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Teng L.,Shanghai University | Teng L.,Shanghai Urban Construction Group Corporation | Zhang H.,Tongji University
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

The process of shield tunneling at Chengdu Metro Line 1 in sandy cobble ground is simulated in meso-scale and marco-scale by laboratory experiment and using particle flow code in 2D (PFC 2D) and finite element software of Plaxis 3D, respectively. The settlement character and failure mechanism driving by earth pressure balance shield (EPBS) in sandy cobble ground are revealed. Based on the comparison of the estimated values from meso and macro simulation results with the in-situ soil settlements and construction parameters, the surface settlement trough and subsidence patterns are approached. The influence of the chamber pressure at the tunnel face and the grouting pressure at the tail gap on the ground surface subsidence are analyzed; and the suitable values for the chamber pressure at the tunnel face and the grouting pressure at the tail gap are suggested. Compared to the grouting pressure, chamber pressure has relatively smaller effect on both the shape of the curve and the maximum surface settlement based on the analysis results. However, much attention should be paid to the chamber pressure, which may have greatly influence on the stability of the tunnel face and result in abruptly collapse in sandy cobble ground due to the effect of arching. Source

Zhou W.,Shanghai Urban Construction Group Corporation
Modern Tunnelling Technology | Year: 2013

An EPB shield with an extra-large diameter of 14.27 m was used for the first time in China in the construction of the Shanghai Bund Channel Project. According to the engineering characteristics, this paper: presents the technical problems concerning the face stability of the extra-large section, excavation under shallow cover, crossing of an adjacent operating metro tunnel and historical buildings; describes in detail the specific design, key construction techniques, and protective measures for the structures; analyzes the impacts on the surrounding environment induced by the extra-large diameter EPB shield driving; and points out the pros and cons of the extra-large diameter EPB shield in comparison to the conventional shield and extra-large diameter slurry shield. In conjunction with the development trends of urban transportation projects in China, the application prospects and directions for the development of extra-large diameter EPB shields in central urban areas are presented. Source

Wu H.,Shanghai University | Wu H.,Shanghai Tunnel Engineering Co LTD | Tang X.,Shanghai Urban Construction Group Corporation
Modern Tunnelling Technology | Year: 2014

The cut-and-cover method is normally used in the construction of works connecting surface roads and underground tunnels, which causes great environmental impacts to the ground. Ground Penetrating Shield Technology (GPST) is an effective way to solve this problem. Based on an experimental project, this paper demonstrates shield tunnel deformation control techniques, such as segment stabilization, synchronous grout control, and improvement of joint stiffness, by analyzing and calculating the influential factors of tunnel deformation. This extends the application of shield tunnelling and provides new ideas for tunnel planning and designing. Source

Zhang Z.,Tongji University | Hu W.,Tongji University | Liu C.,Tongji University | Teng L.,Shanghai Urban Construction Group Corporation
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2013

The creation of ground pass shield tunnelling (GPST) method has conquered the disadvantage of constructing working shaft for shield launching and arrival which is a typical of traditional tunnelling method, and making an innovative turning point on shield tunnelling history. This paper first presents a detail investigation on the key problems of GPST method by adopting large-scale model test, numerical simulation and in-situ monitoring. The surface settlement characteristics of different crossing stages of GPST method have been revealed. In addition, an engineering application of this new method was carried out in Moling-Jiangjun interval of Nanjing intercity fast track; some key tunnelling parameters and effective measures were explored. Comparison was also done between the monitoring data, model test results and numerical results; it is shown a good agreement with each other; and a sound basis is established for the broad application of GPST method. Source

Zhang Z.X.,Tongji University | Liu C.,Tongji University | Huang X.,Tongji University | Kwok C.Y.,University of Hong Kong | Teng L.,Shanghai Urban Construction Group Corporation
Tunnelling and Underground Space Technology | Year: 2016

The paper presents a finite-element analysis of a metro tunnel project using the URUP method in which the shield machine is launched and received at the ground surface level. During the tunnelling process, the cover depth varied from 0.7D (D is the excavation diameter) to -0.3D in which case the shield machine was partially above the ground surface. A three-dimensional finite element model is proposed via the commercial software ABAQUS considering the actual geological condition and tunnelling procedures. Elasto-plasticity constitutive models are utilised for the top three strata in the finite element analysis (FEA). Constant gradients corresponding to material density are assumed for the face supporting pressure and the grouting pressure in the model. The ground contraction method is employed to simulate the shield-induced volume loss. The numerical model is firstly validated against the field measurement data considering the surface settlement. Parametric studies are performed subsequently to investigate the influence of some key tunnelling variables including cover-to-diameter ratio and face supporting pressure on the ground responses. According to the FEA, a critical cover depth of 0.55D is proposed for URUP method below which value instability and collapse of surrounding soils will be highly likely. © 2016 Elsevier Ltd. Source

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