Ultimate pullout resistance of single vertical anchors

1994 ◽  
Vol 31 (5) ◽  
pp. 661-672 ◽  
Author(s):  
Ashraf Ghaly ◽  
Adel Hanna
Keyword(s):  
Theoretical Analysis ◽  
Limit Equilibrium ◽  
Shear Stresses ◽  
Relative Depth ◽  
Uplift Capacity ◽  
Pullout Resistance ◽  
Overconsolidation Ratio ◽  
Shearing Resistance ◽  
Shear Factors ◽  
Good Agreement

An investigation into the performance of single vertical screw anchors installed in sands is presented. Models were developed employing the limit equilibrium method of analysis to predict the uplift capacity of anchors installed into shallow, transition, and deep depths. An experimentally observed log-spiral rupture surface was used in the theoretical analysis. Shear stresses were calculated on the surface of rupture using Kötter's differential equation. Weight and shear factors for shallow and deep anchors are established to simplify the calculation of the uplift capacity from the theories developed. These factors are presented in simple graphs as functions of the angle of shearing resistance of the sand and the relative depth ratio of the anchor. The effect of sand overconsolidation resulting from the application of mechanical compaction was introduced by incorporating the overconsolidation ratio in the uplift capacity calculations. Comparisons between the theoretical values and the experimental results of the present investigation as well as field results reported in the literature showed good agreement. Key words : anchors, failure mechanism, limit equilibrium, overconsolidation ratio, theoretical analysis, uplift capacity.

Ultimate pullout resistance of groups of vertical anchors

1994 ◽  
Vol 31 (5) ◽  
pp. 673-682 ◽  
Author(s):  
Adel Hanna ◽  
Ashraf Ghaly
Keyword(s):  
Group Action ◽  
Theoretical Calculations ◽  
Limit Equilibrium ◽  
Companion Paper ◽  
Relative Depth ◽  
Uplift Capacity ◽  
Rupture Surface ◽  
Dense Sand ◽  
Pullout Resistance ◽  
Shearing Resistance

A theoretical investigation on the group action of vertical screw anchors installed in sands is presented. An experimentally observed rupture surface for single anchors was employed to establish the shape of the rupture surface for groups of anchors. A theory was developed to predict the uplift capacity of groups of anchors with different configurations utilizing the theoretical model described in a companion paper. To calculate the uplift capacity, weight and shear factors for shallow and deep groups of anchors are established. These factors are presented as functions of the angle of shearing resistance of the sand, relative depth ratio of an individual anchor within the group, and (or) the ratio between the height of embedded failure bulb and anchor diameter. The effect of overconsolidation due to the compaction technique used in placing the sand was incorporated in the theoretical calculations of uplift capacity. Comparison between theoretical and experimental results shows good agreement in the case of loose and medium sands and satisfactory agreement in the case of dense sand. An empirical equation, based on theory and experimental data, is proposed to mathematically quantify the effect of densification-on the angle of shearing resistance of the sand. Key words : anchors, group action, limit equilibrium, overconsolidation ratio, theoretical analysis, uplift capacity.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

Seismic uplift capacity of inclined strip anchors

2005 ◽  
Vol 42 (1) ◽  
pp. 263-271 ◽  
Author(s):  
Deepankar Choudhury ◽  
K S Subba Rao
Keyword(s):  
Limit Equilibrium ◽  
Ground Surface ◽  
Failure Surface ◽  
Friction Angle ◽  
Uplift Capacity ◽  
Principle Of Superposition ◽  
Seismic Acceleration ◽  
Acceleration Coefficient ◽  
Angle Of Internal Friction ◽  
Seismic Forces

Uplift capacities of inclined strip anchors in soil with a horizontal ground surface are obtained under seismic conditions. Limit equilibrium approaches with a logarithm-spiral failure surface and pseudostatic seismic forces are adopted in the analysis. The results are presented in the form of seismic uplift capacity factors as functions of anchor inclination, embedment ratio, angle of internal friction of the soil, and horizontal and vertical seismic acceleration coefficients. The uplift capacity factors are worked out separately for cohesion, surcharge, and density components. Use of the principle of superposition for calculating anchor uplift capacity is validated. The vertical seismic acceleration coefficient always reduces the uplift capacity, whereas the horizontal seismic acceleration coefficient reduces the uplift capacity in most cases. The roles of anchor embedment ratio, soil friction angle, and anchor inclination in determination of the seismic uplift capacity are also discussed. Comparisons of the proposed method with available theories in the seismic case are also presented. The present study gives the minimum seismic uplift capacity factors compared with the existing theory.Key words: seismic uplift capacity factors, inclined strip anchors, limit equilibrium, pseudostatic, c–ϕ soil.

scholarly journals Soil-Root System Withholding Strength for River Bank Stability

2016 ◽  
Vol 77 (1) ◽  
Author(s):  
IR. PROF. DR RUSLAN HASSAN HASSAN ◽  
Ding Ibau
Keyword(s):  
Relative Strength ◽  
Shear Stresses ◽  
Strength Increase ◽  
Maximum Displacement ◽  
River Bank ◽  
Slope Stabilisation ◽  
Shearing Resistance ◽  
The Stability ◽  
Direct Shear Apparatus ◽  
Riverbank Restoration

The ability of vegetation to stabilise soils is frequently employed in slope stabilisation projects including riverbank restoration activity. Soil block samples permeated with roots of Bermuda Grass commonly used for remediation and riverbank restoration were tested in a direct shear apparatus. Shear stress results of rooted soils were compared with results of un-vegetated soil bloc—s with similar soil types. The increase of shear strength was determined by comparing shear stresses at speciic horizontal displacements. The relative strength increase at the same displacement was 27.3 kPa compared to 19.1 kPa for un-vegetated soil at a displacement of 13.3cm (Location 3). The relative strength increase at the same displacement of 13.3cm was 43.5% for Location 1 and 42.4% for Location 2. The shear stresses in most of the blocks with roots were still increasing at the end of the test (maximum displacement of about 15cm). These conservative root biomass values and the shearing resistance obtained can be used in the assessment of the stability of the existing vegetated slopes and in the design of vegetated riverbanks.

scholarly journals CONCERNING THE EXTRACTION OF A SLACK SOIL LAYER FROM COMPRESSIBLE THICKNESS OF FOUNDATION STRATUM OF FINITE WIDTH FOUNDATIONS

2019 ◽  
Vol 7 (4) ◽  
pp. 49-56
Author(s):  
Zaven Ter-Martirosyan ◽  
Armen Ter-martirosyan ◽  
Valery DEMYANENKO
Keyword(s):  
Analytical Solutions ◽  
Soft Soil ◽  
Soil Layer ◽  
Horizontal Displacement ◽  
Creep Model ◽  
Shear Stresses ◽  
Finite Width ◽  
Relative Depth ◽  
Weak Layer ◽  
Horizontal Displacements

The paper provides a quantitative assessment of the deflected mode of foundation stratum of finite width foundation, in the compressible thickness of which there is a slack clay soil layer. A number of criteria for assessing the possibility or impossibility of extruding a slack layer depending on its strength and rheological properties, as well as the relative thickness of the layer to its length (h/l) and the relative depth of the layer (h/d) have been given. Closed analytical solutions are given to determine the rate of Foundation precipitation depending on the rate of extrusion of the weak layer, including taking into account the damped and undamped creep. The analytical solutions in the article are supported by the graphical part made with the help of the Mathcad program. Plots of changes in shear stresses in the layer along the x axis at different distances from the axis and at different values 0, contours of horizontal displacement velocities in the weak layer at different distances from the x axis, plots of horizontal displacement velocities in the middle of the weak layer and plots of horizontal displacement velocities in the weak layer at different distances from the x axis are given. As a calculation model for describing the creep of a slack layer, rheological ones of the soil using power and hyperbolic functions and their modifications have been considered. In addition, most modern rheological models that take into account soil hardening during creep have been considered. Based on these models, the problem is solved by means analytical and numerical methods using the Mathcad PC and the PLAXIS PC according to the Soft Soil Creep model. The graphical part shows the isofields of horizontal displacements for 300 days and 600 days and the corresponding contours of horizontal displacements.

Vibration Analysis for Piezoceramic Circular Plates with V-Notches. Part 1: Theory

2014 ◽  
Vol 30 (6) ◽  
pp. 603-609 ◽  
Author(s):  
C.-H. Huang ◽  
Y.-Y. Chen
Keyword(s):  
Theoretical Analysis ◽  
Transverse Vibration ◽  
Stress Singularity ◽  
Trigonometric Polynomials ◽  
Circular Plates ◽  
The Finite Element Method ◽  
Electrical Field ◽  
Ritz’S Method ◽  
Frequency Variations ◽  
Good Agreement

AbstractIn this paper the transverse vibration characteristics of piezoceramic circular plates with V-notches are investigated theoretically through use of the Ritz's method incorporated with the defined equivalent constants. The Ritz's method is employed with two sets of admissible displacement functions, algebraic-trigonometric polynomials and corner functions, to guarantee convergence sufficiently and represent the stress singularity, respectively. Moreover, the equivalent constants derived by comparing the characteristic equations of transverse vibration between isotropic and piezoceramic disks are applied to suspend the electrical field consideration regarding the piezoelectricity. With the aid of theoretical analysis, the non-dimensional frequency parameters of transverse vibration modes for completely free V-notching circular plates are exhibited; in addition, the frequency variations depending on various notch angles and depths are explored. Numerical calculations using the finite element method (FEM) are performed and the results are compared with the theoretical analysis. It is shown that the resonant frequencies predicted by theoretical analysis and calculated by FEM are in good agreement.

Factor of safety of slope stability from deformation energy

2018 ◽  
Vol 55 (2) ◽  
pp. 296-302 ◽  
Author(s):  
Shiguo Xiao ◽  
Wei Dong Guo ◽  
Jinxiu Zeng
Keyword(s):  
Shear Strength ◽  
Factor Of Safety ◽  
Plastic Material ◽  
Limit Equilibrium ◽  
Deformation Energy ◽  
Simple Expression ◽  
Shear Stresses ◽  
Limit Equilibrium Methods ◽  
Coulomb Failure Criterion ◽  
Elastic Plastic Material

The factor of safety of a slope (Fs) is invariably assessed using methods underpinned by moment, force, and (or) shear strength equilibrium concerning slip surfaces. Each method inherently embeds some form of limitations, despite being popularly adopted in practice. In this paper, a new Fs is devised using the ratio of ultimate energy (eu, upon sliding) over accumulated “elastic” energy. The Fs is then reduced to a simple expression of the power to shear stress and shear strength, by taking soil as an elastic–plastic material obeying the Mohr–Coulomb failure criterion. This expression empowers significant efficacy in gaining the factor of safety (without involving energy or directions of shear stresses). The Fs values were calculated for three typical slopes concerning various mechanical properties (dilation, Poisson’s ratio, and shear modulus) and effective computational strategies. All of the Fs values (to a congruous accuracy of available methods) were obtained in less than 1% the time of conventional numerical analyses. The proposed Fs, equally applicable to limit equilibrium methods, may be utilized in practice to expedite slope design.

Vibrational characteristics of an earth dam

1966 ◽  
Vol 56 (6) ◽  
pp. 1207-1226
Author(s):  
W. O. Keightley
Keyword(s):  
Theoretical Analysis ◽  
Natural Frequencies ◽  
Forced Vibrations ◽  
Earth Dam ◽  
Mode Shapes ◽  
Modal Damping ◽  
Vibrational Characteristics ◽  
Good Agreement ◽  
Lower Frequencies

Abstract An earth dam was excited into vibrations, in the upstream-downstream direction, by four rotating eccentric-mass vibration generators which were operated on the crest. Natural frequencies, mode shapes, and equivalent viscous modal damping constants of the dam were revealed by the forced vibrations. A theoretical analysis of the dam, based on consideration of shearing deformations only, shows moderately good agreement with the behavior which was observed at the lower frequencies.

Effect of Bending Rigidity of Stringers Upon Stress Distribution in Reinforced Monocoque Cylinder Under Concentrated Transverse Loads

1948 ◽  
Vol 15 (1) ◽  
pp. 30-36
Author(s):  
Robert S. Levy
Keyword(s):  
Stress Distribution ◽  
Present Method ◽  
Load Application ◽  
Shear Stresses ◽  
Bending Rigidity ◽  
Work Analysis ◽  
Rigidity Results ◽  
Transverse Loads ◽  
Strain Rosette ◽  
Good Agreement

Abstract Least-work analysis of stress distribution in a reinforced circular monocoque cylinder is extended to determine the effect of bending resistant stringers located at the points of application of concentrated transverse loads. Calculations for a numerical example, with applied loads diametrically opposed, indicate that neglect of stringer bending rigidity results in calculated maximum shear stresses approximately 20 per cent conservative in the fields of load application and 50 per cent unsafe in an intermediate field. Further calculations indicate that the bending rigidity of the stringer has less effect when all loads are applied at the same circumferential location. Comparison of shear stresses, calculated by the present method with strain-rosette readings, indicate good agreement.

scholarly journals Double Pendulum Induced Stability

2015 ◽  
Vol 07 (06) ◽  
pp. 1550088
Author(s):  
Bezdenejnykh Nikolai ◽  
Andres Mateo Gabin ◽  
Raul Zazo Jimenez
Keyword(s):  
Theoretical Analysis ◽  
Potential Energy ◽  
High Frequency ◽  
Relative Equilibrium ◽  
Double Pendulum ◽  
Harmonic Vibrations ◽  
Hamilton Equations ◽  
High Frequency Harmonic ◽  
Good Agreement ◽  
Frequency Harmonic

In this work, a study of the relative equilibrium of a double pendulum whose point of suspension performs high frequency harmonic vibrations is presented. In order to determine the induced positions of equilibrium of the double pendulum at different gravity and vibration configurations, a set of experiments has been conducted. The theoretical analysis of the problem has been developed using Kapitsa’s method and numerical method. The method of Kapitsa allows to analyze the potential energy of a system in general and to find the values of the parameters of the problem that correspond to the relative extreme of energy — positions of stable or unstable equilibrium. The results of numerical and theoretical analysis of Hamilton equations are in good agreement with the results of the experiments.

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