Effect of foam conditioning on performance of EPB shield tunnelling through laboratory excavation test

2021 ◽  
pp. 100692
Author(s):  
Hyobum Lee ◽  
Dae-Young Kim ◽  
Dahan Shin ◽  
Jaehyun Oh ◽  
Hangseok Choi
Keyword(s):  
Shield Tunnelling ◽  
Epb Shield

scholarly journals Numerical Simulation of EPB Shield Tunnelling with TBM Operational Condition Control Using Coupled DEM–FDM

2021 ◽  
Vol 11 (6) ◽  
pp. 2551
Author(s):  
Hyobum Lee ◽  
Hangseok Choi ◽  
Soon-Wook Choi ◽  
Soo-Ho Chang ◽  
Tae-Ho Kang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Tunnel Boring Machine ◽  
Chamber Pressure ◽  
Screw Conveyor ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Operational Conditions ◽  
Shield Tunnelling ◽  
Epb Shield

This study demonstrates a three-dimensional numerical simulation of earth pressure balance (EPB) shield tunnelling using a coupled discrete element method (DEM) and a finite difference method (FDM). The analysis adopted the actual size of a spoke-type EPB shield tunnel boring machine (TBM) consisting of a cutter head with cutting tools, working chamber, screw conveyor, and shield. For the coupled model to reproduce the in situ ground condition, the ground formation was generated partially using the DEM (for the limited domain influenced by excavation), with the rest of the domain being composed of FDM grids. In the DEM domain, contact parameters of particles were calibrated via a series of large-scale triaxial test analyses. The model simulated tunnelling as the TBM operational conditions were controlled. The penetration rate and the rotational speed of the screw conveyor were automatically adjusted as the TBM advanced to prevent the generation of excessive or insufficient torque, thrust force, or chamber pressure. Accordingly, these parameters were maintained consistently around their set operational ranges during excavation. The simulation results show that the proposed numerical model based on DEM–FDM coupling could reasonably simulate EPB driving while considering the TBM operational conditions.

Laboratory tests on conditioning the sandy cobble soil for EPB shield tunnelling and its field application

2020 ◽  
Vol 105 ◽  
pp. 103512
Author(s):  
Qianwei Xu ◽  
Lianyang Zhang ◽  
Hehua Zhu ◽  
Zhengyu Gong ◽  
Jianguo Liu ◽  
...  
Keyword(s):  
Laboratory Tests ◽  
Field Application ◽  
Shield Tunnelling ◽  
Epb Shield

scholarly journals Deformation Characteristics of Existing Twin Tunnels Induced by Double Shield Undercrossing with Prereinforcement: A Case Study in Hangzhou

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Xinjiang Wei ◽  
Mobao Zhang ◽  
Shaojun Ma ◽  
Chang Xia ◽  
Xingwang Liu ◽  
...  
Keyword(s):  
Soft Soil ◽  
Earth Pressure ◽  
Plain Concrete ◽  
Horizontal Displacement ◽  
Shield Tunnel ◽  
Deformation Characteristics ◽  
Pressure Balance ◽  
Concrete Wall ◽  
Shield Tunnelling ◽  
Epb Shield

This paper is based on the case of the earth pressure balance (EPB) shield tunnelling project of the new Metro Line 2 undercrossing the existing Metro Line 1 in the soft soil urban area of Hangzhou. Because the EPB shield must break through a plain concrete wall before undercrossing the existing tunnels, the pipe roof prereinforcement was adopted to stabilize the soil between the existing tunnels and the new shield tunnel. The deformation characteristics of the existing tunnels in the process of double shield undercrossing were discussed. According to the variation of shield position, the settlement development could be divided into three stages: shield approaching subsidence, shield crossing heave, and shield leaving subsidence. The horizontal displacement shows a back and forth variation characteristic consistent with the direction of shield tunnelling. At the junction of tunnel and station, the shield undercrossing caused considerable differential settlement between the existing tunnel and the station. The construction of pipe roof prereinforcement will lead to the presettlement of the existing tunnels. The settlement of the existing tunnels caused by the attitude deviation of pipe roof and grouting disturbance should be reduced in reasonable ranges. In addition, the maximum longitudinal settlement of the existing tunnel during the shield second undercrossing was also discussed. It was considered that the influence of wall breaking is greater than the sequence of shield undercrossing. The driving parameters of shield tunnelling should be optimized before the second crossing.

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