scholarly journals Stress Distribution in a Cohesionless Backfill Poured in a Silo

2014 ◽  
Vol 8 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Li Li ◽  
Jonathan D. Aubertin ◽  
Jean-Sébastien Dubé
Keyword(s):  
Soil Structure ◽  
Earth Pressure ◽  
Horizontal Stress ◽  
Density Variation ◽  
Direction Parallel ◽  
Rest State ◽  
Drop Mass ◽  
Drop Tests ◽  
Series Of Experiments ◽  
Infrastructure Rehabilitation

The field of infrastructure rehabilitation and development requires a better understanding of soil-structure interactions. The interaction behaviour between soil and structures has mostly been investigated through theoretical and/or numerical analysis. This paper presents a series of experiments performed on an intermediate-scale physical model made of an instrumented silo. In contrast to most reported laboratory tests, both the horizontal and vertical stresses were monitored during backfilling operations realised by wild pouring. Drop tests were performed to investigate the density variation with respect to the drop (or falling) height of the soil, which were introduced in the pressure interpretation. The results showed that horizontal stress in the direction parallel to the pouring plane is larger than that perpendicular to the pouring plane. Apparently, the vertical stress is well-described using the arching solution by considering the backfill in an active state, whereas the horizontal stress perpendicular to the pouring plane is better described with the arching solution by considering the backfill in an at-rest state. An estimate of the earth pressure coefficients based on the measured vertical and horizontal stresses indicates, however, that the backfill was closer to an at-rest state in the direction perpendicular to the pouring plane, whereas in the direction parallel to the pouring plane, it was in a state between at-rest and passive. These results indicate that it is important to measure both the horizontal and vertical stresses to obtain a whole picture of the state of the backfill. The results showed also that the horizontal stresses can be larger than those calculated by the overburden solution, probably due to dynamic loading by drop mass during the filling operation and stress lock.

Coefficient of earth pressure at rest for sands subjected to vibration

2007 ◽  
Vol 44 (10) ◽  
pp. 1242-1263 ◽  
Author(s):  
Barames Vardhanabhuti ◽  
Gholamreza Mesri
Keyword(s):  
Lake Michigan ◽  
Earth Pressure ◽  
Horizontal Stress ◽  
Vertical Vibration ◽  
Vertical Stress ◽  
Dynamic Changes ◽  
Shearing Resistance ◽  
Interparticle Contacts ◽  
Horizontal Pressure ◽  
Stress Ratios

An oedometer instrumented to measure horizontal pressure was used to examine the behavior of the coefficient of earth pressure at rest, Ko, of clean sands subjected to vertical vibration. Reconstituted specimens of Ottawa, Lake Michigan Beach, and Niigata sands were used in a comprehensive series of tests. The dynamic effort is defined by the ratio of dynamic increase in effective vertical stress to the static effective vertical stress, and frequency and duration of vibration. Dynamic changes in Koare referenced to a series of lines representing the ratio of the increase in effective horizontal stress to the increase in effective vertical stress corresponding to different void ratios or friction angles through the Jaky equation. An increase in Kooccurs when the combination of the initial sand state and dynamic effort results in periodic disengagement of interparticle contacts, producing a periodic decrease in interparticle shearing resistance and thus a periodic fluidization of the sand. The highest values of [Ko]maxas well as the lowest values of eminwere obtained with dynamic stress ratios equal to or greater than 3–4. Vibration of overconsolidated sands results in an initial Kodrop that increases with previbration density and overconsolidation ratio. Thereafter, the behavior of Koand void ratio with vibration depend on the potential for fluidization.

Effect of Surface Roughness on Cavitation Performance of Hydrofoils—Report 3

1967 ◽  
Vol 89 (1) ◽  
pp. 201-209 ◽  
Author(s):  
F. Numachi
Keyword(s):  
Surface Roughness ◽  
Present Series ◽  
Direction Parallel ◽  
Cavitation Performance ◽  
Series Of Experiments ◽  
The Subject ◽  
Effect Of Surface

As a sequel to the first and second reports of the present series of experiments intended to gain knowledge on the effect of surface roughness on hydromechanical characteristics, particularly cavitation performance, the author has this time taken up the case of striations in the direction parallel to the chord, to determine their effect on cavitation efficiency and profile performance in general, for comparison with that of spanwise striations which were the subject of the preceding two reports.

Seismic reprocessing and interpretation of a fractured-basement play: Texas Panhandle

2017 ◽  
Vol 5 (3) ◽  
pp. SK179-SK187 ◽  
Author(s):  
Thang Ha ◽  
Kurt Marfurt
Keyword(s):  
Horizontal Stress ◽  
Wave Impedance ◽  
Azimuthal Anisotropy ◽  
Oil Field ◽  
P Wave ◽  
Coherent Noise ◽  
Seismic Attribute ◽  
Gas Field ◽  
Direction Parallel ◽  
Head Waves

The Panhandle-Hugoton field, of Texas, Oklahoma, and Kansas, is a giant oil field and is the largest conventional gas field in North America. Most hydrocarbon production in this field comes from the Wichita Uplift area, where the basement is the most shallow. Although the field has been extensively produced, many local hydrocarbon accumulations have not been fully exploited. Recent drilling activity in the survey indicates that some wells produce directly from basement fractures, suggesting a new play type for the area. Because the target is shallow, the seismic data are heavily contaminated by coherent noise, such as ground roll and head waves, creating challenges for seismic processing. To improve the seismic interpretation, we carefully reprocessed the field gathers resulting in improved correlation within the sedimentary and the basement sections. Correlating well control to seismic attribute volumes indicates that a fractured basement gives rise to lower P-wave impedance and strong amplitude versus azimuth anomalies. The azimuthal anisotropy is strongest in a direction parallel to the regional maximum horizontal stress, suggesting that these fractures are open. Coherence anomalies indicate a rugose basement surface, whereas curvature shows two lineament sets, consistent with the weathering and fractured exposure of basement in the Wichita Mountains to the southeast.

Experimental characterization of deformation, coefficient of earth pressure at rest, stiffness, and contact force distributions of sand during secondary compression and rebound

2016 ◽  
Vol 53 (5) ◽  
pp. 889-898 ◽  
Author(s):  
Y. Gao ◽  
Y.-H. Wang
Keyword(s):  
Contact Force ◽  
Pressure Sensors ◽  
Earth Pressure ◽  
Horizontal Stress ◽  
Soil Behavior ◽  
Bender Elements ◽  
Secondary Compression ◽  
Comprehensive Picture ◽  
Shear Box ◽  
Deformation Coefficient

This paper aims to provide a comprehensive picture of the sand responses during secondary compression and rebound based on experimental characterizations. The experiment was carried out on dry Leighton Buzzard sand using a modified direct shear box equipped with tactile pressure sensors for the stress measurements and bender elements for stiffness (i.e., Ghv and Ghh) monitoring. It was found that secondary compression and rebound followed the same deformation trends as primary compression and rebound to continuously contract and expand, respectively. The deformation characteristics determined the changes in the associated soil properties; therefore, the opposite soil behavior during secondary compression and rebound was observed. During secondary compression, the corresponding void change, deviatoric strains εq, and the deviatoric strain rate [Formula: see text] increased with increasing vertical stress [Formula: see text] or deviatoric stress q because the sample crept more easily under a higher [Formula: see text] or q. The compression deformation gave rise to an increase in the horizontal stress [Formula: see text] and associated coefficient of earth pressure at rest K0. The soil stiffness also increased as the contact normal forces became more homogenized. During secondary rebound, the sample expanded unabated no matter whether [Formula: see text] was greater or smaller than [Formula: see text]. The corresponding void ratio change, εq, and [Formula: see text] increased with decreasing [Formula: see text] or q because the sample expanded more easily under a lower [Formula: see text] or q. The expansion gradually reduced [Formula: see text] along with the associated K0 value. The sample stiffness continued to decrease, and contact force homogenization was not observed.

Dipole dispersion crossover and sonic logs in a limestone reservoir

Geophysics ◽  
2000 ◽  
Vol 65 (2) ◽  
pp. 390-407 ◽  
Author(s):  
Bikash K. Sinha ◽  
Michael R. Kane ◽  
Bernard Frignet
Keyword(s):  
Horizontal Well ◽  
Matrix Pencil ◽  
Horizontal Stress ◽  
The Other ◽  
Shear Direction ◽  
Direction Parallel ◽  
Porosity And Permeability ◽  
Well Trajectory ◽  
Overburden Stress ◽  
Sonic Logs

Analyses of sonic logs in a horizontal well provide new information about mechanical properties of rocks, made possible by recent developments in our understanding of acoustic wave propagation in prestressed formations. Most sections of this horizontal well exhibit azimuthal shear isotropy, indicating isotropic stresses in the plane perpendicular to the well trajectory, leading to stable wellbore conditions. However, two sections show dipole dispersion crossovers that confirm the presence of stress‐induced shear anisotropy caused by a difference between the maximum and minimum stresses in the plane perpendicular to the well trajectory. The two dipole dispersions are obtained by processing the recorded waveforms by a modified matrix pencil algorithm. The fast‐shear direction is estimated from Alford rotation of the cross‐dipole waveforms. One section of the well exhibits the fast‐shear direction parallel to the overburden stress as the maximum stress direction, whereas the other section has the fast‐shear direction parallel to the horizontal stress that is larger than the overburden stress. The cause of this change in the fast‐shear direction is believed to be the well’s penetration into a 3-ft-thick bed with lower porosity and permeability and significantly higher elastic stiffnesses than those in the other part of the homogeneous, high‐permeability reservoir. A stiff bed is likely to have greater stresses in its plane than perpendicular to it, which would make the horizontal stresses greater than the vertical.

scholarly journals A field test for dynamic soil properties

1971 ◽  
Vol 4 (2) ◽  
pp. 176-204
Author(s):  
G. L. Evans
Keyword(s):  
Earthquake Engineering ◽  
Soil Structure ◽  
Earth Pressure ◽  
Simple Wave ◽  
Wave Form ◽  
S Wave ◽  
Dynamic Moduli ◽  
Seismic Surveys ◽  
Wave Velocities ◽  
Dynamic Earth Pressure

The propogation velocity of waves through ground has been used for many years in the
seismic surveys for the detection of underlying strata. From a knowledge of the percussion (P) and shear (S) wave velocities in different materials, together with their bulk densities, it is possible to derive dynamic moduli and properties, such as the shear modulus (G) and poisson’s ratio (n), which are essential in
 the solution of problems relating to dynamic earth pressure, soil structure interaction and the dynamic analysis of foundation strata relating to earthquake engineering. The principle involved in finding the wave velocities in ground materials is the same as used in finding velocities in any material. A simple wave form or pulse is generated at one point and the travel time to several other
 points is detected with suitable signal receivers.

scholarly journals The Mechanics of Arching in Induced Trench Construction – A New Theoretical Formulation

2021 ◽  
Author(s):  
Campbell Bryden ◽  
Kaveh Arjomandi ◽  
Arun J. Valsangkar
Keyword(s):  
Case Studies ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
Horizontal Stress ◽  
Full Scale ◽  
Theoretical Formulation ◽  
Finite Element Software ◽  
Lateral Earth Pressure ◽  
Earth Pressure Coefficient ◽  
Good Agreement

Full-scale experimental case studies have shown that the induced trench construction method effectively reduces the vertical earth load that is exerted on culverts installed beneath high embankments. Induced trench culverts are traditionally designed on the basis of Marston’s theory; however, various theoretical shortcomings of this formulation have recently come to light. In this paper, a new induced trench theoretical formulation is presented. The proposed analytical model employs inclined shear planes within the embankment fill; such geometry is consistent with experimental findings reported in the literature, and leads to positive arching resulting from a reduction in vertical stress and an increase in horizontal stress (thus increasing the lateral earth pressure coefficient within the induced trench zone). A series of parametric studies are performed using finite element software. The proposed theoretical formulation is shown to be in good agreement with the numerical results, and correlations are developed to provide guidance in selecting the appropriate values of: 1) the induced trench lateral earth pressure coefficient, and 2) the height to the plane of equal settlement. Two instrumented full-scale induced trench case studies are discussed, and the proposed theoretical formulation is shown to produce results that are in good agreement with the experimental data.

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