Time filter

Source Type

Yao Z.,Fujian University of Technology | Yao Z.,Shanghai University | Zhou J.,Shanghai University | Zhang G.,Shanghai University | And 2 more authors.
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2016

Combined with fine measuring equipment, vertical seepage sand piping tests were carried out through a self-designed model slot. The geometry and hydraulic parameters of soils and the particles movement characteristics are obtained during the tests to study the particle grading impact on piping development and to explore the mesoscopic mechanism of piping. In piping type soils, the gradation of movable particles does not affect the final particles loss fraction, while the maximum size and distribution law of loss particles are influenced. Whether the seepage failure occurs or not and the corrosion process are affected greatly by the movable particle content, and the critical content of movable particles and the self-filtering phenomenon should be considered fully. Through the stereo microscope, the self-filtering and self-stabilizing process internal the sand soil with critical content of fine particles is obtained during seepage from the mesoscopic view. It further reveals the interlayer value of D15/d85 resulting from interaction of soil and water is in line with the self-stabilizing gradation characteristics, which leads to the system self-stabilizing, In order to discriminate the seepage failure mode and critical hydraulic gradient magnitude in the case of sand with wide grade distribution and lack of middle size, it is necessary to carry out experimental demonstration for the complex interaction of soil and water, according to the accrual grading feature of engineering soils and the hydraulic conditions based on the traditional judgment formula or experience curves. © 2016, China Water Power Press. All right reserved. Source

Yuan Y.,Chongqing Architectural Design Institute | Jiang T.,Tongji University | Liu F.,Shanghai Xiandai Architectural Design Group
Advances in Environmental Vibration - Proceedings of the 5th International Symposium on Environmental Vibration, ISEV 2011 | Year: 2011

By discussing of several problems encountered in-situ measurement on a section perpendicular to a subway line in Shanghai, some meaningful results related to evaluation and analysis of environmental vibration were obtained as follows: (1) To the same measuring point, the vibration level(VL) analyzed by JGJ/T170-2009 was higher than GB100704988. According to the statistic analysis, the difference of two standards for the measuring points in building was higher than that in tunnel and on ground; (2) Sampling frequency should be 2. 5 times as high as the maximum analysis frequency and approximately equal to the number of 2m. It can avoid distortion induced by data cut off as well as artificial reduction of VL; (3) In process of one-third octave band spectrum (1/3 OCT)analysis, when the sampling time period takes one second, the VL may be zero in some lower 1/3 OCT center frequencies. Longer sampling time is suggested in analysis of 1/3 OCT analysis; (4)The method using overlapping time has little effect on VL. So it is not necessary to use the method of overlapping time. Source

Jiang T.,Tongji University | Yue J.,Shanghai Xiandai Architectural Design Group
Advances in Environmental Vibration - Proceedings of the 5th International Symposium on Environmental Vibration, ISEV 2011 | Year: 2011

A two-dimensional model based on thin layer method (TLM)has been used to analyze the environmental vibration induced by subway in Shanghai and Chengdu. The subway's tunnel was simulated by finite element method (FEM) and the nodes of FEM is coincident with the layer division of TLM. The frequency displacement response functions of ground surface points under action of the displacement at ballast bed were calculated. The vibration level (VL) induced by subway on ground surface with deferent distance away from subway central line was analyzed with measured acceleration time history of ballast bed near rail. Contrasting of calculated results with the measured VL at ground of subway 2# line in Shanghai showed good agreement. The evaluation of vibration reduction effect of the isolation wall and the VL distribution in certain 40 floors building of certain site nearby Chengdu subway 2# line are also analyzed. Source

Cui J.-C.,Tongji University | Cui J.-C.,Shanghai Xiandai Architectural Design Group | Yang L.-P.,Tongji University | Yang L.-P.,Shanghai Xiandai Architectural Design Group | Wu M.-E.,Tongji University
Jianzhu Cailiao Xuebao/Journal of Building Materials | Year: 2013

Uniaxial tensile properties tests of ETFE film were carried out from 20°C to -100°C. The test results show that the stress-strain curve of ETFE film is nearly a continuous curve before the second yield point at low temperature(≤-40°C) while it is two straight lines at normal temperature(20°C). The stress at the first yield point, the strain at the first yield point, the stress at the second yield point and the tensile strength of ETFE film show a nearly linear increase with decreasing temperature. The breaking elongation of ETFE film shows a nearly linear decrease with decreasing temperature. The strain at the second yield point changes a little with decreasing temperature. Compared with that at normal temperature(20°C), the tensile strength of ETFE film has improved greatly and the ductility of ETFE film has decreased obviously at low-temperature. When temperature changes from 20°C to -100°C, the change amplitude of secant elastic modulus of ETFE film is less than 10% and can be ignored for engineering design. Source

Yue J.-Y.,Shanghai Xiandai Architectural Design Group | Yao J.,Shanghai Xiandai Architectural Design Group | Zhou C.,Shanghai Xiandai Architectural Design Group | Pan D.-Y.,Shanghai Xiandai Architectural Design Group | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

Firstly, the design difficulties of differential-settlement control for the foundation of SSRF are described. Secondly, the technology of differential-settlement control with combination of technical measures of reducing settlement for pile foundation and modified settlement calculation method for pile foundation are proposed and studied. Finally, it is demonstrated that the results obtained by the proposed method agree with the measured ones of SSRF, and the measured results meet the strict design criteria for the pile foundation of SSRF. Source

Discover hidden collaborations