scholarly journals Interpretation of vane shear tests for geotechnical stability calculations

2017 ◽  
Vol 54 (12) ◽  
pp. 1775-1780 ◽  
Author(s):  
George Kouretzis ◽  
Jubert Pineda ◽  
Kristian Krabbenhøft ◽  
Lachlan Wilson
Keyword(s):  
Effective Stress ◽  
Slip Surface ◽  
Failure Criteria ◽  
Shear Tests ◽  
Vane Shear Test ◽  
Rate Effects ◽  
Undrained Strength ◽  
Geotechnical Stability ◽  
The Given ◽  
Theoretical Considerations

In this note we consider the problem of calibrating failure criteria for short-term stability calculations based on the results of vane shear tests. Numerical and theoretical considerations supported by experimental data provide evidence that we can use the vane shear test to obtain the undrained strength of a sample tested under simple shear conditions at a normal stress equal to the horizontal effective stress at the given depth. Consequently, it is argued that there is no need to correct the field vane undrained strength to obtain the mobilized strength for embankment stability calculations, provided that soil strength is normalized to the normal effective stress acting on the slip surface and rate effects are properly considered. We further show that the standard Tresca failure criterion, albeit simplistic, will provide reasonable estimates of the mobilized strength if properly calibrated against field vane tests.

Strain rate behaviour of Saint-Jean-Vianney clay

1979 ◽  
Vol 16 (1) ◽  
pp. 34-42 ◽  
Author(s):  
Y. P. Vaid ◽  
P. K. Robertson ◽  
R. G. Campanella
Keyword(s):  
Undrained Shear Strength ◽  
Shear Tests ◽  
Creep Tests ◽  
One Dimensional ◽  
Sustained Loading ◽  
Preconsolidation Pressure ◽  
Constant Rate ◽  
Rate Effects ◽  
Undrained Strength ◽  
Rate Behaviour

Rate effects on one-dimensional compressibility and undrained shear strength of a heavily overconsolidated naturally cemented clay have been studied. It is shown that in constant rate-of-strain consolidation tests the compressibility increases and the apparent preconsolidation pressure decreases with progressive decrease in rate of strain. Also a decrease in undrained strength is shown to occur with slower rates of strain in constant rate-of-strain shear and with increased time of sustained loading in creep tests. Undrained strengths from the two types of shear tests have been correlated.

Assessing the undrained strength cross-anisotropy of three tailings types

2022 ◽  
Vol 12 (1) ◽  
pp. 1-24
Author(s):  
D. Reid ◽  
R. Fanni ◽  
A. Fourie
Keyword(s):  
Principal Stress ◽  
Stress Ratio ◽  
Additional Data ◽  
Layered Materials ◽  
Engineering Practice ◽  
Published Data ◽  
Shear Tests ◽  
Undrained Strength ◽  
Cross Anisotropy ◽  
Current Engineering

The cross-anisotropic nature of soil strength has been studied and documented for decades, including the increased propensity for cross-anisotropy in layered materials. However, current engineering practice for tailings storage facilities (TSFs) does not appear to generally include cross-anisotropy considerations in the development of shear strengths. This being despite the very common layering profile seen in subaerially-deposited tailings. To provide additional data to highlight the strength cross-anisotropy of tailings, high quality block samples from three TSFs were obtained and trimmed to enable Hollow Cylinder Torsional Shear tests to be sheared at principal stress angles of 0 and 45 degrees during undrained shearing. Consolidation procedures were carried out such that the drained rotation of principal stress angle that would precede potential undrained shear events for below-slope tailings was reasonably simulated. The results indicated the significant effects of cross-anisotropy on the undrained strength, instability stress ratio, contractive tendency and brittleness of each of the three tailings types. The magnitude of cross-anisotropy effects seen was generally consistent with previous published data on sands.

scholarly journals Coupled Thermal-Mechanical Progressive Damage Model with Strain and Heating Rate Effects for Lightning Strike Damage Assessment

2019 ◽  
Vol 26 (5-6) ◽  
pp. 1437-1459 ◽  
Author(s):  
S. L. J. Millen ◽  
A. Murphy ◽  
G. Catalanotti ◽  
G. Abdelal
Keyword(s):  
Heating Rate ◽  
Thermal Loading ◽  
Damage Model ◽  
Applied Pressure ◽  
Mechanical Damage ◽  
Failure Criteria ◽  
Lightning Strike ◽  
Progressive Damage ◽  
Rate Effects ◽  
Progressive Damage Model

AbstractThis paper proposes a progressive damage model incorporating strain and heating rate effects for the prediction of composite specimen damage resulting from simulated lightning strike test conditions. A mature and robust customised failure model has been developed. The method used a scaling factor approach and non-linear degradation models from published works to modify the material moduli, strength and stiffness properties to reflect the effects of combined strain and thermal loading. Hashin/Puck failure criteria was used prior to progressive damage modelling of the material. Each component of the method was benchmarked against appropriate literature. A three stage modelling framework was demonstrated where an initial plasma model predicts specimen surface loads (electrical, thermal, pressure); a coupled thermal-electric model predicts specimen temperature resulting from the electrical load; and a third, dynamic, coupled temperature-displacement, explicit model predicts the material state due to the thermal load, the resulting thermal-expansion and the lightning plasma applied pressure loading. Unprotected specimen damage results were presented for two SAE lightning test Waveforms (B & A); with the results illustrating how thermal and mechanical damage behaviour varied with waveform duration and peak current.

scholarly journals Some constraints on the severity of landslide penetration in sensitive deposits

2011 ◽  
Vol 35 (3) ◽  
pp. 301-316 ◽  
Author(s):  
M. A. Carson ◽  
Ginette Lajoie
Keyword(s):  
Case Studies ◽  
Muddy Sediment ◽  
Valley Slope ◽  
Slide Mass ◽  
Topographic Attributes ◽  
Undrained Strength ◽  
First Time ◽  
Theoretical Considerations ◽  
Landslide Retrogression

Theoretical considerations and case-studies are presented to show that, in many cases, the severity of retrogression of an unstable valley slope, in areas of sensitive muddy sediment, is controlled by the topography of the valley. A formula is offered to predict the distance of retrogression from topographic attributes of valleys. It is suggested that most retrogressive landslides in sensitive sediments involve only limited liquefaction of the spoil, and it is for this reason that retrogression is controlled by this topographic constraint. Those situations in which retrogression stops before this limit is reached are also discussed: one important factor which can determine whether or not such aborted retrogression will occur appears to be the nature of the first-time slide. Those situations in which retrogression can exceed this topographic limit are briefly examined as well: attention is focussed on the importance of spoil liquefaction as a prerequisite for such excess landslide retrogression. Data are presented which indicate that the initial undrained strength of the sediment exerts a major control on the degree of spoil liquefaction. Finally the possibility is considered that some assumed retrogressive failures were in fact flake slides in which the slide mass disintegrated after failure. Such 'retrogressive facsimiles' are considered to be rare.

scholarly journals Undrained Strength of Ultra-Weak Cohesive Soils: Relationship Between Water Content and Effective Stress

1997 ◽  
Vol 37 (3) ◽  
pp. 117-128 ◽  
Author(s):  
Diana A. Zreik ◽  
John T. Germaine ◽  
Charles C. Ladd
Keyword(s):  
Water Content ◽  
Effective Stress ◽  
Cohesive Soils ◽  
Undrained Strength

scholarly journals Cracking behaviour of fine-grained soils: from laboratory testing to numerical modelling

2019 ◽  
Vol 92 ◽  
pp. 16004
Author(s):  
Pierre Gerard ◽  
Ian Murray ◽  
Alessandro Tarantino
Keyword(s):  
Effective Stress ◽  
Failure Criterion ◽  
Shear Failure ◽  
Digital Camera ◽  
Failure Criteria ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Desiccation Cracking ◽  
Stress States ◽  
Stress Dependent

Many experimental evidences suggest that desiccation cracks in clay initiate as a result of the mobilization of soil tensile strength. However this mechanical approach disregards the cohesionless and effective stress-dependent behaviour of fine-grained soil. On the other hand recent findings in the literature suggest that effective stress-dependent shear failure criteria would be appropriate to explain the mechanisms of desiccation cracking for tensile total stress states. This work aims at assessing the validity of a shear failure criterion to predict the onset of cracking in clay forms exposed to air drying. Clay forms of various geometries were experimentally subjected to non-uniform hydraulic and mechanical boundary conditions. Time and location for crack initiation are monitored using a digital camera. Cracking experiments are then modelled in a hydro-mechanical framework using an effective-stress shear failure criterion. The comparison of simulations with experimental results for both the time and the location of cracking allows assuming that cracking occurs due to failure in shearing.

Spectrochemical Analysis in the Vacuum Ultraviolet with the Hollow-Cathode Light Source—Part I. Qualitative Analysis

1967 ◽  
Vol 21 (3) ◽  
pp. 172-175 ◽  
Author(s):  
Giulio Milazzo ◽  
Nello Sopranzi
Keyword(s):  
Qualitative Analysis ◽  
Light Source ◽  
Hollow Cathode ◽  
Vacuum Ultraviolet ◽  
Spectrochemical Analysis ◽  
Ultraviolet A ◽  
The Given ◽  
Theoretical Considerations

On the basis of some theoretical considerations concerning the analyzability of elements that have their resonance lines in the vacuum ultraviolet, a hollow-cathode light source of new design has been tested in connection with a vacuum spectrograph. The results, which show an improvement over those reported in the literature, are tabulated. The limit of detectability under the given conditions was at 0.01 μg iodine.

scholarly journals Wind Fragility for Sign Structure in Korea with Chemical Anchor Connection

2018 ◽  
Vol 186 ◽  
pp. 02008 ◽  
Author(s):  
Viriyavudh Sim ◽  
SeongDo Kim ◽  
WooYoung Jung
Keyword(s):  
Simulation Method ◽  
Failure Criteria ◽  
Dominant Factor ◽  
Strong Wind ◽  
Shear Tests ◽  
Pull Out ◽  
Typical Sign ◽  
Concrete Building ◽  
Sign Structure ◽  
Strong Winds

Damage to domestic facilities by strong winds and typhoon is on the rise in recent year. Typical sign structure used in Korea is found on the edge of concrete building, which could be easily affected by strong winds. Therefore, this study focused on sign structure among various vulnerable facilities. The evaluation of wind fragility for sign structure was carried out considering the failure of anchor at their connection to the concrete building. Moreover, pull-out and shear tests were performed to determine the resistance capacity of anchor used in this study. Monte Carlo Simulation method was used to generate random wind loads on sign structure. Additionally, fragility parameters were determined based on the failure criteria of connection anchor. Results show that diameter of the installed anchor was the dominant factor affecting the performance of sign structure subjected to strong wind.

Interpretation of T-bar penetrometer tests at shallow embedment and in very soft soils

2010 ◽  
Vol 47 (2) ◽  
pp. 218-229 ◽  
Author(s):  
D. J. White ◽  
C. Gaudin ◽  
N. Boylan ◽  
H. Zhou
Keyword(s):  
Site Investigation ◽  
Penetration Resistance ◽  
Soil Strength ◽  
Deep Penetration ◽  
Finite Element Analyses ◽  
Soft Soils ◽  
Undrained Strength ◽  
Bar Test ◽  
Shallow Failure ◽  
Theoretical Considerations

The cylindrical T-bar penetrometer was developed for profiling the undrained strength of soft soils in the centrifuge and is now a widely-used offshore site investigation tool. The conventional interpretation of the T-bar test is to convert the measured penetration resistance to soil strength using a single bearing factor associated with steady flow of soil around the bar. This paper describes a new analysis for the interpretation of T-bar penetrometer tests at shallow embedment and in soft soils, which is an increasingly significant consideration in the design of seabed infrastructure, including pipelines. The analysis captures two mechanisms that are usually neglected: (i) soil buoyancy and (ii) the reduced bearing factor arising from the shallow failure mechanism mobilized prior to the full flow of soil around the bar. The framework derives from theoretical considerations and is calibrated using large deformation finite element analyses. The depth at which the steady deep penetration condition is reached is shown to depend on the normalized soil strength, su/γ′D, and may be up to several diameters deep. The effect of this new procedure on the inferred soil strength compared with the conventional approach is illustrated through T-bar tests in three different centrifuge samples, spanning a range of strength ratios.

Effective stress vane shear strength correction factor correlations

1994 ◽  
Vol 31 (3) ◽  
pp. 335-342 ◽  
Author(s):  
Peter H. Morris ◽  
David J. Williams
Keyword(s):  
Shear Strength ◽  
Correction Factor ◽  
Effective Stress ◽  
Liquid Limit ◽  
Plasticity Index ◽  
Soil Parameters ◽  
In Situ Stresses ◽  
Rate Effects ◽  
Made In

A recent effective stress model of vane shear strength testing in soils can relate measured torques to vane shear strengths using theoretical analysis in terms of effective stress parameters. The strength estimates are based on known in situ stresses and soil parameters derived from laboratory testing. The model may be applied, for example, in obtaining theoretical estimates of conventional undrained vane shear strengths for comparison with field data and for use in stability analyses. However, the model incorporates a correction factor μv, analogous to Bjerrum's field vane shear strength correction factor μ, intended to compensate for pore-pressure and shearing-rate effects. This correction factor must be evaluated before reliable torque or shear strength estimates can be made in any given case. To facilitate this, the paper presents correlations of μv with both liquid limit and plasticity index, based on world-wide data from clays and silts. The correlations are compared with independent data from Norwegian clays. Key words : clay, correction factor, effective stress, liquid limit, plasticity index, silt, vane shear strength.

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