Micromechanical behaviour in shearing of reproduced flat LBS grains with strong and weak artificial bonds

Abstract

The shearing behaviour of reproduced flat LBS grains artificially bonded with ordinary Portland cement (OPC) and Plaster of Paris (PP) was examined using micromechanical experiments.Monotonic shearing tests showed a distinct variation in the load-displacement relationship at low, medium and high normal loads and a non-linear shear strength envelope was proposed. For OPC bonded sand grains, a brittle-ductile transition at 20-30 N normal load was observed and three breakage mechanisms in shearing (chipping, shear cracks, and crushing) were distinguished in accordance with the changes in the load-displacement curves. OPC bonded sands showed a predominant dilation at lower normal loads, whereas PP bonded sands were highly compressive. Based on previously published works using element-scale tests, a new mechanism for dilation under micromechanical testing was proposed in the study. Cyclic shearing tests were conducted on OPC bonded sands and the effects of increased displacement amplitude and normal load were highlighted.

Effects of carbonate distribution pattern on the mechanical behaviour of bio-cemented sands: A DEM study

“…The formation of carbonate crystals in bridging pattern contributes to the shear resistance of bio-cemented soil by increasing both the friction angle and cohesion, while it mainly exhibits an increase in cohesion rather than friction angle for samples with contact cementing pattern. As some of the DEM parameters are not yet available from experiments, it is recommended, in future work, to carry out grain-scale micromechanical tests to provide references for DEM parameters and bridge the gap between DEM simulations and physical studies (see Wang et al, 2017;Kasyap et al, 2021;Ren et al, 2021;Reddy et al, 2022, among others). An engineering implication from the findings of the present paper is that to gain strength improvement the most effectively, treatment should ideally be tailored to precipitate calcium carbonate in bridging pattern.…”

A Grain-Scale Study of Mojave Mars Simulant (MMS-1)

“…A micromechanical testing apparatus recently developed by Kasyap et al [ 71 ] was used in this study to investigate the tribological behavior of MMS-1 grain contacts in terms of normal and tangential responses. The apparatus consists of two loading systems in the vertical and horizontal directions which implement the normal and tangential loadings to the grain contacts, respectively.…”

3D DEM analysis of analogue proppant–fractured rock system interaction

“…the normal of the fracture plane and the initial kinetic energy of the impactor are in the Z-direction. The primary intention of the present study is to understand the impactor behaviour upon colliding with the rock base, and hence the microparameters used in the present 3D model were arbitrarily chosen based on the previous micromechanical experiments of the authors (Kasyap and Senetakis 2020; Kasyap et al 2021). Particularly, the impact calibration parameters (i.e.…”