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Wang C.,Tongji University | Ding W.,Tongji University | Zhou L.,Rail Transit Development Co. | Tang Z.,Tongji University | Tang Z.,Wuhan University
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2013

Experiment on rheological properties of (3)2 silty clay layer under complex stress state of different consolidation methods and different loading methods was carried out by setting principal axis of stress in horizontal and vertical directions. And rheological model was identified based on the unified rheological theory and generalized Kelvin model was derived under triaxial stress state. It was feasible to fit experimental curves with the method of least-squares and analyze model parameters under different stress states. The results show that the rheological properties of (3)2 silty clay layer can be described with generalized Kelvin rheological model, but the parameters of generalized Kelvin model are different with different consolidation methods and loading methods. Parameters of rheological model under complex stress state are related not only to stress level, but also confining pressure and loading method. The model parameters of isobaric consolidation are smaller than that of K0 consolidation, and the model parameters of horizontal loading are bigger than that of vertical loading. It means that rheological properties are obvious for isobaric consolidation and vertical loading. This can be used to provide rheological model and model parameters for calculating rheological deformation of silty clay under different stress states. Source

Feng L.-P.,Rail Transit Development Co. | Zheng Y.-L.,Tongji University | Deng S.-X.,Tongji University | Li W.-X.,Tongji University
Yantu Lixue/Rock and Soil Mechanics | Year: 2015

In contrast to the high demands and fast development of shield tunnels, significant deficiencies exist in the shield tunneling techniques and theoretical researches for large-scale deep tunnels, and especially under hydraulic conditions, the issues related to the stability of the deep shield tunnel face become even more prominent. Based on the upper bound limit analysis and the unified parameters of water and earth pressures, the face stability of tunnel in the homogeneous soil is studied with considering the effect of water pressure. A three-dimensional log-spiral failure model of the deep shield tunnel face is designed; and then an equation for calculating the limit support pressure is developed. Based on the soil thickness-weighted average method, the developed theoretical procedure is applied to evaluate the face stability of tunnel in multilayered soils. The limit support pressure of the face in the Shanghai Yangtze River tunnel is determined with the proposed upper bound limit method of three-dimensional log-spiral failure mode. The calculated results are compared with the previous studies and the simulated results. Through this research, the calculation methods of the limit support pressure of deep shield tunnel face under hydraulic condition can be improved, providing a theoretical basis for the determination of the reasonable support pressure during the construction of shield tunnel. ©, 2015, Academia Sinica. All right reserved. Source

Zhang Y.-J.,Tongji University | Zhang Y.-J.,Anhui Transport Consulting and Design Institute Co. | Ding W.-Q.,Tongji University | Dong G.-H.,Rail Transit Development Co. | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The comprehensive understanding of deformation and mechanical behavior of retaining structures under water-earth pressures is of paramount importance for the design of deep excavations. However, there is a certain error between the measured and theoretical pressures. The error induced by various factors affects the security and stability of retaining structures. The Residential Square Station is a representative project of Wuxi Metro Line 1. The variation law of water-earth pressures during the construction process is studied through the analysis of the measured data. The results have guiding significance for similar projects in Wuxi. Source

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