scholarly journals Characterisation of Geogrid and Waste Tyres as Reinforcement Materials in Railway Track Beds

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4162
Author(s):  
Lihua Li ◽  
Yanan Fang ◽  
Bowen Cheng ◽  
Na Chen ◽  
Mi Tian ◽  
...  
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Confining Pressure ◽  
Railway Track ◽  
Strength Ratio ◽  
Stress Strain ◽  
Geogrid Reinforcement ◽  
Deviator Stress ◽  
Waste Tyres ◽  
Waste Tyre

The engineering behaviour of ballast is an important factor to determine the stability and safety of railway tracks. This paper examines the stress–strain, shear strength, peak deflection stress and reinforcement strength ratio of different reinforcement materials and reinforcement locations in ballast track bed layers based on large scale static triaxial shear tests. The results show that geogrid and waste tyre reinforcement have a significant effect on the peak deviator stress of railway track bed layers and the stress–strain relationship is strain-hardened. The peak deviator stress and shear strength of geogrid reinforcement are greater under the same conditions compared with waste tyres. The reinforcement of geogrid and waste tires increases the shear strength of the track bed significantly. The more layers of geogrid reinforcement, the more energy is required for the deformation of the track bed. The energy required for deformation is greater in the centre of the waste tyre than in the other reinforced forms, and the energy required for deformation is minimal in the fully reinforced form. Excessive tyre reinforcement changes the stiffness of the track bed layer, leading to an increase in the settlement rate. The reinforcement strength ratio between geogrid and waste tyre increases significantly with the increasing of the confining pressure and reinforcement layers. Moreover, the reinforcement strength ratio of the geogrid is significantly higher than that of the waste tyre.

scholarly journals Behaviour of tire shred – sand mixtures

2004 ◽  
Vol 41 (2) ◽  
pp. 227-241 ◽  
Author(s):  
Jorge G Zornberg ◽  
Alexandre R Cabral ◽  
Chardphoom Viratjandr
Keyword(s):  
Shear Strength ◽  
Aspect Ratio ◽  
Large Scale ◽  
Experimental Testing ◽  
Volumetric Strain ◽  
Confining Pressure ◽  
Stress Strain ◽  
Aspect Ratios ◽  
Strain Behaviour ◽  
Tire Shreds

Tire shreds and tire shred – soil mixtures can be used as alternative backfill material in many geotechnical applications. The reuse of tire shreds may not only address growing environmental and economic concerns, but also help solve geotechnical problems associated with low soil shear strength. In this study, an experimental testing program was undertaken using a large-scale triaxial apparatus with the goal of evaluating the optimum dosage and aspect ratio of tire shreds within granular fills. The effects on shear strength of varying confining pressure and sand matrix relative density were also evaluated. The tire shred content and tire shred aspect ratio were found to influence the stress–strain and volumetric strain behaviour of the mixture. The axial strain at failure was found to increase with increasing tire shred content. Except for specimens of pure tire shreds and with comparatively high tire shred content, the test results showed a dilatant behaviour and a well-defined peak shear strength. The optimum tire shred content (i.e., the one leading to the maximum shear strength) was approximately 35%. For a given tire shred content, increasing the tire shred aspect ratio led to increasing overall shear strength, at least for the range of tire shred aspect ratios considered in this study. The shear strength improvement induced by tire shred inclusions was found to be sensitive to the applied confining pressure, with larger shear strength gains obtained under comparatively low confinement.Key words: tire shreds, shear strength, reinforcement, triaxial testing, stress–strain behaviour.

scholarly journals Effect of Rock Particle Content on the Mechanical Behavior of a Soil-Rock Mixture (SRM) via Large-Scale Direct Shear Test

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Longqi Liu ◽  
Xuesong Mao ◽  
Yajun Xiao ◽  
Qian Wu ◽  
Ke Tang ◽  
...  
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Large Scale ◽  
Direct Shear Test ◽  
Shear Test ◽  
Volumetric Strain ◽  
Direct Shear ◽  
Stress Strain ◽  
Particle Content ◽  
Rock Particle

The mechanical strength of the landslide deposits directly affects the safety and operation of the roads in the western mountainous area of China. Therefore, the research is aimed at studying the mechanisms of a landslide deposit sample with different rock particle contents by analyzing its characteristics of the stress-strain behavior, the “jumping” phenomenon, the volumetric strain, and the shear strength parameters via a large-scale direct shear test. Stress-strain results show that stress-strain curves can be divided into 3 different stages: liner elastic stage, yielding stage, and strain-hardening stage. The shear strength of SRM behaves more like “soil” at a lower rock particle content and behaves more like “rock joints” at a higher rock particle content. Characteristics of the “jumping” phenomenon results show that the “intense jumping” stage becomes obvious with the increasing rock particle content and the normal stress. However, the lower the rock particle content is, the more obvious the “jumping” phenomenon under the same normal stress is. Volumetric strain results show that the sample with a lower rock particle content showed a dilatancy behavior under the low normal stress and shrinkage behavior under the high normal stress. The dilatancy value becomes smaller with the increasing normal stress. The maximum shear stress value of the rock particle content corresponds to the maximum value of dilatancy or shrinkage. We also conclude that the intercept of the Mohr failure envelope of the soil-rock mixture should be called the “equivalent cohesion,” not simply called the “cohesion.” The higher the normal stress and rock particle content are, the bigger the equivalent cohesion and the internal friction angle is.

Effect of roughness on shear behavior of red clay – concrete interface in large-scale direct shear tests

2015 ◽  
Vol 52 (8) ◽  
pp. 1122-1135 ◽  
Author(s):  
Xiaobin Chen ◽  
Jiasheng Zhang ◽  
Yuanjie Xiao ◽  
Jian Li
Keyword(s):  
Surface Roughness ◽  
Shear Strength ◽  
Large Scale ◽  
Shear Failure ◽  
Friction Angle ◽  
Confining Pressure ◽  
Shear Behavior ◽  
Interfacial Shear ◽  
Red Clay ◽  
Direct Shear Tests

Few studies have focused on evaluating regular surface roughness and its effect on interfacial shear behavior of the red clay – concrete interface. This paper presents the results of a series of laboratory large-scale direct shear tests conducted using different types of red clay – concrete interfaces. The objective is to examine the effect of surface roughness on these types of soil–concrete interfaces. In the smooth-interface tests, the measured peak and residual shear strength values are very close to each other, with no observed shear dilation. The surface roughness is found to have a remarkable effect on the interfacial shear strength and shear behavior, with the shear strength increasing with increased surface roughness level. The shear dilation is likely to occur on rougher interfaces under lower confining pressure due to the behavior of compressed clay matrices. Owing to the clay matrix’s cohesion and friction, the interfacial shear strength on rough interfaces consists of cohesive and frictional forces between the clay and concrete surfaces. The friction angle value is observed to fluctuate between the clay’s friction angle and the smooth interface’s friction angle. This can be related to the position change of the shear failure slip plane. The confining pressure and surface roughness could change the shear failure plane’s position on the interface. Furthermore, the red clay – structure interface is usually known as the weakest part in the mechanical safety assessment.

Study on Particle Breakage and Strength Characteristic of Different Coarse-Grain Contents

2012 ◽  
Vol 246-247 ◽  
pp. 1037-1041
Author(s):  
Guang Jin Wang ◽  
Yue Tong Si ◽  
Xiang Yun Kong
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Large Scale ◽  
Particle Breakage ◽  
Coarse Grained ◽  
Stress Strain ◽  
Breakage Rate ◽  
Deep Soils ◽  
The Relationship ◽  
Coarse Grained Soil

The significant particle size grading and the particle breakage of deep soils are two major characteristics of super-high dumping-site. Based on the refitted large-scale direct shear experiments, this paper studied the particle breakage and shear strength of different coarse-grained soil. The experimental results indicates a conclusion: particle breakage index is very small when upright stress is less than 400kPa .The breakage rate increases obviously with the increase of upright stress. The particle breakage index is very little when coarse-grained contents are less than 46.0% .It increases significantly when coarse-grained contents are larger than 46.0%. Hyperbolic curves can express the relationship between particle breakage index and upright stress. The experiments studied on shear strength shows that the shear stress-strain curves are micro-softening model or micro-hardening model under low upright stress. The curves are slight-softening model at higher upright stress when the coarse-grained contents are equal to 24.0%. At coarse-grained contents equal 78.0%, the shear stress-strain curves are softening model under low upright stress. The shear strength envelope expressed nonlinear under higher upright stress.

scholarly journals Reuse of “End Of Life Tyres” Tyre Chips – Sand Mixture Mechanical Study

2012 ◽  
Vol 58 (3) ◽  
pp. 379-406
Author(s):  
E. Dembicki ◽  
M. Kowalczyk ◽  
P. Gotteland
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Experimental Testing ◽  
Volumetric Strain ◽  
Confining Pressure ◽  
Sand Mixture ◽  
Triaxial Apparatus ◽  
Strain Behaviour ◽  
Mechanical Study ◽  
End Use

Abstract The use of shredded tyre in civil engineering applications is a significant potential end use market. The reuse of tyre chips may not only address growing environmental and economic concerns, but also help to solve geotechnical problems associated with low shear strength. The purpose of this paper is to investigate the properties of tyre chips and tyre chips - sand mixture, and to find the mixture with the highest shear strength. In this study, an experimental testing program was undertaken using a large - scale triaxial apparatus with the goal of evaluating the optimum percentage of tyre chips in sand. The effects on shear strength of varying percentage of tyre chips and varying confining pressure were studied. Tyre chips content was suspected to have influence on stress - strain and volumetric strain behaviour of the mixture. Some tests were conducted to check the influence of number of used membranes, of saturation and compaction, on sample properties.

scholarly journals Experimental Study on Shear Strength of Saturated Remolded Loess

2021 ◽  
Author(s):  
Jie Lai ◽  
Yun Liu ◽  
Yuzhou Xiang ◽  
Wei Wang ◽  
Jiangbo Xu ◽  
...  
Keyword(s):  
Shear Strength ◽  
Shear Rate ◽  
Strain Curve ◽  
Confining Pressure ◽  
Cohesive Force ◽  
Dry Density ◽  
Stress Strain ◽  
Loess Area ◽  
Confining Pressures ◽  
Homogeneous Composition

Abstract Loess has the characteristic of macropore, loose structure, homogeneous composition and collapsibility. It is easy to saturate when it encounters heavy rainfall and irrigation, resulting in landslides, roadbed subsidence and dam instability in the loess area. To study the influence of dry density and shear rate on shear strength of saturated remolded loess, an SLB-6A stress-strain controlled triaxial shear penetration tester was used to conduct Consolidated Undrained(CU) test in the Yan'an area. During the test, three variables of shear rate, confining pressure and dry density were controlled. The dry densities of the samples were 1.5g/cm3, 1.6g/cm3 and 1.7g/cm3 respectively. The CU test of the saturated remolded loess at a confining pressure of 100kPa, 150kPa, and 200kPa was performed at a shear rate of 0.04mm/min, 0.08mm/min, 0.16 mm/min, and 0.4mm/min respectively. It is found that the stress-strain curve of saturated remolded loess gradually moves up with the increase of dry density. When the dry density is equal to ρd=1.5g/cm3, the deviatoric stress under different confining pressures there is a tendency to increase first and then decrease with increases of shear rate. When the dry density is equal to ρd=1.6g/cm3 and ρd=1.7g/cm3, the deviational stress under different confining pressures shows the trend of increasing first, decreasing and then increasing with the increase of shear rate, which is different from that at the dry density ρd =1.5g/cm3 at a shear rate v=0.4mm/min. When the dry density ρd=1.5g/cm3, the cohesive force decreases first and then increases with the increase of shear rate. When the dry density ρd=1.6g/cm3 and ρd=1.7g/cm3, the cohesive force first increases at 0.08 mm/min, and then decreases with the increase of shear rate. The cohesion and internal friction angles tend to increase as the dry density increases.

Stress relaxation behavior in Virginia Beach sand

2015 ◽  
Vol 52 (7) ◽  
pp. 813-835 ◽  
Author(s):  
Poul V. Lade ◽  
Hamid Karimpour
Keyword(s):  
Stress Relaxation ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Beach Sand ◽  
Static Fatigue ◽  
Strain Rates ◽  
Stress Strain ◽  
Deviator Stress ◽  
Virginia Beach

Effects of strain rate on the stress–strain and subsequent stress relaxation behaviors have been studied by performing triaxial compression tests on dense Virginia Beach sand specimens at three different strain rates (ratio of 256 between the slowest and the fastest) under low and high confining pressures. For the tests performed under low confining pressure, the specimens that were initially sheared at a faster rate showed a slightly higher amount of stress relaxation, but almost identical stress–strain behaviors were achieved. For tests performed under high confining pressure, the same amount of strength was achieved at high axial strains (10% to 20%), but specimens sheared at higher strain rates showed a slightly stiffer stress–strain response at low axial strains (up to 10%). Similar to the tests performed under low confining pressure, higher strain rates produced higher amounts of stress relaxation to some extent. Effects of correction of axial strain due to load cell expansion and drainage condition during stress relaxation have also been studied and the results indicated that correction of axial strain and undrained condition will both increase the observed amount of stress relaxation. Moreover, a 1 day stress relaxation curve was obtained by connecting the ending stress–strain points of six stress relaxation tests initiated at different deviator stress levels, and this curve was found to be different from the 1 day creep curve obtained from a previous study. A long-term stress relaxation test was also performed, and it showed linear reduction of deviator stress with the logarithm of time during stress relaxation. Observations made are all aligned with the phenomenon of static fatigue and the proposed mechanism for time effects in granular materials.

Wet compounding with pyrolytic carbon black from waste tyre for manufacture of new tyre – A mini review

2021 ◽  
pp. 0734242X2110047
Author(s):  
Junqing Xu ◽  
Jiaxue Yu ◽  
Wenzhi He ◽  
Juwen Huang ◽  
Junshi Xu ◽  
...  
Keyword(s):  
Carbon Black ◽  
Pyrolytic Carbon ◽  
Research Progress ◽  
Rubber Matrix ◽  
Innovative Technology ◽  
Nano Materials ◽  
Natural Rubber Composites ◽  
Waste Tyres ◽  
Dry Mixing ◽  
Waste Tyre

Pyrolysis offers a more focused alternative to waste tyres treatment. Pyrolytic carbon black (CBp), the main product of waste tyre pyrolysis, and its modified species can be applied to tyre manufacturing realizing its high-value utilization. Modified pyrolytic carbon black/natural rubber composites prepared by a wet compounding (WC) and latex mixing process have become an innovative technology route for waste tyre remanufacturing. The main properties and applications of CBp reported in recent years are reviewed, and the main difficulties affecting its participation in tyre recycling are pointed out. The research progress of using WC technology to replace dry mixing manufacturing of new tyres is summarized. Through literature data and comparative studies, this paper points out that the characteristic of high ash content can be well utilized if CBp is applied to tyre manufacturing. This mini-review proposes a new method for high-value utilization of CBp. The composite mixing of CBp and carbon nano-materials under wet conditions is conducive to the realization of their good dispersion in the rubber matrix. This provides a new idea for customer resource integration and connection of industry development between the tyre production industry and waste tyre disposal management.

scholarly journals Prediction Models of Shear Parameters and Dynamic Creep Instability for Asphalt Mixture under Different High Temperatures

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2542
Author(s):  
Junxiu Lv ◽  
Xiaoyuan Zhang
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Stress Level ◽  
Prediction Models ◽  
Asphalt Mixture ◽  
Confining Pressure ◽  
Shear Strength Parameters ◽  
Dynamic Creep ◽  
Shear Stress Level ◽  
Creep Instability

This study mainly investigates the prediction models of shear parameters and dynamic creep instability for asphalt mixture under different high temperatures to reveal the instability mechanism of the rutting for asphalt pavement. Cohesive force c and internal friction angle φ in the shear strength parameters for asphalt mixture were obtained by the triaxial compressive strength test. Then, through analyzing the influence of different temperatures on parameters c and φ, the prediction models of shear strength parameters related to temperature were developed. Meanwhile, the corresponding forecast model related to confining pressure and shear strength parameters was obtained by simplifying the calculation method of shear stress level on the failure surface under cyclic loading. Thus, the relationship of shear stress level with temperature was established. Furthermore, the cyclic time FN of dynamic creep instability at 60 °C was obtained by the triaxial dynamic creep test, and the effects of confining pressure and shear stress level were considered. Results showed that FN decreases exponentially with the increase in stress levels under the same confining pressure and increases with the increase in confining pressure. The ratio between shear stress level and corresponding shear strength under the same confining pressure was introduced; thus, the relationship curve of FN with shear stress level can eliminate the effect of different confining pressures. The instability prediction model of FN for asphalt mixture was established using exponential model fitting analysis, and the rationality of the model was verified. Finally, the change rule of the parameters in the instability prediction model was investigated by further changing the temperature, and the instability forecast model in the range of high temperature for the same gradation mixture was established by the interpolation calculation.

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