scholarly journals Characteristics of Direct Shear and Particle Breakage of Pebble Gravel Materials

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Chenjie Hong ◽  
Man Huang ◽  
Danyu Zhang ◽  
Pingshan Shou ◽  
Zhiyong Zhu
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Large Scale ◽  
Size Range ◽  
Normal Load ◽  
Particle Breakage ◽  
Direct Shear ◽  
Particle Size Range ◽  
Relationship Model ◽  
Characteristic Particle

Particle size is an important factor affecting the Thermal-Hydraulic-Mechanical (THM) coupling behavior of graveled rock mass, especially for the shear mechanical properties. In this study, three groups of the particle size range and nine particle grading samples are designed for a large-scale direct shear test. The relationships between shear stress and shear displacement, shear strength, stress ratio, shear strength parameters, and particle breakage of pebble gravel are analyzed. The influence of particle size range and grade on the strength and particle breakage of gravel material is discussed. Results show evident particle breakage in the process of direct shear, and the degree of fragmentation is controlled by the normal load and the particle size distribution of the sample. The shear strength of the sample is no longer applicable to Mohr-Coulomb strength theory because of particle breakage that is more in line with the power function relationship. Shear strength of pebble gravel material has scale effect, and a corresponding relationship model between friction coefficient f of material and characteristic particle size of the sample is proposed.

scholarly journals Effect of the Particle Size on the TDA Shear Strength and Stiffness Parameters in Large-Scale Direct Shear Tests

Geotechnics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 1-17 ◽  
Author(s):  
Hany El Naggar ◽  
Khaled Zahran ◽  
Ahmed Moussa
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Large Scale ◽  
Fire Hazard ◽  
Unit Weight ◽  
Direct Shear ◽  
Large Area ◽  
Maximum Particle Size ◽  
Maximum Particle ◽  
Strength And Stiffness

The increase in the number of discarded tires every year is becoming a major issue all over the world. Tires stockpiles and landfills have become a critical issue as they are considered a fertile environment for the breeding of rats and insects, a real fire hazard that may take up to months to extinguish and occupy a valuable, large area of land. One of the safest effective ways of recycling tires is that to use them as backfilling material, among different usages, in civil engineering projects due to their low unit weight and specific gravity. However, to use any material in the construction industry, several material properties must be evaluated, including the shear strength and stiffness parameters. Many factors control the measured parameters. One main factor that is known to have a significant effect is the particle size. This paper focuses on evaluating the effect of the particle size on the shear strength and stiffness parameters of six tire-derived aggregate (TDA) samples having particle sizes range between (9.5–101.6 mm) using a large-scale direct shear machine. The tests were conducted under three normal stresses: 50.1, 98.8 and 196.4 kPa using a constant shearing rate of 0.5 mm/min. The results of this study showed an increasing angle of internal friction as the maximum particle size increases. Moreover, the secant shear modulus also exhibited an increase by increasing the maximum particle size. Furthermore, equations to estimate the stress-strain curves of Type A-TDA for different confidence levels were developed, and their predictions were compared with experimental results to assess their suitability.

381. Sampling Efficiencies of Three Personal Aerosol Samplers within and Beyond the Inhalable Particle Size Range

2001 ◽  
Author(s):  
V. Aizenberg ◽  
P. Baron ◽  
K. Choe ◽  
S. Grinshpun ◽  
K. Willeke
Keyword(s):  
Particle Size ◽  
Size Range ◽  
Particle Size Range

scholarly journals Influence of Structural Plane Microscopic Parameters on Direct Shear Strength

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yanhui Cheng ◽  
Weijun Yang ◽  
Dongliang He
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Direct Shear ◽  
Stiffness Ratio ◽  
Structural Plane

Structural plane is a key factor in controlling the stability of rock mass engineering. To study the influence of structural plane microscopic parameters on direct shear strength, this paper established the direct shear mechanical model of the structural plane by using the discrete element code PFC2D. From the mesoscopic perspective, the research on the direct shear test for structural plane has been conducted. The bonding strength and friction coefficient of the structural plane are investigated, and the effect of mesoscopic parameters on the shear mechanical behavior of the structural plane has been analyzed. The results show that the internal friction angle φ of the structural plane decreases with the increase of particle contact stiffness ratio. However, the change range of cohesion is small. The internal friction angle decreases first and then increases with the increase of parallel bond stiffness ratio. The influence of particle contact modulus EC on cohesion c is relatively small. The internal friction angle obtained by the direct shear test is larger than that obtained by the triaxial compression test. Parallel bond elastic modulus has a stronger impact on friction angle φ than that on cohesion c. Under the same normal stress conditions, the shear strength of the specimens increases with particle size. The shear strength of the specimen gradually decreases with the increase of the particle size ratio.

scholarly journals Scale-up of the jetcutter technology

2003 ◽  
Vol 57 (12) ◽  
pp. 636-640 ◽  
Author(s):  
Ulf Pruesse ◽  
Ulrich Jahnz ◽  
Peter Wittlich ◽  
Klaus-Dieter Vorlop
Keyword(s):  
High Throughput ◽  
Large Scale ◽  
Size Range ◽  
Scale Up ◽  
Viscous Fluids ◽  
Fluid Viscosity ◽  
Efficient Technology ◽  
Particle Size Range ◽  
Hydrogel Beads ◽  
Improved Stability

The JetCutter is a new, simple and efficient technology for the high throughput encapsulation of various materials inside spherical beads. Monodisperse beads in the particle size range from approximately 0.2 mm up to several millimeters can be prepared at high throughput rates with the JetCutter. The generation of beads is not limited by the fluid viscosity. Thus, also highly viscous fluids even with high loadings of solids, can be processed, which leads to an improved stability of the resulting beads. The JetCutter technology is available in different scales and corresponding throughputs ranging from lab-scale devices (liters per day) up to large scale installations for industrial production purposes (tons per day). The application of the JetCutter for industrial purposes has been well established by geniaLab?, which currently produces more than 40 tons/year of small hydrogel beads.

scholarly journals Influence of Maximum Particle Diameter on the Mechanical Behavior of Soil-Rock Mixtures

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Zhuoling He ◽  
Junyun Zhang ◽  
Tao Sun
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Direct Shear Test ◽  
Shear Test ◽  
Particle Diameter ◽  
Size Difference ◽  
Direct Shear ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Maximum Particle

With the steady development of the development of the western region in China, the construction of mountain highways has developed rapidly, and the soil-rock mixed filler, as an excellent filler, is widely used in the subgrade filling of mountain highways. Unlike ordinary fine-grained soil, the source of the soil-rock mixtures (S-RMs) is not unique, and the particle size difference is large and the water content is not uniform, resulting in very complicated mechanical properties. But the current highway embankment codes are still mainly established on the fine-grained soil. It is not fully applicable to soil-rock filled embankment. Based on soil-rock filled embankment engineering practice, this research uses a large-scale direct shear test to research the mechanical characteristics of the S-RMs with different maximum particle diameters. According to the large-scale direct shear test of S-RMs with different maximum particle diameters, the shear displacement vs shear stress curve, shear dilation, and strength characteristics with maximum particle diameter were analyzed. Results demonstrate that whether secondary hardening occurs mainly depends on the normal stress and the maximum particle diameter of the filler. At different maximum particle diameters, the horizontal displacement vs vertical displacement curves of the S-RMs can be roughly divided into continuous shearing and beginning of shearing and quick dilation. And the shear strength increases with the increase of the maximum particle diameter. Moreover, the cohesion decreases first and then increases with the increase of the maximum particle diameter, and the internal friction angle increases with the increase of the maximum particle diameter. Therefore, some RBs with large particle diameter added to filler can effectively improve the shear strength of the S-RMs, which may be valuable for realistic engineering.

Shear Strength of Sand–Clay Interfaces Through Large-Scale Direct Shear Tests

2020 ◽  
Vol 45 (5) ◽  
pp. 4343-4357
Author(s):  
Zhong-Liang Zhang ◽  
Zhen-Dong Cui ◽  
Ling-Zi Zhao
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Direct Shear ◽  
Shear Tests ◽  
Direct Shear Tests

scholarly journals Determining the Shear Strength Properties of a Soil-geogrid Interface Using a Large-scale Direct Shear Test Apparatus

2020 ◽  
Author(s):  
Jakub Stacho ◽  
Monika Sulovska ◽  
Ivan Slavik
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Large Scale ◽  
Direct Shear Test ◽  
Shear Test ◽  
Strength Properties ◽  
Coarse Grained ◽  
Direct Shear ◽  
Test Apparatus ◽  
Fine Gravel

The paper deals with the laboratory testing of coarse-grained soils that are reinforced using a geogrid. The shear strength properties were determined using a large-scale direct shear test apparatus. The tests were executed on original as well as on reinforced soil, when the geogrid was placed on a sliding surface, which permitted determining the shear strength properties of the soil-geogrid interface. The aim of the tests was to determine the interface shear strength coefficient α, which represents the ratio of the shear strength of the soil-geogrid interface to the unreinforced soil. The tests were executed on 3 samples of coarse-grained materials, i.e., poorly graded sand, poorly graded fine gravel and poorly graded medium gravel. Two types of geogrids were tested, i.e., a woven polyester geogrid and a stiff polypropylene geogrid. The results of the laboratory tests on the medium gravel showed that the reduction coefficient α reached higher values in the case of the stiff polypropylene geogrid. In the cases of the fine gravel and sand, the values of the interface coefficient α were similar to each other. The shear strength of the interface was reduced or was similar to the shear strength of unreinforced soil in a peak shear stress state, but significantly increased with horizontal deformations, especially for the fine gravel and sand. The largest value of the coefficient α was measured in the critical shear stress state. Based on the results of the testing, a correlation which allows for determining the optimal grain size distribution was obtained.

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