Effect Of Particle Breakage Research Articles

Laboratory study into engineering characteristics of siliciclastic sedimentary sand

Diverse applications and tremendous usefulness of siliciclastic sedimentary sands make investigation into their mechanics of behaviour very essential globally. This study examines the convergence or otherwise of the specimens in compression; physical, fabric, chemical and mineralogical characteristics and their relationships with compression behaviour; shape characteristics, possible particle breakage and their overall effect on the behaviour of siliciclastic sedimentary sands obtained from two locations. The findings are as follows; (a) Siliciclastic sedimentary sands are poorly graded and coarse in nature. (b) The fabrics are characterized by aggregation of sub rounded particles and smaller particles tend to combine with fines to form coatings around bigger particles. (c) Chemical compositions are predominantly silica and alumina and heamatite are significant. (d) Quartz dominates the mineralogy and the other minerals are muscovite, albite, orthoclase and chlorite. (e) The samples have convergent behaviour and the compressibility is not significantly different but lower than the related materials. (f) The original particle is sub round in shape and the particles become sub angular after the test with no relationship between particle shape and compression behaviour. (g) The particle breakage is linked to coarser nature of the specimens and the overall effect of particle breakage on the compression behaviour of siliciclastic sedimentary sand is small.

Compaction and shear characteristics of recycled construction & demolition aggregates in subgrade: Exploring particle breakage and shape effects

Recycling construction and demolition (C&D) wastes into useable aggregates in subgrade applications offers significant sustainability benefits. However, the characteristics of recycled aggregates, including particle morphology, crushing strength, and shear behavior, differ substantially from natural aggregates. This paper presented an extensive experimental study on the compaction and mechanics performances of recycled concrete and brick aggregates, with a particular focus on the effects of particle breakage and shape characteristics. The compaction of recycled aggregate specimens comprising three structural types was evaluated using heavy Marshall compaction (HMC) and Superpave gyratory compaction (SGC). The compaction characteristics and particle breakage were examined, enabling a profound understanding of the compaction mechanisms associated with both methods. Furthermore, triaxial shear tests were performed to scrutinize the influences of particle shape, compaction degree, and confining pressure on shear characteristics. Results showed that after 80 gyratory rotations in SGC, the compaction degree of recycled aggregates aligned with the targeted results obtained from HMC. Changes in fractal dimension after compaction exhibited direct correlations with the two-dimensional shape distribution. Axial coefficient, fractal dimension and confining pressure most strongly influenced shear strength. In light of these insights, prediction models for shear strength parameters were proposed using multiple regression analysis. Overall, the study provides valuable insights into the relationships between aggregate morphology, compaction response, breakage behavior, and shear performance. These findings can facilitate optimized design and construction using recycled aggregates to advance sustainable infrastructure development.

Thermo-hydro-mechanical (THM) analysis of rock-ice avalanches: Considering the effects of particle breakage in the sliding zone

The high-speed and long-distance sliding characteristics of large-scale rock-ice avalanches usually make them a catastrophic event, which seriously threatens the safety of human beings and infrastructure. Obviously, apart from the lubrication of ice and water, the fragmentation of particles in the slip zone is also an important contribution to the hypermobility of rock-ice avalanches. Up to now, existing researches have not taken into account the impact of particle breakage on rock-ice landslides. In this paper, a thermal-hydro-mechanical (THM) model for the high-speed rock-ice avalanches is developed, which mainly considers the particle breakage due to sliding shear deformation and the ice melting caused by frictional heat. The results of the model analysis applied to the Chamoli avalanche indicate that particle fragmentation has a significant effect on landslide sliding. When the particle breakage is considered, the simulated velocity and displacement of landslide are closer to the existing research results. Both thermal pressurization and particle crushing are two important mechanisms that lead to a high-speed sliding of rock-ice landslide, and these two mechanisms affect each other. It is demonstrated from a set of sensitivity analyses that the initial grain size distribution, fractal dimension and the thickness of the slide mass have clear impacts on the evolution of the granular crushing index, which thus affects the characteristics of the landslide eventually. In particular, the sensitivity analysis of the slide thickness once again demonstrates the importance of considering particle fragmentation in the analysis of landslide sliding.

Effects of Particle Breakage on the Mechanical Behavior of Calcareous Sand Under Confined Compression Tests

Effects of Particle Breakage on the Mechanical Behavior of Calcareous Sand Under Confined Compression Tests

The effect of particle breakage on the dilatancy and shear behavior of marine calcareous and siliceous deposits

A large part of ocean surface is covered by calcareous deposits. The Low stiffness and weak particles of calcareous soils deposited by marine organisms showed significant particle breakage under applied loads, which resulted in different behavior compared to terrigenous soils. A series of compression drained triaxial tests were carried out to evaluate the monotonic shear behavior of crushable and non-crushable soils. Three different soils, including Firoozkuh siliceous sand (as a non-crushable soil) and Hormuz and Bushehr calcareous sands (as crushable soils) which were different in mineralogy compositions were obtained from northern and southern Iran. The specimens were prepared in different relative densities (i.e., loose, medium and dense conditions) and consolidated under confining pressures ranging from 100 to 600 kPa. The monotonic shear and dilatancy behaviors of the soils have been presented in detail and the effect of particle breakage has been discussed. The results showed that particle breakage has a significant effect on the mobilized friction and dilatancy angles of marine crushable soils. There is a linear relationship between the amount of particle breakage occurring during a triaxial test and breakage angle. In addition, the mineralogical difference influences the breakage properties of calcareous deposits.

Macro–microscopic mechanism of suffusion in calcareous sand under tidal fluctuations by coupled CFD-DEM

Numerous offshore transportation infrastructures built with delicate calcareous sand (CS) experience intricate seepage conditions caused by tidal fluctuations. Traffic loads can cause substantial particle crushing, leading to mass loss and subsequent settlement. This paper presents a numerical analysis of suffusion mechanisms in three representative volume elements (RVEs) under cyclic seepage using the coupled computational fluid dynamics-discrete element method (CFD-DEM). The microscopic parameters of CS are calibrated by comparing the results with direct shear experiments. The effect of particle breakage on cyclic suffusion can be assessed by varying breakage ratios of crushed soil. Several suffusion tests under periodic seepage are conducted to investigate the fines migration behavior and examine the contact characteristics, with a particular focus on the middle element of the three RVEs. Test results confirm that mass loss of the sample is intensified by particle breakage but is effectively inhibited under high-stress conditions. Fine particles exhibit different migration behaviors in this study compared to those observed under unidirectional seepage, including reverse migration. The change in connectivity of the particle assembly during cyclic seepage indicates a gradual weakening of its overall stability. Lastly, the anisotropy of the normal contact force distribution exhibits a significant increase as more particles are eroded.

Breakage in quasi-static discrete element simulations of ice rubble

Breakage of particles plays a key role in force transmission in granular materials. Discrete element method (DEM) simulations are often used to model granular materials, but modeling particle breakage in them remains a challenge. Models for breakage of non-spherical particles are scarce and often the existing models are computationally heavy to be used in simulations with large numbers of particles. To address this, the present study develops a particle breakage model for quasi-static DEM simulations of non-spherical particles that fail due to shear. The model is novel, since it is based on experimental observations and high resolution modeling. Breakage models based on experimental evidence are rare as it is often virtually impossible to gain detailed data on the mechanisms related to breakage. The developed particle breakage model was integrated into a DEM code and direct shear box experiments on ice rubble, a granular material consisting of ice particles, were then simulated. Accounting for particle breakage in DEM simulations improved their accuracy: simulations were compared to experiments and the results were found to be in better agreement when particle breakage was taken into account. The effect of particle breakage on the shear strength of a granular material was found to be independent of particle size, decreasing fast with increasing particle strength. The combined effect of shear box length and breakage was also studied. The results showed that the strength of a granular material may be determined reasonably well with a shear box that has a box to particle length ratio greater than 60.

Experimental study on the effect of particle breakage on the shear characteristics of large-displacement soil exposed to heat treatment

Ring shear tests were performed in this study to investigate the large-displacement shear characteristics of quartz sand samples subjected to different degrees of volume effect and high temperature. The influencing principles of normal stress, temperature, and particle breakage on the large-displacement shear characteristics of the specimens were obtained. The influencing mechanism was further elucidated with reference to a previous study. On the basis of an analysis of the similarities and differences between the large-displacement shear behavior of samples before and after exposure to a temperature of 800 °C, we believe that samples impacted by temperature, particle breakage, and normal stress exhibit strain softening under large-displacement shear behavior that has an upper limit of approximately 600 kPa after heat treatment. Meanwhile, the high temperature affects the shear characteristics of the basal facies of a landslide by influencing the rock and soil breakage. The difference in the interlocking forces caused by the particle shape and breakage and the resulting fluctuation of the shear stress are further discussed.

Influence of fine content on undrained monotonic behavior of carbonate sand

The behavior of carbonate sand is different from that of siliceous sand in terms of high compressibility and crushability, specific particle shape, and physical properties. Thus, investigating the behavior of these soils is of great importance because of their prevalence in coastal areas. Nevertheless, a few studies have considered the presence of fines in the mixture with carbonate sand. The present study explores the influence of non-plastic fines on the undrained monotonic behavior of Bushehr carbonate sand. For this purpose, 30 undrained monotonic triaxial tests were performed on carbonate sand with silt ranges of 0% to 40% with two different void ratios. According to the results, the undrained shear strength of carbonate sand diminished with the addition of silt percentage up to 20%, and increased dramatically at 30% silt content. Also, the results of 40% silty sand revealed that this sample is stronger than samples with 10% and 20% silt content. By surveying the location of the phase transformation point in samples, it was observed that silt particles reduce the dilative phase. Also, confining pressure intensified the contractive phase while relative density had the opposite effect. The results showed that the effect of particle breakage is negligible in this study.

Effects of particle breakage on the mechanical characteristics of geogrid-reinforced granular soils under triaxial shear: A DEM investigation

A series of numerically triaxial shear tests on crushable and uncrushable granular soils reinforced by geogrid were conducted using 3-Dimension Particle Flow Code. The macroscopic behaviors of crushable and uncrushable granular soil during shearing were compared. Also, the underlying macro–micro linkages were explored. The main findings are as follows: Particle breakage decreases the contact forces between soil particles to reduce the shear strength of granular soils; The reinforcement effect of geogrids on the shear strength of granular soils can be attributed to the increase in fabric and force anisotropies; The particle displacement distribution of crushable soil samples is more uniform than that of uncrushable samples, and the shear band of crushable samples is not obvious; The reinforcement effect of geogrid with the aperture size ratio of 4.4 is the highest among the samples because the number of crushed particles and the deformation of geogrids reaches a balance.

Microscopic mechanism analysis of influence of high effective confining pressure on mechanical properties of hydrate-bearing sediments

It was discovered in tests that the increase in effective confining pressure could have a great impact on the mechanical behavior of hydrate-bearing sediment, which was not only decreased the internal friction angle and dilatancy, but also enhanced cohesion and strength. Significant crushing of the hydrate-host sand was founded after shearing under high pressure. In this study, a discrete element method (DEM) model considering the effects of particle breakage and hydrate repolymerization was proposed, and a series of numerical triaxial tests were performed to shed light on the mechanism of mechanical properties evolution observed in the physical tests. The numerical results revealed that the breakage of host particles was a leading cause of the decrease in the internal friction angle and transformation from shear dilation to contraction. As the hydrate saturation, axial strain, and effective confining pressure increased, the force chain network of the model became denser and the force magnitude on the chains became increasingly uniform, which leads to the increase in model strength; the number and force of bonded contact also increased gradually, resulting in increased cohesion on the macro scale.

Effect of Particle Breakage on Strength Characteristics of Limestone Aggregate

Particle breakage is one of the issues that significantly affect the strength characteristics of aggregate. In this paper, the strength of pre-crushed limestone aggregate was evaluated through investigating the friction angle, stress–strain behaviour, and single-particle strength. The particle breakage phenomenon was studied for samples prepared at different conditions, including non-soaked samples, water-soaked samples, and acid-soaked samples. The purpose of preparing the samples at different conditions was to simulate the effect of environmental factors on the breakage behaviour of limestone aggregate. The test program of this paper consists of two phases of triaxial tests: the initial shearing and second shearing. The test results showed remarkable variations among the samples since limestone aggregate tended to experience more particle breakage after being soaked in water and acid solution. Also, the volume change results exhibited an increase in dilation as the breakage index increases. The test results of this study presented the importance of considering the role of environmental factors in evaluating the particle breakage of limestone aggregate.

A constitutive model for cyclic densification of coarse-grained soil filler for the high-speed railway subgrade considering particle breakage

PurposeThis study aims to propose a semiempirical and semitheoretical cyclic compaction constitutive model of coarse-grained soil filler for the high-speed railway (HSR) subgrade under cyclic load.Design/methodology/approachAccording to the basic framework of critical state soil mechanics and in view of the characteristics of the coarse-grained soil filler for the HSR subgrade to bear the train vibration load repeatedly for a long time, the hyperbolic empirical relationship between particle breakage and plastic work was derived. Considering the influence of cyclic vibration time and stress ratio, the particle breakage correction function of coarse-grained soil filler for the HSR subgrade under cyclic load was proposed. According to the classical theory of plastic mechanics, the shearing dilatation equation of the coarse-grained soil filler for the HSR subgrade considering particle breakage was modified and obtained. A semiempirical and semitheoretical cyclic compaction constitutive model of coarse-grained soil filler for the HSR subgrade under cyclic load was further established. The backward Euler method was used to discretize the constitutive equation, build a numerical algorithm of “elastic prediction and plastic modification” and make a secondary development of the program to solve the cyclic compaction model.FindingsThrough the comparison with the result of laboratory triaxial test under the cyclic loading of coarse-grained soil filler for the HSR subgrade, the accuracy and applicability of the cyclic compaction model were verified. Results show that the model can accurately predict the cumulative deformation characteristics of coarse-grained soil filler for the HSR subgrade under the train vibration loading repeatedly for a long time. It considers the effects of particle breakage and stress ratio, which can be used to calculate and analyze the stress and deformation evolution law of the subgrade structure for HSR.Originality/valueThe research can provide a simple and practical method for calculating deformation of railway under cyclic loading.

DEM studies on the effect of particle breakage on the critical state behaviours of granular soils under undrained shear conditions

A number of discrete element analyses of undrained triaxial shear tests on crushable assemblies are performed using 3-dimensional particle flow code (PFC3D). The undrained shear of the samples is simulated by assigning different velocities at the boundaries to control the constant volume of the samples during the shear. Particle breakage is studied using the octahedral shear stress breakage criterion and the fragment spawning mode satisfying an Apollonian sphere packing. The microparameters of the soils are obtained by simulating the test results reported on a Nansha calcareous sand. The effects of particle breakage and drainage condition on the critical state behaviours of the sand are intensively examined. It is found that particle breakage and drainage condition do not affect the slope of the critical state p′−q line. In the ecs−(p′cs/pa)0.7 space, the critical state line translates downward and rotates clockwise when particle breakage is considered, whilst drainage condition does not affect the critical state line. The intrinsic macro–micro correlations underlying the critical state behaviours are explored by analysing the evolution of representative micromechanical indicators such as coordination number, redundancy ratio, and fabric and force anisotropies.

Effect of particle breakage on the behavior of soil-structure interface under constant normal stiffness condition with DEM

Previous studies show that extensive particle breakage occurs at the soil-structure interface, which may influence the shear strength, but a corresponding comprehensive micro-mechanical analysis, particularly with constant normal stiffness (CNS), is missing. In this study, a series of interface shear tests under CNSs are simulated with the discrete element method (DEM) to understand the role of particle breakage at the interface. Through a rigorous calibration process, the interface model in DEM is first validated with identifying micro-mechanical parameters. Then, by modifying the reference tensile strength of particles, the effect of particle breakage on the behavior of soil-structure interface is quantitatively investigated. All results demonstrate that, particle breakage decreases the dilation, normal stress, shear stress, and shear zone thickness in the interface shear test; particle breakage decreases the peak friction angle while increases the residual friction angle at the interface; and particle breakage decreases soil anisotropy at the interface. In addition, the degree of particle breakage is increased by normal stiffness. The findings of this study may provide deeper insights on the role of particle breakage at the interface with CNS and allow engineers to have a better estimation of the interface strength.

Breakage effect of calcareous sand on pile tip resistance and the surrounding soil stress

Due to the irregular shape, high porosity and fragility of calcareous sand particles, the construction of reef engineering is seriously affected, and the application of pile foundation engineering technology in calcareous sand stratum is also faced with great challenges. Based on the discrete element method (DEM), the pile installation process in the fractured calcareous sand stratum and non-fractured silica sand stratum are simulated, respectively, and the influence of particle breakage of calcareous sand on soil stress around the pile and pile tip resistance are discussed. The results show that the particle contact has no obvious dominant direction, and the particle breakage has little contribution on the variation of the particle contact normal directions while has great influence on the number of contact normals and the magnitude of contact normal force which is more uniform after particle breakage. The vertical and horizontal stresses in calcareous sand stratum are obviously lower than that in siliceous sand stratum. With the increase of the pile penetration depth, the number of crushing particles increases gradually. The particle breakage only can be found within the range of 3 times of pile diameter at the bottom of the pile and also within the range of 1 time of pile diameter around the pile. The effect of particle breakage on pile tip resistance is mainly reflected in the later stage of pile sinking. In calcareous sand, when the pile tip resistance increases to a certain extent, particle breakage occurs and the stresses in the soil cannot continually increase. Therefore, the pile tip resistance fluctuates around a stable value (∼0.3MPa). This is the reason that the pile tip resistance in calcareous sand is far less than that in siliceous sand, which is prone to pile foundation failure.

Effect of particle breakage on the shear strength of calcareous sands

The particle breakage of calcareous sands plays a key role in determining the particle shape and shear strength. This process has been analysed in the current study by employing the ring shear tests on calcareous sands sampled from the South China Sea. In this study, a set of parameters, e.g. roundness and aspect ratio, have been employed to quantify the geometrical properties of calcareous sands pre- and after the breakage. These two parameters have been found to correlate well with the vertical loading stress level, shear strain and shear strength. The particle breakage leads to the change of micro-structure during the shear test, as illustrated by the Scanning Electron Microscopy (SEM) images. It is found that during the shearing deformation, particle breakages can effectively reduce, while particle rearrangements can increase the shear strength of the calcareous sands.

Constitutive model of metal matrix composites at high strain rates and its application

Particle reinforced metal matrix composites (PRMMCs) frequently undergo impact or shock loading during routine utilization. However, studies on the dynamic response of PRMMCs are currently insufficient compared with those on the quasistatic response. In this study, the multi-particle representative volume element (RVE) models were established to comprehensively investigate the influence of particle parameters (particle content and aspect ratio) on the dynamic behavior of PRMMCs, and a modified dynamic constitutive law was proposed to describe the dynamic mechanical behavior of PRMMCs more efficiently based on the concept of particle breakage probability. The verification results show that the dynamic stress–strain behaviors predicted by the RVE models agree better with the experimental data than those predicted by single-particle unit cell (RUC) models. Furthermore, the results predicted by the modified dynamic constitutive law agree well with the corresponding experimental data because the effect of particle breakage was included in the modified dynamic constitutive law. This paper provides the necessary guidance for the development and preparation of the particle reinforced metal matrix composites.

Effects of particle breakage on the compression behaviour of gap graded carbonate sand–silt mixtures

Isotropic compression tests were conducted on a series of gap-graded mixtures of a carbonate sand (CS) from the South China Sea and a fine crushed quartz silt. The purpose of these tests is to expl...

The effects of particle breakage and shape on the strength parameters of sandy soil

Many laboratory and full-scale studies found that pile foundation is a reliable structure that has a long-term durability. This aspect makes it favourable when construction is in an area like the coastal where granular materials are normally in great scale. Generally, method used for the installation of pilling such as the drop hammer method will involve high energy to drive a single pile into the ground. Hence, the soil particles may undergo serious physical changes that will affect the engineering properties of soil used in the design work. The main aim of this research is to know the impact of pile installation work on sand particles. To understand the impact of sand particle breakage to the soil strength, an actual soil breaking mechanism simulated in the laboratory by using an automated soil compactor where the sand samples were crushed using 500 and 1000 times of blows respectively. The behaviour of sand were then analysed using a series of test which are; sieve analysis, specific gravity, relative density and the shear box test in order to measure the engineering properties of the sand. Mackintosh probe test was conducted in-situ to identify the undrained shear strength of sand and to correlate the cohesion of the sand with laboratory testing. This research confirmed that particle breakage has a significant influence with sand shape and therefore its strength changes with crushing impact.