Effect of particle breakage on the shear strength of calcareous sands

Abstract

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.

Mechanical behavior of porous crushable soils: effect of intragranular porosity

“…The analytical results (Eqs. 8, 9, and 10) obtained using the fitting parameters, including 𝛼 𝑥 = 1, 𝐷 𝑥 = 0.1, and 𝜌 𝑠 = 2.742 g/cm 3 , demonstrate a good agreement with the experimental results. This validation further confirms that as particle size decreases, the particle porosity decreases as well, indicating that the crushing process exposes intra-particle voids and leads to a reduction in particle porosity.…”

“…The microscopic analysis reveals the porous nature of the soil material. The soil being studied has a solid density, 𝜌 𝑠 , of 2.742 g/cm 3 . The minimum and maximum dry densities, 𝜌 𝑚𝑖𝑛 and 𝜌 𝑚𝑎𝑥 , are 0.600 and 0.696 g/cm 3 , respectively.…”

“…The soil being studied has a solid density, 𝜌 𝑠 , of 2.742 g/cm 3 . The minimum and maximum dry densities, 𝜌 𝑚𝑖𝑛 and 𝜌 𝑚𝑎𝑥 , are 0.600 and 0.696 g/cm 3 , respectively. For the experimental setup, cylindrical specimens with a diameter of 50 mm and a height of 100 mm were prepared under fully saturated conditions.…”

“…The microstructure of individual particles, including factors such as intraparticle voids, plays a significant role in their crushing responses, governing the overall macroscopic responses, which, in turn, influence the macroscopic behavior of the soil. However, previous studies in this area have primarily focused on the macroscopic behavior of porous crushable soils [2][3][4], overlooking the microscopic influence of intragranular voids. This limitation arises from the inherent challenges associated with directly measuring and characterizing intragranular porosity during laboratory testing.…”

3D DEM Analysis of Particle Breakage Effect on Direct Shear Tests of Coarse Sand

“…From field practice and laboratory tests, it is widely observed that stress levels sufficient for particle breakage are encountered in deep penetration and compaction, and examples of such situations include displacement pile driving, cone penetration testing in coarse-grained soils and high earth or rockfill dams. Particle breakage is a phenomenon that is commonly observed in offshore engineering practices, occurring in various types of soil particles, including both strong particles like quartz sand, as well as weaker ones such as carbonate or calcareous sands [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”