scholarly journals Influence of the structure on the collapse potential and shear strength of a residual soil in the semiarid region of Northeast Brazil

2021 ◽  
Vol 337 ◽  
pp. 01003
Author(s):  
Valteson da Silva Santos ◽  
Allan B.Silva de Medeiros ◽  
Romário S.Amaro da Silva ◽  
Olava F. Santos ◽  
Osvaldo de Freitas Neto ◽  
...  
Keyword(s):  
Shear Strength ◽  
Expansive Soils ◽  
Friction Angle ◽  
Semiarid Region ◽  
Original Structure ◽  
Residual Soil ◽  
Residual Soils ◽  
Strength Parameters ◽  
Effective Measure ◽  
Two Samples

In the last decades, several engineering works have been developed in the Northeast of Brazil, a region marked by the occurrence of collapsible and expansive soils. This work aimed to characterize and study the behavior of two samples of residual soils collected in the municipality of Salgueiro-PE regarding their collapse potentials and shear strength parameters, in natural and disturbed conditions, evaluating the influence of the applied vertical stresses and the structural arrangement in these properties. The results obtained showed that the two samples analyzed show collapsible behavior, however, the observed potential for collapse was lower after the original structure arrangement was undone. From the direct shear strength tests, the strength parameters of the two soils were obtained, which pointed effective friction angle close to 30° and cohesive intercept close to 0 kPa. The destructuring of the samples did not cause a considerable variation in these parameters. Thus, it was possible to conclude that for these samples the microstructure has a predominant influence on the occurrence of collapsibility, but does not have the same relevance on the shear strength, such that the material’s destructuring can be considered as an effective measure to reduce the potential collapse.

scholarly journals Influence of shear rate on the soil's shear strength

2021 ◽  
Vol 8 (1-2) ◽  
pp. 39-47
Author(s):  
Anja Bek ◽  
Goran Jeftić ◽  
Stjepan Strelec ◽  
Jasmin Jug
Keyword(s):  
Shear Strength ◽  
Shear Rate ◽  
Maximum Shear Stress ◽  
Friction Angle ◽  
Second Phase ◽  
High Plasticity ◽  
Direct Shear ◽  
Strength Parameters ◽  
Residual Shear Strength ◽  
Two Samples

One of the most important mechanical properties is shear strength. It is conditioned by the value of the maximum shear stress that the soil can withstand before failure. Exceeding the shear strength causes one particle to slide next to another, causing the failure of soil. The shear strength of the soil for effective stresses is1 a combination of drained strength parameters: internal friction angle (φ) and cohesion (c) defined by the Mohr-Coulomb failure criterion. It is determined “in situ” and by laboratory experiments. Direct shear is the oldest and the simplest laboratory experiment to determine the shear strength of the soil. The first phase of experiment is specimen consolidation under specific vertical stress, and in the second phase specimens are sheared at a given shear rate, depending on the consolidation properties of the soil. Cohesionless soils are sheared at up to 100 times higher shear rate compared to cohesive soils. Shear rate and drainage conditions affect the magnitude of soil strength parameters. The paper is based on the comparison and demonstration of the influence of different shear rates on the peak and residual shear strength in the direct shear device. The tests were performed on two samples of low plasticity clay (CL) and one sample of high plasticity clay (CH).

Study on the Granular Shear Strength Parameters of Dumping Site

2012 ◽  
Vol 256-259 ◽  
pp. 358-361
Author(s):  
Xiang Yun Kong ◽  
Guang Jin Wang ◽  
Xiao Chao Zhou
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Dumping Site ◽  
Size Grading

Apparent particle size grading is the important characteristic of super-high bench dumping site, and the critical factors with the impact of its stability and disaster prevention are the fragmentation distribution and shear strength parameters of granular. With the copper mine dumping site which had the feature of apparent particle size grading, the thesis carried out the study of on-site particle size investigation and indoor laboratory. The particle-size distribution law with the changing of dumping-site height was analyzed and quantitative relationship between the fragmentation distribution and shear strength parameters of granular was discussed. The research results indicated that coarse-grain contents and maximum grain size were increased significantly according to the decreasing of dumping-site height, which showed that the dumping-site had the feature of apparent particle size grading. The coarse particle content in the grain size composition and internal friction angle φ of shear strength parameters increased with the obvious increment of the distribution value B. The relationship between distribution value B and the internal friction angle φ could be expressed by exponential function curve.

scholarly journals Improving Shear Strength Parameters of Sandy Soil using Enzyme-Mediated Calcite Precipitation Technique

2018 ◽  
Vol 20 (2) ◽  
pp. 91 ◽  
Author(s):  
Heriansyah Putra ◽  
Hideaki Yasuhara ◽  
Naoki Kinoshita ◽  
Erizal . ◽  
Tri Sudibyo
Keyword(s):  
Shear Strength ◽  
Sandy Soil ◽  
Friction Angle ◽  
Soil Improvement ◽  
Soil Mass ◽  
Shear Strength Parameters ◽  
Calcite Precipitation ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Potential Applications

Several methods have been established for their various potential applications as soil improvement technique, and recently the application of grouting technique using biological process have been proposed. This study discussed the applicability of enzyme-mediated calcite precipitation (EMCP) in improving the shear strength parameters of sandy soil.  In this study, soil specimens were prepared and treated with the grouting solutions composed of urea, calcium chloride, magnesium sulfate and enzyme of urease. Evolutions in the cohesion and internal friction angle of the improved soil were examined through the direct shear tests. The presence of the precipitated materials, comprising 4.1 percent of the soil mass of the treated sand, generated a cohesion of 53 kPa. However, contrary to the improvement of cohesion, the friction angle is relatively constant. It indicated that the application of the EMCP technique has no significant impact on the friction angle

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.

scholarly journals The Influence of Compaction and Water Conditions on Shear Strength and Friction Resistance between Geotextiles and Ash-Slag Mixture

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1086
Author(s):  
Andrzej Gruchot ◽  
Tymoteusz Zydroń ◽  
Agata Michalska
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Saturation ◽  
Friction Angle ◽  
Interaction Coefficient ◽  
Interfacial Friction ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Angle Of Internal Friction ◽  
Friction Resistance

The paper presents the results of tests of the shear strength of the ash–slag mixture taken from the landfill located in Kraków (Poland) and the interfacial friction resistance at the contact between the ash–slag mixture and woven or nonwoven geotextiles. The tests were carried out in a direct shear apparatus on samples with and without water saturation. The samples for testing were formed in the apparatus box at the optimum moisture by compacting them to IS = 0.90 and 1.00. The test results reveal that the shear strength parameters of the ash-slag mixture were large. It was stated the significant influence of the compaction, the growth of which has resulted in an increase in the angle of internal friction (from 7% to 9%) and cohesion (from 60% to 97%). Whereas the saturation of the samples reduced the shear strength parameters (from 4% to 6%, of the internal friction angle and 30% to 43% of cohesion). The values of the interfacial friction resistance at the contact between the ash–slag mixture and the geotextiles were large as well, but slightly smaller than the values of the shear strength parameters of the mixture itself. The compaction caused an increase in the angle of interfacial friction (from 1% to 5%) and adhesion (from 31% to 127%). The water-saturation of the samples caused a change in the angle of interfacial friction (from −6% to 3%) and decline in the adhesion (from 22% to 69%). Values of the interaction coefficient were about 0.8–1.0 and they tended to rise with increasing the normal stress. Higher values of this parameter were obtained in tests with water saturation and for non-woven geotextiles.

Geological and soil engineering properties of shallow landslides occurring in the Kutupalong Rohingya Camp in Cox’s Bazar, Bangladesh

Landslides ◽  
2022 ◽  
Author(s):  
A. S. M. Maksud Kamal ◽  
Farhad Hossain ◽  
Md. Zillur Rahman ◽  
Bayes Ahmed ◽  
Peter Sammonds
Keyword(s):  
Shear Strength ◽  
Bulk Density ◽  
Mineralogical Composition ◽  
Fine Sand ◽  
Liquid Limit ◽  
Engineering Properties ◽  
Anthropogenic Factors ◽  
Residual Soil ◽  
Geological Condition ◽  
Residual Soils

AbstractThe Forcibly Displaced Myanmar Nationals (FDMN), historically known as ‘Rohingya’ who fled the 2017 ethnic atrocities and genocide in the Northern Rakhine State of Myanmar, took shelter in Cox’s Bazar District of Bangladesh. The camp network, known as Kutupalong Rohingya Camp (KRC), is situated in the tectonically active tertiary hilly terrain. The KRC has been experiencing hydrometeorological hazards, where landslides are frequent. This study investigated the slopes’ geological condition, engineering properties and human interventions, which influence the landslides. The exposed slopes were relatively high (> 10 m) and steep ranging from 40° to 60° that have numerous polygonal tension cracks and fissures. From the geological and geotechnical aspects, there are three successive units of slope materials: (1) residual soils of sandy silt with clay, (2) highly weathered silty sandstones and (3) shale/clay with silt and fine sand intercalations at the bottom of the slopes. Field observations revealed that most slope failures occurred in the residual soil and weathered silty sandstone units. The residual soils have a bulk density of 1.49–1.97 g/cm3, a liquid limit of 25–48%, a plasticity index of 5–16% and an undrained shear strength of 23–46 kPa. The silty sandstones have a bulk density of 1.44–1.94 g/cm3, an internal friction angle of 34°–40° and a cohesion of 0.5–13 kPa. The mineralogical composition determined by the X-ray diffraction shows low clay mineral content, which does not affect landslides. However, the slope geometry, low shear strength with strain softening properties and torrential rainfall accompanied by anthropogenic factors cause numerous landslides every year. This study will help take proper mitigation and preparedness measures for slope protection in the KRC area and surroundings.

scholarly journals Measuring shear strength parameters of polymer-added bentonite-sand mixtures in laboratory experiments

2019 ◽  
Vol 92 ◽  
pp. 11014
Author(s):  
Hakki O. Ozhan
Keyword(s):  
Shear Strength ◽  
Tap Water ◽  
Friction Angle ◽  
Unit Weight ◽  
Polymer Content ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Anionic Polymer ◽  
Sand Mixture ◽  
Polymer Addition

In order to evaluate the shear strength parameters of an anionic polymer-added bentonite-sand mixture that was permeated with tap water, Proctor compaction tests and direct shear tests were performed on the mixture with a bentonite content of 15% by mass. The polymer content in the polymer-bentonite mixture was chosen as 0.5, 1, 2, 5, 10, 15 and 20% by mass, respectively. According to the results, maximum dry unit weight (Vdmax) first decreased as the polymer content was increased to 1% and then, increased. Vdmax of 20% polymer-added mixture and the mixture without polymer addition was measured as 17.55 and 17.28 kN/m3, respectively. Test results indicated that cohesion (c) increased and internal friction angle (ø) decreased due to polymer addition. 2% polymer addition caused an increase of 42 kPa in c but a decrease of 4.2° in ø. As the polymer content increased, maximum shear strength of the mixture (τmax) increased. τmax increased from 171.8 to 197.8 kPa as the polymer content was increased from 0 to 2%. As a result, 2% anionic polymer-added bentonite-sand mixture provided sufficient increase in the shear strength of the mixture.

Analysis of self-boring pressuremeter (SBPM) and Marchetti dilatometer (DMT) tests in granite saprolites

2000 ◽  
Vol 37 (4) ◽  
pp. 796-810 ◽  
Author(s):  
F Schnaid ◽  
J AR Ortigao ◽  
F M Mántaras ◽  
R P Cunha ◽  
I MacGregor
Keyword(s):  
Site Investigation ◽  
Friction Angle ◽  
Soil Parameters ◽  
Residual Soil ◽  
Residual Soils ◽  
In Situ Tests ◽  
Cemented Sand ◽  
Fundamental Parameters ◽  
Analysis Technique

This paper presents the analyses of the results of the site investigation programme carried out at the Kowloon Bay site in Hong Kong. The tests consisted of self-boring pressuremeter (SBPM), Marchetti dilatometer (DMT), and laboratory tests carried out in a granite saprolite, which can be described as a lightly cemented sand. The purpose of this research project is to stimulate the development of methods to interpret data obtained from tests in residual soils. In particular, the work aims to evaluate the analyses of the SBPM data through a curve-fitting technique. Both the loading and unloading portions of the SBPM curve were analysed and the results compared with those from other tests. The advantage of this analysis technique is the possibility of constructing a theoretical curve that reproduces a pressuremeter test from which a set of fundamental parameters can be derived, namely the friction angle, cohesion intercept, lateral stress, and shear modulus. The DMT proved to be a reliable tool that yielded good soil parameters at a small fraction of the cost of the other in situ tests.Key words: residual soil, in situ tests, pressuremeter, Marchetti dilatometer.

scholarly journals Strength Characteristics and Slope Stability of Expansive Soil from Pingdingshan, China

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ju-yun Zhai ◽  
Xiang-yong Cai
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Expansive Soil ◽  
Friction Angle ◽  
Natural Soil ◽  
Soil Slope ◽  
The Finite Element Method ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
The Stability

By analyzing the characteristics of expansive soil from Pingdingshan, China, the shear strength parameters at different water contents, dry densities, and dry-wet cycles of expansive soil are obtained. It is found that, at higher soil-water content, the internal friction angle is 0° and the shallow layer of expansive soil slope will collapse and destroy; this has nothing to do with the height of the slope and the size of the slope. The parameters of soil influenced by atmosphere are the ones which have gone through dry-wet cycles, and the parameters of soil without atmospheric influence are the same as those of natural soil. In the analysis of slope stability, the shear strength parameters of soil can be determined by using the finite element method, and the stability coefficient of the expansive soil slope can be calculated.

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