Analysis of Excavation Parameters on Face Stability in Small Curvature Shield Tunnels

Niu, Yaliang; Ren, Tielun; Zhou, Qiang; Jiao, Xueyang; Shi, Jiuqiang; Xiang, Ke; Jin, Tao; Zhai, Qian; Satyanaga, Alfrendo

doi:10.3390/su15086797

Cited by 5 publications

(4 citation statements)

References 30 publications

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“…∑ Y i = 0, N 1 cos θ − µ N1 N 1 sin θ − c • S sin θ − µ N0 N 0 sin δ + N 0 cos δ = 0 (10) The normal force N 1 acting on the material on the fracture surface and the normal force N 0 acting on the material by the tool on the rake face can be obtained by solving the above two equations. The sum of the forces in the same direction is the tangential force and normal force generated by the tool cutting, which are respectively Formulas (11) and ( 12):…”

Section: Theoretical Model Of Japanese Scholarsmentioning

confidence: 99%

“…When cutting a reinforced concrete diaphragm wall, the cutter should use the low-penetration-depth excavation pattern. Niu et al [11] investigated the face stability of small curvature shield tunnels during excavation and its relationship with various excavation parameters. The effects of different excavation parameters such as jacking force, cutting speed, and soil conditioning on face stability were analyzed.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanical Properties and Influencing Factors of Shield Cutting Existing Station Supporting Piles

Guan,

Liu,

et al. 2023

Sustainability

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Based on the shield-cutting existing station supporting piles project of Zhengzhou metro line 6, the process and mechanism of concrete in the process of pile cutting were analyzed by establishing a three-dimensional model of concrete with a cutter. The magnitude and variation rules of cutting force, penetration force, and tangential force were explored. The variation rules of cutting force with four factors of cutting speed, cutting depth, cutter width, and tool rake angle were explored. The correctness of the numerical model and results were verified by the theoretical analysis method. Finally, the significance of the influencing factors of pile cutting was studied by means of range analysis and variance analysis using the orthogonal test method, and the cutter parameters were optimized. The cutting mechanism is that the front concrete is compressed and crushed to produce a dense core. The cutting force increases rapidly to its maximum value in a short time during the cutting process. The cutting force is always larger than the penetration force and tangential force. The cutter contact force basically remains unchanged with the change in cutting speed; however, it increases with the increase in cutting depth and cutter width. The significant order of the three influencing factors is cutting depth, cutter width, and rake angle. It is suggested that the cutting depth be adjusted preferentially, followed by the cutter width. And the principle of rake angle should be considered last.

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Section: Theoretical Model Of Japanese Scholarsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Influencing Factors of Shield Cutting Existing Station Supporting Piles

Guan,

Liu,

et al. 2023

Sustainability

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“…In such situations, groundwater seepage conditions may vary along the surrounding rocks of deep tunnels. As pointed out by Niu et al [15], the major factors affecting tunnel stability include variability in groundwater conditions. In fact, varying states of groundwater around surrounding rocks can cause anisotropic states and make tunnel instability more pronounced.…”

Section: Introductionmentioning

confidence: 99%

Seepage Actions and Their Consequences on the Support Scheme of Deep-Buried Tunnels Constructed in Soft Rock Strata

Frenelus,

Peng,

Zhang

2024

Infrastructures

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The stability of deep soft rock tunnels under seepage conditions is of particular concern. Aiming at thoroughly discussing seepage actions and their consequences on the support schemes of such structures, the host rocks of the Weilai Tunnel situated in the Guangxi province of China are used as the research subject. Emphasis is placed on adequately examining the seepage conditions, stresses, displacements and plastic zone radii along the surrounding rocks of such tunnels, taking into consideration the Mogi–Coulomb strength criterion and the elastic-plastic theory. Explicitly, this article proposes analytical solutions for stresses, displacements and plastic radii around deep tunnels in soft rocks under seepage conditions by considering the aforesaid criterion and nonlinear elastoplastic approaches. Subsequently, based on the strain-softening model, the coupled actions of seepage and softening on the rocks surrounding the tunnel are studied. In order to investigate the effects of relevant influencing factors on tunnel stability, parametric studies are thoroughly examined. According to the results, it is revealed that the support scheme of deep soft rock tunnels must be of the highest resistance possible to better decrease the plastic zone and the tangential stress along the host rocks. Moreover, throughout the surrounding rocks, the dissemination of pore water pressure is strongly affected by the uneven permeability coefficient under anisotropic seepage states. The combined effects of softening and seepage are very dangerous for the surrounding rocks of deep-buried tunnels. It is also shown that the seepage pressure substantially affects the plastic radii and tunnel displacements. Under high seepage pressure, the surface displacements of the tunnel are excessive, easily exceeding 400 mm. To better guarantee the reasonable longevity of such tunnels, the long-term monitoring of their support structures with reliable remote sensors is strongly recommended.

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“…In the excavation of tunnels and underground cavities, the stability and safety of excavation faces are important prerequisites for the smooth penetration and timely delivery of the tunnel. Numerous contributions have been made to predict the required support pressure and to ensure safety by various methods [1,2], such as the limit equilibrium method [3][4][5][6], numerical simulation [7][8][9], limit analysis method, and their combinations [10][11][12][13]. Compared with the limit analysis method, the limit equilibrium method, as a classic theoretical method, solves the stability problems from the viewpoint of static equilibrium.…”

Section: Introductionmentioning

confidence: 99%

Seismic Stability Analysis of Tunnel Faces in Heterogeneous and Anisotropic Soils Using Modified Pseudodynamic Method

2023

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This work assesses the seismic stability of tunnel faces advanced in heterogeneous and anisotropic soils based on the plastic limit theorem. A discretized kinematic velocity field respecting the normal flow rule is generated via a point-to-point discretization technique. The distribution of soil parameters in the depth direction including cohesion, friction angle, and unit weight are considered by four kinds of profiles. The variation in cohesion with shear direction caused by consolidation and sedimentation is considered by including an anisotropy coefficient. The seismic acceleration is represented by the modified pseudodynamic method (MPD) rather than the conventional pseudodynamic method (CPD). Based on the energy equilibrium equation, an upper-bound solution is derived. The accuracy and rationality of the proposed procedure are substantiated by comparing with the solutions obtained by conventional log-spiral mechanism and CPD. A parametric study indicates that nonlinear profiles tend to predict a smaller required face pressure than the constant and linear profiles due to the convexity of nonlinear profiles. The over-consolidated soil is more sensitive to the anisotropy coefficient than normally consolidated soil. Moreover, the adverse effect of horizontal seismic acceleration is much greater than that of vertical acceleration, and the resonance effect is more prone to happen, especially for shallow-buried tunnels.

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Analysis of Excavation Parameters on Face Stability in Small Curvature Shield Tunnels

Cited by 5 publications

References 30 publications

Mechanical Properties and Influencing Factors of Shield Cutting Existing Station Supporting Piles

Mechanical Properties and Influencing Factors of Shield Cutting Existing Station Supporting Piles

Seepage Actions and Their Consequences on the Support Scheme of Deep-Buried Tunnels Constructed in Soft Rock Strata

Seismic Stability Analysis of Tunnel Faces in Heterogeneous and Anisotropic Soils Using Modified Pseudodynamic Method

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