scholarly journals Mechanical Behavior of Tunnel Lining with Cracks at Different Positions

Symmetry ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 194 ◽  
Author(s):  
Jie Su ◽  
Yinming Jie ◽  
Xiaokai Niu ◽  
Chang Liu ◽  
Xuan Liu
Keyword(s):  
Carrying Capacity ◽  
Three Dimensional ◽  
Side Wall ◽  
Internal Force ◽  
Structural Failure ◽  
Three Dimensional Model ◽  
Lining Structure ◽  
Internal Forces ◽  
Stress And Deformation ◽  
Longitudinal Cracks

Cracks in the lining significantly reduce the safety of a tunnel during operation. It is urgent to figure out the influence of cracks on tunnel carrying capacity. In this paper, three-dimensional model tests were conducted to investigate deformation, internal force, and deterioration laws of the lining with prefabricated cracks at different positions. The main conclusions were obtained as follows: (1) The carrying capacity of the lining structure with prefabricated cracks was reduced, and the deformation of the lining structure increased. The penetration of the vault crown crack accelerated the damage of the lining structure, and structural failure occurred when the crack went through at the left arch spring. (2) The internal force of the lining was greatly affected by the positions of prefabricated cracks. The internal forces of the lining structure decreased with the existence of prefabricated cracks. Whether or not there were prefabricated cracks, tension cracks appeared in the inside fiber of the vault and inverted arch. (3) The deformation of the lining structure with the existence of prefabricated cracks increased. When the prefabricated crack was located at the vault, the deformation was the largest, followed by the arch spring, side wall, and arch shoulder. (4) The analysis shows that prefabricated cracks at the vault are the most damaging under stress and deformation of the lining structure, so longitudinal cracks at the vault should be strengthened.

Composite Lining Aseismic Design for Fault-Crossing Tunnel Structures

2014 ◽  
Vol 971-973 ◽  
pp. 30-34
Author(s):  
Chun Lei Xin ◽  
Bo Gao
Keyword(s):  
Active Faults ◽  
Three Dimensional ◽  
Bending Moment ◽  
Simulation Method ◽  
Internal Force ◽  
Great Earthquake ◽  
Underground Structures ◽  
Lining Structure ◽  
Internal Forces ◽  
Composite Lining

Although underground structures have stronger aseismic performance than ground structures, seismic disasters of mountain tunnels were fairly conspicuous in Wenchuan Great Earthquake. On the basis of seismic disaster analysis, a composite lining designfor tunnel structures across active fault was put forward. Three-dimensional numerical simulation method was used to analyze aseismic and damping effect of this structure. The results show that: (1)After setting aseismic and damping structure, the maximum internal forces value in lining the pattern of internal forces will not change. (2)Aseismic and damping structure setting can directly reduce the bending moment value and increase the axial force and stress force value in lining structure. (3) Relative to aseismic and damping structure, grouting region around damping layer can ameliorate internal force condition in lining structure and improve the effect of aseismic and damping structure. The above research results contribute to provide reference for seismic fortification of tunnel structures across active faults.

The Research on Seismic Performance of Tower under Icing Condition

2014 ◽  
Vol 986-987 ◽  
pp. 677-680
Author(s):  
Yu Chen Tian ◽  
Wei Jian Xue ◽  
Ying Zhou ◽  
Lan Jiang
Keyword(s):  
Transmission Lines ◽  
Southwest China ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Seismic Action ◽  
The Finite Element Method ◽  
Three Dimensional Model ◽  
Deformation Law ◽  
Prone Area ◽  
Internal Forces

Southwest area of china is the zone of the transmission lines which often happens icing disaster. It is also an earthquake-prone area, also influenced by the interaction between ice and earthquake. This article uses the finite element method (fem), establishing three-dimensional model for steel towers in southwest china, to analyze the dynamic performance of the ice condition and the analysis of seismic action. The aim is to get internal forces for steel towers under the action of earthquake and deformation law along with the change of ice thickness.

scholarly journals The Influence of the Internal Forces of the Buckling Modes on the Load-Carrying Capacity of Composite Medium-Length Beams under Bending

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 455 ◽  
Author(s):  
Monika Zaczynska ◽  
Zbigniew Kolakowski
Keyword(s):  
Carrying Capacity ◽  
Internal Force ◽  
Load Carrying Capacity ◽  
Buckling Modes ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Load Carrying ◽  
Internal Forces ◽  
The Individual ◽  
Interactive Buckling

The distribution of the internal forces corresponding to the individual buckling modes of lip-channel (LC) beams is investigated using the Semi Analytical Method (SAM) and the Finite Element Method (FEM). Channel section beams made of 8-layered GFRP (Glass Fiber Reinforced Polymer) laminate with three different layer arrangements were considered. The effect of the internal forces on the non-linear first-order coefficients corresponding to the interactive buckling was also studied. Moreover, distributions of the internal forces corresponded to the loading, leading to structure failure for which the load-carrying capacity was determined. The results indicated a high influence of the Nx internal force component on the buckling loads and load-carrying capacity of the LC-beams.

Three-dimensional analysis of anchored wall with concrete bearing pads

2020 ◽  
Vol 18 (6) ◽  
pp. 1469-1486
Author(s):  
Hamed Arefizadeh ◽  
Hadi Shahir
Keyword(s):  
Design Methodology ◽  
Three Dimensional ◽  
Bending Moments ◽  
Dimensional Model ◽  
Discrete Elements ◽  
Three Dimensional Model ◽  
Content Type ◽  
Finite Element Software ◽  
Internal Forces ◽  
Soldier Pile

Purpose Anchorage with concrete bearing pad is commonly used in Iran for stabilization of excavations because of the ease of construction, less costs and less time consumption than the soldier pile method. In this method, a wall facing which includes the concrete bearing pads at the location of the anchors and a shotcrete layer between the bearing pads is constructed parallel to the excavation operation similar to the nailing method. Design/methodology/approach In this paper, using the finite element software Abaqus, a three-dimensional model of the above-mentioned type of wall is constructed, and the effect of spacing and size of bearing pads on the wall behavior is discussed. Findings According to the obtained results, the size of the concrete bearing pads has little effect on wall deformations, but the internal forces and bending moments developed in the shotcrete layer between the bearing pads are greatly influenced by the bearing pads dimensions and spacing. Originality/value Owing to the discrete elements of the wall facing, the behavior of this system is completely three-dimensional.

Mechanical Behavior of Segmented Lining Structure of Tunnel under Acting Ground Fractures in Xi’an Zone

2011 ◽  
Vol 261-263 ◽  
pp. 1778-1783
Author(s):  
Sheng Jun Shao ◽  
Fang Tao She ◽  
Juan Fang
Keyword(s):  
Tensile Stress ◽  
Mechanical Behavior ◽  
Compressive Stress ◽  
Three Dimensional ◽  
Vertical Displacement ◽  
Maximum Tensile Stress ◽  
Internal Force ◽  
Subway Tunnel ◽  
Lining Structure ◽  
Pass Through

Xi’an ground fracture, caused by the extraction of groundwater and the movement of fault under soil strata, is a geo-hazard. The movement of ground fracture originates the uneven settlement of upward block and downward block. In Xi’an ground fracture region, the segmented lining structure was adopted in subway tunnel to pass through the ground fracture, so as to adapt for the uneven settlement. Three-dimensional elastic-plastic finite difference method was applied to simulate the initial lining structure, second segmented lining structure, surrounding soils and ground fracture. The horizontal and vertical displacement of segmented lining structure, surrounding soils pressure and internal force of segmented lining structure in subway tunnel were analyzed by the calculation results. The knowledge on mechanical behavior of segmented lining structure passing through an active ground fracture and surrounding soils was shown as following. The relative vertical displacement between segmented lining structure sects beside the ground fracture increases remarkably with the movement of ground fracture, and the segmented lining structure located in upward displaceent block near ground fracture originates notable rotary. Tension or compression deformation occured in the deformation joint between adjacent segmented lining structures near the ground fracture.There was a significant change in the contact pressure of the first sect of lining structure in the upward displace block. Under the same uniform settlement at the bottom of upward diaplacement block, the relativly vertical displacemtn on the surfaceof ground fracture strata without tunnel equals 50cm, but the relativly vertical displacement between adjacent segmented lining structure at ground fracture is 18.2cm on the design level of arch top of lining strcutre. the maximum tensile stress of segmented lining structure is 2.02MPa, the maximum compressive stress of segmented lining is 3.49MPa. In conclusion, segmented lining structure can adapts to the uneven settlement caused by the movement of ground fracture. Though maximum tensile and compressive stress of sengmented lining structure passing through the active ground fracture is bigger than the general lining structure located in soils strata without the ground fracture, the segmented lining structure constructed by the steel fibre concrete can bear with the maximum tensile stress.

scholarly journals Load carrying capacity of partially encased columns for different fire ratings

Fire Research ◽  
2016 ◽  
Author(s):  
Abdelkadir Fellouh ◽  
Nourredine Benlakehal ◽  
Paulo Piloto ◽  
Ana Ramos ◽  
Luís Mesquita
Keyword(s):  
Fire Resistance ◽  
Carrying Capacity ◽  
Three Dimensional ◽  
Thermal Inertia ◽  
Load Carrying Capacity ◽  
The Finite Element Method ◽  
Three Dimensional Model ◽  
Load Carrying ◽  
Solution Methods ◽  
Two Parameters

Partially encased columns have significant fire resistance in comparison with steel bare columns. However, it is not possible to assess the fire resistance of such members simply by considering the temperature of the steel. The presence of concrete increases the mass and thermal inertia of the member and the variation of temperature within the cross section, in both the steel and concrete components. The annex G of EN1994-1-2:20051 allows to calculate the load carrying capacity of partially encased columns, for a specific fire rating time, considering the balanced summation model. New formulas will be proposed to calculate the plastic resistance to axial compression and the effective flexural stiffness. These two parameters are used to determine the buckling resistance. The finite element method is used to compare the results for the elastic critical load and the load carrying capacity of partially encased columns for different fire ratings of 30 and 60 min. This work compares the results from both solution methods, provides the validation of the three-dimensional model and demonstrates that a new design curve should be used for the buckling analysis of partially encased columns.

The Effects of Side-Wall Conduction on Natural Convection in a Slot

1987 ◽  
Vol 109 (2) ◽  
pp. 419-426 ◽  
Author(s):  
G. D. Mallinson
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Radiation Effects ◽  
Three Dimensional ◽  
Side Wall ◽  
Thermal Coupling ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
High Prandtl Number ◽  
Side Walls

A numerical model for the interaction between natural convection in a slot and conduction in the side walls that are parallel to the plane of the slot is described. Two-dimensional equations containing source terms which account for the viscous and thermal coupling between the fluid and the walls are solved by a finite difference method. The model neglects radiation effects. Solutions for a slot of square cross section filled with a high Prandtl number fluid and heated from below are compared with the results of a Galerkin analysis made by Frick [8] and with solutions obtained by a fully three-dimensional model. Solutions for a slot filled with air and heated from the side are also validated by comparison with three-dimensional solutions. The data produced by the model predict that the more conventional Hele Shaw analysis overestimates heat transfer when the slot aspect ratio is greater than 0.05. Perfectly conducting walls are shown to reduce the rate of heat transfer by the fluid but to increase the strength of the flow. Some effects of walls that are neither adiabatic nor perfectly conducting are assessed.

Rigidity calculation model for transverse joint of prefabricated utility tunnel based on physical guidance

2021 ◽  
pp. 62-73
Author(s):  
Tang Ruihua ◽  
◽  
Ding Weimin ◽  
Qian Yun ◽  
◽  
...  
Keyword(s):  
Flexural Rigidity ◽  
Three Dimensional ◽  
Internal Force ◽  
Calculation Model ◽  
Shear Rigidity ◽  
Three Dimensional Model ◽  
Whole Process ◽  
Transverse Joint ◽  
Utility Tunnel ◽  
Loading Methods

The rigidity calculation model for transverse joint of prefabricated utility tunnel is established by Midas FEA software based on physical guidance.Taking the prefabricated multi-utility tunnel of South Kemugong road of Guangzhou Intelligent City as the experimental object, the position of its transverse joint is analyzed from the aspects of construction and internal force. Midas FEA is used to establish and analyze the three-dimensional model for the transverse joint of the utility tunnel, and the calculation parameters, boundary conditions and loading methods of the materials are obtained, so that the calculation models for the bending and axial rigidity of the transverse joint are established.The results show that the theoretical calculation value of the model is consistent with the experimental value, and it can accurately describe the deformation and internal force state of the joint in the whole process of stress. The shear rigidity of the transverse joint is 3.524×106 kN/m and the flexural rigidity of transverse joint is 1.001×105 kN×m/rad under the condition of 500 kN/m horizontal axial force per linear meter.

Analysis of microdiffuser/nozzles

2006 ◽  
Vol 220 (8) ◽  
pp. 1289-1296 ◽  
Author(s):  
K-S Yang ◽  
M-S Liu ◽  
I-Y Chen ◽  
C-C Wang
Keyword(s):  
Reynolds Number ◽  
Flow Separation ◽  
Pressure Loss ◽  
Three Dimensional ◽  
Side Wall ◽  
Loss Coefficient ◽  
Opening Angle ◽  
Three Dimensional Model ◽  
Velocity Change ◽  
Pressure Loss Coefficient

In this study, an analysis of the performance of micronozzle/diffusers is performed and fabrication of the micronozzle/diffuser is conducted and tested. It is found that the ratio of the loss coefficient of nozzle and diffuser increases with the Reynolds number and with the opening angle. At a given Reynolds number, the pressure loss coefficient for nozzle is higher than that of the diffuser due to considerable difference in the momentum change. At a fixed volumetric flowrate, a ‘minimum’ phenomenon of the pressure loss coefficient versus nozzle/diffuser depth is encountered. This is related to the interactions of velocity change and friction factor. Good agreements of the measured data with the predicted results are found in this study except at a diffuser having an opening angle of 20°. This is because of the presence of flow separation. The departure of this case to the prediction is due to the separation phenomenon in a larger angle of the diffuser. Hence, a more complicated two- and three-dimensional model is adopted to verify this flow separation inside the diffuser. For the simulation of the two-dimensional case, asymmetry flow field is seen for low Reynolds number region, whereas this phenomenon is not seen under three-dimensional simulation due to the confinement of the side wall.

Analysis of the Effects on Metro Station’s Main Structure Generated by Foundation Pit Support Structure

2014 ◽  
Vol 1065-1069 ◽  
pp. 421-425
Author(s):  
Hui Wang ◽  
Feng Zuo Liu
Keyword(s):  
Optimization Design ◽  
Side Wall ◽  
Internal Force ◽  
Wall Structure ◽  
Support Structure ◽  
Foundation Pit ◽  
Main Structure ◽  
Bored Pile ◽  
Complex Interactions ◽  
Lining Structure

For the present open cut method is still the main method of the construction of metro stations. Foundation pit support structure and lining structure are composed of three basic side wall structure systems (single wall, compound wall and composite wall). In the calculation of internal force of structure, complex interactions between foundation pit support structures including bored pile and diaphragm wall, and the side wall of main structures are investigated. One form is that the foundation pit support structure and side wall can only deliver pressure and separate partly; another is that they deform together by construction measures. In this paper, the effects on the internal force of main structure influenced by foundation pit support structure are quantitative studied, and the reference resources for optimization design are provided.

Sign in / Sign up

Export Citation Format

Share Document