Crushability of sand significantly influences its index properties and mechanical properties like shear strength behaviour, volume compressibility, and stiffness. In conventional geotechnical practice, the effects of crushing are often neglected for apparent reasons. However, such effects cannot be overlooked for weak carbonate sands, which are usually deposited in the coastal and offshore areas, undergo significant crushing due to their biogenic origin under normal working stress conditions. The effects of fragment creation and the consequent response of sand are even more complex in the case of dynamic and cyclic loading. An attempt has been made to understand the possible effects of fines generation during crushing on the macro-scale behaviour under cyclic loading. A well-known kinematic hardening-based soil constitutive model, SANISAND, is enhanced with the breakage evolution law for evaluating the shear modulus degradation in crushable soils. The model is implemented in ABAQUS FE package using UMAT routine to solve boundary value problems like the response of piles in crushable soil during seismic excitation.

Civil Engineering structures like bridges, roads, tunnels etc. are built on rock supports, and thus stability and serviceability of these structures are highly controlled by the mechanical properties of rocks. The presence of complex geological formations and discontinuities enhances rock anisotropy, heterogeneity, and rate dependency. Therefore, understanding the rate-dependent behaviours of rocks is essential to predict geological hazards in rock engineering as their behaviours vary with loading rate. This work investigates the effect of a pre-existing impersistent joint with varying infill conditions on the rate-dependent mechanical behaviour of jointed rock samples. SHPB coupled with DIC and static UCS experiments were performed on intact samples and three types of jointed samples intersected with an – i) unfilled joint, ii) cement grouted joint, and iii) epoxy grouted joint at strain rates varying from 10e-4 /s to 130 /s.