Effect of initial compaction on geomechanical characteristics of crushable coal mine waste

In this study, a series of triaxial tests were conducted on coal mine waste (CMW) samples obtained from the Tylorstown colliery tip in Wales to investigate the impact of particle breakage on the mechanical response of these geomaterials within the critical state soil mechanics framework. The results indicate that subjecting the CMW samples to an initial particle breakage through compaction, combined with continuous breakage during shearing, alters their fabric, making them more susceptible to liquefaction under undrained conditions, without affecting their undrained shear strength. Additionally, the effect of initial breakage remains in the sample's memory, establishing a unique ultimate state in the e − ln ⁡ p′ space that corresponds to the initial breakage, regardless of the sample's initial density or the total extent of particle breakage. However, in the stress space ( p′ – q), all samples share a common ultimate state.