scholarly journals Three-Dimensional Discrete Element Analysis on Tunnel Face Instability in Cobbles Using Ellipsoidal Particles

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3347
Author(s):  
Chao Liu ◽  
Liufeng Pan ◽  
Fei Wang ◽  
Zixin Zhang ◽  
Jie Cui ◽  
...  
Keyword(s):  
Model Test ◽  
Discrete Element ◽  
Soil Disturbance ◽  
Triaxial Tests ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Element Analysis ◽  
Micro Scale ◽  
Dem Simulations

Soil disturbance has always been the major concern in shield tunneling activity. This paper presents the investigation on the micro-scale responses of the soils during shield tunnel excavation in sandy-cobble stratum. The code paraEllip3d is employed in discrete element method (DEM) analysis in which the soils are mimicked as an assembly of ellipsoids. Triaxial tests on the micro-scale responses of cobbles are carried out using the materials sampled from the tunnel face during construction period, and corresponding DEM simulations are performed to calibrate the micro parameters for the ellipsoids. On this basis, the face instability process during the shield tunneling in cobbles is studied using 1 g model test as well as corresponding DEM simulation. The micro-scale responses of cobbles are investigated by triaxial test as well as corresponding DEM simulations. Multiple material responses are discussed in the DEM simulations, including the stress–strain relationship, the contact distribution, and the force chain evolution in the elementary and model test. Finally, the mechanism of tunnel face instability in cobbles are discussed on the basis of aforementioned investigations.

Analysis of Soil Disturbance by Shield Tunneling

2013 ◽  
Vol 734-737 ◽  
pp. 502-506
Author(s):  
Meng Lin Xu ◽  
De Shen Zhao
Keyword(s):  
Numerical Simulation ◽  
Soil Disturbance ◽  
Technical Support ◽  
Surface Subsidence ◽  
Stress Redistribution ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Soil Deformation ◽  
Shield Tunneling ◽  
Induced Stress

The shield tunneling will be bound to disturb surrounding strata, induced stress redistribution in soil, soil deformation and surface subsidence. We analyzed characteristics of soil disturbance by shield tunneling with numerical simulation. To provide technical support for the future urban shield tunnel construction. It shows practically significant in studying shield tunnel construction.

In Situ Study on Soil Disturbance Induced by Shield Tunneling in Tianjin

2013 ◽  
Vol 368-370 ◽  
pp. 1674-1677
Author(s):  
Yong Hua Cao ◽  
Xiao Qiang Kou
Keyword(s):  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Soil Disturbance ◽  
Ground Settlement ◽  
Soil Pressure ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Tunneling Process

In urban environment, the soil disturbance induced by shield tunneling can be sensitive because it can cause deformation of the ground and damage the near structure. To study this disturbance in the construction process of Tianjin metro line No.3, in-situ monitoring of pore water pressure, soil pressure and ground settlement were conducted. The pore water pressure was monitored for the soil around the tunnel. The soil pressure was monitored for the soil around the tunnel and on the tunnel face. It was revealed that the pore water pressure and soil pressure changed twice in the tunneling process and these changes were induced by cutting face and grouting at the shield tail. The soil pressure on the tunnel face reached its maximal value when the distance between the cutting face and the sensor elements was around the diameter of the tunnel. Ground settlement developed in the tunneling process. The shape of ultimate settlement trough is closed to the one obtained by Pecks method.

scholarly journals Investigation on the Influence Caused by Shield Tunneling: WSN Monitoring and Numerical Simulation

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hao Liu ◽  
Jinjiang Shi ◽  
Jiasen Li ◽  
Chao Liu
Keyword(s):  
Signal Transmission ◽  
Monitoring Data ◽  
Shield Tunnel ◽  
Support Pressure ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Wireless Monitoring ◽  
Mems Sensor ◽  
Grouting Pressure ◽  
Transmission Test

Traditional monitoring techniques are faced with the problems of low acquisition frequency and easy to be affected by the construction environment during the shield tunneling, which cannot meet the actual needs of timeliness monitoring of surrounding environmental impact on shield tunnel construction. Based on this actual demand, a wireless sensor network (WSN) system was used to monitor the response of shield tunnel segments and surrounding buildings during the shield tunneling in this study. According to the result of the signal transmission test, an optimization scheme of microelectromechanical system (MEMS) sensor layout is designed to improve the monitoring efficiency of the WSN system. Through the comparative analysis of WSN system monitoring data and traditional monitoring data, it is found that, with the increasing distance between the monitoring section and the tunnel face, the convergence value of tunnel lining clearance gradually tends to be stable, and the wireless monitoring results of transverse clearance convergence of the tunnel in this section are consistent with the overall deformation trend of the convergence gauge monitoring results. This study also simulated the shield tunneling adjacent buildings using a nonlinear finite element method. A parameter sensitivity analysis of the support pressure of the excavation face and the grouting pressure at the tail of the shield is carried out. The results show that the surface settlement can be reduced by properly increasing the grouting pressure and the support pressure of the excavation face. Moreover, increasing the support pressure of the excavation face has a better inhibition effect on the settlement of the surface soil than increasing the grouting pressure.

Three Dimensional Numerical Analysis of Ground Settlement Induced by Shield Tunneling

2012 ◽  
Vol 182-183 ◽  
pp. 937-940
Author(s):  
Zhong Chang Wang
Keyword(s):  
Soil Layer ◽  
Three Dimensional ◽  
Ground Surface ◽  
Vertical Displacement ◽  
Ground Subsidence ◽  
Shield Tunnel ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Maximum Settlement

The fine numerical simulation is used to study the ground settlement of complex stratum owing to shield construction by ANSYS program. It is shown that the closer the distance between soil layer and the axis of tunnel is, the smaller the disturbance of construction is, the obvious the ground surface settlement is. The value of the maximum settlement at the center of the surface is 7.4mm. The maximum settlement of vault is 14mm. The ground subsidence in cross section distribution is shaped of normal distribution. The closer the distance between soil layer and ground surface is, the smaller the vertical displacement is, the bigger the width of settlement trough of soil layers is. The width of settlement trough is 25m. The volume loss rate of shield tunnel is about 0.32%. The width coefficient of ground settlement trough is 0.56. The tendency of ground settlement decrease to become gentle with the advance of shield construction. The ground settlement keeps constant after tunnel face advancing to 30m.

An analysis of three-dimensional ground movements: the Thunder Bay tunnel

1991 ◽  
Vol 28 (1) ◽  
pp. 25-41 ◽  
Author(s):  
K. M. Lee ◽  
R. K. Rowe
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Triaxial Tests ◽  
Soil Parameters ◽  
Tunnel Face ◽  
Element Analysis ◽  
Soft Clays ◽  
Ground Deformations ◽  
Thunder Bay ◽  
Stress Dependent

A three-dimensional (3D) elastoplastic finite-element analysis, which is capable of simulating the advance of a tunnelling shield and the associated ground losses resulting from the tunnelling process, is used to calculate the deformations caused by the excavation of the Thunder Bay sewer tunnel. The soil parameters adopted in the analysis were based on the results determined from stress-dependent triaxial tests. The results of this analysis are compared with the measured soil displacements. Reasonable agreement between the calculated and observed 3D settlement distribution and horizontal displacements at different distances from the tunnel face is reported. This overall agreement for displacements under 3D conditions suggests that the method of analysis may be applicable to design problems involving tunnelling in soft clays similar to that at the Thunder Bay sewer tunnel provided that the soil parameters are reliably determined. Key words: tunnelling, three-dimensional analysis, finite element, elastoplastic displacements, ground deformations, Thunder Bay tunnel.

Numerical Simulation for Surface Displacement of Shield Tunnel Construction under Building Load

2013 ◽  
Vol 405-408 ◽  
pp. 1350-1354
Author(s):  
Hui Ting Zhan ◽  
Hong Yuan ◽  
Jia Yu Wu ◽  
Yu Sen Yuan
Keyword(s):  
Surface Displacement ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
3D Finite Element ◽  
Surface Uplift ◽  
Building Load ◽  
3D Finite Element Method ◽  
Jacking Force

The tunnel construction causes deformation, even damage of the nearby buildings and other types of structures. Using 3d finite element method can simulate the process of shield tunneling construction. The paper studies the influence of different building load on the deformation of soil, when considering different excavation steps in the process of tunnel construction. The results show that the building load has important influence on the surface displacement during the construction of tunnel. With the advancement of excavation, sedimentation tank will move forward and become larger. By the influence of jacking force, the soil and rock in front of tunnel face moves forward and upward, thus forming the surface uplift.

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