Effects of Particle Breakage on the Mechanical Behavior of Calcareous Sand Under Confined Compression Tests

Particle breakage plays a pivotal role in shaping the deformation behavior of granular soils when subjected to compression. To comprehensively assess the influence of particle breakage on the evolution of particle size distribution and the compression characteristics of calcareous sand, this study conducted 63 sets of confined compression tests on calcareous sand, specifically under high-pressure conditions. The results indicated that the compression behavior of calcareous sand can be classified into three distinct stages within the logarithmic coordinate system of void ratio (e) and vertical pressure (σ_v): (1) σ_v < 2.18 MPa, (2) 2.18 MPa < σ_v < 4.35 MPa, and (3) σ_v > 4.35 MPa, with the first and third stages representing linear relationships. Furthermore, the concept of yield stress ascertained within the e–logσ_v coordinate system proves invaluable in assessing the effects of the initial void ratio (e₀) and particle size (d) on particle breakage. Notably, when σ_v exceeds 2.18 MPa, the relative breakage index experiences a substantial increase. The characteristic particle sizes (d₁₀, d₃₀, d₅₀, and d₆₀) of calcareous sands exhibit a consistent decrease with an increase in the relative breakage index (B_r); however, this relationship is independent of e₀ but is closely related to the particle size (d) of calcareous sands. The one-dimensional compression characteristics of calcareous sand are effectively represented using a power function relationship, and a formula for calculating the compression modulus (E_s) of calcareous sand is theoretically derived. The deformation (Δs) of calcareous sand can be calculated using the index parameters obtained through the E_s–σ_v curve method. In addition, a method for computing the preconsolidation pressure (p_c) of calcareous sand is introduced. This method uses the parameter (e_b) as an indicator of particle breakage and has been experimentally validated.