scholarly journals Effects of different processes of tunneling on displacements soil using 3D Finite Element Method

2021 ◽  
Vol 16 (2) ◽  
pp. 203-217
Author(s):  
Nawel Bousbia
Keyword(s):  
Three Dimensional ◽  
Urban Site ◽  
Tunnel Excavation ◽  
Excavation Process ◽  
Tunneling Method ◽  
The Stability ◽  
Full Face ◽  
Ground Stability ◽  
3D Finite Element Method ◽  
Underground Constructions

Abstract The excavation process of tunnels induces stresses and deformation in the surrounding soil. The method of excavation is one of the major problems related to the safety of the operators and the ground stability during the construction of underground works. So, it is necessary to choose an ideal method to minimize the displacements and stresses induced by tunneling. The main aim of this study is to simulate numerically the effect of different processes of tunneling on ground displacements, the settlements at surface soil and the internal efforts induced in the lining tunnel; in order to select the best process of excavation, which gives us a less effects on displacements generated by tunneling, thus, ensuring the stability and the solidity of the underground constructions. In addition, this study allows us to control and to predict the diverse movements generated by tunneling (displacements, settlements, efforts internes) exclusively for the shallow tunnel nearby to the underground constructions in the urban site. This modeling will be done by employing five different processes for tunnel excavation using the NATM (New Austrian Tunneling Method) method. The first process, the modeling of the excavation tunnel, is done almost in the same way as in reality; the partial face excavation, with seven slices, made by the excavation. The second process, by partial face excavation, is divided into eleven slices, next, we used the partial face excavation by nine slices, and then in thirteen slices. Finally, the dig is made by full-face excavation. The paper contributes to the prediction of the response of the soil environment to tunnel excavation using the NATM method and to minimize the diverse movements generated by tunneling. The appropriately chosen methodology confirms that displacements and subsidence are strongly influenced by the tunneling method. The three-dimensional Finite Elements Method using Plaxis3D program has been applied in the numerical simulation. The study resulted in the recommendation of a process that minimizes the effect of excavation on subsidence and ground displacement for a particular Setiha tunnel.

Analysis of Surge Shaft Excavation Process Based on 3-Dimensional Finite Difference Method

2014 ◽  
Vol 620 ◽  
pp. 69-74
Author(s):  
Zhen Zhong Shen ◽  
Ning Wang ◽  
Nan Yao ◽  
Chao Xin Shao
Keyword(s):  
Finite Difference ◽  
Three Dimensional ◽  
Surrounding Rock ◽  
Hydroelectric Power Station ◽  
Hydroelectric Power ◽  
Analysis Method ◽  
3 Dimensional ◽  
Hydroelectric Project ◽  
Excavation Process ◽  
The Stability

As an important part of the structure of hydroelectric power station, surge shaft is embedded in the rock mass, whose body size and loading conditions are typically complex. Thus, it is necessary to evaluate safety of the design scheme in order to ensure construction safety. With upper background, three dimensional finite difference model of the surge shaft and surrounding rock of a hydroelectric project in Zambia were established based on three dimensional nonlinear finite difference analysis method. Calculation of the surge shaft stepped excavation with supporting at all levels of the construction process was done. The deformation and stress state of the surrounding rock of surge shaft and its variation law in excavation process was analyzed. Furthermore, the stability of surrounding rocks and rationality of the designed support measures were evaluated.

Hydro-Mechanical Coupling Analyses of Cofferdam Stability of Taian Pumped Storage Power Station

2004 ◽  
Vol 261-263 ◽  
pp. 1545-1550
Author(s):  
Shu Cai Li ◽  
Shu Chen Li ◽  
Wei Shen Zhu ◽  
Wei Zhong Chen ◽  
Le Wen Zhang ◽  
...  
Keyword(s):  
High Pressure ◽  
Three Dimensional ◽  
Power Station ◽  
Local Effects ◽  
Mechanical Coupling ◽  
Excavation Process ◽  
Calculation Results ◽  
Pressure Grouting ◽  
Pumped Storage ◽  
The Stability

Three-dimensional hydro-mechanical coupling analyses have been conducted on the water-tight structure of the cofferdam for both intake and outlet of Taian pumped storage power station, located in Shandong Province of China. In addition, the effects of excavation on the cofferdam and foundation slopes were also studied by using the 3D FLAC. The calculation results show that the central core of high-pressure grouting has a prefect anti-seepage effect and therefore is able to strengthen the stability of the cofferdam and foundation slopes. The excavation process has only some local effects on the cofferdam and does not greatly affect the global stability of the cofferdam. Therefore, no failure takes place around slope toes. The results show that the width of platform left on the excavation side is reasonable.

Slope Strengthening by Using a Grid Beam System

2012 ◽  
Vol 204-208 ◽  
pp. 842-847
Author(s):  
Fan Yang ◽  
Bo Chen ◽  
Chun Fang Song ◽  
Peng Yun Li
Keyword(s):  
Three Dimensional ◽  
Element Model ◽  
Bending Moments ◽  
Beam System ◽  
Excavation Process ◽  
Geological Conditions ◽  
Commercial Package ◽  
Vertical Beam ◽  
The Stability ◽  
Dimensional Element

The evaluation of slope strengthening by using a grid beam system is carried out in this study by using a real slope existed in China is taken as the example to investigate the effects of the strengthening approach. The geological conditions of the example slope are introduced at first. The three dimensional element model of the slope is constructed with the aiding of the commercial package FLAC3D. The excavation process is simulated to obtain the stress distribution and displacement status. The slope performances without and with strengthening are numerical investigated and compared. The different bending moments of vertical beam of the frame and foundation pressure of slope reinforced with binding bolts, pre-pressed anchors and stress dispersion cables are computed. The made observations indicate that the stability of the slope has been obviously improved by applying the strengthening. The approach utilized in this study can also be adopted in the slope strengthening on the other sites.

A Liquid Metal Flow Between Two Coaxial Cylinders System

2019 ◽  
Vol 11 (1) ◽  
pp. 79-86
Author(s):  
Abdelkrim Merah ◽  
Ridha Kelaiaia ◽  
Faiza Mokhtari
Keyword(s):  
Couette Flow ◽  
Metal Flow ◽  
Three Dimensional ◽  
Liquid Sodium ◽  
Taylor Vortex ◽  
Turbulent Regime ◽  
Coaxial Cylinders ◽  
Concentric Cylinders ◽  
Ideal Tool ◽  
The Stability

Abstract The Taylor-Couette flow between two rotating coaxial cylinders remains an ideal tool for understanding the mechanism of the transition from laminar to turbulent regime in rotating flow for the scientific community. We present for different Taylor numbers a set of three-dimensional numerical investigations of the stability and transition from Couette flow to Taylor vortex regime of a viscous incompressible fluid (liquid sodium) between two concentric cylinders with the inner one rotating and the outer one at rest. We seek the onset of the first instability and we compare the obtained results for different velocity rates. We calculate the corresponding Taylor number in order to show its effect on flow patterns and pressure field.

Handheld Laser Scanner Research

2019 ◽  
Vol 952 (10) ◽  
pp. 47-54
Author(s):  
A.V. Komissarov ◽  
A.V. Remizov ◽  
M.M. Shlyakhova ◽  
K.K. Yambaev
Keyword(s):  
Point Cloud ◽  
Three Dimensional ◽  
Laser Scanner ◽  
Test Site ◽  
Optical Systems ◽  
Advantages And Disadvantages ◽  
Site Survey ◽  
Laser Scanners ◽  
Three Dimensional Models ◽  
The Stability

The authors consider hand-held laser scanners, as a new photogrammetric tool for obtaining three-dimensional models of objects. The principle of their work and the newest optical systems based on various sensors measuring the depth of space are described in detail. The method of simultaneous navigation and mapping (SLAM) used for combining single scans into point cloud is outlined. The formulated tasks and methods for performing studies of the DotProduct (USA) hand-held laser scanner DPI?8X based on a test site survey are presented. The accuracy requirements for determining the coordinates of polygon points are given. The essence of the performed experimental research of the DPI?8X scanner is described, including scanning of a test object at various scanner distances, shooting a test polygon from various scanner positions and building point cloud, repeatedly shooting the same area of the polygon to check the stability of the scanner. The data on the assessment of accuracy and analysis of research results are given. Fields of applying hand-held laser scanners, their advantages and disadvantages are identified.

scholarly journals Gum Tragacanth (GT): A Versatile Biocompatible Material beyond Borders

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1510 ◽  
Author(s):  
Mohammad Ehsan Taghavizadeh Yazdi ◽  
Simin Nazarnezhad ◽  
Seyed Hadi Mousavi ◽  
Mohammad Sadegh Amiri ◽  
Majid Darroudi ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Food Packaging ◽  
Three Dimensional ◽  
Great Promise ◽  
Anionic Polymer ◽  
Gum Tragacanth ◽  
New Horizons ◽  
Tissue Healing ◽  
The Stability ◽  
Therapeutic Substance

The use of naturally occurring materials in biomedicine has been increasingly attracting the researchers’ interest and, in this regard, gum tragacanth (GT) is recently showing great promise as a therapeutic substance in tissue engineering and regenerative medicine. As a polysaccharide, GT can be easily extracted from the stems and branches of various species of Astragalus. This anionic polymer is known to be a biodegradable, non-allergenic, non-toxic, and non-carcinogenic material. The stability against microbial, heat and acid degradation has made GT an attractive material not only in industrial settings (e.g., food packaging) but also in biomedical approaches (e.g., drug delivery). Over time, GT has been shown to be a useful reagent in the formation and stabilization of metal nanoparticles in the context of green chemistry. With the advent of tissue engineering, GT has also been utilized for the fabrication of three-dimensional (3D) scaffolds applied for both hard and soft tissue healing strategies. However, more research is needed for defining GT applicability in the future of biomedical engineering. On this object, the present review aims to provide a state-of-the-art overview of GT in biomedicine and tries to open new horizons in the field based on its inherent characteristics.

scholarly journals Emergent chiral symmetry in a three-dimensional interacting Dirac liquid

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
András L. Szabó ◽  
Bitan Roy
Keyword(s):  
Fixed Points ◽  
Chiral Symmetry ◽  
Rotational Symmetry ◽  
Three Dimensional ◽  
Spatial Dimension ◽  
Dirac Fermions ◽  
Electronic Interactions ◽  
Emergent Phenomena ◽  
Ordered Phases ◽  
The Stability

Abstract We compute the effects of strong Hubbardlike local electronic interactions on three-dimensional four-component massless Dirac fermions, which in a noninteracting system possess a microscopic global U(1) ⊗ SU(2) chiral symmetry. A concrete lattice realization of such chiral Dirac excitations is presented, and the role of electron-electron interactions is studied by performing a field theoretic renormalization group (RG) analysis, controlled by a small parameter ϵ with ϵ = d−1, about the lower-critical one spatial dimension. Besides the noninteracting Gaussian fixed point, the system supports four quantum critical and four bicritical points at nonvanishing interaction couplings ∼ ϵ. Even though the chiral symmetry is absent in the interacting model, it gets restored (either partially or fully) at various RG fixed points as emergent phenomena. A representative cut of the global phase diagram displays a confluence of scalar and pseudoscalar excitonic and superconducting (such as the s-wave and p-wave) mass ordered phases, manifesting restoration of (a) chiral U(1) symmetry between two excitonic masses for repulsive interactions and (b) pseudospin SU(2) symmetry between scalar or pseudoscalar excitonic and superconducting masses for attractive interactions. Finally, we perturbatively study the effects of weak rotational symmetry breaking on the stability of various RG fixed points.

scholarly journals Biomechanical Effects of Torquing on Upper Central Incisor with Thermoplastic Aligner: A Comparative Three-Dimensional Finite Element Study with and Without Auxillaries

2021 ◽  
pp. 030157422097434
Author(s):  
V Sandhya ◽  
AV Arun ◽  
Vinay P Reddy ◽  
S Mahendra ◽  
BS Chandrashekar ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Three Dimensional ◽  
Central Incisor ◽  
Dimensional Finite Element ◽  
Attachment Model ◽  
Three Dimensional Finite Element ◽  
3D Finite Element Method ◽  
Root Movement ◽  
Maxillary Dentition

Background and Objectives: This study was conducted to determine the effective method to torque the incisor with thermoplastic aligner using a three-dimensional (3D) finite element method. Materials and Methods: Three finite element models of maxilla and maxillary dentition were developed. In the first model, thermoplastic aligner without any auxiliaries was used. In the second and third models, thermoplastic aligner with horizontal ellipsoid composite attachment and power ridge were used, respectively. The software used for the study was ANSYS 14.5 FE. A force of 100 g was applied to torque the upper right central incisor. The resultant force transfer, stress distribution, and tooth displacement were evaluated. Results: The overall tooth displacement and stress distribution appeared high in the model with power ridge, whereas the root movement was more in the horizontal ellipsoid composite attachment model. The model without any auxillaries produced least root movement and stress distribution. Conclusion: Horizontal ellipsoid composite attachment achieved better torque of central incisor than the model with power ridge and model without any auxillaries.

Stability and instability of some nonlinear dispersive solitary waves in higher dimension

1996 ◽  
Vol 126 (1) ◽  
pp. 89-112 ◽  
Author(s):  
Anne de Bouard
Keyword(s):  
Solitary Waves ◽  
Acoustic Waves ◽  
Vries Equation ◽  
Three Dimensional ◽  
Higher Dimension ◽  
Ion Acoustic Waves ◽  
Stability And Instability ◽  
Ion Acoustic ◽  
De Vries ◽  
The Stability

We study the stability of positive radially symmetric solitary waves for a three dimensional generalisation of the Korteweg de Vries equation, which describes nonlinear ion-acoustic waves in a magnetised plasma, and for a generalisation in dimension two of the Benjamin–Bona–Mahony equation.

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