scholarly journals Study on the Generalized Displacement Boundary and Its Analytical Prediction for Ground Movements Induced by Shield Tunneling

2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Qianlong Tang ◽  
Fudong Chen ◽  
Mingfeng Lei ◽  
Binbin Zhu ◽  
Limin Peng
Keyword(s):  
Boundary Condition ◽  
Ground Movement ◽  
Shield Tunnel ◽  
Analytical Prediction ◽  
Displacement Boundary Condition ◽  
Shield Tunneling ◽  
Displacement Boundary ◽  
Ground Movements ◽  
Gap Parameter ◽  
Tunnel Depth

The process of shield tunnel excavation would inevitably cause surrounding ground movement, and excessive displacement in the soil could lead to large deformation and even collapse of the tunnel. The methods estimating convergence deformation around tunnel opening is summarized. Then, a universal pattern of displacement boundary condition around the tunnel cavity is originally introduced, which is solved as the combination of three fundamental deformation modes, namely, uniform convergence, vertical translation, and ovalization. The expression for the above-mentioned displacement boundary condition is derived, by imposing which the analytical solution for ground movements, based on the stress function method, is proposed. The reliability and applicability of this proposed solution are verified by comparing the observed data in terms of surface settlement, underground settlement, and horizontal displacement. Further parametric analyses indicate the following: (1) the maximum settlement increases linearly with the gap parameter and the tunnel radius, while it is negatively related to the tunnel depth; (2) the trough width parameter is independent of the gap parameter and the radius, while it is proportional to the tunnel depth. This study provides a new simple and reliable method for predicting ground movements induced by shield tunneling.

Similarity Solution for the Synchronous Grouting of Shield Tunnel Under the Vertical Non-Axisymmetric Displacement Boundary Condition

2016 ◽  
Vol 9 (1) ◽  
pp. 205-232 ◽  
Author(s):  
Jinfeng Zou ◽  
Songqing Zuo
Keyword(s):  
Boundary Condition ◽  
Similarity Solution ◽  
Ground Surface ◽  
Vertical Displacement ◽  
Vertical Surface ◽  
Parameter Analysis ◽  
Shield Tunnel ◽  
Displacement Boundary Condition ◽  
Displacement Boundary ◽  
Grouting Pressure

AbstractSimilarity solution is investigated for the synchronous grouting of shield tunnel under the vertical non-axisymmetric displacement boundary condition in the paper. The synchronous grouting process of shield tunnel was simplified as the cylindrical expansion problem, which was based on the mechanism between the slurry and stratum of the synchronous grouting. The stress harmonic function on the horizontal and vertical ground surfaces is improved. Based on the virtual image technique, stress function solutions and Boussinesq's solution, elastic solution under the vertical non-axisymmetric displacement boundary condition on the vertical surface was proposed for synchronous grouting problems of shield tunnel. In addition, the maximum grouting pressure was also obtained to control the vertical displacement of horizontal ground surface. The validity of the proposed approach was proved by the numerical method. It can be known from the parameter analysis that larger vertical displacement of the horizontal ground surface was induced by smaller tunnel depth, smaller tunnel excavation radius, shorter limb distance, larger expansion pressure and smaller elastic modulus of soils.

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.

Numbering Analysis of Ground Settlement by Shield Method Based on the Model of Corrected ‘Equivalent Circle Zone’

2014 ◽  
Vol 580-583 ◽  
pp. 1072-1075
Author(s):  
Ze Lin Zhou ◽  
Shou Gen Chen
Keyword(s):  
Ground Deformation ◽  
Back Analysis ◽  
Movement Pattern ◽  
Ground Movement ◽  
Shield Tunnel ◽  
Ground Settlement ◽  
Unknown Parameters ◽  
Shield Tunneling ◽  
Gap Parameter ◽  
Circle Model

Through the analysis of ‘gap parameter’ and ground movement pattern in shield tunnel, this paper researched and corrected the model of ‘equivalent circle zone’ proposed by predecessors. The ‘equivalent circle zone’, which is a comprehensive reflection of shield gap, grouting filling and stratum perturbation, is considered to be unequal thickness in this paper. With the measured data of practical shield tunneling, the unknown parameters of corrected ‘equivalent circle model’ can be obtained by back analysis through numbering analysis. The back analysis of Shen Zhen line-5 is carried out to validate the rationality of the method proposed in this paper. Research shows that: the corrected model can reflect the feature and values of ground settlement more factually than the previous model and can offer a reference to predict ground deformation during shield tunneling.

The Influence of Underpass on Surface Subsidence Caused by Double-Tube Shield Tunneling

2014 ◽  
Vol 915-916 ◽  
pp. 108-113
Author(s):  
Wei Kai Zong
Keyword(s):  
Simulation Method ◽  
Surface Subsidence ◽  
Channel Width ◽  
Ground Movement ◽  
Shield Tunnel ◽  
Underground Structures ◽  
Shield Tunneling ◽  
Underground Channel ◽  
Underground Passage ◽  
The Impact

Shield construction will cause surface subsidence, and the presence of underground structures above the tunnel has an impact on surface subsidence. Based on this, with the engineering of undercross shield tunnel construction on railway station as background, used numerical simulation method to analyze the effect of surface subsidence of underground passage, and studied the influence of depth and width of underpasses on ground movement induced. The results show that: The impact of the underground passage to the wire surface subsidence caused by the shield cannot be ignored. Surface subsidence caused by double shield will be decreased because of the existence of the underground passage, and that related to the channel depth and width. The greater the depth of underground channel, the greater the surface subsidence; greater the underground channel width, the smaller surface subsidence. Meanwhile, the surface subsidence trough width and the largest settlement scope unrelated to the depth of underground tunnels but the underground channel width, and increases with the increasing of the underpass width.

Research on Chamber Earth Pressure of EPB Shield Considering Soil Arching Effect

2014 ◽  
Vol 1065-1069 ◽  
pp. 373-377
Author(s):  
Jing Cao ◽  
Hai Xing Yang ◽  
Bo Liang ◽  
Hai Ming Liu
Keyword(s):  
Earth Pressure ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Soil Arching ◽  
Shield Tunneling ◽  
Arching Effect ◽  
Soil Arching Effect ◽  
Earth Pressure Balance ◽  
Tunnel Depth ◽  
Epb Shield

Chamber earth pressure is one of the significant parameters during the Earth Pressure Balance (EPB) shield construction processing. The soil arching effect is existence when the tunnel depth is enough. It is significant to consider the influence of arching effect to analyze the pressure in soil chamber in shield tunneling. In this paper, the influence of arching effect is considered to calculate the chamber earth pressure. Firstly, the soil is supposed as loose media, and the necessary buried depth of producing arching affects is deduced according to the loose media theory. Then, based on the characteristic of proper arching axis, the equation and the height of proper arch are obtained. At last, the calculation formula of minimum chamber earth pressure of EPB shield tunnel is deduced which can consider the effect of arching effect.

Modeling Input Motion Boundary Conditions for Simulations of Geotechnical Shaking Table Tests

2010 ◽  
Vol 26 (2) ◽  
pp. 349-369 ◽  
Author(s):  
Mahadevan Ilankatharan ◽  
Bruce Kutter
Keyword(s):  
Boundary Condition ◽  
Boundary Conditions ◽  
Shaking Table ◽  
Experimental Result ◽  
Displacement Boundary Condition ◽  
Displacement Boundary ◽  
Input Motion ◽  
Displacement Approach ◽  
Table Motion ◽  
Motion Boundary

This paper discusses the effects of using different input-motion-boundary-conditions on the sensitivity of numerical simulations results to errors in material properties of a specimen tested on a shaking table. In the flexible-actuator-prescribed-force-boundary-condition, input is specified by a force across an actuator element that connects the shaking table to a reaction mass. In the prescribed-displacement-boundary-condition, the measured shaking table motion in the experiment is prescribed in the simulation. The flexible-actuator-prescribed-force approach yielded smaller, almost constant sensitivity of simulation results to input properties. The prescribed-displacement approach yielded larger and more variable sensitivities. The sensitivity of results depends on the how the boundary conditions are handled has further implications: the assessment of a comparison between a simulation and an experimental result should be performed with due consideration to the effect of the boundary conditions on the comparison, and numerically determined sensitivities may not be physically meaningful if the boundary condition is not accurately modeled.

Study on Influencing Factor of Ground Deformation Induced by Shield Tunneling

2013 ◽  
Vol 734-737 ◽  
pp. 690-693
Author(s):  
Meng Lin Xu ◽  
De Shen Zhao
Keyword(s):  
Ground Deformation ◽  
Influencing Factor ◽  
Ground Movement ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Tunnel Excavation ◽  
Security Issues ◽  
Surrounding Environment ◽  
Strata Deformation ◽  
Complex Construction

The complex construction behavior inevitably disturb surrounding environment, even when the tunneling goes through building, which may be wrecked. The security issues of the subway project stems from ground movement and structure dynamic interaction. So it is academic and application good value for study on construction influences of shield tunnel excavation to the neighboring buildings. This paper focuses on the shield tunnel construction strata deformation factors. The results provided the theory basis for safety construction.

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

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