From Basic Particle Gradation Parameters to Water Retention Curves and Tensile Strength of Unsaturated Granular Soils

2020 ◽  
Vol 20 (6) ◽  
pp. 05020003
Author(s):  
Ji-Peng Wang ◽  
Bertrand François ◽  
Pierre Lambert
Keyword(s):  
Tensile Strength ◽  
Water Retention ◽  
Granular Soils ◽  
Basic Particle ◽  
Unsaturated Granular Soils

scholarly journals Application of single-board computers in experimental research on unsaturated soils

2020 ◽  
Vol 195 ◽  
pp. 02022
Author(s):  
Marius Milatz
Keyword(s):  
Uniaxial Compression ◽  
Mechanical Behaviour ◽  
Unsaturated Soils ◽  
Water Retention ◽  
University Teaching ◽  
Water Retention Curve ◽  
Raspberry Pi ◽  
Granular Soils ◽  
Compression Tests ◽  
Unsaturated Granular Soils

In this contribution, the application of single-board computers for the investigation of the hydro-mechanical behaviour of unsaturated granular soils is presented. Single-board computers, such as the Raspberry Pi or Arduino, have recently experienced a hype of applications in school and university teaching, in the maker scene, amongst hobbyists, but also in research. In combination with easy to learn and open programming languages, such as Python, individual experimental set-ups for research in unsaturated soil mechanics, using actuators and sensors can be easily developed with the help of different programmable hardware, such as stepper motors, analog-to-digital converters and other controller boards. For the experimental application in imaging of unsaturated granular soils by computed tomography (CT), we present a miniaturized uniaxial compression device for the measurement of unsaturated shear strength and capillary cohesion in CT-experiments. The device has already been applied for CT-imaging of the development of water distribution and capillary bridges in between different shear steps. Furthermore, a new fully programmable hydraulic experimental set-up for the automated investigation of transient hydraulic paths of the water retention curve of granular media is presented. Both devices have been developed in the framework of the Raspberry Pi single-board computer and Python programming language with simple and relatively inexpensive hardware components. In addition to the technical development of the testing devices, experimental results of the hydro-mechanical behaviour of unsaturated sand and glass beads, derived from uniaxial compression tests and water retention tests, will be presented.

Bearing Capacity Characteristic of Unsaturated Granular Soils

2011 ◽  
Vol 261-263 ◽  
pp. 989-993 ◽  
Author(s):  
Anuchit Uchaipichat ◽  
Ekachai Man Koksung
Keyword(s):  
Bearing Capacity ◽  
Matric Suction ◽  
Ultimate Bearing Capacity ◽  
Experimental Program ◽  
Granular Soils ◽  
Test Results ◽  
High Level ◽  
Unsaturated Granular Soils ◽  
Capacity Characteristic

An experimental program of laboratory bearing tests was performed to characterize the bearing capacity of foundation on unsaturated granular soils. All tests were performed by pushing a circular rod on the surface of compacted sand specimens with different values of matric suction until failure. The test results show an increase in ultimate bearing capacity with increasing matric suction at low suction value but a decrease in that at high level of suction. The comparisons between the test results and simulations using the expressions proposed in this paper are presented and discussed. Good agreements are achieved for all testing values of suction.

Determination of the tensile strength of unsaturated tailings using bending tests

2015 ◽  
Vol 52 (11) ◽  
pp. 1874-1885 ◽  
Author(s):  
Bibiana Narvaez ◽  
Michel Aubertin ◽  
Faustin Saleh-Mbemba
Keyword(s):  
Tensile Strength ◽  
Water Content ◽  
Water Retention ◽  
Water Retention Curve ◽  
Initial Water Content ◽  
Ambient Conditions ◽  
Initial Water ◽  
Bending Tests ◽  
Retention Curve ◽  
Apparent Cohesion

Bending tests were conducted on specimens of unsaturated tailings from three hard rock mines to evaluate their tensile strength. Saturated samples were prepared at an initial water content, w0, of 40% and then naturally dried under ambient conditions to pre-selected degrees of saturation, Sr, which can be related to the corresponding suction using the water retention curve. The basic interpretation of the bending tests results is based on an elastic–brittle behavior. The results show how the tensile strength, σt, of unsaturated tailings varies with water content, w (and Sr). The experimental data are also used to evaluate Young’s modulus in tension, Et, and to estimate the apparent cohesion, capp, as a function of Sr. Predictive equations are also applied to estimate the values of σt of unsaturated tailings using the water retention curve.

scholarly journals Micro- and macro-scale water retention properties of granular soils: contribution of the X-Ray CT-based voxel percolation method

Soil Research ◽  
2019 ◽  
Vol 57 (6) ◽  
pp. 575
Author(s):  
Erika Shiota ◽  
Toshifumi Mukunoki ◽  
Laurent Oxarango ◽  
Anne-Julie Tinet ◽  
Fabrice Golfier
Keyword(s):  
Water Retention ◽  
Drainage Water ◽  
Transport Processes ◽  
Water Retention Curve ◽  
Granular Soils ◽  
Pore Scale ◽  
Micro Computed Tomography ◽  
X Ray ◽  
Percolation Method ◽  
Macro Scale

Water retention in granular soils is a key mechanism for understanding transport processes in the vadose zone for various applications from agronomy to hydrological and environmental sciences. The macroscopic pattern of water entrapment is mainly driven by the pore-scale morphology and capillary and gravity forces. In the present study, the drainage water retention curve (WRC) was measured for three different granular materials using a miniaturised hanging column apparatus. The samples were scanned using X-ray micro-computed tomography during the experiment. A segmentation procedure was applied to identify air, water and solid phases in 3D at the pore-scale. A representative elementary volume analysis based on volume and surface properties validated the experimental setup size. A morphological approach, the voxel percolation method (VPM) was used to model the drainage experiment under the assumption of capillary-dominated quasi-static flow. At the macro-scale, the VPM showed a good capability to predict the WRC when compared with direct experimental measurements. An in-depth comparison with image data also revealed a satisfactory agreement concerning both the average volumetric distributions and the pore-scale local topology. Image voxelisation and the quasi-static assumption of VPM are likely to explain minor discrepancies observed at low suctions and for coarser materials.

Grainsize dependence of clastic yielding in unsaturated granular soils

2014 ◽  
Vol 16 (4) ◽  
pp. 469-483 ◽  
Author(s):  
Y. D. Zhang ◽  
G. Buscarnera
Keyword(s):  
Granular Soils ◽  
Unsaturated Granular Soils
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