scholarly journals Development and Research on the Vertical Center Diaphragm Method Applied in Shallow Tunnel Construction

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 855
Author(s):  
Zhenliang Zhou ◽  
Zhongsheng Tan ◽  
Jinpeng Zhao ◽  
Han Liang
Keyword(s):  
Three Dimensional ◽  
Earth Pressure ◽  
Internal Force ◽  
Surrounding Rock ◽  
Surface Settlement ◽  
Shallow Tunnel ◽  
Connection Line ◽  
Axisymmetric Structure ◽  
Arch Stress ◽  
Construction Efficiency

As a common method applied in the construction of tunnels with Grade IV and Grade V surrounding rock, the center diaphragm (CD) method has the advantage of resisting the inward horizontal convergence of the tunnel. However, due to the small lateral earth pressure of the shallow tunnel, the curved center diaphragm would have an unstable stress state and cannot provide sufficient support to the surrounding rock. Based on the CD method, this study presents a vertical center diaphragm (VCD) method with an axisymmetric structure. The application condition of the VCD method relies on the comparison of the surface settlement and tunnel deformation with the two methods in different surrounding rock grades and buried depths by using a three-dimensional finite-difference code. Based on the Shenzhen Eastern Transit Expressway Connection Line Tunnel, which has six lanes of double lines, the deformation regularities and mechanical characteristics of the VCD method, including the surface settlement, tunnel deformation, internal force of the center diaphragm, surrounding rock pressure, and steel arch stress, are investigated by numerical calculations and a field comparative test. The results obtained in this study provide several suggestions for constructing shallow tunnels. Furthermore, the construction efficiency and economy of the VCD method are evaluated.

Study on the Mechanical Behavior of Excavation and Support Construction of Shallow Tunnel

2013 ◽  
Vol 353-356 ◽  
pp. 1693-1698
Author(s):  
Zhen Xing Yang ◽  
Liang Song ◽  
Hao Wang ◽  
Yu Yong Jiao ◽  
Shu Cai Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Mechanical Behavior ◽  
Rock Pressure ◽  
Simulation Method ◽  
Internal Force ◽  
Surrounding Rock ◽  
Shallow Tunnel ◽  
Maximum Value ◽  
Surrounding Rock Pressure ◽  
Peak Value

In this paper, the mechanical behavior of excavation and support construction of Weishe tunnel, which is a section of the Yangwu expressway, is studied quantitatively using 3D finite difference numerical simulation method. A sequential excavation method is used and the results show that the vault settlement occurs mainly on the phase of upper bench excavation. The convergences of upper and lower sidewalls occur mainly on the phase of lower bench excavation. During the construction, the surrounding rock pressure in the vault and sidewall of the tunnel decrease. Axial force of anchor reaches the maximum value after the finish of second lining. However, the surrounding rock pressure and internal force of steel arch reach the maximum value after completing the upper bench excavation, and then become as smaller as half of the peak value during the lower bench excavation.

Mechanical Calculation for Collapse Mechanism of Surrounding Rock on Shallow Tunnel

2014 ◽  
Vol 580-583 ◽  
pp. 1148-1152
Author(s):  
Ying Peng ◽  
Jun Sheng Yang ◽  
Yan Hua Shen ◽  
Jian Hua Liu
Keyword(s):  
Upper Bound ◽  
Limit Analysis ◽  
Earth Pressure ◽  
Surrounding Rock ◽  
Collapse Mechanism ◽  
Shallow Tunnel ◽  
Upper Bound Method ◽  
Collapse Mechanisms ◽  
Surrounding Rock Pressure

The upper bound method of limit analysis is used for surrounding pressure calculation of shallow tunnel. Two rigid-block translational collapse mechanisms are assumed for shallow tunnel and the corresponding formulas are deduced. The earth pressure of shallow tunnel has been transformed into a mathematic optimization problem, we can get optimization solutions for the surrounding rock pressure by corresponding calculating program. It is concluded that the upper bound method of limit analysis is a feasible approach for the determination of surrounding pressures on shallow tunnel.

Study on the Vertical Rational Structure of Tunnel Lining in the Fault-Rupture Zone

2011 ◽  
Vol 368-373 ◽  
pp. 2870-2874
Author(s):  
De Wu Li
Keyword(s):  
Three Dimensional ◽  
Internal Force ◽  
Surrounding Rock ◽  
Tunnel Lining ◽  
Rupture Zone ◽  
Fault Rupture ◽  
Finite Element Program ◽  
Element Program ◽  
Initial Support ◽  
In The Beginning

Related to the actual project in the new Qi Daoliang tunnel between Lanzhou and Lintao highway, select 300-meter calculation range along the tunnel vertically including fault-rupture zone and effect fault-rupture zone, utilize 8 -node, 6-plane block element to scatter the calculating range, at the same time, use the deduced 8 -node, three dimensional jointed element to imitate the transformation gap of the tunnel lining, employ three-dimensional elasto-plastic static finite element program to analyze stress and transformation state of surrounding rock and lining in different construction stages of the new Qi Daoliang tunnel. Through the analysis and comparison of the calculation result of the three conditions: not placing transformation gap through, placing one transformation gap in the middle of the fault-rupture zone, placing two transformation gaps in the beginning and the end of the fault-rupture zone etc, we can get the following points: ①The gallery transformation in the fault-rupture zone and the plastic area in the surrounding rock are obviously bigger than the non-fault-rupture zone. ②Owing to the effect of fault-rupture zone, the increasing range of internal force of the initial support and twice lining is about 10% to 30%. ③Placing the transformation gap in the fault-rupture zone can obviously play a role in releasing lining internal force and transformation energy in the surrounding rock. ④In the start and end changing point of fault-rupture zone, the transformation gap should be placed in the tunnel lining.

Deformation and Stability Study of PBA Extension Method Based on Air Defense Tunnel

2012 ◽  
Vol 204-208 ◽  
pp. 1347-1355
Author(s):  
Jian Jia ◽  
Shun Hua Zhou ◽  
Xi Ping Yao ◽  
Chen Shen
Keyword(s):  
Internal Force ◽  
Stability Study ◽  
Surrounding Rock ◽  
Surface Settlement ◽  
Ground Settlement ◽  
Ground Displacement ◽  
Air Defense ◽  
Surrounding Rock Pressure ◽  
Unloading Effect

Jiaohua Square Station of Harbin Metro Line 1 is built by PBA method with the existence of No. 7381 air defense tunnel. In order to control the ground settlement during PBA construction, numerical model is performed to analyse the surrounding rock pressure, plastic zone and structure internal force. The result shows the lower pilot headings have stronger impact on existing tunnel than the upper ones in that the lower ones get the loading effect while the upper ones the unloading effect. The internal force of air defense tunnel and ground displacement can be well controlled by reducing the area of lower pilot headings at the stages of pilot heading excavation, but the final surface settlement is unqualified. The scheme of lower big pilot heading in part with the support of portal frame meets the requirement of surface settlement. The in-situ surface settlement and the vault settlement of defense tunnel are essentially consistent with numerical results.

scholarly journals Mechanical Behavior of Supporting Structure of Rectangular Deep Ventilation Shaft in Rail Transit

2019 ◽  
Vol 136 ◽  
pp. 02021
Author(s):  
Jinke Gu ◽  
Lin Huang ◽  
Feng Qiu ◽  
Xiaoguang Jin
Keyword(s):  
Mechanical Behavior ◽  
Axial Force ◽  
Three Dimensional ◽  
Bending Moment ◽  
Internal Force ◽  
Surrounding Rock ◽  
Rail Transit ◽  
Support Design ◽  
Supporting Structure ◽  
Ventilation Shaft

In order to analyze the mechanical behavior of surrounding rock and initial support during shaft excavation and support process, reveal the law of stratum displacement, the stress characteristics of surrounding rock and the internal force of supporting structure during construction, this paper establishes a three-dimensional finite element numerical model relying on the construction process of a ventilation shaft in Chongqing Rail Transit. The results show that the stress of shotcrete, the bending moment of supporting structure, the axial force of bolt and the axial force of I-beam are all within the allowable range. The "S" shape bending occurs in the range of 60m~70m for the axial force of bolt and cross brace I-beam. According to the results of model test, there is inflection point in the pressure distribution of rectangular deep ventilation shaft in rail transit, which provides a basis for the support design of deep ventilation shaft.

scholarly journals Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
High Strength ◽  
Element Model ◽  
Internal Force ◽  
Foundation Pit ◽  
Dimensional Finite Element ◽  
Influence Of Temperature On ◽  
Scale Experiment ◽  
Three Dimensional Finite Element

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

Numerical solutions for strain-softening surrounding rock under three-dimensional principal stress condition

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sheng Yu-ming ◽  
Li Chao ◽  
Xia Ming-yao ◽  
Zou Jin-feng
Keyword(s):  
Finite Element ◽  
Principal Stress ◽  
Stress Condition ◽  
Strain Softening ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Strength Criterion ◽  
Surrounding Rock ◽  
Flow Rule ◽  
Finite Element Software

Abstract In this study, elastoplastic model for the surrounding rock of axisymmetric circular tunnel is investigated under three-dimensional (3D) principal stress states. Novel numerical solutions for strain-softening surrounding rock were first proposed based on the modified 3D Hoek–Brown criterion and the associated flow rule. Under a 3D axisymmetric coordinate system, the distributions for stresses and displacement can be effectively determined on the basis of the redeveloped stress increment approach. The modified 3D Hoek–Brown strength criterion is also embedded into finite element software to characterize the yielding state of surrounding rock based on the modified yield surface and stress renewal algorithm. The Euler implicit constitutive integral algorithm and the consistent tangent stiffness matrix are reconstructed in terms of the 3D Hoek–Brown strength criterion. Therefore, the numerical solutions and finite element method (FEM) models for the deep buried tunnel under 3D principal stress condition are presented, so that the stability analysis of surrounding rock can be conducted in a direct and convenient way. The reliability of the proposed solutions was verified by comparison of the principal stresses obtained by the developed numerical approach and FEM model. From a practical point of view, the proposed approach can also be applied for the determination of ground response curve of the tunnel, which shows a satisfying accuracy compared with the measuring data.

A three-dimensional numerical model for delaminations, transverse crack or debonding in composite sandwich plates with piezoelectric sensors

2021 ◽  
pp. 1045389X2110386
Author(s):  
Yaogang Wu ◽  
Zhengguang Xiao ◽  
Kangwei Liu ◽  
Dinghe Li
Keyword(s):  
Transverse Crack ◽  
Three Dimensional ◽  
Piezoelectric Sensor ◽  
Internal Force ◽  
Piezoelectric Sensors ◽  
Sandwich Plates ◽  
Composite Sandwich ◽  
Finite Element Software ◽  
Solid Element ◽  
Composite Sandwich Plates

An Extended Layerwise/Solid-Element (XLW/SE) method is developed based on the Extended Layerwise method (XLWM) and eight-node solid element method for the static analysis of damaged composite sandwich structures with piezoelectric sensor. In this method, the XLWM is used to model the facesheets and piezoelectric sensors, and the eight-node solid element is used for the lattice. Based on the equilibrium conditions of displacement and internal force of the overlapped joints at the facesheet/sensors and facesheet/lattice interfaces, the general governing equation is established. In the numerical examples, the proposed method is verified by comparing with the 3D elasticity model developed in the commercial finite element software, and composite sandwich plates with delamination and/or transverse crack and/or debonding are analyzed.

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