Characterization of Cemented Sand by Experimental and Numerical Investigations

TLDR

At small strains, dilatancy is hindered by a web‑patterned force‑chain network, but after yielding dilatancy accelerates, and peak strength is governed by a trade‑off between bond breakage reducing strength and dilatancy increasing it. The study investigates how cementation affects the stress–dilatancy behavior and strength of cemented sand using triaxial tests and discrete element simulations. Increasing strain transforms the force‑chain distribution into a thick columnar shape concentrated within the shear band. The peak‑state dilatancy rises with cement content, making peak‑state strength parameters c′ and ϕp′ reflective of cementation; at failure, cement bonds form clusters that preserve volumetric dilation and prevent force‑chain buckling, thereby enhancing strength.

Abstract

In this study, the effects of cementation on the stress–dilatancy and strength of cemented sand are investigated through experimental characterizations using triaxial tests and numerical simulations using the discrete element method. At small strains, dilatancy is hindered by the intact bonding network that produces a web-patterned force chain. After yielding, the increase in the dilatancy accelerates. Two competing but intimately related processes determine the peak strength: Bond breakages cause a strength reduction but the associated dilatancy leads to a strength increase. This finding and the experimental observation that the dilatancy at the peak state increases with increasing cement content explain why the measured peak-state strength parameters, c′ and ϕp′, are relevant to the cement content. With increasing strain, the force-chain distribution gradually changes to a thick columnar shape, which mostly appears inside the shear band. At the ultimate state, the cementing bonds remain to form clusters, even within the shear band. The existence of clusters not only helps maintain the overall volumetric dilation but also prevents force-chain buckling, which in turn increases the associated strength.