scholarly journals A Laboratory Study on the Shear Strength Behavior of Two Till Deposits from Northern Germany

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1692
Author(s):  
Henok Hailemariam ◽  
Frank Wuttke
Keyword(s):  
Shear Strength ◽  
Laboratory Study ◽  
Elevated Temperatures ◽  
Constitutive Models ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Experimental Program ◽  
Soil Behavior ◽  
Northern Germany ◽  
Triaxial Cell

This paper presents the findings of a laboratory study of the shear strength and yielding behavior of two glacial till soil deposits from the area of Heiligenhafen, northern Germany. The tests were conducted on reconstituted forms of the soils using a triaxial cell capable of controlling the temperature of the specimens. The experimental program included a series of multi-stage consolidated drained (CD) compression triaxial tests at temperature ranges between 20 and 60 °C. For the temperature range considered in this study, a mild reduction in the effective friction angle of the two till soils of less than 1° was observed due to an increase in temperature from 20 to 60 °C. All the results were carefully assessed in view of the intrinsic soil behavior and fabric, and existing trends are highlighted. The findings of this study provide valuable insights into the shearing properties of till deposits, and can contribute to the enhancement of existing soil constitutive models as well as the development of new models that are particularly suited to the behavior of glacial tills under elevated temperatures.

On the Hypothesis of Effective Stress in Consolidation and Strength for Unsaturated Soils

2012 ◽  
Vol 256-259 ◽  
pp. 108-111
Author(s):  
Seboong Oh ◽  
Ki Hun Park ◽  
Oh Kyun Kwon ◽  
Woo Jung Chung ◽  
Kyung Joon Shin
Keyword(s):  
Shear Strength ◽  
Soil Water ◽  
Effective Stress ◽  
Unsaturated Soils ◽  
Water Retention Curve ◽  
Triaxial Tests ◽  
Residual Soil ◽  
Soil Behavior ◽  
Soil Water Retention Curve ◽  
Soil Water Retention

The hypothesis on effective stress of unsaturated soils is validated by consolidation strength results of triaxial tests for the compacted residual soil. The effective stress can describe the unsaturated soil behavior, which was defined from shear strength or from soil water characteristic curves. Since the effective stress from consolidation agrees with that from the shear strength, the effective stress from soil water retention curve could describe the unsaturated behavior consistently on both consolidation path and stress at failure. The effective stress can describe the entire unsaturated behavior from consolidation to failure.

Experimental behaviour and modelling of an unsaturated compacted soil

2000 ◽  
Vol 37 (4) ◽  
pp. 748-763 ◽  
Author(s):  
Celestino Rampino ◽  
Claudio Mancuso ◽  
Filippo Vinale
Keyword(s):  
Unsaturated Soils ◽  
Mechanical Response ◽  
Stress Path ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Experimental Program ◽  
State Variables ◽  
Soil Response ◽  
Optimum Water Content ◽  
Triaxial Cell

This paper reports the experimental study and modelling of the mechanical response of a silty sand used in the core of the Metramo dam, Italy. Specimens were prepared by compacting the soil at optimum water content conditions using the modified Proctor technique. Tests were performed under suction-controlled conditions by a stress path triaxial cell and an oedometer. The experimental program consists of 23 tests carried out in the suction range of 0-400 kPa. The findings indicate the strong influence of suction on compressibility, stiffness, and shear strength. The mechanical properties of the soil improve with suction following an exponential law with decreasing gradient. Furthermore, the soil exhibited collapsible behaviour upon wetting even at low stress levels. Interesting results were also achieved in elastoplastic modelling as well. The results led to characterization of soil behaviour with reference to widely accepted modelling criteria for unsaturated soils, providing noteworthy suggestions about their applicability for granular materials with a non-negligible fine component. Finally, some remarks are made for the extension under unsaturated conditions of the "Nor sand" model for saturated granular soils. The proposed approach yields improved predictions of deviator soil response of the tested soil when Cambridge-type frameworks prove invalid.Key words: unsaturated soils, stress state variables, triaxial tests, oedometer tests, constitutive model.

Triaxial tests on model sand columns in clay

2004 ◽  
Vol 41 (2) ◽  
pp. 299-312 ◽  
Author(s):  
V Sivakumar ◽  
D McKelvey ◽  
J Graham ◽  
D Hughes
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Stone Columns ◽  
Triaxial Tests ◽  
Column Length ◽  
Uniform Loading ◽  
Moist Sand ◽  
Triaxial Cell ◽  
Foundation Type ◽  
Undrained Shear

Vibro-stone columns can improve the bearing capacity and reduce the settlement of foundations. Their performance depends on the strength of the column material, reinforcement method of column installation, type of in situ soil, area replacement ratio, and column length. This paper examines the behaviour of small laboratory specimens of soft clay (undrained shear strength ≈ 30 kPa) reinforced with sand columns when tested under known boundary stress conditions. Two series of tests were carried out on kaolin specimens (diameter 100 mm, height 200 mm) in a triaxial cell. In the first series, specimens were reinforced with a 32 mm diameter column of sand, 80, 120, 160, or 200 mm long. Columns were installed by (i) compacting moist sand into a prebored hole or (ii) freezing a column of moist sand before inserting it into a prebored hole. In the second series, columns were reinforced with geo-grids before installation. The specimens were subjected to (i) uniform loading in which the load was applied over the entire surface area of the specimen or (ii) foundation-type loading in which only a small area in the centre of the specimen was loaded. Under uniform loading, the specimens containing a full-depth column were significantly stronger than specimens without columns. Specimens with single, partially penetrating columns installed by wet compaction were weaker than specimens without columns. When frozen columns were installed, strengths increased progressively. Under foundation-type loading, bearing capacities increased with an increase in column length. Geo-grid reinforcement produced significant increases in load-carrying capacity.Key words: ground improvement, undrained shear strength, consolidation, stress path.

scholarly journals Shear strength of compacted Chlef sand: effect of water content, fines content and others parameters

2020 ◽  
Vol 42 (1) ◽  
pp. 18-35 ◽  
Author(s):  
Djamel Bouri ◽  
Abdallah Krim ◽  
Abdelkader Brahim ◽  
Ahmed Arab
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Laboratory Study ◽  
Significant Influence ◽  
Mechanical Behaviour ◽  
Friction Angle ◽  
Mechanical Parameters ◽  
Test Results ◽  
Fines Content ◽  
Dense State

AbstractThis paper presents a laboratory study of the combined effect of the water content and fines content on the mechanical behaviour of Chlef sand in a medium dense state (RD = 65%) and dense state (RD = 80%). Several mechanical parameters were evaluated such as shear strength, cohesion and friction angle at different water content w = 0, 1, 2 and 3% and different fines content Fc = 0, 10, 20, 30 and 40%. The test results showed that the shear strength of Chlef sand decrease with the increase fines content Fc = 0 to 40%, our tests result also showed that the water content has a significant influence on the shear strength which decreases with the increase in the water content w = 0 to 3%. The fines content and the water content have a significant influence on the mechanical parameters c and φ. Cohesion increases with the percentage of fines and decreases with the increase of the water content while the friction angle decreases with the increase the fines content and the water content.

scholarly journals UNDRAINED SHEAR STRENGTH PARAMETERS OF SAPROCK FROM A WEATHERING PROFILE OVER PORPHYRITIC BIOTITE GRANITE AT KM 31 OF THE KUALA LUMPUR - KARAK HIGHWAY, PENINSULAR MALAYSIA

2021 ◽  
Vol 33 (2) ◽  
Author(s):  
John Kuna Raj
Keyword(s):  
Shear Strength ◽  
Friction Angle ◽  
Undrained Shear Strength ◽  
Triaxial Tests ◽  
Regression Analyses ◽  
Shear Strength Parameters ◽  
Weathering Profile ◽  
Strength Parameters ◽  
Zone Ii ◽  
Undrained Shear

Three broad zones can be differentiated at the weathering profile; an upper, 9.4 m thick, pedological soil (zone I), an intermediate, 31.7 m thick, saprock (zone II) and the bottom bedrock (zone III). The saprock (zone II) comprises gravelly silty sands that distinctly preserve the minerals, textures and structures of the original granite and can be separated into sub-zones II A, II B, II C, and II D, based on differences in preservation of relict structures and content of litho-relicts (core-boulders). To characterize the undrained strength of saprock, samples were collected from sub-zones II A, II B, II C and II D and their physical and soil index properties determined before unconsolidated undrained triaxial tests were carried out on remolded samples. Three to four individual samples from each sub-zone were compressed under confining pressures of 138 kPa, 207 kPa, 276 kPa and/or 345 kPa. Plots of pf = [(σ1 + σ3)/2] versus qf = [(σ1 - σ3)/2] were then used to calculate apparent cohesions of 41.9 kPa, 100.3 kPa, 76.1 kPa and 73.9 kPa, and friction angles of 32.2o, 28.1o, 26.6o and 27.8o, for the samples from sub-zones II A, II B, II C, and II D, respectively. Regression analyses show apparent cohesions to decrease with increasing clay contents, and degrees of saturation; features indicating the influence of negative pore water (or suction) pressures. Regression analyses also show apparent friction angle to increase with increasing sand contents; a feature attributed to greater inter-locking and resistance to displacement of these particles. It is concluded that the undrained shear strength parameters of saprock are characterized by an average apparent cohesion of 54.6 kPa, and friction angle of 30.5o; the parameters influenced by the degree of saturation as well as clay and sand contents.

Influence of Water Content on the Behavior of Partially Saturated Fouled Ballast

2016 ◽  
Author(s):  
Zhenning Yang ◽  
Carlton L. Ho ◽  
Richard Joy ◽  
Nandan C. Dabhade
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Modulus Of Elasticity ◽  
Coulomb Friction ◽  
Field Capacity ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Strengthening Effect ◽  
Partially Saturated ◽  
Fouled Ballast

The water content of fouled ballast is important when considering the shear strength and deformability of the ballast, and therefore critical in evaluating whether the track is at risk of excessive deformations warranting a speed restriction order. Fouled ballast from northeastern United States was tested in the laboratory to assess changes in shear strength and deformability as a function of water content. X-ray fluorescence analysis determined that the fouling material was 95% by weight basalt in origin. No more than 5% of the fouling material could be attributed to the abraded concrete ties. The field capacity of the fouled ballast was measured to be at a water content of 10%. Freezing and thawing tests indicated that approximately 4% of mass loss could be expected as a result of 25 freeze/thaw cycles. 6-inch triaxial tests, TX-CIDC, were conducted on the ballast at water contents between dry and field capacity (10%). As the ballast was partially saturated, volume change was measured using circumferential string potentiometers. The water content had an influence on the shear strength and the modulus of elasticity of the fouled ballast. The Mohr-Coulomb friction angle decreased from 47.3° for the dry ballast to 42.5° for the field capacity ballast. The Mohr-Coulomb cohesion decreased from 3.38 psi to nearly zero with initial addition of water, but increased to 6.18 psi as the water content reached field capacity. This is likely attributable to changes in capillary tension of the partially saturated fouling material. The average shear strength, Mohr-Coulomb friction angle, Mohr-Coulomb cohesion, modulus of elasticity and Poisson’s Ratio all showed weakening and strengthening effect by addition of water.

Shear strength of the weathered Champlain clay measured in a large diameter triaxial test

1982 ◽  
Vol 19 (4) ◽  
pp. 413-420
Author(s):  
J. Lafleur ◽  
G. Lefebvre ◽  
M. Marcotte ◽  
V. Silvestri
Keyword(s):  
Shear Strength ◽  
Triaxial Test ◽  
Large Diameter ◽  
Back Analysis ◽  
Sampling Procedure ◽  
Triaxial Tests ◽  
Large Sample Size ◽  
Compression Tests ◽  
Strength Parameters ◽  
Triaxial Cell

This paper describes the sampling procedure and the results of large diameter (150 mm) CID triaxial tests made on samples recovered from the weathered clay crust of the Champlain sea deposits.A visual inspection of the fissures at the depth of sampling (3 m) revealed two types of discontinuities: (a) sub-vertical joints containing black organic matter, spaced approximately every 10 cm, and (b) closed microfissures, randomly distributed in spacing and direction. In order to recover unremoulded samples of this material and avoid a difficult retrimming in the laboratory, a double core barrel 150 mm in diameter (the same as that of the triaxial cell base) was used. Eight compression tests under low confining stresses were made; they showed that the post-peak strength parameters were substantially higher than those back-calculated from a landslide involving the same weathered crust. Examination of the shape of the failure planes and of the stress–strain curves led to the conclusion that, in spite of the large sample size, the propagation of the fractures was controlled by the intact clay matrix rather than by the fissures. Since this was not believed to reproduce the actual field behaviour, a complementary test programme was undertaken, which indicated that the strength parameters were better evaluated from CID tests performed in the normally consolidated range. Keywords: fissured clays, weathering, landslides, triaxial test, shear strength parameters, sampling, back-analysis.

Isothermal modeling of sand–bentonite mixtures at elevated temperatures

1995 ◽  
Vol 32 (1) ◽  
pp. 78-88 ◽  
Author(s):  
B.E. Lingnau ◽  
J. Graham ◽  
N. Tanaka
Keyword(s):  
Shear Strength ◽  
Elevated Temperatures ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Compression Tests ◽  
Strain Behavior ◽  
Bentonite Buffer ◽  
State Boundary ◽  
Increasing Temperature ◽  
Triaxial Compression Tests

Two models are proposed for describing the stress–strain behavior of sand–bentonite (buffer) mixtures at elevated temperatures: (1) isothermal pseudoelasticity and (2) isothermal elastic-plasticity. Data to support the models come from consolidated undrained triaxial compression tests performed on dense saturated buffer specimens at effective confining stresses up to 9.0 MPa and temperatures of 26°, 65°, and 100 °C. Measurements indicate that volumes decrease with increasing temperature if the tests are carried out under drained conditions. These trends can be modelled by a family of hardening lines in semilog compression space. Power law relationships are presented for undrained shear-strength envelopes that increase in size with an increase in temperature. The slopes of unload-reload lines, κ, in semilog compression space vary with temperature and can be related to systematic variation in the friction angle [Formula: see text]. The shear modulus G50 at 50% peak strength also depends on temperature. Several plotting techniques are used to show the existence of different state boundary surfaces for each test temperature. Key words : sand–bentonite, buffer, compression, shear strength, temperature, modelling.

scholarly journals Effect of Polypropylene Fibers on the Shear Strength–Dilation Behavior of Compacted Lateritic Soils

2021 ◽  
Vol 13 (22) ◽  
pp. 12603
Author(s):  
Maitê Rocha Silveira ◽  
Sabrina Andrade Rocha ◽  
Natália de Souza Correia ◽  
Roger Augusto Rodrigues ◽  
Heraldo Luiz Giacheti ◽  
...  
Keyword(s):  
Shear Strength ◽  
Constitutive Models ◽  
Friction Angle ◽  
Polypropylene Fibers ◽  
Fiber Reinforced ◽  
Lateritic Soils ◽  
Reinforced Soils ◽  
Direct Shear Tests ◽  
Fibers Orientation ◽  
Soil Mix

The stress–dilatancy relationship for fiber-reinforced soils has been the focus of recent studies. This relationship can be used as a foundation for the development of constitutive models for fiber-reinforced soils. The present study aims to investigate the effect of recycled polypropylene fibers on the shear strength–dilation behavior of two lateritic soils using the stress–dilatancy relationship for direct shear tests. Results show that fibers improved the shear strength behavior of the composites, observed by increases in the friction angle. Fibers’ orientation at the sheared interface could be observed. The volumetric change during shearing was altered by the presence of fibers in both soils. Overall, results indicate that the stress–dilatancy relationship is affected by inclusions in the soil mix. Results can be used to implement constitutive modeling for fiber-reinforced soils.

A review on modelling of the stress-strain behaviour of soil.

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Mary Dhanya ◽  
Priyanka P Manjanath
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Construction Material ◽  
Constitutive Models ◽  
Constitutive Modelling ◽  
Slope Instability ◽  
Triaxial Tests ◽  
Stress And Strain ◽  
Strain Behaviour ◽  
Soil Behaviour

Soil has been used as a construction material since antiquity with both success and failure. As the earth material is widely available and relatively economical, it has been found very useful in the construction of foundations, subgrades, embankments and as backfill. The collapsibility of soil is mainly due to the decrease of shear strength and macro-deformation with the increase of moisture content. This can result in some serious problems, such as the differential settlement of the foundation, landslides, and slope instability, resulting in a series of damages of infrastructures and loss of human lives to some degree. In civil engineering, it is very important to make realistic predictions of the behaviour of soil under various conditions. Triaxial tests are to be carried out to study soil behaviour. The results will indicate the shear damage characteristics during the test. The relation of stress and strain of soils can be expressed using constitutive models. It can provide a brief idea about how soil will behave under different conditions. Application of Neural Network can be used to develop a data-driven constitutive modelling of the soil. Keywords- Shear strength, Triaxial test, moisture content, constitutive model

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