Modélisation du comportement du milieu granulaire en fonction de l'écrasement des grains

1998 ◽  
Vol 35 (3) ◽  
pp. 517-523
Author(s):  
Afif Rahma
Keyword(s):  
Mechanical Properties ◽  
Computer Simulations ◽  
Numerical Solutions ◽  
High Stress ◽  
Physical And Mechanical Properties ◽  
Plastic Work ◽  
Constitutive Law ◽  
Grain Crushing ◽  
Stress Levels ◽  
Good Agreement

The influence of grain crushing under high stress levels is introduced in the elasto-plastic constitutive law (Hujeux's model) using additional variables that change with the physical and mechanical properties of the grains. These variables are defined as functions of the amount of dissipated plastic work, which is proposed as a parameter for describing the material yield. The results of computer simulations along oedometric and triaxial paths indicate a very good agreement between the experimental curves and the numerical solutions. The proposed modifications are therefore validated.Key words: correlation, grain crushing, constitutive law, modelization, plastic work.[Journal translation]

Physical and mechanical properties of a compacted silty sand with low bentonite fraction

1998 ◽  
Vol 35 (6) ◽  
pp. 909-925 ◽  
Author(s):  
Filippo Santucci de Magistris ◽  
Francesco Silvestri ◽  
Filippo Vinale
Keyword(s):  
Mechanical Properties ◽  
Critical State ◽  
Physical And Mechanical Properties ◽  
Silty Sand ◽  
Granular Soils ◽  
Fine Grained ◽  
Optimum Water Content ◽  
Geotechnical Structures ◽  
Slurry Consolidation ◽  
Good Agreement

Compacted granular soils with small additions of bentonite have been used to build geotechnical structures such as impervious liners and cores of zoned earth dams. This paper presents a laboratory study showing how physical and mechanical characteristics of a silty sand are modified by a low percentage of bentonite. The effects of the addition of bentonite on the silty sand are reflected by an increase in the plasticity index, a reduction in maximum modified Proctor density, and a decrease in hydraulic conductivity. The most significant consequences on the mechanical properties are an increase of compressibility and secondary consolidation coefficients, and a reduction in shear strength. Different mixtures were either dynamically compacted at the optimum water content (compacted samples) or prepared after slurry consolidation from the minimum density (remoulded samples). Although the compacted and remoulded specimens show different isotropic compression lines, their critical-state lines in the v:p':q space are identical, where v is specific volume, p' is average effective stress, and q is deviator stress. Comparisons of the mechanical parameters with the existing literature database show that the compression coefficients of the remoulded mixtures are comparable to those of normally consolidated clayey soils of similar plasticity; nevertheless, those of the compacted mixtures are considerably lower. Also, the slopes of their critical-state lines in the q:p' plane are in good agreement with those predicted by empirical correlations for fine-grained soils.Key words: bentonite, silty sand, compaction, physical properties, compressibility, critical state.

scholarly journals Deformation Mechanism and Support Technology of Deep and High-Stress Soft Rock Roadway

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Lujing Zheng ◽  
Yujun Zuo ◽  
Yafei Hu ◽  
Wei Wu
Keyword(s):  
Mechanical Properties ◽  
Bearing Capacity ◽  
High Stress ◽  
Soft Rock ◽  
Physical And Mechanical Properties ◽  
Surrounding Rock ◽  
Rock Fragmentation ◽  
The Stability ◽  
Soft Rock Roadway ◽  
Rock Roadway

In this study, the analysis and control of stability of surrounding rock in deep fractured soft rock roadway located in the underground mine of Jinfeng gold mine in Guizhou Province, China, has been investigated. The surrounding rock of roadway has been analyzed to characterize its deformation and failure mechanism through field survey, testing of rock physical and mechanical properties, in situ stress measure, analysis of mineral components of rock, and investigation of rock fragmentation degree. Based on the numerical simulation technology, the influence of different factors on the stability of roadway is studied. The physical and mechanical properties of surrounding rock and the bearing capacity of surrounding rock layer are to be improved to maintain the stability of broken soft rock roadway as high ground stress, rock fragmentation, and poor lithology leading to tunnel instability. Hence, a high-strength “cable bolt + fiber-reinforced shotcrete + steel mesh + split sets + resin bolt + cement grouting” combined support system has been proposed to improve the effective bearing structure significantly with high integrity and bearing capacity.

scholarly journals A Nonlinear Fractional Viscoelastic-Plastic Creep Model of Asphalt Mixture

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1278
Author(s):  
Yongjun Zhang ◽  
Xiu Liu ◽  
Boyuan Yin ◽  
Wenbo Luo
Keyword(s):  
Permanent Deformation ◽  
High Stress ◽  
Asphalt Mixture ◽  
Creep Model ◽  
Creep Process ◽  
Creep Tests ◽  
Model Predictions ◽  
Stress Levels ◽  
Plastic Creep ◽  
Good Agreement

The mechanical behavior of asphalt mixture under high stresses presents nonlinear viscoelasticity and permanent deformation. In this paper, a nonlinear fractional viscoelastic plastic (NFVEP) creep model for asphalt mixture is proposed based on the Nishihara model, with a Koeller spring-pot replacing the Newton dashpot. The NFVEP model considers the instantaneous elasticity, viscoelasticity with damage and time-hardening viscoplasticity with damage concurrently, and the viscoelastic response is modeled by fractional derivative viscoelasticity. To verify the model, uniaxial compressive creep tests under various stresses ranging from 0.4 MPa to 0.8 MPa were carried out at room temperature. The NFVEP model predictions are in good agreement with the experiments. The comparison with the modified Nishihara model and the Burgers model reveals the advantages of the NFVEP model. The results show that the NFVEP model, with the same set of parameters, can not only describe the primary and steady-state creep stages of asphalt mixture under low stress levels but also the whole creep process, including the tertiary creep stage, of asphalt mixture under high stress levels.

Outburst Hazard Prediction Based on the Monitoring Data in Heading Face

2013 ◽  
Vol 734-737 ◽  
pp. 786-790
Author(s):  
Fu Sheng Wu ◽  
Shui Wen Liu
Keyword(s):  
Mechanical Properties ◽  
Real Time ◽  
Monitoring System ◽  
Physical And Mechanical Properties ◽  
Monitoring Data ◽  
The Real ◽  
Verification Test ◽  
Outburst Hazard ◽  
Good Agreement ◽  
Predictive Indicators

To analyse the outburst hazard of heading face in real time, based on the mechanism of coal and gas burst and its forecasting principle, four real-time predictive indicators were proposed, which involve three aspects: crustal stress, gas, physical and mechanical properties of coal, and had a verification test. The results show that the real-time predictive indicators are in good agreement with the traditional indicators, whose deviation are mainly caused by gas exceeded. With the monitoring data in monitoring system, the outburst hazard of heading face could be predicted in real time, which could help to prevent outburst.

scholarly journals Silver Matrix Composites - Structure and Properties

2016 ◽  
Vol 61 (1) ◽  
pp. 323-328 ◽  
Author(s):  
J. Wieczorek ◽  
B. Oleksiak ◽  
J. Łabaj ◽  
B. Węcki ◽  
M. Mańka
Keyword(s):  
Mechanical Properties ◽  
Tribological Properties ◽  
Volume Fraction ◽  
Physical And Mechanical Properties ◽  
Plastic Work ◽  
Matrix Composites ◽  
Alloy Matrix ◽  
Ceramic Particles ◽  
Mechanical And Tribological Properties ◽  
The Matrix

Phase compositions of composite materials determine their performance as well as physical and mechanical properties. Depending on the type of applied matrix and the kind, amount and morphology of the matrix reinforcement, it is possible to shape the material properties so that they meet specific operational requirements. In the paper, results of investigations on silver alloy matrix composites reinforced with ceramic particles are presented. The investigations enabled evaluation of hardness, tribological and mechanical properties as well as the structure of produced materials. The matrix of composite material was an alloy of silver and aluminium, magnesium and silicon. As the reinforcing phase, 20-60 μm ceramic particles (SiC, SiO2, Al2O3 and Cs) were applied. The volume fraction of the reinforcing phase in the composites was 10%. The composites were produced using the liquid phase (casting) technology, followed by plastic work (the KOBO method). The mechanical and tribological properties were analysed for plastic work-subjected composites. The mechanical properties were assessed based on a static tensile and hardness tests. The tribological properties were investigated under dry sliding conditions. The analysis of results led to determination of effects of the composite production technology on their performance. Moreover, a relationship between the type of reinforcing phase and the mechanical and tribological properties was established.

PEMANFAATAN KAYU AKASIA MANGIUM (Acacia mangium Willd) UNTUK MEBEL

2012 ◽  
Vol 4 (1) ◽  
pp. 1
Author(s):  
Djoko Purwanto
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Physical Properties ◽  
Treatment Process ◽  
Acacia Mangium ◽  
Physical And Mechanical Properties ◽  
Wood Fibers ◽  
Test Parameters ◽  
Mechanical And Physical Properties ◽  
Scale Scores

Timber Acacia mangium (Acacia mangium, Willd) for Furniture. The study aims to determine the mechanical and physical properties and the decorative value (color and fiber) wood of acacia mangium with using finishing materials. This type of finishing material used is ultran lasur natural dof ,ultran lasur classic teak, aqua politur clear dof, aqua politur akasia dan aqua politur cherry. After finishing the wood is stored for 3 months. Test parameters were observed, namely, physical and mechanical properties of wood, adhesion of finishing materials, color and appearance of the fiber, and timber dimensions expansion. The results showed that the mechanical physical properties of acacia wood qualified SNI. 01-0608-89 about the physical and mechanical properties of wood for furniture, air dry the moisture content from 13.78 to 14.89%, flexural strength from 509.25 to 680.50 kg/cm2, and compressive strength parallel to fiber 342.1 - 412.9 kg/cm2. Finishing the treatment process using five types of finishing materials can increase the decorative value (color and fiber) wood. Before finishing the process of acacia mangium wood has the appearance of colors and fibers and less attractive (scale scores 2-3), after finishing acacia wood fibers have the appearance of colors and interesting and very interesting (scale 4-5).Keywords: mangium wood, mechanical properties, decorative value, finishing, furniture.

Physical and Mechanical Properties of Tenun Pahang Fabrics using Alternative Yarns

2016 ◽  
Vol 13 (2) ◽  
pp. 67
Author(s):  
Engku Liyana Zafirah Engku Mohd Suhaimi ◽  
Jamil Salleh ◽  
Suzaini Abd Ghani ◽  
Mohamad Faizul Yahya ◽  
Mohd Rozi Ahmad
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
The Other ◽  
Silk Fabrics ◽  
Recovery Angle ◽  
Made In

An investigation on the properties of Tenun Pahang fabric performances using alternative yarns was conducted. The studies were made in order to evaluate whether the Tenun Pahang fabric could be produced economically and at the same time maintain the fabric quality. Traditional Tenun Pahang fabric uses silk for both warp and weft. For this project, two alternative yarns were used which were bamboo and modal, which were a little lower in cost compared to silk. These yarns were woven with two variations, one with the yarns as weft only while maintaining the silk warp and the other with both warp and weft using the alternative yarns. Four (4) physical testings and three (3) mechanical testings conducted on the fabric samples. The fabric samples were evaluated including weight, thickness, thread density, crease recovery angle, stiffness and drapability. The results show that modal/silk and bamboo silk fabrics are comparable in terms of stiffness and drapability, hence they have the potential to replace 100% silk Tenun Pahang.

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