Effects of Particle Shape and Microstructure on Strength and Dilatancy During a Numerical Direct Shear Test
نویسنده
چکیده
ABSTRACT: Discrete element method offers insights into the soil behaviour at the microscopic level. In this investigation, a series of numerical direct shear tests is carried out by a three-dimensional discrete element code PFC. The size of the shear box is 6 cm long, 3 cm wide and 4 cm high. Non-spherical shaped particles are created by joining primary constitutive spherical balls together with the aid of the built-in clump logic in the code. Particles of three different aspect ratios (defined as length/width of a particle): 1.0, 1.5, and 2.0, are generated and studied in this paper. The box is filled with particles by the deposition method. By controlling the friction among particles as well as the direction of deposition, particle assemblies with very similar density but different microstructures before shearing are obtained. The deformational characteristics of the particle assemblages are studied at both microscopic and macroscopic level. The effects of particle shape and microstructure on the assemblage’s strength and dilatancy are studied and discussed. It is found that assemblages with elongated particles give slightly less dilative response in general. Microstructure, however, have a strong influence on the shear strength. Evolution of microstructures is also investigated and the results show that the change in particles’ major axis at the end of shear is insignificant.
منابع مشابه
Shear Capacity of Reinforced Concrete Flat Slabs Made with High-strength Concrete: A Numerical Study of the Effect of Size, Location, and Shape of the Opening (TECHNICAL NOTE)
Nowadays, concrete with strength higher than 50 MPa is utilized due to the ever increasing need for higher strength and prolonged healing properties. Despite the widespread use of high-strength concrete, only a few research projects have been conducted on the punching shear strength of high-strength concrete slabs. Reinforced concrete flat slabs are widely employed in structural systems. The lo...
متن کاملThe Correlation between the CBR and Shear Strength in Unsaturated Soil Conditions
In pavement design, the CBR and direct shear tests are two very common laboratory investigations for predicting the strength of a subgrade layer. The relationship between the CBR and water content has been commonly presented in analyses, with the result of the direct shear being expressed from the aspect of effective cohesion and the internal friction angle. Even though most natural soil is in...
متن کاملStudying the effect of roughness on soil-geotextile interaction in direct shear test
Abstract One of the methods of increasing soil resistance against failure is soil reinforcement using geosynthetics. Soil-geosynthetic interactions are of great importance and are affected by friction and adhesion at their interface. Soil gradation, contact surface roughness and geotextile density are among the factors affecting soil-geotextiles interaction this study, to investigate the eff...
متن کاملExperimental and FDM study on the effect of geogrid tensile strength on pullout resistance
This paper presents the effect of geogrid tensile strength by calculating pullout resistance and geogrid-soil interaction mechanism. In order to investigate this interface, a series of pullout tests have been conducted by large scale reformed direct shear test apparatus in both cohesive and granular soils. In numerical, finite difference software FLAC3D has been carried out on experimental test...
متن کاملEffects of shape and size polydispersity on strength properties of granular materials.
By means of extensive contact dynamics simulations, we analyze the combined effects of polydispersity both in particle size and in particle shape, defined as the degree of shape irregularity, on the shear strength and microstructure of sheared granular materials composed of pentagonal particles. We find that the shear strength is independent of the size span, but unexpectedly, it declines with ...
متن کامل