Groundwater and drawdown in a large earth excavation

1980 ◽  
Vol 17 (2) ◽  
pp. 185-202 ◽  
Author(s):  
F. Debidin ◽  
C. F. Lee
Keyword(s):  
Finite Element Method ◽  
Steady State ◽  
The Finite Element Method ◽  
Approximate Methods ◽  
Groundwater Response ◽  
The Stability ◽  
Under Construction ◽  
A Site ◽  
Ontario Hydro ◽  
Transient And Steady State

In deep excavations below the water table, the transient and steady state drawdown conditions are often of interest. Particularly in moderately pervious soils, the stability of the slopes, the excavation methods, and equipment are affected by the groundwater response in the excavation. The extent of the drawdown in the area beyond the excavation must also be determined.For a site under construction by Ontario Hydro, a test excavation to determine the drawdown response in the irregularly stratified soils is described. Analyses of the data by the finite element method and by the theory of aquifer tests are presented. The effect of recharge on the steady state and transient drawdown is discussed.For the main excavation, approximate methods to determine the rate of drawdown, the quantity of seepage, and the steady state drawdown position with recharge from infiltration or deep seepage are outlined.

scholarly journals Finite Element Analysis of Thermoelastic Contact Stability

1994 ◽  
Vol 61 (4) ◽  
pp. 919-922 ◽  
Author(s):  
Taein Yeo ◽  
J. R. Barber
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Steady State ◽  
Eigenvalue Problem ◽  
Linear Perturbation ◽  
Dimensional System ◽  
The Finite Element Method ◽  
One Dimensional ◽  
Thermoelastic Contact ◽  
Element Method

When heat is conducted across an interface between two dissimilar materials, theimoelastic distortion affects the contact pressure distribution. The existence of a pressure-sensitive thermal contact resistance at the interface can cause such systems to be unstable in the steady-state. Stability analysis for thermoelastic contact has been conducted by linear perturbation methods for one-dimensional and simple two-dimensional geometries, but analytical solutions become very complicated for finite geometries. A method is therefore proposed in which the finite element method is used to reduce the stability problem to an eigenvalue problem. The linearity of the underlying perturbation problem enables us to conclude that solutions can be obtained in separated-variable form with exponential variation in time. This factor can therefore be removed from the governing equations and the finite element method is used to obtain a time-independent set of homogeneous equations in which the exponential growth rate appears as a linear parameter. We therefore obtain a linear eigenvalue problem and stability of the system requires that all the resulting eigenvalues should have negative real part. The method is discussed in application to the simple one-dimensional system of two contacting rods. The results show good agreement with previous analytical investigations and give additional information about the migration of eigenvalues in the complex plane as the steady-state heat flux is varied.

scholarly journals Comprehensive ensuring of quality of surfaces of details at centrifugal-planetary volume processing

2018 ◽  
Vol 224 ◽  
pp. 01123 ◽  
Author(s):  
Alexander Zverovshchikov ◽  
Vladimir Zverovshchikov ◽  
Sergey Nesterov
Keyword(s):  
Finite Element Method ◽  
System Analysis ◽  
Processing Parameters ◽  
Modeling Processes ◽  
Working Fluid ◽  
The Finite Element Method ◽  
The Stability ◽  
Abrasive Working ◽  
Bulk Processing

The results of the system analysis of the set of input factors of the volumetric centrifugal-planetary processing, allowing to implement a comprehensive approach to the provision of quality processing parameters, are considered. A sequence of modeling processes ensuring the quality of surfaces during bulk processing is given. The results of modeling the contact of an abrasive working body with the surface of a workpiece with a microrelief are shown. The factors determining the stability of reliable achievement of qualitative indicators are noted. A dependence has been developed to determine the parameter of the surface roughness to be reduced, based on the results of modeling the contact between the surfaces of the working fluid and the workpiece by the finite element method. The experience of designing volumetric centrifugal processing operations on the basis of modeling is generalized. Methodical methods of technological preparation of manufacture for volumetric processing are offered.

An Investigation in Optimal Locations by Genetic Algorithm for Balancing Flexible Rotor-Bearing Systems

2005 ◽  
Author(s):  
Tsu-Wei Lin ◽  
Yuan Kang ◽  
Chun-Chieh Wang ◽  
Chuan-Wei Chang ◽  
Chih-Pin Chiang
Keyword(s):  
Genetic Algorithm ◽  
Finite Element Method ◽  
Steady State ◽  
Hermitian Matrix ◽  
Influence Coefficient ◽  
Steady State Response ◽  
Flexible Rotor ◽  
The Finite Element Method ◽  
State Response ◽  
Rotor Bearing

This study utilizes genetic algorithm to minimize the condition number of Hermitian matrix of influence coefficient (HMIC) to reduce the computation errors in balancing procedure. Then, the optimal locations of balancing planes and sensors would be obtained as fulfilling optimization. The finite element method is used to determine the steady-state response of flexible rotor-bearing systems. The optimization improves the balancing accuracy, which can be validated by the experiments of balancing a rotor kit.

The Influence of Tangential Roller Pressure on the Stability of Circular Saw Blade

2014 ◽  
Vol 614 ◽  
pp. 32-35 ◽  
Author(s):  
Ming Song Zhang ◽  
Yi Zhang ◽  
Jian Jun Ke ◽  
Xiao Wei Li ◽  
Lian Bing Cheng
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Symmetric Model ◽  
The Finite Element Method ◽  
Circular Saw ◽  
The Face ◽  
Circular Saw Blade ◽  
Cyclic Symmetric ◽  
The Stability ◽  
Saw Blade

The finite element method was used to study tangential roller method impact on the stability of circular saw blade. Using 30 ° cyclic symmetric model is analyzed. The results show that the tension of the saw blade is not the same, and tensioning effect is different, when the tangential roller pressure is not same. At the same time, after tangential roller, the face run out of saw blade is small, which show that the smoothness of tangential roller is better.

Transverse Ribs Affect the Stability of Steel-Concrete Composite Box Beams

2014 ◽  
Vol 587-589 ◽  
pp. 1663-1667
Author(s):  
Chong Yang Zhou ◽  
Jian Rong Yang ◽  
Wan Wan Jiang
Keyword(s):  
Finite Element Method ◽  
The Finite Element Method ◽  
Box Girder ◽  
Linear Buckling ◽  
Box Beams ◽  
Buckling Coefficient ◽  
Stiffening Ribs ◽  
The Stability ◽  
Lateral Bracing ◽  
Linear Buckling Analysis

The paper uses the finite element method to the specific structure of the linear buckling analysis to study the steel - concrete buckling coefficient changes when the changes and adjustments in the case of composite box girder structure different density transverse stiffening ribs buckling coefficient bracing spacing, Thus obtained that the almost linear relationship between the change in distance between the transverse stiffening ribs and buckling coefficient. Meanwhile get when bracing spacing when a valid range, coefficient of variation of buckling structure is not particularly obvious. Which is to adjust the spacing and lateral bracing number of stiffening ribs provide a space.

Out-of-Plane Stability Analysis for Crane Jib with Single Cable Considering Lateral Flexibility of the Cable Fixed Joint

2014 ◽  
Vol 685 ◽  
pp. 240-244 ◽  
Author(s):  
Peng Lan ◽  
Teng Fei Wang ◽  
Nian Li Lu
Keyword(s):  
Differential Equation ◽  
Finite Element Method ◽  
Characteristic Equation ◽  
Lateral Stiffness ◽  
Stiffness Coefficient ◽  
The Finite Element Method ◽  
Lateral Direction ◽  
Out Of Plane ◽  
Lateral Constraint ◽  
The Stability

The out-of-plane stability of crane jib is studied considering the lateral flexibility of the fixed joint. The analytical expression of the out-of-plane buckling characteristic equation for the crane jib with single cable is obtained by establishing the bending deflection differential equation of jib under the instability critical state with the method of differential equation. The equilibrium equation of the fixed point in the lateral direction is introduced to solve the differential equation besides the boundary conditions. The analytical results obtained agree very well with the finite element method (FEM) results. To consider the lateral flexibility of the cable fixed joint, a dimensionless stiffness coefficient measuring the lateral constraint was introduced to derive the out-of-plane buckling characteristic equation. The degeneration forms of the characteristic equation under the limit cases of zero lateral stiffness, infinite lateral stiffness are further discussed. And the influence of the lateral stiffness of fixed joint on the stability of jib is investigated. It is shown that the increase of the lateral stiffness will significantly improve the buckling load of the crane jib especially when the lateral stiffness is very small.

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