scholarly journals Shear Parameters of Rammed Earth Material: Results from Different Approaches

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
R. El-Nabouch ◽  
Q.-B. Bui ◽  
P. Perrotin ◽  
O. Plé
Keyword(s):  
Numerical Model ◽  
Seismic Performance ◽  
Numerical Models ◽  
Construction Material ◽  
Experimental Studies ◽  
Friction Angle ◽  
Rammed Earth ◽  
Shear Tests ◽  
Direct Shear Tests ◽  
Experimental Values

Rammed earth (RE) is a construction material which is manufactured by compacting the soil in a formwork, in different layers. Several recent studies have investigated this material. The seismic performance of RE buildings is an important topic which needs to be carefully investigated. The complex numerical model seems a performant approach to investigate the seismic performance of a whole building. To correctly establish the model, the shear parameters of the material, which are the cohesion and the friction angle, should be identified. This paper first presents experimental studies on the shear parameters of RE through the direct shear tests, at two different scales. The differences of the results at different scales are analyzed. Then, the obtained experimental values are used in a numerical model to simulate the shear behavior of RE walls which are loaded by a constant vertical stress and pushed horizontally on the top. From the obtained results, the values for numerical models are recommended.

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 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.

scholarly journals Assessing the Seismic Behavior of Rammed Earth Walls with an L-Form Cross-Section

2019 ◽  
Vol 11 (5) ◽  
pp. 1296 ◽  
Author(s):  
Quoc-Bao Bui ◽  
Tan-Trung Bui ◽  
Mai-Phuong Tran ◽  
Thi-Loan Bui ◽  
Hoang-An Le
Keyword(s):  
Cross Section ◽  
Seismic Performance ◽  
Seismic Behavior ◽  
Rectangular Cross Section ◽  
Construction Material ◽  
Numerical Approach ◽  
Rammed Earth ◽  
3D Fem ◽  
Earthquake Performance ◽  
Earth Walls

Rammed earth (RE) is a construction material which is made by compacting the soil in a formwork. This material is attracting the attention of the scientific community due to its sustainable characteristics. Among different aspects to be investigated, the seismic performance remains an important topic which needs advanced investigations. The existing studies in the literature have mainly adopted simplified approaches to investigate the seismic performance of RE structures. The present paper adopts a numerical approach to investigate the seismic behavior of RE walls with an L-form cross-section. The 3D FEM model used can take into account the plasticity and damage of RE layers and the interfaces. The model was first validated by an experimental test presented in the literature. Then, the model was employed to assess the seismic performance of a L-form wall of a RE house at different amplitudes of earthquake excitations. Influences of the cross-section form on the earthquake performance of RE walls were also investigated. The results show that the L-form cross-section wall has a better seismic performance than a simple rectangular cross-section wall with similar dimensions. For the L-form cross-section wall, the damage observed concentrates essentially on the connection between two flanges of the wall.

Experimental Study on Shear Behavior of Short-Fill-Age MSW

2010 ◽  
Vol 113-116 ◽  
pp. 479-483
Author(s):  
Li Sha Ma ◽  
Huan Li Wang ◽  
Wei Wang ◽  
Zheng Wen Zhang
Keyword(s):  
Shear Strength ◽  
Shear Failure ◽  
Friction Angle ◽  
Exponential Model ◽  
Hyperbolic Model ◽  
Displacement Curve ◽  
Shear Tests ◽  
Direct Shear Tests ◽  
Cohesion Force ◽  
Coulomb Criterion

Mechanical behavior of municipal solid waste (MSW) is important to geo-environment engineering, and it is necessary to properly understand it. Laboratory direct shear tests were conducted on MSW with 3 short fill ages, namely 1d, 4d and 7d. Three different densities were taken into accounted in each fill age. Experimental data show that MSW’s shear failure still satisfies the Mohr-Coulomb criterion. As to bigger density, shear strength of MSW increases within 1-7d fill age. When density becomes smaller, its shear strength increases within 1-4d fill age but decreases within 4-7d fill age. With fill-age developing, friction angle of MSW increase monotonously, but cohesion force of it first increases and then decreases. Experimented shear stress-displacement curve of MSW can not be well fitted by either hyperbolic model or exponential model. This experimental research is helpful for design and numerical simulation of corresponding MSW landfill.

An Experimental Study on the Mechanical Characteristics of Sandstone-Like Material with Preset Filling Joints

2013 ◽  
Vol 353-356 ◽  
pp. 644-649
Author(s):  
Xin Yu Liu ◽  
Ai Hua Liu ◽  
Bang Biao Wu
Keyword(s):  
Internal Friction ◽  
Uniaxial Compression ◽  
Shear Failure ◽  
Experimental Studies ◽  
Deformation Modulus ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Filling Material ◽  
Shear Tests ◽  
Intact Specimen

This paper investigates the strength and deformation characteristics of the sandstone-like material containing the preset filling joints. The test specimens are designed with different height-diameter ratio. The uniaxial compression and shear tests were performed during the experimental studies. The results show that: (1) the failure models of the 3 kinds specimens including ones without joints, ones with "cruciform" joints and ones with "intersecting parallels" joints are similar to the general trend, e.g. X-shaped conjugated single-slope shear failure and single-slope shear failure under compression and shear tests ; (2) under uniaxial compression, the performance of intact specimen is clearly affected by its size, and the strength of jointed one is significantly affected by the weakening of the structure. This impact depends on the joints conditions, e.g. joint density, with filling material or without filling material; (3) Deformation modulus E and Cohesion c have no significant change for the 2 kinds jointed specimens, but the internal friction angle is obviously affected by joints and their fillings. The internal friction angle decreases rapidly with the increase of joints number.

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.

scholarly journals Influence of thermal cycles on the deformation of soil-pile interface in energy piles

2019 ◽  
Vol 92 ◽  
pp. 13004
Author(s):  
Roxana Vasilescu ◽  
Kexin Yin ◽  
Anne-Laure Fauchille ◽  
Panagiotis Kotronis ◽  
Christophe Dano ◽  
...  
Keyword(s):  
Numerical Models ◽  
Seasonal Temperature ◽  
Direct Shear ◽  
Thermal Cycles ◽  
Shear Tests ◽  
Temperature Cycles ◽  
Direct Shear Tests ◽  
Energy Piles ◽  
The Impact ◽  
Submerged Conditions

Energy piles are double purpose foundation elements used both for transferring loads to the soil and temperature regulation in buildings. The response of the pile-soil interface is influenced by daily and seasonal temperature variations. In order to assess the impact of thermal cycles on the mobilization of shear strength in energy piles, a series of saturated soil-concrete interface direct shear tests were performed in the laboratory for different temperature gradients with a new interface direct shear device adapted for thermomechanical loading. As natural soils are very complex due to a high variability of mineralogy and anisotropy, silica and carbonate sands were chosen in this study. Those sands are considered as the main types of sandy soils commonly met in geotechnics. The experimental campaign is divided in two parts: (i) Concrete-soil direct shear tests at 13°C (constant temperature) to be used as a reference (ii) Concrete-soil direct shear tests after 10 temperature cycles with a gradient ΔT=10°C, under submerged conditions. For these two types of soils, realistic temperature cycles applied between 8 and 18°C cause the overall low contraction of the samples. However the interface friction angles are not significantly modified before and after the temperature cycles. Even if the vertical strains of soils are cumulative along temperature cycles, soil’s strains and friction angle changes are relatively negligible for the temperatures and water content tested, which support the low impact of temperature cycles on the deformation of soil concrete foundation under submerged conditions. These experimental results bring new features which will be implemented in numerical models to study the long-term use of energy piles.

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