Influence of Particle Size on the Friction and Interfacial Shear Strength of Sands of Similar Morphology

Abstract

Size and morphological characteristics of particles play vital role on the shear and interfacial shear strength of sands. Often, effects of these parameters are merged and cannot be easily separated. Effect of size of the particles on the shear and interfacial shear strength of sands is presented in this paper through direct shear and interface direct shear tests complemented with image analyses and surface roughness studies. To eliminate the effect of morphological characteristics, three sands of different particle sizes with similar morphological characteristics like angularity, roundness, sphericity and roughness were selected for the study. These morphological characteristics for all three sands were determined from the analysis of scanning electron microscope images and were found to be similar for all three sands. It was observed from the symmetric direct shear tests that the particle size has no effect on the peak friction angle when the tests were carried out at same void ratio. However, ultimate friction angles were affected by the particle size. Shear band thickness was estimated from image segmentation analysis of the profiles of colored sand columns during shear and the same was correlated to the particle size. Interface direct shear tests were carried out on sand-geomembrane interfaces to study the effect of particle size on the interfacial shear strength. Microscopic images of geomembranes were captured after the interface shear tests to understand the change in surface roughness of the geomembrane due to particle indentations. Surface roughness studies on geomembrane samples after the tests confirmed that the plowing and groove formation on geomembranes during interface shear tests depend on the particle size as well as the relative roughness of the sand particles with respect to the membrane. Sand of medium particle size showed highest interfacial strength because of more number of effective contacts per unit area of the interface.

Influence of particle size on vertical plate penetration into dense cohesionless granular materials (large-scale DEM simulation using real particle size)

“…These results indicate that the ratio of the band thickness to the mean particle diameter was almost constant, even though the particle size changed. In contrast, Vangla and Latha [52] observed that the band thickness decreased from between 21d 50 and 24d 50 to between 10d 50 and 12d 50 when the mean particle size increased from 0.22 to 0.87 mm. Owing to the particle size dependence of the shear band thickness, with a decreasing B/d 50 , the thickness became relatively larger with respect to the plate thickness.…”

“…We could not confirm a local peak corresponding to shear band (II). Various researchers [32,[48][49][50][51][52] have reported that the shear band thickness is strongly affected by the absolute size of the particles. Nemat-Nasser and Okada [50] reported that when the mean particle diameters d 50 were 0.22 and 0.48 mm, the band thicknesses were 11d 50 and 15d 50 , respectively.…”

Shear Strength Behavior of Different Geosynthetic Reinforced Soil Structure from Direct Shear Test

“…No significant difference in the soil friction angle between two types of boxes are found, the variation in friction angle was less than 3.3 %, the angle was slightly lower in the samples prepared in the square box (100 9 100 mm 2 ). It has been found that the friction angle and angle of repose are somewhat correlated [13,24,25]. The average angle of repose for the two types of soil used in this experimental program was estimated in accordance with the procedures given in ASTM C1444 [26].…”

“…Palmeira [1] presents test types that characterize, various conditions that can occur in some structures of reinforced soil. Some studies found in the literature, provides laboratory test results with the reinforcement layer positioned parallel to the failure plane induced for the shear box [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In other research the reinforcing layer is placed perpendicular or rotated to the failure plane [15][16][17][18][19][20].…”

Change of soil mechanical properties due to triaxial sample size

“…The main reason of such a tests lack -very difficult to provide triaxial tests with over consolidated moraine clay. During these experiments it can appear problems with saturation (Kadkhodaie & Rezaee, 2016;Dong, Kong, & Zhe, 2016;Glover, 2017), big particles appearance in shearing plane (Zhang, Baudet, Hu, & Xu, 2017;Vangla & Latha, 2015), long term investigations (Suzuki, Dyvik, & Schmertmann, 2017;Liu, Xie, Shao, & Conil, 2018) and etc. Specimen size effect on the shear strength parameters can affect the design and analysis of many geotechnical constructions.…”