scholarly journals Interface Direct Shear Tests on JEZ-1 Mars Regolith Simulant

2021 ◽  
Vol 11 (15) ◽  
pp. 7052
Author(s):  
Kexin Yin ◽  
Jiangxin Liu ◽  
Jiaxing Lin ◽  
Andreea-Roxana Vasilescu ◽  
Khaoula Othmani ◽  
...  
Keyword(s):  
Internal Friction ◽  
Friction Angle ◽  
Interface Roughness ◽  
Steel Plates ◽  
Direct Shear ◽  
Shear Tests ◽  
Interface Friction ◽  
Direct Shear Tests ◽  
Swelling Soil ◽  
Martian Regolith

The mechanical behaviors of Martian regolith-structure interfaces are of great significance for the design of rover, development of excavation tools, and construction of infrastructure in Mars exploration. This paper presents an experimental investigation on the properties of a Martian regolith simulant (JEZ-1) through one-dimensional oedometer test, direct shear test, and interface direct shear tests between JEZ-1 and steel plates with different roughness. Oedometer result reveals that the compression and swelling indexes of the JEZ-1 are quite low, thus it is a less compressible and lower swelling soil. The cohesion and adhesion of JEZ-1 are lower than 5 kPa. The values of the internal friction angle range from 39.7° to 40.6°, and the interface friction angles are 16.7° to 36.2° for the smooth and rough interface. Furthermore, the direct shear and interface direct shear results indicate that the interface friction angles are lower than the internal friction angles of JEZ-1 and increase close to the internal friction angles with increasing interface roughness.

scholarly journals Sand- and Clay-Photocured-Geomembrane Interface Shear Characteristics Using Direct Shear Test

2021 ◽  
Vol 13 (15) ◽  
pp. 8201
Author(s):  
Lihua Li ◽  
Han Yan ◽  
Henglin Xiao ◽  
Wentao Li ◽  
Zhangshuai Geng
Keyword(s):  
Soil Surface ◽  
Friction Angle ◽  
Direct Shear ◽  
Tensile Crack ◽  
Shear Tests ◽  
Interface Shear ◽  
Direct Shear Tests ◽  
Carbon Black Powder ◽  
Shear Characteristics ◽  
Impermeable Layer

It is well known that geomembranes frequently and easily fail at the seams, which has been a ubiquitous problem in various applications. To avoid the failure of geomembrane at the seams, photocuring was carried out with 1~5% photoinitiator and 2% carbon black powder. This geomembrane can be sprayed and cured on the soil surface. The obtained geomembrane was then used as a barrier, separator, or reinforcement. In this study, the direct shear tests were carried out with the aim to investigate the interfacial characteristics of photocured geomembrane–clay/sand. The results show that a 2% photoinitiator has a significant effect on the impermeable layer for the photocured geomembrane–clay interface. As for the photocured geomembrane–sand interface, it is reasonable to choose a geomembrane made from a 4% photoinitiator at the boundary of the drainage layer and the impermeable layer in the landfill. In the cover system, it is reasonable to choose a 5% photoinitiator geomembrane. Moreover, as for the interface between the photocurable geomembrane and clay/sand, the friction coefficient increases initially and decreases afterward with the increase of normal stress. Furthermore, the friction angle of the interface between photocurable geomembrane and sand is larger than that of the photocurable geomembrane–clay interface. In other words, the interface between photocurable geomembrane and sand has better shear and tensile crack resistance.

scholarly journals Effect of the Quasi Rate of Loading in Particle Crushing and Engineering Properties of Black Tough Sand

2021 ◽  
Author(s):  
Omar Al hattamleh ◽  
Abdulla Sharo’ ◽  
Laith Abu Shanab ◽  
Hussein Aldeeky ◽  
Reyad Al Dwairi
Keyword(s):  
Microstructural Analysis ◽  
Friction Angle ◽  
Sem Analysis ◽  
Particle Breakage ◽  
Engineering Properties ◽  
Sieve Analysis ◽  
Direct Shear ◽  
Shear Tests ◽  
Direct Shear Tests ◽  
Rate Of Loading

Abstract In this study, the effect of the quasi rate of loading in the crushing of black tough sand will be studied experimentally. The experimental works will be conducted at different normal stresses, different relative densities, and different rates of loading using the direct shear tests. All test specimens were prepared with uniformly graded sand, passing sieve #4, and retained sieve #8.The results of direct shear tests were used to investigate the factors influencing the amount of particle breakage and consequently the friction angle. After shearing of each specimen, sieve analysis was performed in order to determine the percentage of particle breakage. Results showed that the rate of loading in direct shear plays a significant role in the amount of crushing and in internal friction angles. The amount of crushing as well as shear strength was increased with the increased rate of loading. Moreover, microstructural analysis used scanning electron microscopy (SEM) analysis shown that the crushing from granular have primarily resulted from disintegration, grinding and abrasion of particles.

scholarly journals Pile Side Resistance in Sands for the Unloading Effect and Modulus Degradation

2019 ◽  
Vol 69 (334) ◽  
pp. 185 ◽  
Author(s):  
C. F. Zhao ◽  
Y. Wu ◽  
C. Zhao ◽  
Q. Z. Zhang ◽  
F. M. Liu ◽  
...  
Keyword(s):  
Shear Stress ◽  
Maximum Amount ◽  
Interface Roughness ◽  
Direct Shear ◽  
Shear Tests ◽  
Interface Shear ◽  
Direct Shear Tests ◽  
Side Resistance ◽  
Unloading Effect ◽  
Concrete Interface

A total of 36 groups of sand-concrete interface loading and unloading direct shear tests were used to analyze the mechanical properties of the pile side-soil interface. The test results show that the interface residual shear stress for the same applied normal stress tends to be constant for the rough sand-concrete interface. The initial shear modulus and peak shear stress of the interface both decrease with the degree of unloading and increase with the interface roughness. The maximum amount of interface shear dilatancy increases with the degree of unloading, and the maximum amount of interface shear shrinkage decreases with unloading for the same interface roughness. A pile side resistance-displacement model is established using the shear displacement method. The proposed function considers both the radial unloading effect and modulus degradation of soil around the pile. The effect of radial unloading and interface roughness on the degradation of the equivalent shear modulus is analyzed using a single fitting parameter b. Good agreement of the proposed model is confirmed by applying the direct shear tests of the 36 groups.

scholarly journals Reliability Analysis of a Direct Shear Test of Modified Iron Tailings Based on the Monte Carlo Algorithm

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Ping Jiang ◽  
Jian Qian ◽  
Na Li
Keyword(s):  
Monte Carlo ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Direct Shear ◽  
Shear Tests ◽  
Type Curve ◽  
Direct Shear Tests ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

The resource utilization of iron tailings is of great significance for all countries in the world. Considering the particle composition and physicochemical characteristics of iron tailings, fiber and lime were used to modify iron tailings. The fiber content was 0%, 0.25%, 0.5%, 0.75%, and 1%, and the lime content was 0%, 2%, 4%, 8%, and 10%, respectively. Through a direct shear test, the shear stress displacement (τ-δ) curves and shear strength of modified iron tailings, under the action of a 0 freeze-thaw cycle and 1 freeze-thaw cycle, were tested. As statistics have shown that there are uncertainty factors associated with direct shear tests, the shear strength index cohesion c and internal friction angle φ of the modified iron tailings were analyzed using the Monte Carlo method. The results show that the τ-δ curve of the fiber-modified iron tailings is a hardening-type curve and that of the lime-modified iron tailings is a softening-type curve. In the direct shear tests, the main uncertain factors are the specimen diameter, vertical force, and horizontal force. The diameter of the sample obeys a normal distribution, and the vertical and horizontal forces obey a uniform distribution. The results of the Monte Carlo simulation show that both c and φ obey a normal distribution. Under a 95% confidence condition, the effect of fiber on the cohesion on iron tailings is obvious, but the effect on the internal friction angle is not obvious. However, the values of c and φ of the iron tailings are clearly improved by lime. Additionally, the iron tailings modified by a fiber content of 1% and those modified by a lime content of 8% have the best frost resistance.

Soil-geotextile interface friction by direct shear tests

2000 ◽  
Vol 37 (1) ◽  
pp. 238-252 ◽  
Author(s):  
K M Lee ◽  
V R Manjunath
Keyword(s):  
Shear Strength ◽  
Friction Coefficient ◽  
Direct Shear ◽  
Shear Tests ◽  
Physical Damage ◽  
Residual Shear Strength ◽  
Interface Friction ◽  
Direct Shear Tests ◽  
Stress Uniformity ◽  
Interface Behaviour

This paper describes large-size direct shear tests on soil-geotextile interfaces. Medium-grained, uniform sand and three varieties of woven and nonwoven geotextiles manufactured with different techniques are utilized to investigate the soil-geotextile interface friction coefficient (f*). Tests were carried out using an apparatus specifically designed for interface testing, and results were compared with those obtained from the conventional direct shear equipment. The results obtained from this study indicated that the determination of peak interface behaviour was not a trivial matter, as the results were significantly affected by the boundary and testing conditions of the testing apparatus. The residual interface behaviour was investigated by multiple reversal direct shear tests. Since the use of multiple reversal direct shear tests on the proposed apparatus can impose a high degree of shear displacement and stress uniformity on the soil-geotextile interface, a more reliable definition of the residual interface friction can be obtained. The results indicate that woven-nonwoven geotextile interfaces exhibit a significant postpeak strength loss after a number of shear cycles. In the case of woven geotextiles, this is attributed to the opening up of the filaments associated with the physical damage caused during shear, whereas for nonwoven geotextiles it is due to the pulling out or tearing of filaments.Key words: geotextile, direct shear test, interface friction coefficient, peak shear strength, residual shear strength.

Study on the Effect of Water Content on Shearing Strength Parameters of Unsaturated Loess

2014 ◽  
Vol 638-640 ◽  
pp. 585-588 ◽  
Author(s):  
Si Zhong Qian
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Direct Shear ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Micro Particles ◽  
Shearing Strength ◽  
Unsaturated Loess

This paper experiments on typical Malan loess, performs consolidated quick direct shear tests under different water contents by conventional direct shear apparatus, then analyzes the effects of water content on shearing strength parameters, namely cohesion and internal friction angle. The results show that cohesion decreases linearly as the water content increasing, and the relation could be obtained by data fitting. However, internal friction angle keeps basically stable with the increase of water content. Finally, based on the force analysis for micro particles, the changing rules of cohesion and internal friction angle with water content were deeply explained.

scholarly journals Contribution of Particles Size Ranges to Sand Friction

2013 ◽  
Vol 3 (4) ◽  
pp. 497-501 ◽  
Author(s):  
E. Mostefa Kara ◽  
M. Meghachou ◽  
N. Aboubekr
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Granular Material ◽  
Physical Properties ◽  
Friction Angle ◽  
Direct Shear ◽  
Shear Tests ◽  
Direct Shear Tests ◽  
Marine Sand

This work studies the correlation between certain physical properties of granular material such as the friction angle and the grain size distribution. In the laboratory, the determination of friction angle requires hard and expensive testing. Prediction of this parameter from the grading curve proves to be very interesting. Direct shear tests were performed on actual marine sand of Tergha (Algeria) and on seventeen different samples arranged from the same sand with various particle size ranges. Results showed that the friction angle of sand is a result of contribution of various constituent granular classes.

scholarly journals Determination of the Effect of Soil Particle Size Distribution on the Shear Behavior of Sand

2021 ◽  
Vol 5 (2) ◽  
pp. 125
Author(s):  
Mohammad Afrazi ◽  
Mahmoud Yazdani
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Particle Sizes ◽  
Direct Shear ◽  
Shear Tests ◽  
Direct Shear Tests

Many geotechnical problems require the determination of soil engineering properties such as shear strength. Therefore, the determination of the reliable values for this parameter is essential. For this purpose, the direct shear test, as one of the oldest tests to examine the shear strength of soils, is the most common way in laboratories to determine the shear parameters of soil. There are far too many variables that influence the results of a direct shear test. In this paper, a series of 10 × 10 cm direct shear tests were carried out on four different poorly graded sands with different particle size distributions to determine their shear behaviors. Four different poorly graded sands with a different median diameter or medium value of particle size distribution (D50) (0.2, 0.53, 1.3, and 2.3 mm) has been selected, and about 40 direct shear tests were conducted. It was concluded that a soil’s friction angle is affected by coarse-grained material. Accordingly, sandy soils with bigger particle sizes record a higher friction angle than soils containing small particles. The investigations also showed that sand with bigger particle sizes has a higher dilation angle. In addition, a non-linear regression analysis was performed to establish the exact relationship between the friction angle of the soil and the characteristics of the soil particles. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

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