Three-Dimensional Fluid–Solid Coupling Numerical Simulation of Effects of Underlying Karst Cave on Shield Tunnel Through Sand Stratum

Abstract The construction of shallow tunnels in urban areas requires a prior assessment of their effects on the existing structures. In the case of shield tunnel boring machines (TBM), the various construction stages carried out constitute a highly three-dimensional problem of soil/structure interaction and are not easy to represent in a complete numerical simulation. Consequently, the tunnelling- induced soil movements are quite difficult to evaluate. A 3D simulation procedure, using a finite differences code, namely FLAC3D, taking into account, in an explicit manner, the main sources of movements in the soil mass is proposed in this paper. It is illustrated by the particular case of Toulouse Subway Line B for which experimental data are available and where the soil is saturated and highly overconsolidated. A comparison made between the numerical simulation results and the insitu measurements shows that the 3D procedure of simulation proposed is relevant, in particular regarding the adopted representation of the different operations performed by the tunnel boring machine (excavation, confining pressure, shield advancement, installation of the tunnel lining, grouting of the annular void, etc). Furthermore, a parametric study enabled a better understanding of the singular behaviour origin observed on the ground surface and within the solid soil mass, till now not mentioned in the literature.

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Finite Element Analysis of the Surface Settlement Induced by the Shield Tunnel Construction

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.501-504.111 ◽

2014 ◽

Vol 501-504 ◽

pp. 111-114

Author(s):

Ling Xia Gao ◽

Xiang Jun Yang ◽

Li Kun Qin

Keyword(s):

Numerical Simulation ◽

Finite Element ◽

Three Dimensional ◽

Longitudinal Direction ◽

Element Model ◽

Surface Settlement ◽

Shield Tunnel ◽

Empirical Formulas ◽

Element Analysis ◽

Polynomial Expression

Three-dimensional non-linearity finite element model of shield tunnel was established on basis of the Z1 line of Tianjin subway. And then it was applied to simulate construction process of shield tunnel. Surface settlement of the tunnel during the construction was obtained. The settlement data of transverse and longitudinal direction from numerical simulation were fitted through a polynomial expression. Then a contrastive analysis of curves from numerical simulation and matching formulae were made. The result shows that it is feasible to utilize the empirical formulas like Pecks to predict surface settlement in Tianjin caused by shield construction.

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A Displacement-Based Theory for Predicting the Support Force on the Shield Tunneling Surface in Sandy Soil Layers

Advances in Civil Engineering ◽

10.1155/2021/9980837 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Guang Sun ◽

Han Liu ◽

Zhiyuan Guo ◽

Ranjie Li ◽

Tao Li

Keyword(s):

Numerical Simulation ◽

Sandy Soil ◽

Soil Layer ◽

Three Dimensional ◽

Earth Pressure ◽

Shield Tunnel ◽

Soil Pressure ◽

Pressure Balance ◽

Shield Tunneling ◽

Support Force

Due to the poor stability of the loose sandy soil layer, if the support force is not properly controlled during the construction process of the shield tunnel using the earth pressure balance method, it is easy to cause the ground to collapse or uplift. Therefore, understanding the support force of the excavation surface of shield tunneling in sandy soil layer is very vital to ensure the stability of the excavation surface. Firstly, it is assumed that the damaged soil is a three-dimensional wedge and a modified three-dimensional wedge in the active and passive failure modes, respectively. The shallow soil pressure theory and the soil plastic limit equilibrium theory are derived by analyzing the stress distribution on the damaged soil. The equation for revealing the inner essence between the support force of the shield excavation surface and excavation surface displacement under the condition of sand-covered soil is used. Secondly, the numerical simulation method analyzes the displacement of the excavation surface when the support force changes under different working conditions, and the relationship curve between the excavation surface support force and the shield tunneling displacement is obtained. The comparison and analysis between the numerical simulation calculation and the theoretical analysis indicate that the deduced calculation equation for the excavation surface support force based on the displacement earth pressure is reasonable.

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3D Numerical Simulation of Shield Tunnel Subjected to Swelling Effect Considering the Nonlinearity of Joint Bending Stiffness

Periodica Polytechnica Civil Engineering ◽

10.3311/ppci.13996 ◽

2019 ◽

Author(s):

Qixiang Yan ◽

Chuan Zhang ◽

Wang Wu ◽

Hongxue Zhu ◽

Wenbo Yang

Keyword(s):

Numerical Simulation ◽

Numerical Model ◽

Elastic Shell ◽

Three Dimensional ◽

Bending Stiffness ◽

Shield Tunnel ◽

Shell Elements ◽

Swelling Soils ◽

Internal Forces ◽

Engineering Projects

In this paper, the authors developed a three dimensional shell-spring numerical model of a shield tunnel, in which the elastic shell elements were adopted to model the segments and the spring models were used for the simulation of the segmental joints. The highlight of this research is that the non-linearity of the joint bending stiffness was taken into consideration, which was first determined through the numerical simulation by using a refined 3D continuum model of the segment-joint structure. The automatic iteration of the joint bending stiffness was achieved through programming with the ANSYS ADPL software. Based on a specific engineering example, a 3D continuum-shell-spring model was established to analyze the internal forces of shield tunnel segmental linings subject to swelling soils. The developed numerical model and its application in the analysis of the internal forces of shield tunnel segmental linings in swelling ground will provide useful reference and guidance for the numerical calculation in similar engineering projects in future.

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