scholarly journals Analysis of Ground Settlement Caused by Double-line TBM Tunnelling under Existing Building

2021 ◽  
Author(s):  
Dongxue Hao ◽  
Renjun Zhu ◽  
Ke Wu ◽  
Rong Chen
Keyword(s):  
Numerical Model ◽  
Cross Section ◽  
Three Dimensional ◽  
Ground Settlement ◽  
Double Line ◽  
Existing Building ◽  
Ground Deformations ◽  
Geological Conditions ◽  
Line Construction ◽  
The Right

Abstract TBM tunnelling is less used in the subway construction in prosperous city due to the limitation of the engineering geological conditions. The studies on the influence of the TBM construction on the existing buildings are also limited. Therefore, based on the engineering case of tunnel crossing existing building in the section of Haiboqiao ~ Xiaocunzhuang station of Qingdao Metro Line 1, the numerical model that simulates the construction process of TBM tunnelling in slightly weathered granite layer is established by three-dimensional finite difference software FLAC3D to analyze the influence of TBM tunneling on ground settlement. The comparisons of ground deformations obtained from FLAC3D and field monitoring in different construction stages of double-line tunnel have been made firstly to validate the numerical model. Then the ground settlement characteristics, differential settlement and the stress distribution of the existing building and the stress of segment structure have been analyzed. Ground settlement groove along the transverse and vertical sections occurs near the building and tunnels, and the settlement becomes smaller with the farther distance from them. The settlement curve on the cross section changes dynamically and is approximately V-shaped, and its width is about 5 ~ 6 times diameter of the tunnel. For the same cross section, the range of the settlement groove after tunnelling right line increases obviously compared with that after tunnelling left line (construction first), the settlement values also increase, and the symmetrical axis of the settlement curve is shifted to the right. This paper can provide important practical reference for relative construction engineering.

Design of Circular Cross-Section Corner-Filleted Flexure Hinges for Three-Dimensional Compliant Mechanisms

2002 ◽  
Vol 124 (3) ◽  
pp. 479-484 ◽  
Author(s):  
Nicolae Lobontiu ◽  
Jeffrey S. N. Paine
Keyword(s):  
Cross Section ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Three Dimensional ◽  
Circular Cross Section ◽  
Axial Loading ◽  
Flexure Hinge ◽  
Flexure Hinges ◽  
Element Simulation ◽  
The Right

The paper introduces the circular cross-section corner-filleted flexure hinges as connectors in three-dimensional compliant mechanism applications. Compliance factors are derived analytically for bending, axial loading and torsion. A circular cross-section corner-filleted flexure hinge belongs to a domain delimited by the cylinder (no fillet) and the right circular cross-section flexure hinge (maximum fillet radius). The analytical model predictions are confirmed by finite element simulation and experimental measurements. The circular cross-section corner-filleted flexure hinges are characterized in terms of their compliance, precision of rotation and stress levels.

scholarly journals Effects of Bridge-Shaped Microchannel Geometry on the Performance of a Micro Laminar Flow Fuel Cell

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 822
Author(s):  
Muhammad Tanveer ◽  
Kwang-Yong Kim
Keyword(s):  
Fuel Cell ◽  
Numerical Model ◽  
Laminar Flow ◽  
Cross Section ◽  
Cross Sections ◽  
Three Dimensional ◽  
Narrow Channel ◽  
Navier Stokes ◽  
Cross Sectional ◽  
Square Channel

A laminar flow micro fuel cell comprising of bridge-shaped microchannel is investigated to find out the effects of the cross-section shape of the microchannel on the performance. A parametric study is performed by varying the heights and widths of the channel and bridge shape. Nine different microchannel cross-section shapes are evaluated to find effective microchannel cross-sections by combining three bridge shapes with three channel shapes. A three-dimensional fully coupled numerical model is used to calculate the fuel cell’s performance. Navier-Stokes, convection and diffusion, and Butler-Volmer equations are implemented using the numerical model. A narrow channel with a wide bridge shape shows the best performance among the tested nine cross-sectional shapes, which is increased by about 78% compared to the square channel with the square bridge shape.

Numerical Simulation of Vertical Forced Plume in a Crossflow of Stably Stratified Fluid

1995 ◽  
Vol 117 (4) ◽  
pp. 696-705 ◽  
Author(s):  
Robert R. Hwang ◽  
T. P. Chiang
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Cross Section ◽  
Three Dimensional ◽  
Experimental Measurements ◽  
Secondary Vortex ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Vortex Pairs ◽  
Plume Flows

In this study, an investigation using a three-dimensional numerical model, which treats conservation of mass, momentum, and salinity simultaneously, was carried out to study the character of a vertical forced plume in a uniform cross-stream of stably linear stratified environment. A k-ε turbulence model was used to simulate the turbulent phenomena and close the solving problem. The performance of the three-dimensional model is evaluated by comparison of the numerical results with some available experimental measurements. Results indicate that the numerical computation simulates satisfactorily the plume behavior in a stratified crossflow. The secondary vortex pairs in the cross section induced by the primary one change as the plume flows downstream. This denotes the transformation of entrainment mechanism in stratified crossflow.

Stratified rotating flow over and around isolated three-dimensional topography

1987 ◽  
Vol 322 (1564) ◽  
pp. 213-241 ◽  
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Wave Pattern ◽  
The Body ◽  
Lee Waves ◽  
Lee Wave ◽  
Long Time ◽  
Dynamical Parameters ◽  
The Right ◽  
Eddy Shedding

Laboratory and numerical experiments have been conducted on the flow of a linearly stratified rotating fluid past isolated obstacles of revolution (conical and cosinesquared profiles). Laboratory experiments are considered for a range of Rossby, Ekman and Burger numbers, the pertinent dynamical parameters of the system. In these experiments, inertial, Coriolis, pressure, viscous and buoyancy forces all play a significant role. Emphasis is given to examining the nature of the time development of the flow fields as well as its long-time behaviour, including eddy shedding. It is shown, for example, that increased stratification tends to diminish the steering effect of the obstacle, other parameters being fixed, at elevation levels above the topography. At levels below the top of the obstacle, increased stratification tends to force the fluid around rather than over the body and this, in turn, tends to develop vortex shedding at smaller Reynolds numbers than would occur in corresponding lower stratification cases. Data for the cone reveal that the Strouhal number for the eddy-shedding regime is relatively insensitive to the values of Ro , Ek and S for the range of parameters investigated. Stratification tends to induce lee waves in the topography wake, and the nature of this lee-wave pattern is modified by the presence of rotation. For example, it is demonstrated that for vertically upward rotation, the lee waves on the right, facing downstream, have a larger amplitude than their counterparts at the same location on the left. The steering effects, as predicted by a three-level quasigeostrophic numerical model, are shown to be in good agreement with the laboratory results for a narrow range of parameter space. The numerical model is used to examine the effects of rotation, friction and stratification in modifying the flow. The quasigeostrophic numerical simulations do not produce eddy shedding, and it is concluded that a full, primitive equation numerical model would be needed to explore this phenomenon.

Experimental Study on Cracking and Integrity Stability of Xiluodu Arch Dam

2007 ◽  
Vol 353-358 ◽  
pp. 2565-2568 ◽  
Author(s):  
R.K. Wang ◽  
P. Lin ◽  
W.Y. Zhou
Keyword(s):  
Water Pressure ◽  
Three Dimensional ◽  
Arch Dam ◽  
Dam Failure ◽  
Geological Conditions ◽  
Normal Water ◽  
Local Slip ◽  
The Right ◽  
Cracking Process ◽  
Cracking Zone

In this paper, by employing a three dimensional geomechanics model test whose scale is 1:250, the dam cracking process was observed, and integrity stability was analyzed and evaluated under overloading test. The experimental results show that: the stress and strain of the dam can basically meet the requirements of dam safety under normal water load, and the dam failure mode of the left abutment is different from that in the right side because of different types of dam figure and geological conditions. Firstly, the local slip fracture is formed on the foundation, then extends along the bottom of dam, and leads to instability and final failure. In overloading process, crack initiate from dam heel under twice normal water pressure, and form a small cracking zone, then yielding continuously and crack band appearing in downstream surface under 4.5th normal water pressure, and overall failure under 8.5th normal water pressure. The integrity stability is shown strong enough with experimental dam shape (XLD03 Figure) and the configuration of its foundation.

Measurement of white matter fiber-bundle cross-section in multiple sclerosis using diffusion-weighted imaging

2020 ◽  
pp. 135245852093899
Author(s):  
Loredana Storelli ◽  
Elisabetta Pagani ◽  
Paolo Preziosa ◽  
Massimo Filippi ◽  
Maria A Rocca
Keyword(s):  
Multiple Sclerosis ◽  
White Matter ◽  
Cross Section ◽  
Fiber Bundle ◽  
Diffusion Weighted Imaging ◽  
Three Dimensional ◽  
Spherical Deconvolution ◽  
Diffusion Weighted ◽  
Morphometry Analysis ◽  
The Right

Background: When investigating white matter (WM) microstructure, the axonal fiber orientation should be considered. Constrained spherical deconvolution (CSD) is a diffusion-weighted imaging (DWI) method that estimates distribution of fibers within each imaging voxel. Objective: To study fiber-bundle cross-section (FC) as measured by CSD in multiple sclerosis (MS) patients versus healthy controls (HCs). Methods: DWI and three-dimensional (3D) T1-weighted magnetic resonance imaging (MRI) were obtained from 45 MS patients and 45 HCs. We applied fixel-based morphometry analysis to assess differences of FC in MS against HCs and voxel-based analysis of fractional anisotropy (FA). Results: We found a significant widespread reduction of WM FC in MS compared to HCs. The decrease in FA was less extensive, mainly located in regions with high lesion occurrence such as the periventricular WM and the corpus callosum. Progressive MS patients showed a significant FC reduction in the right anterior cingulum, bilateral cerebellum, and in several mesencephalic and diencephalic regions compared to relapsing-remitting MS patients. Conclusion: The CSD method can be applied in MS for a fiber-specific study of WM microstructure and quantification of FC. Fixel-based findings offered greater anatomical specificity and biological interpretability by identifying tract-specific differences and allowed substantial abnormalities to be detected.

Numerical investigation on the effect of tow tension on the geometry of three-dimensional orthogonally woven fabric

2018 ◽  
Vol 89 (18) ◽  
pp. 3779-3791 ◽  
Author(s):  
Zhiping Ying ◽  
Xudong Hu ◽  
Xiaoying Cheng ◽  
Zhenyu Wu
Keyword(s):  
Numerical Model ◽  
Numerical Investigation ◽  
Cross Section ◽  
Mechanical Performance ◽  
Three Dimensional ◽  
Transverse Force ◽  
Woven Fabric ◽  
Textile Composite ◽  
A Chain ◽  
Good Agreement

The fabric geometry determines the mechanical performance of a textile composite. This paper investigates the effect of tow tension on the fabric geometry during the weaving process. A numerical model at the fiber scale was established by representing the fiber as a chain of truss elements connected by fully flexible hinges and having strong tensile modules. Fabric samples were woven on a homemade loom under different tension configurations to verify the numerical model. The model results with respect to the tow cross-section and path are in good agreement with observations of the homemade fabric sample. The tow cross-section deformation is the consequence of fiber rearrangement due to the transverse force originating from Z-binder tension. It is also found that the crimps of weft tows are different to those of warp tows. For weft tows, appreciable crimping is found in the regions of intercrossing with the Z-binder tow. Meanwhile, fibers undulate at the edges and remain straight in the middle of warp tows.

Numerical Investigation of Oblique Pipeline/Soil Interaction in Sand

2010 ◽  
Author(s):  
Nasser Daiyan ◽  
Shawn Kenny ◽  
Ryan Phillips ◽  
Radu Popescu
Keyword(s):  
Numerical Model ◽  
Numerical Study ◽  
Three Dimensional ◽  
Element Model ◽  
Relative Displacement ◽  
Soil Behavior ◽  
Ground Deformations ◽  
Centrifuge Tests ◽  
Parametric Studies ◽  
Pass Through

Energy pipelines pass through various environmental and geotechnical conditions. They are usually buried and can be subjected to geohazards like landslides, fault movements or large subsidence resulting in large permanent ground deformations along part of their length. The effect of large permanent ground deformations on buried pipelines can be critical for their integrity and safety. Understanding this effect is important for pipeline designers. In the current engineering guidelines the pipeline/soil interaction has been idealized using structural modeling which evaluates the soil behavior using discrete springs with load-displacement relationships provided in three perpendicular directions (longitudinal, lateral horizontal and vertical). These springs are usually independent and during a 3D pipe/soil relative displacement they can not account for cross effects due to shear interaction between different soil zones along the pipe. Some studies in the past including an experimental study by the authors have shown the importance of cross effects between axial and lateral soil restraints on the pipeline during oblique axial/lateral pipeline/soil relative movements. In this numerical study a three-dimensional continuum finite element model is developed using ABAQUS/Standard software. The model has been calibrated against the centrifuge tests conducted by the authors. The numerical model successfully reproduces the ultimate loads and also the shape of failure surfaces observed during physical tests. The numerical model will be used to extend the physical investigation results by parametric studies in future works.

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