Residual shear strength of fine-grained soils and soil–solid interfaces at low effective normal stresses

2015 ◽  
Vol 52 (2) ◽  
pp. 198-210 ◽  
Author(s):  
Hisham T. Eid ◽  
Ruslan S. Amarasinghe ◽  
Khaled H. Rabie ◽  
Dharma Wijewickreme
Keyword(s):  
Shear Strength ◽  
Large Strain ◽  
Laboratory Research ◽  
Normal Stresses ◽  
Interface Shear ◽  
Residual Shear Strength ◽  
Fine Grained ◽  
Solid Interface ◽  
Wide Range ◽  
Shear Area

A laboratory research program was undertaken to study the large-strain shear strength characteristics of fine-grained soils under low effective normal stresses (∼3–7 kPa). Soils that cover a wide range of plasticity and composition were utilized in the program. The interface shear strength of these soils against a number of solid surfaces having different roughness was also investigated at similar low effective normal stress levels. The findings contribute to advancing the knowledge of the parameters needed for the design of pipelines placed on sea beds and the stability analysis of shallow soil slopes. A Bromhead-type torsional ring-shear apparatus was modified to suit measuring soil–soil and soil–solid interface residual shear strengths at the low effective normal stresses. In consideration of increasing the accuracy of assessment and depicting the full-scale field behavior, the interface residual shear strengths were also measured using a macroscale interface direct shear device with a plan interface shear area of ∼3.0 m2. Correlations are developed to estimate the soil–soil and soil–solid interface residual shear strengths at low effective normal stresses. The correlations are compared with soil–soil and soil–solid interface drained residual shear strengths and correlations presented in the literature.

Some Observations on Soil-Pipe Interface Shear Strength in Direct Shear Under Low Effective Normal Stresses and Large Displacements

2016 ◽  
Author(s):  
Ruslan S. Amarasinghe ◽  
Dharma Wijewickreme ◽  
Hisham T. Eid
Keyword(s):  
Shear Strength ◽  
Accurate Determination ◽  
Direct Shear ◽  
Normal Stresses ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Fine Grained ◽  
Direct Shear Tests ◽  
Macro Scale ◽  
Soil Pipe

Experimental work is undertaken at the University of British Columbia (UBC) to study the soil-pipe interface shear strength at levels of shear displacements and effective normal stresses typically encountered in offshore soil-pipe interaction problems. A macro-scale interface direct shear apparatus having a test specimen footprint of 1.72 m × 1.75 m was designed and built for this purpose. The apparatus is capable of testing various soil-pipe interfaces under effective normal stresses in the range of 3 kPa to 6 kPa. A maximum shear displacement of 1.2 m is achievable at rates ranging from 0.1 μm/s to 1 mm/s. Sensors mounted at the interface enable the accurate determination of the effective normal stress at the interface when fully saturated fine-grained soils are tested. This paper presents some observations arising from a series of interface direct shear tests involving fine-grained soils of different plasticity against bare and epoxy coated steel surfaces.

Thermomechanical Behavior of Low CTE Metal-Matrix Composites Fabricated Through Ultrasonic Additive Manufacturing

2012 ◽  
Author(s):  
Ryan Hahnlen ◽  
Marcelo J. Dapino
Keyword(s):  
Shear Strength ◽  
Additive Manufacturing ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Large Strain ◽  
Matrix Composites ◽  
Interface Shear ◽  
Mechanical Coupling ◽  
Ultrasonic Additive Manufacturing

Shape memory and superelastic NiTi are often utilized for their large strain recovery and actuation properties. The objective of this research is to utilize the stresses generated by pre-strained NiTi as it is heated in order to tailor the CTE of metal-matrix composites. The composites studied consist of an Al 3003-H18 matrix with embedded NiTi ribbons fabricated through an emerging rapid prototyping process called Ultrasonic Additive Manufacturing (UAM). The thermally-induced strain of the composites is characterized and results show that the two key parameters in adjusting the effective CTE are the NiTi volume fraction and prestrain of the embedded NiTi. From the observed behavior, a constitutive composite model is developed based constitutive SMA models and strain matching composite models. Additional composites were fabricated to characterize the NiTi-Al interface through EDS and DSC. These methods were used to investigate the possibility of metallurgical bonding between the ribbon and matrix and determine interface shear strength. Interface investigation indicates that mechanical coupling is accomplished primarily through friction and the shear strength of the interface is 7.28 MPa. Finally, using the developed model, a composite was designed and fabricated to achieve a near zero CTE. The model suggests that the finished composite will have a zero CTE at a temperature of 135°C.

Characterisation of Residual Shear Strength at the Sheringham Shoal Offshore Wind Farm

2014 ◽  
Author(s):  
Thi Minh Hue Le ◽  
Gudmund Reidar Eiksund ◽  
Pål Johannes Strøm
Keyword(s):  
Shear Strength ◽  
Wind Farm ◽  
Offshore Wind ◽  
Interface Shear ◽  
Residual Shear Strength ◽  
Axial Capacity ◽  
Ring Shear ◽  
Stiff Clay ◽  
Soil Units ◽  
Shear Box

For offshore foundations, the residual shear strength is an important soil parameter for the evaluation of installation resistance and axial pile capacity (for jacket foundation). Estimation of residual shear strength can be conducted in a shear box test in the conventional way, or with the introduction of an interface to evaluate the change in residual shear strength under influence of friction between soil and the interface. In addition, the residual effective friction angle can be measured in the ring shear test using the Bromhead apparatus. In this study, the three above-mentioned methods are employed to estimate the values of residual shear strength of two soil units: the Swarte Bank Formation and the Chalk Unit sampled from the Sheringham Shoal offshore wind farms. The Swarte Bank Formation is dominated by heavily over-consolidated stiff clay, while the Chalk Unit is characterized by putty white chalk which behaves in a similar manner to stiff clay if weathered, or to soft rock if unweathered. These soil units are located at the bottom of the soil profile at the Sheringham Shoal wind farm and hence are important in providing axial capacity to the foundation. Samples from the two soil units are tested and compared at different rates of shearing to evaluate the change in axial capacity and installation resistance of the offshore wind turbine foundations under various possible loading and drainage conditions. Comparison is also made between residual shear strength with and without a reconsolidation period to assess the potential for soil set-up and its influence on the soil capacity. The results show that, for both the clay and the chalk, the estimated residual shear strengths are quite similar between the conventional and interface shear tests and tend to increase with increasing shearing rate. This can be attributed to the increasing dominance of the turbulent shearing mode. Relative to the peak shear strength, the values of residual shear strength are approximately 5 to 35% lower in most cases. Reconsolidation for a period of 24 hours appears to have, if any, marginal positive effect on residual shear strength of the two soils in both shear box and interface shear box tests. The residual friction angles derived from the shear box and ring shear tests are comparable and fall in the immediate range of shear strength. The various test results imply that the pile foundations at the Sheringham Shoal would have considerably large axial capacity, assuming that the horizontal stress is similar to the normal stress used in testing. The test data however should be used with caution and combined with piling experience in comparable soils where possible. The study aims to provide a source of reference for design of pile foundations for sites with similar soil conditions.

Residual Shear Strength for Interfaces between Pipelines and Clays at Low Effective Normal Stresses

2007 ◽  
Vol 133 (6) ◽  
pp. 695-706 ◽  
Author(s):  
S. S. Najjar ◽  
R. B. Gilbert ◽  
E. Liedtke ◽  
B. McCarron ◽  
A. G. Young
Keyword(s):  
Shear Strength ◽  
Normal Stresses ◽  
Residual Shear Strength

scholarly journals Plane strain shear strength of unsaturated fiber-reinforced fine-grained soils

2021 ◽  
Author(s):  
Houman Soleimani-Fard ◽  
Diethard König ◽  
Meisam Goudarzy
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Hydraulic Conductivity ◽  
Soil Conditions ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Fine Grained ◽  
Vapor Equilibrium ◽  
Wide Range ◽  
Ductile Behavior

AbstractDiscrete randomly distributed fibers are commonly used to improve the engineering characteristics of the soil and thus soil properties such as shear strength, compressibility, density, and hydraulic conductivity. Most studies have so far focused on describing the behavior of soils containing randomly distributed fibers under dried or saturated conditions. However, the water table may seasonally fluctuate, thus generating unsaturated soil conditions. Therefore, a better understanding of the hydro-mechanical properties of unsaturated improved soils is of high necessity. In this research, the shear strength parameters of fine-grained soils were evaluated using the biaxial device available at Ruhr Universität Bochum. The applied device was modified to test unsaturated fine-grained soils with various degrees of saturation using axis translation and vapor equilibrium techniques. The experiments were conducted on fine soils containing 0, 0.5, and 1% fiber contents under a wide range of matric suctions. The ductile behavior was more noticeable in samples with lower suctions and higher straw contents. Furthermore, the shear strength of both unreinforced and reinforced fine-grained soils considerably increased by an increase in the suction. Finally, shear band inclination increased by the suction while decreasing by straw content.

scholarly journals Experimental and numerical evaluations of composite concrete-to-concrete interfacial shear strength under horizontal and normal stresses

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0252050
Author(s):  
M. Yahya Al-Fasih ◽  
M. E. Mohamad ◽  
I. S. Ibrahim ◽  
Y. Ahmad ◽  
M. A. Mohd Ariffin ◽  
...  
Keyword(s):  
Shear Strength ◽  
Failure Mode ◽  
Failure Modes ◽  
Shear Failure ◽  
Zone Model ◽  
Normal Stresses ◽  
Interface Shear Strength ◽  
Interface Shear ◽  
Surface Textures ◽  
Roughened Surface

Effects of different surface textures on the interface shear strength, interface slip, and failure modes of the concrete-to-concrete bond are examined through finite element numerical model and experimental methods in the presence of the horizontal load with ‘push-off’ technique under different normal stresses. Three different surface textures are considered; smooth, indented, and transversely roughened to finish the top surfaces of the concrete bases. In the three-dimensional modeling via the ABAQUS solver, the Cohesive Zone Model (CZM) is used to simulate the interface shear failure. It is observed that the interface shear strength increases with the applied normal stress. The transversely roughened surface achieves the highest interface shear strength compared with those finished with the indented and smooth approaches. The smooth and indented surfaces are controlled by the adhesive failure mode while the transversely roughened surface is dominated by the cohesive failure mode. Also, it is observed that the CZM approach can accurately model the interface shear failure with 3–29% differences between the modeled and the experimental test findings.

scholarly journals Influence of the Diatomite Specie on the Peak and Residual Shear Strength of the Fine-Grained Soil

2021 ◽  
Vol 11 (4) ◽  
pp. 1352
Author(s):  
Carlos J. Slebi-Acevedo ◽  
Daniel A. Zuluaga-Astudillo ◽  
Juan C. Ruge ◽  
Daniel Castro-Fresno
Keyword(s):  
Shear Strength ◽  
Physical And Mechanical Properties ◽  
Friction Angle ◽  
Shear Resistance ◽  
Strength Test ◽  
Residual Shear Strength ◽  
Shear Strength Test ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Mexican Species

Diatomite is a powdering mineral mainly composed of diatom microfossils present in marine and lacustrine soils, which influences their physical and mechanical properties. Although many articles have been found in the literature concerning the influence of diatomite in the overall behavior of natural soils, few research efforts have been carried out to evaluate the influence of the diatom microfossil species on their shear resistance. Therefore, in this research, the influence of the diatomite species and the content in the peak and the residual shear strength of diatomite-fine grained soil mixtures was analyzed using the annular shear strength test. Scanning electron microscopy (SEM) and Atterberg limits were also carried out as additional tests to explain the interlocking effect between the microfossils and the soil. Overall, both diatomite species increased both peak and residual shear strength of the soil similar to dense sands. Nevertheless, the Mexican species reveal higher friction angle values compared with Colombian species.

scholarly journals COMPREHENSIVE STUDY OF THE PROPERTIES OF FINE-GRAINED CONCRETE UNDER DYNAMIC TENSION AND SHEAR

2020 ◽  
Vol 82 (4) ◽  
pp. 442-457
Author(s):  
M.E. Gonov
Keyword(s):  
Shear Strength ◽  
Dynamic Properties ◽  
Test Sample ◽  
Dynamic Strain ◽  
Shear Stresses ◽  
Direct Tension ◽  
Fine Grained ◽  
Kolsky Method ◽  
Wide Range ◽  
Comprehensive Study

An experimental study of the dynamic properties of fine-grained concrete under tensile and shear stresses has been carried out. A comprehensive study of the dynamic properties of concrete allows obtaining experimental data and constants. These data and constants are needed to equip dynamic strain and fracture models. The system of experiments is based on modifications of the Kolsky method. This system of experiments allows one to determine a wide range of strength and time characteristics of concrete under shock loading. The experimental setup according to the Kolsky method includes a system of measuring rods between which a test sample is installed, a gas gun for accelerating a cylindrical striker, strain gauges, a speed meter, recording and computing equipment with a software package. Conducted dynamic tests of concrete in a wide range of deformation rates (102–104 s–1). In experiments on direct tension and to determine the ultimate tensile stress of fine-grained concrete during splitting, two speed modes are implemented. In tests of shear strength, a modification of the Hopkinson split bar method was used to determine the dynamic shear strength, in which a sample made of the material under study is located in a rigid holder cut at an angle to the sample axis. The pulse recorded in the reference dipstick is used to plot the shear stress in the sample over time. Shear tests were carried out for three speeds. The results of the performed experiments on tensile, splitting and shearing are presented in the form of diagrams of stress versus deformation and stress versus time. The obtained characteristics can be used to equip computational experiments in the study of the strength of concrete structures subjected to dynamic influences.

scholarly journals Effect of temperature on the residual shear strength of fine grained soil

2021 ◽  
Author(s):  
Marcin Witowski ◽  
Witold Bogusz
Keyword(s):  
Shear Strength ◽  
Natural Variability ◽  
Heat Extraction ◽  
Effect Of Temperature ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Residual Shear Strength ◽  
Temperature Changes ◽  
Fine Grained ◽  
The Impact

Abstract The impact of low-range temperature variation on the residual shear strength parameters has been investigated. For this purpose, a standard ring shear apparatus has been subjected to low-cost modifications and equipped with thermoelectric temperature control system constructed in-house. This allowed to conduct a series of tests for clay samples at temperatures of 5°C and 20°C, which is a typical range of variation for thermo-active structures during heat extraction. In order to distinguish the impact of temperature from the natural variability of the soil samples, additional temperature changes during shearing were performed, after residual strength had been reached. The obtained results revealed an observable impact of the temperature change on the residual shear strength of tested clay; however, the variance has been close to the resolution of the measurement sensor and within the range comparable to the natural variability of fine-grained soils. Therefore, low-range temperature changes can be considered as negligible in regard to the residual shear strength parameters.

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