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Su Y.,Beijing Railway Construction and Management Co. | Wang G.-F.,Beijing Railway Construction and Management Co. | Zhou Q.-H.,Beijing University of Technology
Journal of Central South University | Year: 2014

An analysis of the stability of large-diameter circular tunnels and ground settlement during tunnelling by a pressurized shield was presented. An innovative three-dimensional translational multi-block failure mechanism was proposed to determine the face support pressure of large-shield tunnelling. Compared with the currently available mechanisms, the proposed mechanism has two unique features: (1) the supporting pressure applied to the tunnel face is assumed to have a non-uniform rather than uniform distribution, and (2) the method takes into account the entire circular excavation face instead of merely an inscribed ellipse. Based on the discrete element method, a numerical simulation of the Shanghai Yangtze River Tunnel was carried out using the Particle Flow Code in two dimensions. The immediate ground movement during excavation, as well as the behaviour of the excavation face, the shield movement, and the excavated area, was considered before modelling the excavation process. © 2014 Central South University Press and Springer-Verlag Berlin Heidelberg.

Du Y.-Q.,Beijing Jiaotong University | Bai M.-Z.,Beijing Jiaotong University | Ni S.-R.,Beijing Railway Construction and Management Co.
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2014

The dynamic finite element coupled model of train-track-subgrade system was established for two CRH3 trains opposite running on the double-track high-speed railway via ABAQUS to analyze the dynamic stress distribution and transfer rule of this system's subgrade under the moving units with different coupling speeds. Results indicate that, dynamic stress distributed along the lateral direction in surface layer and bottom layer of subgrade bed is unsymmetric, but in embankment is symmetric relatively. The dynamic stress attenuates almost linearly when the depth is less than 2.7 m away from the surface of the surface layer of subgrade bed, the value of dynamic stress accounted for about 50% of the maximum stress. The dynamic stress attenuates slowly within 2.7~7.2 m and slowest beyond 7.2 m. The equivalent stress amplitude is lower with the increased of the opposite running units speed beyond 4.5 m depth. The stress distribution of the surface layer of subgrade bed presents to be a double-hump, and the stress reaches its maximum value when the first and second bogie is lateral coaxial respectively. With the speed of opposite running units increasing, the dynamic stress's vibration amplitude also increases, with more durable and harmful influence on the surface layer of subgrade bed.

Guo F.,Beijing University of Technology | Huang J.,CCTEB Civil Defense and Underground Space Institute | Su Y.,Beijing Railway Construction and Management Co. | Bian J.,Beijing University of Technology | Xu Q.,Beijing University of Technology
Beijing Gongye Daxue Xuebao/Journal of Beijing University of Technology | Year: 2014

Cutter and soil structure interaction, muck and segment transport vehicle, shield equipment were the primary cause of shield construction vibration based on field investigation and preliminary test in Beijing metro line shield tunnels. According to the researches of field investigation and numerical simulation, the following conclusions could be drawn: 1) vibration frequency band caused by cutter is wide, and dominant frequency is concentrated in the range of 20~90 Hz; 2) vibration amplitude value caused by supporting vehicles is smaller than other factors, and frequency band of vibration amplitude is concentrated in the range of 0~20 Hz; 3) there is no attenuation in medium high frequency result from the interaction between track and structure. The frequency correspond to vibration amplitude is concentrated in 70~90 Hz. The frequency will drop below 20 Hz when vibration propagates to the earth surface. Vibration incidence is concentrated in the scope of 15 m from tunnel center line. The researches have reference for the vibration induced by shield construction in sand and gravel stratum in Beijing, Chengdu, Shenyang and so on. ©, 2014, Beijing University of Technology. All right reserved.

Li J.,Beijing University of Technology | Too L.,Beijing University of Technology | An J.,Beijing University of Technology | Wang G.,Beijing Railway Construction and Management Co. | Hao Z.,Beijing Urban Construction Design & Research Institute Co.
Modern Tunnelling Technology | Year: 2014

As the Gongzhufen station of Beijing Metro line 10 closely passes under the existing station of line 1 and it required floor settlement of existing station to be no more than 3mm, in this case a new method combining CRD (flat top and straight wall) and multiple pre-struts was firstly proposed and adopted. Based on field monitoring, the paper also studied the deformation characteristics of the existing station, analyzed the reasons for settlement, put up relevant countermeasures and verified the reliability and security of the new method. ©, 2015, Editorial Office of "Modern Tunnelling Technology". All right reserved.

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