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