Effect Of Particle Breakage Research Articles

Fractional order modelling of the cumulative deformation of granular soils under cyclic loading

To model the cumulative deformation of granular soils under cyclic loading, a mathematical model was proposed. The power law connection between the shear strain and loading cycle was represented by using fractional derivative approach. The volumetric strain was characterized by a modified cyclic flow rule which considered the effect of particle breakage. All model parameters were obtained by the cyclic and static triaxial tests. Predictions of the test results were provided to validate the proposed model. Comparison with an existing cumulative model was also made to show the advantage of the proposed model.

콘크리트 재생 순환골재의 파쇄 효과에 따른 다짐 및 열저항 특성 연구

콘크리트 재생 순환골재의 파쇄 효과에 따른 다짐 및 열저항 특성 연구

Shear strength and breakage of disturbed snail fossils adjacent to the preservation zone in the Mae Moh coal mine

The preserved area of snail fossils, with layers of up to 10 m deep, in the lignite coal mining area of Mae Moh in northern Thailand has been set aside; however, there is concern about the impact of weathering and erosion in the long term due to the breakage and low strength of snail fossils. Therefore, the present study aims to investigate the strength properties of the snail fossils in association with the effect of particle breakage using a direct simple shear test. Disturbed snail fossil samples were collected from the subsurface of the Mae Moh coal mine outside the preservation area. The results indicate that snail fossils are highly compressible due to the angular and delicate snail particles. In addition, the internal friction angle of snail fossils is close to 31°, which is much lower than that of other carbonate sands, but comparable to those of hard particle sands or commonly encountered sands.

Effect of particle breakage on the behavior of simulated angular particle assemblies

Many attempts have been made to find various relationships for different parameters and some kinds of constitutive models for studying the behavior of particulate media. All these models are based on concepts of continuous media. Using a numerical method such as discrete element method, one can figure out what is happening through a discontinuous media where soil particles play the main role in introducing the shear strength and deformation characteristics. The behavior of the media with breakable particles is studied in this paper and compared with that of the assembly with non-breakable particles. In this paper, the hyperbolic elastic model is investigated for the assembly of polygon shaped particles in two different test series. In addition, evolution of different macro parameters of the assembly such as volume strain, angle of friction, angle of dilatancy and elastic modulus is studied during the simulation tests both for non-breakable and breakable soil particles. At the end, a parametric study is performed on the effect of strength of particle breakage on the assembly behavior.

A new elastoplastic constitutive model for coarse granular aggregates incorporating particle breakage

A new elastoplastic stress–strain constitutive model is developed for granular coarse aggregates incorporating the degradation of particles during triaxial shearing. Coarse granular aggregates are subjected to breakage during excessive stress changes. Most of the available constitutive models do not consider the degradation of particles during shearing. In the current model, a plastic flow rule has been developed incorporating the energy consumption due to particle breakage during shear deformation. A non-associated flow and a kinematic type yield locus have been adopted in the model. A general formulation for the rate of particle breakage during shearing has been developed and incorporated in the plastic flow rule. The effects of particle breakage on the plastic distortional and volumetric deformations are incorporated in the current model. The stress–strain formulations are developed within the general critical state framework. The model can accurately predict the stress–strain and volume change behaviour of coarse granular aggregates. The plastic dilation and contraction features of coarse aggregates at various confining pressures are well captured, and the strain-hardening and post-peak strain-softening behaviour of coarse granular media is adequately represented. A particular feature of the model is its capability to predict the degree of particle breakage at any stage of shear deformation.Key words: constitutive modelling, coarse granular aggregates, particle breakage, dilatancy, non-associated flow, plasticity.

Deformation-Strength Evaluation of Crushable Volcanic Soils by Laboratory and In-Situ Testing

This paper aims to clarify static and cyclic deformation-strength properties and evaluation method for volcanic coarse-grained soils with particle crushing, based on site investigations which were conducted using standard penetration test (SPT), cone penetration test (CPT) and seismic cone penetration test (SCP). In addition to these in-situ tests, a series of laboratory tests on disturbed and undisturbed samples was also carried out to obtain the mechanical properties such as shear strength, cyclic undrained triaxial strength, pseudo elastic shear modulus and damping ratio. From the results of drained and undrained triaxial compression tests, plane strain compression test and cyclic undrained triaxial test on volcanic soils, it was understood that the effect of particle crushing and fabric anisotropy on the cyclic and static strength-deformation behavior of volcanic coarse-grained soils could not be ignored. Furthermore, the effect of particle breakage on results of dynamic penetration test was also discussed based on the correlation between the sounding data and triaxial test results.

Energy aspects of particle breakage in drained shear of sands

The effect of particle breakage on the shear strength of sand is studied by considering the energy consumption due to particle breakage at the contacts between sand particles. A stress–dilatancy relationship for sand under a triaxial loading condition is developed, adopting Rowe's minimum energy ratio principle. Particle breakage and its relation to the shear strength of a sand can then be evaluated based on this relationship. The increment of specific surface of the sand is used as an indication of the amount of particle breakage. Results of laboratory triaxial compression tests for Fulung sand, Tamsui River sand and a decomposed granite are examined and compared with the stress–dilatancy relationship. The effect of particle breakage on the shear strength of a sand can be correlated with rate of energy consumption of particle breakage and rate of increment in particle surface area per unit volume of sand as proposed in this study. The rate of energy consumption by particle breakage increases with increasing confining pressure, but is only slightly affected by the relative density of sand. The effect of energy consumption of particle breakage on the friction angle of these sands is also evaluated.

The effects of particle breakage and abrasion—from simulated fluvial transport, on phosphorus sorption by two soils

Phosphorus sorption studies were carried out on particle size fractions of soils collected from the walls of gullies through a granitic and a sedimentary soil, as well as on particle size classes derived from breakage and abrasion of the 500 to 1400 μm components of these soils Sorption of phosphorus by the particle size classes of the sedimentary soil was much greater than those of the granite soil, and this also applied to the particles derived from breakage and abrasion. For the original sedimentary soil, sorption of phosphorus by the particle size components was strongly associated with the iron content and less strongly associated with the aluminium content and this also applied to the particles derived from breakage and abrasion. For the granitic soil these relationships were much less precise. A period of vigorous mixing, after 165 hours of gentle mixing, caused release of a proportion of the sorbed phosphorus from all particle sizes of the original granitic soil and for most of the breakage/abrasion derived particles. The released phosphorus was re-sorbed during a subsequent 48 hour period of settling Relationships were evident between labile P and sorbed P for the particle size classes of the soils and treatments tested. Bacause particle size, lithology of the transported sediments and flow dynamics affect the distribution of phosphorus between water and sediments, they can also be expected to effect bio-availability of phosphorus. Particle breakage and abrasion during sediment transport is another factor likely to influence the bioavailability of P.

The effects of particle breakage and abrasion on the magnetic properties of two soils

The effects of particle breakage and abrasion on the magnetic properties of two soils

The effects of particle breakage and abrasion on the magnetic properties of two soils

As mineral magnetism is used as a tracer for sourcing river and dam sediments, changes in the magnetic properties that may occur during transport between the source and sink must be considered. Abrasion and breakage of particles will occur during transport. These processes were examined in simulation experiments with a granitic and a sedimentary soil. The effects of these processes on the magnetic properties of a granitic and a sedimentary soil were examined using a simulated breakage/abrasion experiment. Breakage and/or abrasion had substantial effects on the magnetic properties of both soils. All particle sizes were affected, but the magnitude varied through the size range of derived particles. The major effect was on the concentration of magnetic minerals, with differences between the concentrations in particle sizes of the original material and those generated by the experiments being as much as 20 times. The effect on the granite soil was to reduce the concentrations, i.e. derived material was less than original material; whereas for the sedimentary soil the derived particles had higher concentrations. The effect on magnetic grain size, as indicated by the magnetic ratios, was less than the effect on the mass magnetic properties, but still substantial for some ratios for some sizes. © 1998 John Wiley & Sons, Ltd.

Effects of particle breakage on mechanical characteristics of decomposed granite soils : Makiuchi, K; Miyamori, T; Iwai, S Proc Symposium on Environmental Geotechnics and Problematic Soils and Rocks, Bangkok, Decemver 1985P527–532. Publ Rotterdam: A A Balkema, 1988

Effects of particle breakage on mechanical characteristics of decomposed granite soils : Makiuchi, K; Miyamori, T; Iwai, S Proc Symposium on Environmental Geotechnics and Problematic Soils and Rocks, Bangkok, Decemver 1985P527–532. Publ Rotterdam: A A Balkema, 1988