scholarly journals Structural Monitoring of Metro Infrastructure during Shield Tunneling Construction

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
L. Ran ◽  
X. W. Ye ◽  
G. Ming ◽  
X. B. Dong
Keyword(s):  
Ground Surface ◽  
Structural Monitoring ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Construction Monitoring ◽  
Infrastructure Monitoring ◽  
Ground Freezing ◽  
Artificial Ground Freezing ◽  
Metro Tunnel ◽  
General Architecture

Shield tunneling construction of metro infrastructure will continuously disturb the soils. The ground surface will be subjected to uplift or subsidence due to the deep excavation and the extrusion and consolidation of the soils. Implementation of the simultaneous monitoring with the shield tunnel construction will provide an effective reference in controlling the shield driving, while how to design and implement a safe, economic, and effective structural monitoring system for metro infrastructure is of great importance and necessity. This paper presents the general architecture of the shield construction of metro tunnels as well as the procedure of the artificial ground freezing construction of the metro-tunnel cross-passages. The design principles for metro infrastructure monitoring of the shield tunnel intervals in the Hangzhou Metro Line 1 are introduced. The detailed monitoring items and the specified alarming indices for construction monitoring of the shield tunneling are addressed, and the measured settlement variations at different monitoring locations are also presented.

scholarly journals Integration of Multiband InSAR and Leveling Measurements for Analyzing the Surface Subsidence of Shield Tunneling at Beijing-Zhangzhou High-Speed Railway

2021 ◽  
Vol 2021 ◽  
pp. 1-24
Author(s):  
Yueguan Yan ◽  
Qian Yang ◽  
Zhihui Jia ◽  
Xiaoyi Zhang ◽  
Huayang Dai ◽  
...  
Keyword(s):  
High Speed ◽  
Ground Surface ◽  
Synthetic Aperture ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Modern Life ◽  
Tunnel Excavation ◽  
High Speed Railway ◽  
Synthetic Aperture Radar Interferometry ◽  
Surrounding Environment

In modern life, metro and high-speed rails have become indispensable transportation and have been playing an important role in many areas, especially in cities. The metro and high-speed rails have varying degrees of impact on the surface and surrounding buildings, which must be carefully understood to minimize the risk of hazards. This work is aimed at investigating the deformation of ground surface and the surrounding structures, caused by the excavation of underground tunnels. Because of the spatiotemporal characteristics of the land subsidence induced by underground tunnel construction, the measurements obtained from InSAR (Synthetic Aperture Radar Interferometry) and leveling techniques are integrated to study the subsidence phenomenon of the ground surface above the shield tunnels and the surrounding buildings. The subsidence-related parameters, including the advance angles, lag angles, and boundary angles, are derived from the deformation results. This study suggests that leveling and InSAR observations can provide technical support to study the subsidence of dense buildings on the surface of shield tunnel excavation and to protect the surrounding environment.

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.

scholarly journals Risk Mitigation and Construction Control for Effective Underwater Recovery of an EPB Shield: A Case Study of the First Metro Tunnel in Tel Aviv

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Weiqiang Qi ◽  
Zhiyong Yang ◽  
Yusheng Jiang ◽  
Zhiyong Liu ◽  
Yinxin Guo ◽  
...  
Keyword(s):  
Risk Mitigation ◽  
Fine Sand ◽  
Diaphragm Wall ◽  
Screw Conveyor ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Shield Tunneling ◽  
Tel Aviv ◽  
Metro Tunnel ◽  
Epb Shield

Shield recovery in water-rich sand strata is a challenging issue in the field of shield tunnel engineering, especially when the end of the shaft cannot be reinforced by jet grouting or freezing or when the shield cannot be supported with a steel sleeve. Therefore, it is important to develop an effective recovery approach and adopt suitable techniques to control the risks. In this study, a new method based on filling the receiving shaft with water is proposed for the underwater recovery of an earth pressure balance (EPB) shield with zero end reinforcement from a metro tunnel in Tel Aviv, Israel. Several additional techniques are used to ensure safe recovery of the shield, including the design of a concrete cradle, drilling of pressure relief holes, control of excavation parameters, screw conveyor sealing, portal sealing, tail sealing, and grouting. Furthermore, according to the actual situation on site, filling the shaft with water to 1 m above the water level in the strata can prevent the fine sand from percolating into the shaft. Before the cutterhead approaches the underground diaphragm wall, the driving attitude should be strictly controlled, and the edge hob should be inspected for wear. The necessary thrust of shield tunneling in the underground diaphragm wall and shaft is calculated theoretically. In order to ensure the deformation control of the underground diaphragm wall and the smooth tunneling of the shield, the thrust of the shield excavating the underground diaphragm wall will not be larger than 12 000 kN, and the penetration degree will be limited to 3 mm/r. Qualitative observations and measurements of surface subsidence in the metro tunnel indicate that these risk mitigation techniques are effective and suitable for the underwater recovery of EPB shields in water-rich sand strata.

Numerical Simulation on the Stress and Strain of Lining Structure with Double Shield Tunneling Construction

2012 ◽  
Vol 605-607 ◽  
pp. 2425-2429
Author(s):  
Feng Wang ◽  
Tie Jun Cui
Keyword(s):  
Ground Surface ◽  
Calculation Model ◽  
Tunnel Lining ◽  
Concrete Lining ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Three Dimension ◽  
Shield Tunneling ◽  
Deformation Law ◽  
Lining Structure

This paper takes the Section 201 of shield construction engineering in Dalian Metro Line 2 as an example to analyze the deformation law of surrounding soil and the tunnel lining structure stress during shield tunnel construction. The shield tunnel construction is simulated dynamically by ADINA and the shield tunnel structure model of the concrete lining is established. This model is a three-dimension nonlinear finite element calculation model concerned with the grouting soil and original state soil. Taking the soil lithology in the upper layer and interact influences, we analyzed the dynamic process of shield construction, soil grouting and lining supporting and the stress distribution in difference reinforced concrete supporting segments and the ground settlement characteristics. Through numerical analysis method to study the deformation law of soil surrounding tunnel and the stress in tunnel lining, we get the results to compare with the results of Peck formula under the same condition. After generating the conclusions, we can provide several suggestions for shield tunneling construction, lining segment design and control of the ground surface settlement during the construction.

scholarly journals Slurry shield tunneling in soft ground. Comparison between field data and 3D numerical simulation

2019 ◽  
Vol 41 (3) ◽  
pp. 115-128
Author(s):  
Mohammed Beghoul ◽  
Rafik Demagh
Keyword(s):  
Urban Areas ◽  
Ground Surface ◽  
Injection Pressure ◽  
Tunnel Boring Machine ◽  
Surface Settlement ◽  
Ground Movement ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Ground Movements ◽  
Ground Surface Settlement

Abstract In urban areas, the control of ground surface settlement is an important issue during shield tunnel-boring machine (TBM) tunneling. These ground movements are affected by many machine control parameters. In this article, a finite difference (FD) model is developed using Itasca FLAC-3D to numerically simulate the whole process of shield TBM tunneling. The model simulates important components of the mechanized excavation process including slurry pressure on the excavation face, shield conicity, installation of segmental lining, grout injection in the annular void, and grout consolidation. The analysis results from the proposed method are compared and discussed in terms of ground movements (both vertical and horizontal) with field measurements data. The results reveal that the proposed 3D simulation is sufficient and can reasonably reproduce all the operations achieved by the TBM. In fact, the results show that the TBM parameters can be controlled to have acceptable levels of surface settlement. In particular, it seems that moderate face pressure can reduce ground movement significantly and, most importantly, can prevent the occurrence of face-expected instability when the shield crosses very weak soil layers. The shield conicity has also an important effect on ground surface settlement, which can be partly compensated by the grout pressure during tail grouting. Finally, the injection pressure at the rear of the shield significantly reduces the vertical displacements at the crown of the tunnel and, therefore, reduces the settlement at the ground surface.

3D Finite Element Simulation on During Shield Tunneling

2011 ◽  
Vol 90-93 ◽  
pp. 1950-1955
Author(s):  
Yi Liu ◽  
Ji Shun Li ◽  
Bao Lian Wang
Keyword(s):  
Finite Element ◽  
Numerical Procedure ◽  
Ground Surface ◽  
Element Model ◽  
Small Strain ◽  
Ground Movement ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Shield Tunneling ◽  
Epb Shield

Based on the comprehensive analysis on the primary components of ground movement associated with earth pressure balance (EPB) shield tunneling, a three-dimensional nonlinear finite element model for simulating EPB shield tunneling is proposed. The proposed modeling techniques are applied to simulate a tunneling project. The distributions of soil displacement on the ground surface associated with the advance-ment process of shield tunnel are analyzed. According to the comparisons of numerical results with field measurements, the proposed numerical procedure is found to be an effective approach for predicting the deformation dun to shield tunneling. The further analysis shows that the computed results of the small-strain constitutive model are more reasonable, and the small-strain mechanical behaviors of soils should be taken into account

scholarly journals Spatial Variability of Grouting Layer of Shield Tunnel and Its Effect on Ground Settlement

2020 ◽  
Vol 10 (14) ◽  
pp. 5002
Author(s):  
Zhongzheng Wang ◽  
Dalong Jin ◽  
Chenghua Shi
Keyword(s):  
Spatial Variability ◽  
Negative Impact ◽  
Ground Surface ◽  
Surface Settlement ◽  
Shield Tunnel ◽  
Ground Settlement ◽  
Shield Tunneling ◽  
Spatial Characteristics ◽  
Ground Surface Settlement ◽  
Prediction Approach

This study aims to investigate the effect of the spatial variability of grouting-layer thickness on ground-surface settlement caused by shield tunneling and to provide a rational prediction method. The spatial characteristics of grouting layers were obtained based on statistical analysis. The random finite element method was used to study the effect of spatial variability of different parameters on ground-surface settlement. Simulation results indicate that the spatial variability of the grouting layer has a negative impact on ground settlement. The surface settlement will be underestimated without considering the spatial characteristics of the grouting layer. Thus, a reliable prediction approach of the maximum ground settlement was proposed to control the construction quality.

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