Effective friction angle of clays and silts from piezocone penetration tests

2018 ◽  
Vol 55 (9) ◽  
pp. 1230-1247 ◽  
Author(s):  
Zhongkun Ouyang ◽  
Paul W. Mayne
Keyword(s):  
South Carolina ◽  
Effective Stress ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Fine Grained ◽  
Undisturbed Samples ◽  
Undrained Conditions ◽  
Plastic Clays ◽  
Penetration Tests ◽  
Effective Friction

An existing effective stress limit plasticity solution for piezocone penetration tests (CPTu) is calibrated to evaluate the effective stress friction angle ([Formula: see text]) for undrained conditions for a variety of fine-grained soils ranging from natural lean to plastic clays and clayey silts from marine, alluvial, lacustrine, deltaic, and glaciofluvial origins. Data from 105 clay sites are compiled to examine the CPTu-interpreted [Formula: see text] values in comparison with laboratory benchmark values obtained from undrained consolidated anisotropic (CAUC) and undrained compression (CIUC) triaxial tests made on undisturbed samples. An approximate inversion of the theoretical solution is developed to allow profiles of [Formula: see text] to be evaluated with depth. Five well-documented case studies in Illinois, Louisiana, South Carolina, Ireland, and Massachusetts are presented to illustrate the application of the solution. Lastly, results from 1g chamber tests involving kaolin and kaolinitic–silica mixtures tested by miniature piezocone probes are shown for additional verification.

Steady-state lines of sand–silt mixtures

2006 ◽  
Vol 43 (11) ◽  
pp. 1213-1219 ◽  
Author(s):  
S L Yang ◽  
R Sandven ◽  
L Grande
Keyword(s):  
Steady State ◽  
Key Words ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Fines Content ◽  
Undrained Conditions ◽  
Drained And Undrained Conditions ◽  
Intergranular Void

The steady-state lines (SSLs) for sand–silt mixtures with various fines contents (0%, 5%, 10%, 15%, 20%, 30%, 50%, 70%, and 94%) were studied. It was indicated that the location of the SSL in the e–p′ space is different for each mixture, but the SSLs are parallel. In the e – ln p′ plot, the SSLs are similar for the mixtures with a fines content of less than the transitional fines content (TFC) when tested under drained and undrained conditions and the intergranular and interfine void ratios are used. The data diverge when the fines contents are equal to or greater than the TFC, even though the interfine void ratios are used. The results of the tests conducted under drained and undrained conditions produced a unique SSL in the p′–q space for each material. Different SSLs in the p′–q space were observed for the studied materials, and the friction angle at steady state varied in the range of 37.3°–42.2°. The study showed that the SSLs can be represented by one line in tests under drained conditions if the fines contents are less (0%–30%) than the TFC and the corrected intergranular void ratios are used. The lines can also be represented by one line for sand–silt mixtures with high fines contents (50%–94%) if the corrected interfine void ratios are used instead of void ratios. Key words: steady-state line, sand–silt mixtures, transitional fines content, drained and undrained triaxial tests.

scholarly journals Experimental study on fibre reinforced sandy soils behaviour under static loadings - drained and undrained conditions

2019 ◽  
Vol 92 ◽  
pp. 12002
Author(s):  
Jorge Hernán Flórez-Gálvez ◽  
Lucas Festugato ◽  
Nilo Cesar Consoli
Keyword(s):  
Experimental Study ◽  
Sandy Soils ◽  
Friction Angle ◽  
The Other ◽  
Triaxial Tests ◽  
Polypropylene Fibres ◽  
Undrained Conditions ◽  
Positive Effect ◽  
Drained And Undrained Conditions ◽  
Sustained Increase

The effect of the addition of 0.5% of randomly distributed polypropylene fibres in a round grained sand, composed mainly of silica, is presented on laboratory scale. The samples were compacted with two void ratios (0.75 and 0.63), corresponding to values of relative density of 50% and 90% respectively. 24 monotonic triaxial tests were performed, with initial effective mean pressures of 20, 100 and 200 kPa. Half of samples were tested in drained conditions, and the other half in undrained conditions. For the samples subjected to drained conditions, the effect of the fibres was identified at the post-failure stage, by showing sustained increase of strength. The positive effect of fibres could also be observed through the increase of material friction angle. In the samples subjected to undrained tests, the addition of fibres reduced the contractive behaviour, mainly for those more compacted.

Postfailure analysis: Tramping Lake causeway, Saskatchewan, Canada

1989 ◽  
Vol 26 (4) ◽  
pp. 687-704
Author(s):  
J. L. Labossiere ◽  
E. K. Sauer ◽  
E. A. Christiansen
Keyword(s):  
Pore Water ◽  
Slip Surface ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Lake Basin ◽  
Pore Water Pressures ◽  
Back Calculation ◽  
Vertical Subsidence ◽  
Sand And Gravel ◽  
Effective Friction

A traffic causeway placed on the sediments of saline Tramping Lake failed during construction in the summer of 1982. Vertical subsidence has continued until present (1988). The failure mechanism was controlled by sedimentary structure and artesian groundwater conditions. The shear zone is in a soft, near normally consolidated lacustrine sandy silt unit 22 m thick. The lake basin contains lacustrine, deltaic, and fluvial deposits of postglacial origin. Artesian conditions in the Upper Cretaceous Judith River Formation and postglacial fluvial sand and gravel dominate the hydrogeology at the site. The failure took place along a composite slip surface when excess pore-water pressures developed during loading [Formula: see text]. The estimated effective friction angle from triaxial tests and back calculation was 27° assuming c′ = 0. However, a parametric analysis showed that at very high pore-water pressures the effective friction angle required for equilibrium is very sensitive to small variations in ru. The calculated cohesion at [Formula: see text] required for equilibrium was 3.9 kPa, whereas the remolded vane strength measured in the field was 5.0 kPa. Key words: Foundation failure, artesian, saline environment, groundwater discharge, silty clays, postglacial fluvial and lacustrine deposits.

Hydromechanical behaviour of overconsolidated unsaturated soil in undrained conditions

2019 ◽  
Vol 56 (11) ◽  
pp. 1609-1621 ◽  
Author(s):  
Shengshen Wu ◽  
Annan Zhou ◽  
Jie Li ◽  
Jayantha Kodikara ◽  
Wen-Chieh Cheng
Keyword(s):  
Effective Stress ◽  
Unsaturated Soils ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Volumetric Strain ◽  
Degree Of Saturation ◽  
Triaxial Tests ◽  
Conventional Triaxial Compression ◽  
Hydromechanical Behaviour ◽  
Undrained Conditions

Hydromechanical behaviour of an unsaturated silt with various suctions and different overconsolidated ratios (OCRs) was investigated through a series of undrained triaxial tests (constant water contents, CW). All the samples were prepared from the slurry state. Different OCRs (= 1, 2, 4, and 8 in net stress) were achieved by unloading the samples to 400, 200, 100, and 50 kPa from an initial confining net pressure of 400 kPa. Then the samples were dried to various suctions (0, 100, 200, 300, and 400 kPa). Unsaturated samples with different OCRs were then sheared at CW conditions following the conventional triaxial compression (CTC) paths. Full hydromechanical responses including the changes in deviator stress, stress ratio, volumetric strain, suction, and degree of saturation with axial strain were monitored and are presented in this paper. Some key findings include (i) the critical state for unsaturated soils with different OCRs can be well defined by Bishop’s effective stress; (ii) the peak strength in Bishop’s effective stress increases with increase of OCR, but decreases with increase of suction in the undrained condition; and (iii) the volume change of unsaturated soils in undrained conditions is related to OCRs and the volume of pore air.

scholarly journals Experimental Study of Stress-Seepage Coupling Properties of Sandstone under Different Loading Paths

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Xi Chen ◽  
Wei Wang ◽  
Yajun Cao ◽  
Qizhi Zhu ◽  
Weiya Xu ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Pore Pressure ◽  
Complex Loading ◽  
Friction Angle ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Biot Coefficient ◽  
Cyclic Loading And Unloading ◽  
Loading And Unloading

The study on hydromechanical coupling properties of rocks is of great importance for rock engineering. It is closely related to the stability analysis of structures in rocks under seepage condition. In this study, a series of conventional triaxial tests under drained condition and hydrostatic compression tests under drained or undrained condition on sandstones were conducted. Moreover, complex cyclic loading and unloading tests were also carried out. Based on the experimental results, the following conclusions were obtained. For conventional triaxial tests, the elastic modulus, peak strength, crack initiation stress, and expansion stress increase with increased confining pressure. Pore pressure weakened the effect of the confining pressure under drained condition, which led to a decline in rock mechanical properties. It appeared that cohesion was more sensitive to pore pressure than to the internal friction angle. For complex loading and unloading cyclic tests, in deviatoric stress loading and unloading cycles, elastic modulus increased obviously in first loading stage and increased slowly in next stages. In confining pressure loading and unloading cycles, the Biot coefficient decreased first and then increased, which indicates that damage has a great impact on the Biot coefficient.

scholarly journals Spatial variability characteristics of the effective friction angle of Crag deposits and its effects on slope stability

2022 ◽  
Vol 141 ◽  
pp. 104532
Author(s):  
Samzu Agbaje ◽  
Xue Zhang ◽  
Darren Ward ◽  
Luisa Dhimitri ◽  
Edoardo Patelli
Keyword(s):  
Slope Stability ◽  
Spatial Variability ◽  
Friction Angle ◽  
Effective Friction

scholarly journals Geotechnical Investigations of an Earth-Filled Site for Construction of a Building

2020 ◽  
Vol 18 (02) ◽  
pp. 71-74
Author(s):  
Riaz Bhanbhro ◽  
Zafar Ali Siyal ◽  
Bashir Ahmed Memon ◽  
Shahnawaz Zardari ◽  
Amjad Hussain Bhutto ◽  
...  
Keyword(s):  
Friction Angle ◽  
Complex Materials ◽  
Strength Parameters ◽  
Strain Behavior ◽  
The Earth ◽  
Undisturbed Samples ◽  
Geotechnical Investigations ◽  
Allowable Bearing Capacity ◽  
Allowable Load ◽  
Silty Soils

There is a growing need of construction around the globe. This need tends to provide newer opportunities for construction of buildings over reclaimed lands or earth filled areas. Mostly, the earth is filled with soils as it is an easily available material. Soil is a complex materials, and its properties can vary due to several reasons. If not understood properly, it can damage undisturbed samples collected from earth-filled soils. The basic properties of soils, the stress-strain behavior and strength parameters are presented and discussed. Results show that soil exhibits strain hardening and normally consolidated behavior in direct shear and oedometer test respectively. It is observed that the compression index values are in the range of 0.157 to 0.182 which indicates that the material is silty soils with low plasticity. The allowable bearing capacity in our study was 305 kPa and allowable load on footing was 987 kN. The strength parameters, i.e., friction angle and cohesion are 37 degree and 2 kPa respectively.

The strength and dilatancy of sand

1992 ◽  
Vol 29 (3) ◽  
pp. 522-526 ◽  
Author(s):  
Y. P. Vaid ◽  
S. Sasitharan
Keyword(s):  
Relative Density ◽  
Triaxial Test ◽  
Friction Angle ◽  
Stress Path ◽  
Triaxial Tests ◽  
Confining Stress ◽  
Peak Friction Angle ◽  
Loading Direction ◽  
Dilation Rate ◽  
Unique Relationship

The effects of stress path and loading direction in the triaxial test on strength and dilatancy of sand are investigated. It is shown that the unique relationship observed between peak friction angle and dilation rate at peak in conventional triaxial tests is followed regardless of stress path, confining stress at failure, relative density, and the mode of loading (compression or extension). Key words : sand, peak friction angle, dilatancy, stress path, triaxial test.

scholarly journals On the variability of the effective friction angle of Saint Lucian soils: investigations through a laboratory database

ce/papers ◽  
2018 ◽  
Vol 2 (2-3) ◽  
pp. 779-784 ◽  
Author(s):  
Casey J. SHEPHEARD ◽  
Paul J. VARDANEGA ◽  
Elizabeth A. HOLCOMBE ◽  
Rose HEN-JONES ◽  
Flavia DE LUCA
Keyword(s):  
Friction Angle ◽  
Effective Friction

scholarly journals Implications of the principle of effective stress

2020 ◽  
Author(s):  
Gerd Gudehus
Keyword(s):  
Critical Phenomena ◽  
Pore Water ◽  
Effective Stress ◽  
Critical Points ◽  
Pore Water Pressure ◽  
Numerical Models ◽  
Water Pressure ◽  
Shear Bands ◽  
Triaxial Tests ◽  
Water Saturated

AbstractWhile Terzaghi justified his principle of effective stress for water-saturated soil empirically, it can be derived by means of the neutrality of the mineral with respect to changes of the pore water pressure $$p_w$$ p w . This principle works also with dilating shear bands arising beyond critical points of saturated grain fabrics, and with patterns of shear bands as relics of critical phenomena. The shear strength of over-consolidated clay is explained without effective cohesion, which results also from swelling up to decay, while rapid shearing of water-saturated clay can lead to a cavitation of pore water. The $$p_w$$ p w -neutrality is also confirmed by triaxial tests with sandstone samples, while Biot’s relation with a reduction factor for $$p_w$$ p w is contestable. An effective stress tensor is heuristically legitimate also for soil and rock with relics of critical phenomena, particularly for critical points with a Mohr–Coulomb condition. Therein, the $$p_w$$ p w -neutrality of the solid mineral determines the interaction of solid fabric and pore water, but numerical models are questionable due to fractal features.

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