Numerical Analysis of New Shield Tunnel on Mechanical Behavior of Existing Parallel Tunnel

2012 ◽  
Vol 204-208 ◽  
pp. 1429-1434
Author(s):  
Xue Feng Li ◽  
Shou Ji Du ◽  
Ding Feng Zhang
Keyword(s):  
Numerical Analysis ◽  
Mechanical Behavior ◽  
Safety Concern ◽  
Bending Moment ◽  
Soil Mass ◽  
Shield Tunnel ◽  
Configuration Model ◽  
Tunnel Excavation ◽  
Parallel Tunnel ◽  
Plastic Zones

A three-dimensional numerical analysis was conducted to investigate the effects of a new shield tunnel excavation on the internal forces and deformation induced in an existing parallel tunnel and soil plastic zones around it. Special attention was paid to the influence of relative positions between two tunnels. The results of the analysis show that the relative positions affect the mechanical behavior of the existing parallel tunnel and the soil mass behavior around it. When a new tunnel is driven below or above an existing parallel tunnel, important increments are induced in deformation and bending moment in the lining of existing tunnel at its crown and springline, compared to that of induced by new tunnel excavation in horizontally parallel to the existing one. The plastic zones around tunnels also extend larger when tunnels are driven in vertically parallel than they are in horizontally parallel. For the safety concern, it is concluded that horizontally parallel configuration model between two tunnels should be adopted in practice.

Coupled Numerical Analysis of Tunnel Excavation in Saturated Soft Clay under High Groundwater

2011 ◽  
Vol 368-373 ◽  
pp. 2533-2536
Author(s):  
Hua Yuan ◽  
Hai Tao Wan ◽  
Zhi Liang Zhao
Keyword(s):  
Soft Clay ◽  
Three Dimensional ◽  
Bending Moment ◽  
High Water ◽  
Shield Tunnel ◽  
Deep Soil ◽  
Tunnel Excavation ◽  
Axial Forces ◽  
Reduction Effect ◽  
Saturated Soft Clay

A coupled numerical simulation of a river-crossing shield tunnel excavation in saturated soft clay with high groundwater has been performed using a three-dimensional finite difference model, which takes into account variation of soil permeability with stress, anisotropy of permeability, reduction effect of joints on segment bending stiffness and the hardening process of synchronized grouting material. Groundwater seepage conditions around the tunnel, bending moment, axial forces and strength safety factor of tunnel segment as well as deep soil displacement during tunnel diving are investigated numerically. The analyses provide valuable information concerning the mechanical behavior of tunnel segment and hydrological field in soil around tunnel during advancing. The result also is benefited to control groundwater for river-crossing tunnel in soft clay under high water table.

scholarly journals Effects of Water Inrush from Tunnel Excavation Face on the Deformation and Mechanical Performance of Shield Tunnel Segment Joints

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Tingsheng Zhao ◽  
Wen Liu ◽  
Zhi Ye
Keyword(s):  
Mechanical Performance ◽  
Coupling Effect ◽  
Water Inrush ◽  
Bending Moment ◽  
Sharp Decrease ◽  
Shield Tunnel ◽  
Cross Sectional ◽  
Tunnel Excavation ◽  
Water Head ◽  
Control Criterion

Water inrush from the excavation face often occurs in the current shield construction of metro tunnels. In this study, the discontinuity of shield tunnel lining and the interaction between the tunnel segments, the grouting layer, and the surrounding rock are considered. Based on the 3D nonlinear contact theory, a hybrid model of the shield tunnel is constructed. Considering the fluid-solid coupling effect of water and soil, the influences of different water head differences on the mechanical performance and deformation of segments and joints in the shield tunnel are studied. The water gushing from the excavation face leads to vertical convergence of the cross-sectional area of the shield tunnel, and joint opening and dislocation result in sharp decrease of the waterproof capacity of joints. Meanwhile, the stress in the vicinity of segment joints increases sharply, and local cracks occur in the segment lining. The axial force, shear force, and bending moment in the joint bolt are also significantly increased. Based on the current metro standard and the computational results in this study, an emergency control criterion is put forward by means of controlling the discharge of water: the water head difference over the excavation face is required less than 4.6 M.

Ground Movements in Shield Tunneling and Impacts on Railway Culvert

2014 ◽  
Vol 680 ◽  
pp. 190-193
Author(s):  
Yu Zhuo Jia ◽  
Rui Li
Keyword(s):  
High Speed ◽  
Soil Layer ◽  
Element Model ◽  
Soil Mass ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Tunnel Excavation ◽  
High Speed Railway ◽  
Railway Operation ◽  
Box Culvert

The excavation of the tunnel will inevitably cause the displacement of soil layer, and then further threatens the safety of high-speed railway operation. Under the engineering background of high-speed rail’s box culvert, using the technique of MIDAS/GTS, the establishment is based on 3 d finite element model of tunnel, soil mass and box culvert, to analyze the effects of box culvert settlement that led by shield tunnel excavation. The research indicates that tunnel excavation causes settlement of box culvert to some large extents, the soil mass should be reinforced to ensure the safety of the high-speed railway operations during the shield construction.

Experimental and numerical analysis to identify the performance limiting mechanisms in solid-state lithium cells under pulse operating conditions

2019 ◽  
Vol 21 (41) ◽  
pp. 22740-22755 ◽  
Author(s):  
Mei-Chin Pang ◽  
Yucang Hao ◽  
Monica Marinescu ◽  
Huizhi Wang ◽  
Mu Chen ◽  
...  
Keyword(s):  
Solid State ◽  
Numerical Analysis ◽  
Energy Density ◽  
Lithium Ion Batteries ◽  
Lithium Batteries ◽  
Safety Concern ◽  
Lithium Ion ◽  
Thermal Runaway ◽  
Operating Conditions ◽  
Lithium Cells

Solid-state lithium batteries could reduce the safety concern due to thermal runaway while improving the gravimetric and volumetric energy density beyond the existing practical limits of lithium-ion batteries.

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